bluuebunny/crossref_metadata_2025 huggingface dataset:
Endometrial response to deciduogenic stimulus in ovariectomized rhesus monkeys treated with oestrogen and progesterone: an ultrastructural study
Authors: Sengupta J. , Given R. L. , Talwar D. , Ghosh D.
Published: December 2008

The present work continues our aim of establishing an experimental model to study the decidual cell reaction to an artificial deciduogenic stimulus in the long-term ovariectomized rhesus monkey treated with oestrogen followed by progesterone. The fine structural details of decidual, granular and plaque cells, which constituted the endometrial cellular response to the deciduogenic stimulation in the present study, revealed striking similarities with those reportedly present in an endometrial response to blastocyst implantation in the rhesus monkey. Plaque epithelia showed a significant degree of hypertrophy, hyperplasia and differentiation followed by a steady degeneration by day 32 (equivalent to day 16 after trauma) of treatment. The plaque cells were shown to contain numerous regular-shaped mitochondria, polyribosomes and large amounts of rough endoplasmic reticulum (RER) in their cytoplasm and were characteristically arranged in clusters or acini formation surrounded by discrete basal laminae. As early as day 28 of treatment, the initiation of stromal decidual cell transformation was noted and, by day 48, a sizeable pool of decidual cells was found. The decidual cells had rounded nuclei and elaborate arrangements of interconnected cisternae of RER which were often moderately dilated and filled with amorphous, electron-dense material. Granular cells were characterized by eccentrically located nuclei and numerous membrane-bound, electron-dense granules in their cytoplasm and were found in increasing numbers in the stroma around decidual cells, blood vessels and glandular epithelia. Based on the ultrastructural and temporal characteristics of the endometrial cells studied it has been suggested that the cells have secretory functions, and that the differential maturation profiles of the cell types might be caused by their differences in sensitivities and by their integral response to progesterone.

Journal of Endocrinology (1990) 124, 53–57
Ontogeny and secretory patterns of plasma insulin-like growth factor-I concentrations in meat-type chickens
Authors: Johnson R. J. , McMurtry J. P. , Ballard F. J.
Published: December 2008

The ontogeny and secretory pattern of plasma insulin-like growth factor-I (IGF-I) in relation to GH secretion were studied in meat-type (broiler) poultry during prepubertal and post-pubertal growth. Male and female broiler chickens of two commercial strains (strains A and B) were reared from 1 to 198 days of age. From 1 to 49 days of age birds were reared in raised-wire cages and thereafter in deep-litter pens, with food available ad libitum. Blood samples were taken at regular intervals during growth, and at 29 and 43 days of age representative birds were cannulated and serial blood samples taken at 10-min intervals for 5 to 7 h. Plasma concentrations of GH and IGF-I were measured by radioimmunoassay.

Birds of strain A were heavier (P<0·05) than those of strain B from 12 to 35 days of age. In general, male birds were heavier (P<0·01) than females from 12 to 35 days of age. Plasma GH concentrations were significantly higher (P<0·05) from 12 to 35 days of age, while plasma IGF-I concentrations were lower (P<0·05) from 6 to 21 days of age in male compared with female birds. Plasma IGF-I concentration increased with age, reaching a plateau at 28 days of age, while plasma GH concentration declined over the same period. Plasma IGF-I concentrations declined in a linear manner from 49 to 198 days of age, and there was no evidence of a pubertal increase. There were no differences between strains in the plasma concentrations of GH or IGF-I. Serial blood sampling at 29 and 43 days of age showed that there was no relationship between GH and IGF-I, despite a highly pulsatile GH secretory pattern which existed at 29 days of age. These results show that as the plasma concentration of GH declines that of IGF-I increases. Plasma concentration of both GH and IGF-I in broiler chickens was sexually dimorphic, especially during the early growth phase to about 35 days of age.

Journal of Endocrinology (1990) 124, 81–87
Developmental patterns of plasma insulin-like growth factor-I (IGF-I) and body growth in mice from lines divergently selected on the basis of plasma IGF-I
Authors: Siddiqui R. A. , Blair H. T. , McCutcheon S. N. , Mackenzie D. D. S. , Gluckman P. D. , Breier B. H.
Published: December 2008

A study was conducted to investigate developmental patterns of plasma concentrations of insulin-like growth factor-I (IGF-I), body growth and body composition in mice from lines selected for seven generations on the basis of low (L) or high (H) plasma IGF-I, and in a random-bred control (C) line. Litter size was standardized to eight individuals with equal sex ratios (as far as possible) within 48 h of birth. Pups were weaned at an average of 21 days and separated on the basis of sex. Blood samples were collected from one male and one female of each litter on days, 21, 42, 63 and 105 for analysis of plasma concentrations of IGF-I. The animals were then killed and analysed for water, fat and crude protein content.

The plasma concentration of IGF-I was influenced by line (P<0·05) but not by sex. Significant (P< 0·001) differences in liveweight between mice from L and H lines were first evident at 21 days of age. From 28 until 105 days of age the H line was significantly (P< 0·001) heavier than both L and C lines, but differences between C and L lines were inconsistent and mostly non-significant. The growth velocity of the H line was significantly greater than that of C or L lines between 14 and 42 days of age, but differences in growth velocities of C compared with L lines were generally non-significant.

Nose–anus length was significantly (P<0·01) affected by sex and line from 42 to 105 days of age, but anus–tail length was not affected by sex or line at any age. Effects of sex and line on empty (digesta-free) body weight and wet weights of carcass and skin plus viscera fractions followed a pattern similar to those of liveweights. The effects of sex and line on protein, water and fat content also paralleled their effects on body size. Differences between males and females, and between the lines, in amount of protein, water and fat could be entirely accounted for by the corresponding differences in body weight.

It is concluded from these results that divergent selection on the basis of plasma IGF-I at 42 days of age resulted in lines of animals differing in plasma IGF-I from 21 days of age until maturity. These divergent concentrations of IGF-I are associated with differences between the lines in body growth, particularly during the period of accelerated growth at puberty, but not with changes in body composition.

Journal of Endocrinology (1990) 124, 151–158
Sex differences in hepatic cytochrome P-450 monooxygenase activities in rainbow trout during an annual reproductive cycle
Authors: Förlin L. , Haux C.
Published: December 2008

Hepatic microsomal cytochrome P-450 monooxygenase activities were investigated in rainbow trout during an annual reproductive cycle. The fish were kept in tanks supplied with fresh water at a constant temperature of 10 °C. The daily light and darkness cycle was adjusted to follow the natural photoperiod. Sampling was performed once every month for 1 year. Higher benzo(a)pyrene-hydroxylase (or aryl hydrocarbon hydroxylase; AHH), ethoxycoumarin-O-deethylase (ECOD) and ethylmorphine-N-demethylase (END) activities and cytochrome P-450 content were found during the late stage of sexual development in rainbow trout. When monooxygenase activities were expressed on a per cytochrome P-450 basis, sex-dependent differences were observed only for AHH and ECOD activities. It was thus found that sex-dependent variations of END were closely correlated with the total amount of cytochrome P-450. The results indicate that differences exist in hepatic cytochrome P-450 isoenzyme patterns between the sexes in rainbow trout. The similarity of the annual pattern of plasma levels of oestradiol and testosterone to that of sex-dependent differences in the cytochrome P-450 monooxygenases support the contention that sex steroids play a role in regulating the cytochrome P-450 system.

Journal of Endocrinology (1990) 124, 207–213
Participation of tri-iodothyronine and metabolic clearance rate in the inhibition of growth hormone secretion in thyroxine-treated domestic fowl
Authors: Harvey S. , Klandorf H. , Scanes C. G.
Published: December 2008

Surgical thyroidectomy increases basal and TRH-induced GH concentrations in the peripheral plasma of immature domestic fowl. Replacement therapy with thyroxine (T4; 100 μg/kg per day for 7 days, i.m.) suppressed the GH responses to thyroidectomy. Bolus administration of T4 (10 μg/kg, i.m.) to thyroidectomized birds promptly lowered the circulating GH concentrations, which remained suppressed for at least 4 h. Chronic (daily injections for 7 days) or acute (one injection) pretreatment of thyroidectomized birds with iopanoic acid (IOP; 40 mg/bird, i.m.) before the bolus administration of T4 attenuated, but did not prevent, inhibition of circulating GH levels by T4. Administration of IOP (40 mg/bird i.m.) 24 h and immediately before the administration of tri-iodothyronine (T3; 3 μg/kg, i.m.) or T4 (10 μg/kg, i.m.) also failed to suppress thyroidal inhibition of circulating GH concentrations in thyroidectomized birds. Administration of IOP alone had no effect on GH concentrations. Circulating T3 concentrations were not enhanced following the administration of T4 to IOP-treated birds, indicating its inhibition of hepatic monodeiodinase activity.

The metabolic clearance rate (MCR) of 125I-labelled chicken GH in the plasma of thyroidectomized fowl was less than that in sham-thyroidectomized birds. Following pretreatment with T4 (100 μg/kg per day for 7 days) sham-thyroidectomized and thyroidectomized birds did not differ significantly in their MCR. The GH secretion rate in thyroidectomized birds was similar to that in sham-thyroidectomized birds and in both groups was markedly reduced following pretreatment with T4.

These results demonstrate thyroidal inhibition of circulating GH concentrations in fowl. Both T3 and T4 inhibited GH concentrations and the effect of T4 was not simply due to its role as a T3 prohormone. In the absence of thyroid hormones, the MCR of GH was reduced but its secretion rate was not enhanced. A significant reduction of GH secretion rate occurs in response to exogenous T4, in the absence of any change in GH metabolism.

Journal of Endocrinology (1990) 124, 215–223
Role of LHRH in the gonadotrophin response to restraint stress in intact male rats
Authors: López-Calderón A. , Gonzaléz-Quijano M. I. , Tresguerres J. A. F. , Ariznavarreta C.
Published: December 2008

A hypothalamic site of action has been hypothesized for the inhibitory effect of chronic stress on gonadotrophin secretion. The aim of the present study was to examine the temporal changes in hypothalamic LHRH content and gonadotrophin secretion during restraint stress, and the pituitary responsiveness to LHRH stimulation in chronically stressed rats. Adult male rats were killed after being restrained for 0, 20, 45, 90, 180 and 360 min or for 6 h daily over 2, 3 and 4 days. After 20–45 min of stress there was an increase in plasma concentrations of LH (P<0·01) and a decrease in hypothalamic LHRH content (P<0·01), suggesting a negative correlation between plasma LH and hypothalamic LHRH concentrations. Plasma concentrations of FSH were also increased by restraint, but the FSH response was slower and less than the plasma LH response, being significant after 90 min of restraint. Plasma LH and FSH and hypothalamic LHRH concentrations were decreased in chronically stressed rats. In rats restrained for 6 h daily over 4 days, the response of plasma gonadotrophins to administration of 500 ng LHRH was enhanced 45 min after the injection. On the basis of these observations we concluded that in the intact rat, stress may acutely stimulate LHRH and gonadotrophin secretion, and the inhibitory effect of chronic stress on plasma LH and FSH seems not to be due to a reduction in pituitary responsiveness to LHRH, but rather to a decrease in LHRH secretion.

Journal of Endocrinology (1990) 124, 241–246
Growth hormone increases insulin-like growth factor-I (IGF-I) and decreases IGF-II in plasma of growing pigs
Authors: Owens P. C. , Johnson R. J. , Campbell R. G. , Ballard F. J.
Published: December 2008

Insulin-like growth factor-I (IGF-I) and IGF-II have been measured in plasma obtained from male and female pigs of two strains during daily administration of pituitary-derived porcine GH (pGH; 100 μg/kg) from 60 to 90 kg body weight. Each plasma sample was first chromatographed to separate the IGF from binding proteins in order to obtain reliable measurements. IGF-I concentrations showed no differences between strains, but were higher in untreated males (497 ± 43 (s.e.m.) μg/l) than females (299±15 μg/l). GH-treated animals had two-fold higher concentrations of IGF-I. IGF-II concentrations were not significantly different between sexes or strains, but were decreased in pigs treated with pGH (299 ± 28 μg/l) compared with controls (431 ± 32 μg/l). Binding protein concentrations, measured as interference in the IGF-I and IGF-II assays, were not different between sexes or strains, but were increased in pGH-treated animals. Taken together, these results indicate that in addition to the expected increase in IGF-I concentrations, exogenous administration of pGH to pigs leads to an increase in IGF-binding protein and a depression in IGF-II concentrations.

Journal of Endocrinology (1990) 124, 269–275
Physiological roles of chicken LHRH-I and -II in the control of gonadotrophin release in the domestic chicken
Authors: Sharp P. J. , Talbot R. T. , Main G. M. , Dunn I. C. , Fraser H. M. , Huskisson N. S.
Published: December 2008

The physiological roles of chicken LHRH-I and -II (cLHRH-I and -II) in the regulation of gonadotrophin release were investigated in the domestic chicken. Measurements of the neuropeptides, using specific radioimmunoassays, in brain sections cut in three planes or in grossly dissected brain areas, showed that cLHRH-II occurs in low amounts throughout the brain whereas cLHRH-I is most abundant in the diencephalon. Within the diencephalon, the largest amount of cLHRH-I occurred in the median eminence of the hypothalamus. The amount of cLHRH-I in the median eminence was higher (P<0·05) in laying than in out-of-lay hens. No cLHRH-II was detected in the median eminence in either reproductive state. The amount of cLHRH-I in the hypothalamus was increased (P<0·05) in cockerels at the onset of puberty and in somatically immature birds after castration. There were no correlated changes in the amounts of hypothalamic cLHRH-II measured in the same experimental samples.

Active immunization of laying hens against cLHRH-I but not against cLHRH-II resulted in the complete regression of the reproductive system and a depression in the concentration of plasma LH.

These observations, taken together, suggest that gonadotrophin secretion in the hen is more likely to be directly regulated by cLHRH-I than by cLHRH-II.

Journal of Endocrinology (1990) 124, 291–299
High stocking density affects cortisol secretion and tissue distribution in brook charr, Salvelinus fontinalis
Authors: Vijayan M. M. , Leatherland J. F.
Published: December 2008

Preparations of head kidney tissue (containing the interrenal cells) from brook charr (Salvelinusfontinalis) which had been held at a high stocking density (120 kg/m3) showed a higher spontaneous secretion rate of cortisol than those from brook charr held at a low stocking density (30 kg/m3). Challenges with ACTH at 5 and 500 mU/ml stimulated the secretion of cortisol in interrenal preparations taken from fish stocked at low density but the high ACTH challenge resulted in a lower cortisol secretion rate. The ACTH-stimulated cortisol secretion by the interrenal cells of brook charr stocked at high density was lower than that of the low density group.

There was no difference in the metabolic clearance rate of cortisol in brook charr held at the two stocking densities. The clearance rate of [3H]cortisol from the tissues suggested that in fish held at high stocking density cortisol is rapidly taken up by the liver and subsequently catabolized. Cortisol uptake by the liver in fish held at high stocking density may be an adaptation, which results in altered hepatic metabolic activity.

Journal of Endocrinology (1990) 124, 311–318
Human 'pregnancy-associated endometrial α1-globulin', a 32 kDa insulin-like growth factor-binding protein: immunohistological distribution and localization in the adult and fetus
Authors: Waites G. T. , James R. F. L. , Walker R. A. , Bell S. C.
Published: December 2008

We have previously shown that pregnancy-associated α1-globulin, a small molecular weight (32 kDa) insulin-like growth factor-binding protein (IGF-BP), is quantitatively the major secretory protein product of the decidualized endometrium during human pregnancy and is localized principally in the decidual cell. In the present study, employing monoclonal antibodies in immunohistological techniques, the distribution and localization of IGF-BP has been examined in normal and pathological tissues of the adult and first trimester fetus. In the adult, most intense reactivity was associated with endometrial stroma and their derived decidual cells in the uterus or in ectopic sites in patients with endometriosis. During the menstrual cycle, the appearance of IGF-BP in endometriotic tissue was linked with its appearance in uterine endometrial tissue. The only other adult cells where significant staining was detected was in the luteal cells of the corpus luteum. Production of the protein was not a feature of carcinomas. In the fetus, the protein was localized in lymphoid-myeloid progenitor cells and hepatocytes of the liver and at lower levels in testicular Leydig cells and adenocortical cells. These observations suggest highly specific tissue expression of this protein and support a specialized role for this protein in progenitor cells of the lymphomyeloid system, in certain steroid hormone-producing cells and in the decidual cell in pregnancy.

Journal of Endocrinology (1990) 124, 333–339
The depletion of plasma prolactin by pantethine in oestrogen-primed hyperprolactinaemic rats
Authors: Jeitner T. M. , Oliver J. R.
Published: December 2008

Pantethine was investigated for its potential to deplete prolactin in the plasma and pituitary cells of oestrogen-primed hyperprolactinaemic rats. This compound has been used in the past to deliver cysteamine systemically, through its congener pantetheine, a metabolic precursor for cysteamine. Cysteamine itself, specifically reduces plasma and pituitary prolactin.

The addition of pantethine (2–10 mmol/l) to the media of isolated pituitary cells over 4 h did not appreciably alter the intracellular content of immunoreactive prolactin. Moreover, oral administration of pantethine at 0·5 and 1·0 g/kg body weight did not influence the concentration of immunoreactive plasma prolactin. However, the concentration of plasma prolactin fell by 48 and 67%, when pantethine was injected i.p. at 0·5 and 1·0 g/kg body weight, after 4 h. Intravenous administration of pantethine resulted in even greater losses of prolactin, in the order of 50 and 81% depletion for 0·5 and 1·0 g/kg body weight respectively and within 2 h of administration. However, cysteamine was found to be more efficacious than pantethine on a molar basis with regard to depleting the plasma concentration of prolactin in hyperprolactinaemic rats.

Journal of Endocrinology (1990) 124, 397–402
Effects of dietary sodium restriction and posture on plasma levels of atrial natriuretic peptide, aldosterone and free aldosterone in normal human pregnancy
Authors: Steegers E. A. P. , Benraad Th. J. , Jongsma H. W. , Tan A. C. I. T. L. , Hein P. R.
Published: December 2008

The effects of dietary sodium restriction and posture on plasma concentrations of atrial natriuretic peptide (ANP), aldosterone and free aldosterone were investigated in ten women between weeks 29 and 33 of normal pregnancy. Hormone levels were studied during unrestricted sodium intake and on day 6 of a low sodium diet. On both occasions venous blood was obtained in the sitting as well as in the left lateral tilt position.

Plasma concentrations of ANP during the unrestricted sodium intake were not raised compared with control values in healthy non-pregnant females. Recovery experiments showed no differences in the degradation of ANP in blood from pregnant and non-pregnant women. Plasma concentrations of ANP significantly decreased (by 32%) in response to the low sodium regime in both positions. Concentrations of aldosterone and free aldosterone (in women in the sitting position) increased twofold after sodium restriction. Mean values of ANP were higher in women in the left lateral tilt position that in those in the sitting position, but the difference was not significant. Concentrations of aldosterone and free aldosterone were significantly lower (by around 30%) in women in the left lateral tilt position compared with those in the sitting posture.

Journal of Endocrinology (1990) 124, 507–513
Gonadotrophin glycosylation and function
Authors: Wilson C. A. , Leigh A. J. , Chapman A. J.
Published: December 2008

This review emphasizes the heterogeneous structure of the gonadotrophin hormones and the influence of different oligosaccharide structures on the bioactivity of these hormones. A summary has been made of the changes in biopotency of the gonadotrophins throughout the life-cycle of the human and in different endocrine states in the rat.

In general it appears that the charge of the gonadotrophin conferred by the acid radicals attached to the terminal groups on the oligosaccharide structures strongly influences biopotency. Basic structures have a greater potency in in-vitro assays, but a short half-life in the circulation, while acidic isoforms are less potent, but have a longer circulatory time and are thus more active in in-vivo estimations. More basic forms are secreted over the adult reproductive years compared with the prepubertal period and old age. The glycosyl structure of the carbohydrate groups also alters in different endocrine states and is probably also important for the bioactivity and potency of the hormone.

Gonadotrophin-releasing hormone (GnRH) and gonadal steroids can influence the type of isoform synthesized and released, and therefore affect the function of gonadotrophins. GnRH enhances glycosylation, sulphation and biopotency. Oestradiol potentiates the glycosylation induced by GnRH and reduces sialylation, while testosterone increases sialylation.

Journal of Endocrinology (1990) 125, 3–14
Atriopeptins are potent inhibitors of ACTH secretion by rat anterior pituitary cells in vitro: involvement of the atrial natriuretic factor receptor domain of membrane-bound guanylyl cyclase
Authors: Dayanithi G. , Antoni F. A.
Published: December 2008

The current concept of the regulation of adenohypophysial corticotrophin secretion assigns a stimulatory role to neuropeptides of hypothalamic origin and an inhibitory function to adrenocortical glucocorticoid hormones. It has been shown that in isolated perifused rat anterior pituitary cells atriopeptins (1–28) and (5–28), but not (5–25), potently suppress corticotrophin secretion elicited by 41-residue corticotrophin-releasing factor and arginine vasopressin. The action of atriopeptins is associated with a marked increase in the cellular content of cyclic GMP. Moreover, 8-Br-cyclic GMP, a cell membrane permeant analogue of cyclic GMP, also inhibited secretagogue-stimulated corticotrophin release. It is suggested that atriopeptins of hypothalamic and perhaps of cardiac origin may be functionally significant corticotrophin-release inhibiting factors.

Journal of Endocrinology (1990) 125, 39–44
Emergence of the diurnal rhythm in plasma melatonin concentrations in newborn lambs delivered to intact or pinealectomized ewes
Authors: Nowak R. , Young I. R. , McMillen I. C.
Published: December 2008

We have monitored the 24-h profiles of plasma melatonin concentrations between birth and 10 weeks of age, in lambs which were delivered to, and suckled, either pineal-intact (control group) or pinealectomized (pinealectomized group) ewes. Between 0 and 2 weeks of age, plasma concentrations of melatonin in lambs suckling either intact or pinealectomized ewes were highest at 01.00 h. At this age, however, there was no significant difference in the mean plasma concentrations of melatonin between the entire dark and light phases in lambs in either the control group (dark, 39·7 ± 6·0 (s.e.m.) pmol/l; light, 39·5 ± 8·1 pmol/l) or the pinealectomized group (dark, 79·8 ± 43·3 pmol/l; light, 60·9 ±8·7 pmol/l). Between 3 and 4 weeks of age, however, a diurnal rhythm in plasma melatonin concentrations was clearly present in the lambs in both the control and pinealectomized groups (control group: dark, 164·1 ± 5·6 pmol/l; light 26·2 ± 2·5 pmol/l; pinealectomized group: dark, 52·7± 8·0 pmol/l; light, 19·1 ± 5·3 pmol/l; P<0·001). Between 3 and 10 weeks of age, plasma concentrations of melatonin in the dark phase were significantly (P<0·05) lower in the lambs suckling pinealectomized ewes than in the control group. In both the control lambs and lambs suckling pinealectomized ewes, the mean plasma concentrations of melatonin in the dark and light phases increased significantly (P<0·05) between 3 and 6 weeks after birth.

In conclusion, we have demonstrated that a clear diurnal plasma rhythm in melatonin concentrations does not emerge until 3–4 weeks of age in lambs suckling either pinealectomized or intact ewes. We have also measured lower melatonin concentrations during the dark phase in lambs suckling pinealectomized ewes when compared with lambs suckling pineal-intact ewes between 3 and 10 weeks of age.

Journal of Endocrinology (1990) 125, 97–102
The inhibition by calmodulin of thyroid-stimulating hormone binding to epididymal fat, testis and thyroid membranes in the guinea-pig
Authors: Inui T. , Ochi Y. , Hachiya T. , Kajita Y. , Ishida M. , Nakajima Y. , Nagamune T.
Published: December 2008

Calmodulin inhibited 125I-labelled TSH binding to the membranes of various target tissues for TSH (thyroid, epididymal fat and testis) of the guinea-pig. This inhibition was abolished by adding EGTA (1 mmol/l). Calmodulin did not inhibit the binding of 125I-labelled epidermal growth factor (EGF) to these membranes. It is suggested that the inhibitory effect of calmodulin on the binding of TSH to the receptor is specific and that this mechanism is due to the direct binding of calmodulin to receptor membranes. The ability of calmodulin to bind to the membranes was calciumsensitive while that of TSH was not. The binding of 125I-labelled calmodulin to these membranes increased significantly when the endogenous calmodulin in the membranes was removed by EGTA. It was not inhibited by a pure preparation of TSH, but it was inhibited by contaminated calmodulin in a crude TSH preparation. On the other hand, 125I-labelled TSH binding to these membranes did not change after the removal of endogenous calmodulin.

In conclusion, exogenous calmodulin has an inhibitory effect on the binding of TSH but not of EGF to the membranes of guinea-pig thyroid, epididymal fat and testis.

Journal of Endocrinology (1990) 125, 103–107
Growth hormone and insulin-like growth factor-I responses in steers actively immunized against somatostatin or growth hormone-releasing factor
Authors: Trout W. E. , Schanbacher B. D.
Published: December 2008

Steers were actively immunized at 81 days of age against human serum albumin (hSA; controls) or hSA conjugated to either somatostatin (SRIF) or growth hormone-releasing factor (GRF). Binding titres were observed for the respective peptide antigens after all steers had been given booster immunizations. Although no effects of treatment were observed in SRIF-immunized steers, mean serum concentrations of GH and insulin-like growth factor (IGF-I) were suppressed (P<0·01) in GRF-immunized steers when compared with hSA-immunized controls. Mean concentrations of prolactin did not differ with treatment but showed seasonal fluctuations (P<0·001) associated with changes in the daylength. In contrast to its marked effect upon serum concentrations of IGF-I, immunization against GRF resulted in a relatively small (6%) but significant decrease in body weight gain (P<0·01) and an increase in carcass backfat thickness (P<0·05). In summary, our findings have shown the susceptibility of steers to growth modulation by GRF immunoneutralization. Secondly, the poor relationship observed between serum concentrations of IGF-I and growth rates in GRF-immunized steers suggested that circulating IGF-I may not be the principle factor determining the post-weaning growth rate in cattle.

Journal of Endocrinology (1990) 125, 123–129
The antifertility effect of passive immunization of mice against progesterone is influenced by genetic factors other than H-2 haplotype
Authors: Nowak R. A. , Wang M.-W. , Heap R. B.
Published: December 2008

The anti-fertility effect of passive immunization against progesterone is influenced by genotype in mice. In order to quantify this finding we determined the effective dose that blocks pregnancy in 50% of treated mice (ED50) for two different anti-progesterone monoclonal antibodies (DB3 and 11/32) in four different strains of mice (BALB/cJ, CBA/Ca, Tuck's no. 1 and F1C). Efficacy was greatest in the two inbred strains (BALB/cJ and CBA/Ca) with ED50 values of 0·46–1·4 nmol. The F1C hybrid mice were more resistant to antibody treatment (ED50 2·2–3·0 nmol), while the outbred Tuck's no. 1 strain required much higher doses (ED50 7·0–8·2 nmol). There were no intrastrain differences between the two monoclonal antibodies.

We have examined the possible role of the H-2 haplotype on antibody efficacy in different strains and crosses. The antibody was highly effective in blocking implantation in three congenic BALB strains of different H-2 haplotype, in another inbred strain CBA/Ca, and in reciprocal BALB/cJ×CBA/Ca crosses. The F1 hybrid crosses were somewhat resistant, but the C57BL/10Sn and B10.BR congenic strains were most resistant to treatment. The results show that the pregnancy-blocking effect of the anti-progesterone antibody was not influenced by the H-2 haplotype, but rather by background genes.

Journal of Endocrinology (1990) 125, 257–262
Testosterone regulates the secretion of thyrotrophin-releasing hormone (TRH) and TRH precursor in the rat hypothalamic-pituitary axis
Authors: Pekary A. E. , Knoble M. , Garcia N. H. , Bhasin S. , Hershman J. M.
Published: December 2008

Orchidectomy has been reported to decrease concentrations of thyrotrophin (TSH) in the circulation of male rats without affecting serum levels of thyroid hormones. To understand the mechanism underlying this observation, we have measured the effect of gonadal status on the in-vitro release of TSH-releasing hormone (TRH) by male rat hypothalamic fragments. Because hormone release rates can be affected by changes in the post-translational processing of the hormonal precursors, we have also studied the corresponding changes in the concentrations of TRH and TRH-Gly, a TRH precursor peptide in hypothalamus and pituitary, by radioimmunoassay.

We observed a significant decline in the in-vitro release of TRH from incubated hypothalami 1 week after castration, which was quantitatively reversed by testosterone replacement. Concentrations of TRH and TRH-Gly in the posterior pituitary, on the other hand, which derive from neurones of hypothalamic origin, increased significantly with castration and were returned to the normal range by testosterone replacement.

We conclude that the primary effect of testosterone is the stimulation of hypothalamic TRH release, resulting in the depletion of TRH and TRH precursors from TRH-containing neurones which project into the median eminence and posterior pituitary.

Journal of Endocrinology (1990) 125, 263–270
Normoprolactinaemia in spontaneously hypertensive rats: absence of a close relationship between plasma concentrations of prolactin and systolic blood pressure
Authors: Aguilar E. , Rodríguez-Padilla M. L. , Pinilla L.
Published: December 2008

Prolactin has been involved in different types of hypertension both in man and in rats. In an attempt to substantiate this hypothesis, we have analysed the correlation between plasma concentrations of prolactin and systolic blood pressure (SBP) in female and male rats from spontaneously hypertensive (SH) and normotensive Wistar–Kyoto strains (30, 60 and 90 days old), as well as in adult female Wistar rats rendered hyperprolactinaemic by the administration of 100 μg testosterone propionate on day 1 of life, or adult males with low plasma concentrations of prolactin after administration of bromocriptine (4 mg/kg per day) over 15 days. Our results indicate a lack of correlation between plasma concentrations of prolactin and SBP since plasma concentrations of prolactin were normal in male and female SH rats and hyper- and hypoprolactinaemia did not affect SBP.

In spite of these normal plasma concentrations of prolactin, SH rats showed subtle changes in the secretion of this hormone in vitro and in vivo in response to exogenous serotonin administration and to immobilization.

Journal of Endocrinology (1990) 125, 359–364
Regulation of insulin-like growth factor-I gene expression by growth factors in cultured vascular smooth muscle cells
Authors: Bornfeldt K. E. , Arnqvist H. J. , Norstedt G.
Published: December 2008

The aim of this investigation was to study the regulation of insulin-like growth factor-I (IGF-I) gene expression in cultured rat aortic smooth muscle cells. Near-confluent cells were deprived of serum for 24 h and then exposed to IGF-I, insulin, serum, basic fibroblast growth factor (basic FGF), platelet-derived growth factor (PDGF-BB; consisting of B-chain homodimer) or GH for 24 h. Levels of IGF-I mRNA were measured by solution hybridization. The level of IGF-I mRNA was markedly decreased by 10% (v/v) newborn calf serum (78 ± 4 (s.e.m.) % decrease), 1 nmol basic FGF/1 (53 ± 8%), and 1 nmol PDGF-BB/1 (40 ± 3%) when measured after 24 h. The effect of PDGF-BB was significant after 6 h and became more marked after 24 h. GH (1 nmol/l or 0.1 μmol/l or insulin (1 nmol/l had no effect after 24 h, whereas IGF-I (1 nmol/l and insulin (10 μmol/l increased IGF-I mRNA 64 ± 20% and 46±14% respectively. The increase caused by IGF-I was demonstrated after 3 h, and was most marked after 24 h. Using Northern blot analysis of cultured aortic smooth muscle cells, IGF-I transcripts of 7-4, 1.7 and 1.1–0.8 kilobases were observed. Exposure of the cells to 10% serum, 1 nmol basic FGF/1 or 1 nmol PDGF-BB/1 for 48 h increased the cell number by 104 ±7%, 64 ± 3% and 61±22% respectively, while IGF-I, insulin and GH had little effect. In conclusion, IGF-I, and high concentrations of insulin, increased IGF-I mRNA in vascular smooth muscle cells, whereas factors which were stronger mitogens decreased IGF-I gene expression.

Journal of Endocrinology (1990) 125, 381–386
Growth hormone and thyroxine affect lipoprotein metabolism in hypothyroid and hypophysectomized rats
Authors: Hoogerbrugge-v.d.Linden N. , Jansen H. , Wouters N. M. H. , Birkenhäger J. C.
Published: December 2008

The aim of this study was to evaluate the effect of thyroxine (T4) and GH replacement therapy on serum lipoproteins in rats with primary and secondary hypothyroidism and to see whether recovery of GH activity was associated with normalization of serum lipoproteins. In both the primary and secondary hypothyroid rats, total cholesterol (TC) was higher than in normal controls, due to an increase in low-density lipoprotein cholesterol (LDL-c) and to a lesser extent also in high-density lipoprotein cholesterol (HDL-c). Treatment of hypophysectomized rats with GH induced a decrease in the concentration of TC, LDL-c and HDL-c, while liver lipase activity (LLA) increased. The effect of GH on HDL-c was correlated with the increase in LLA. T4 replacement therapy of hypophysectomized rats normalized LDL-c, but HDL-c and LLA were unaffected.

During primary hypothyroidism, T4 treatment induced GH activity, increased LLA and reduced the HDL-c concentration. GH treatment of primary hypothyroid rats had a similar influence on the lipid levels and LLA as in hypophysectomized animals, although the lowering of HDL-c was less prominent. These results demonstrate that GH determines serum lipoproteins during both primary and secondary hypothyroidism.

Journal of Endocrinology (1990) 125, 403–407
Characterization of insulin-like growth factor-binding proteins secreted by isolated sheep thyroid epithelial cells
Authors: Wang J.-F. , Becks G. P. , Buckingham K. D. , Hill D. J.
Published: December 2008

We have characterized the insulin-like growth factor-binding proteins (IGF-BPs) released by isolated sheep thyroid epithelial cells. Thyroid follicles were isolated with collagenase and cultured in Coon's modified F-12 M (OH medium) supplemented with insulin, cortisol, transferrin, glycyl-histidyl-lysine and somatostatin (5H medium) and TSH (6H medium). Conditioned OH medium specifically bound both 125I-labelled IGF-I and -II, although binding capacity was reduced following acid-gel filtration to separate endogenous IGF-BP complexes, suggesting some destruction of BPs. The binding of 125I-labelled IGF-I or -II to conditioned (OH) medium was progressively displaced by increasing amounts of unlabelled homologous peptides, while fractionation on concanavalin A-Sepharose showed that the IGF-BPs consisted of both glycoprotein and non-glycoprotein components. The molecular sizes of the IGF-BPs were resolved by separation of OH medium on SDS-PAGE and ligand blot analysis with 125I-labelled IGF-I or -II. Conditioned medium contained four specific binding species for IGF-II of 19, 30, 38 and 46 kDa; all but the smallest also binding radiolabelled IGF-I. Prior fractionation on concanavalin A-Sepharose showed that the 46 kDa binding species was a glycoprotein. Competition studies with increasing concentrations of unlabelled IGF-I or -II during ligand blotting suggested that the 46 and 30 kDa binding species had a greater affinity for IGF-II than IGF-I, while the 38 kDa had a greater relative affinity for IGF-I. Incubation of cells in 5H medium reduced the abundance of the 46 kDa binding protein, while incubation in 6H medium decreased the release of all binding protein species. Results show that isolated thyroid follicles released several forms of IGF-BP with differing relative affinities for IGF-I and -II. Gross changes seen in the presence of BPs between OH, 5H and 6H media suggest acute hormonal control of release.

Journal of Endocrinology (1990) 125, 439–448
Role of the paraventricular nucleus in controlling the frequency of milk ejection and the facilitatory effect of centrally administered oxytocin in the suckled rat
Authors: Wakerley J. B. , Juss T. S. , Farrington R. , Ingram C. D.
Published: December 2008

The milk-ejection reflex was studied in anaesthetized, lactating Wistar rats in order to evaluate the contribution of the paraventricular nucleus (PVN) to the patterning of milk ejection and the facilitatory action of centrally administered oxytocin. In the first series of experiments, radiofrequency lesions were performed and centred: (1) antero-dorsal to the PVN, damaging parts of the medial septum and anterior hypothalamus; (2) in the PVN, such that much of the parvocellular division was destroyed, but parts of the magnocellular division remained intact; or (3) in the PVN, destroying both parvocellular and magnocellular divisions. Suckling tests performed before and after lesioning showed that the milk-ejection interval was significantly increased (decreased frequency) after lesioning in groups 2 and 3, but that milk-ejection amplitude was significantly decreased only in group 3. These results suggest that damage to the parvocellular division of the PVN affects milk-ejection frequency, but that damage to the magnocellular PVN only affects amplitude. Subsequent tests on rats injected into the PVN with the neurotoxin N-methyl-d,l-aspartate revealed a fall in the amplitude and frequency of milk ejection, similar to that after complete radiofrequency lesions of the PVN.

In the second series of experiments, the facilitatory action of centrally administered oxytocin (1 mU, 2.2 ng) was examined in animals bearing either sham or complete PVN lesions. In both groups, intracerebroventricular injection of oxytocin was able to increase the frequency of milk ejections, although the incidence of milk ejection was lower in the pre- and post-injection period in the PVN-lesioned animals.

In conclusion, the parvocellular component of the PVN may be an important site for regulating milk-ejection frequency, possibly mediated by its centrally projecting oxytocin neurones. However, the PVN does not appear to be the principle target site by which central oxytocin exerts its facilitatory effect on the frequency of milk ejection.

Journal of Endocrinology (1990) 125, 467–475
Immunological and insulin secretory studies on isolated porcine islets of Langerhans
Authors: Crowther N. J. , Gotfredsen C. F. , Moody A. J. , Green I. C.
Published: December 2008

Since porcine islets are considered a likely tissue source for islet transplantation we have studied the insulin secretory responses to stimuli and some of the cell surface antigen characteristics of porcine islet cells.

In a static incubation system, the threshold level of glucose required for the stimulation of insulin secretion from freshly isolated porcine islets was found to be between 2·8 and 4·2 mmol glucose/l. Arginine (5 mmol/l) and 3-isobutyl-1-methylxanthine (1 mmol/l) potentiated insulin release induced by 8·3 mmol glucose/l. Leucine (5 mmol/l) initiated release in the presence of 2 mmol glucose/l. Neither β-hydroxybutyrate (10 mmol/l) nor octanoate (5 mmol/l) potentiated insulin release induced by 8·3 mmol glucose/l, but β-hydroxybutyrate initiated release in the presence of 2 mmol glucose/l while octanoate did not.

A 125I-labelled protein A binding assay and an enzyme-linked immunosorbent assay system were used to detect antibody binding to islet and non-islet cells. Monoclonal antibodies raised against intact rat islets were shown to bind to both porcine and rat islet cells but not to rat hepatoma tissue culture cells or rat insulinoma cells. The serum from recently diagnosed type I diabetics was shown to bind to rat islet cells in a 125I-labelled protein A binding assay, while serum from control subjects showed little, if any, binding. Porcine islet cells were unable to distinguish between the sera of recently diagnosed type I diabetics and controls in a similar assay.

In conclusion, porcine islets respond to many of the major insulin secretagogues to which human islets are sensitive. However, they have a lower secretory response to these compounds compared with that reported for human islets. Monoclonal antibody and human sera binding studies show that rat and porcine islets share some cell surface antigens but it remains to be seen whether the inability of porcine islets to discriminate between diabetic and non-diabetic sera is an advantage for transplantation, indicating less likelihood of an islet-specific autoimmune-like humoral attack.

Journal of Endocrinology (1990) 126, 43–4
Metabolic response of teleost hepatocytes to glucagon-like peptide and glucagon
Authors: Mommsen T. P. , Moon T. W.
Published: December 2008

Salmon glucagon-like peptide (GLP), bovine glucagon (B-glucagon) and anglerfish glucagon (AF-glucagon), all activate glucose production in teleost hepatocytes through gluconeogenesis and glycogenolysis, but notable species differences exist in their respective effectiveness. In trout hepatocytes, gluconeogenesis appears to be the main target of hormone action. In eel cells, sampled in November, glycogenolysis was activated threefold, while gluconeogenesis was increased by 12% only. In March, glycogenolytic activation was 1·7-fold, while gluconeogenesis was increased by about 1·7-fold after exposure to B-glucagon. In brown bullhead cells, increases in glycogenolysis from seven- (GLP) to tenfold (B- and AF-glucagon) were noted, while activation of gluconeogenesis was slight. Fragments of two AF-glucagons (19–29) revealed only insignificant metabolic activity. Treatment of eel cells with B-glucagon led to large (up to 20-fold) increases in intracellular cyclic AMP (cAMP) concentrations, while exposure to GLP was accompanied by a modest (< twofold) increase in cAMP, although metabolic effectiveness (gluconeogenesis and glycogenolysis) was similar for the two treatments. Under identical conditions, brown bullhead cellular cAMP responded poorly. Levels of cAMP peaked within 15 min following hormone application. The results imply that no simple or direct relationship exists between the amount of intracellular cAMP and the metabolic action of the glucagon family of hormones. It can further be concluded that GLPs are important regulators of hepatic metabolism, influencing identical targets as glucagon, while the mechanisms of action seem to differ.

Journal of Endocrinology (1990) 126, 109–118
A rat granulosa cell plasminogen activator bioassay for FSH in human serum
Authors: Thakur A. N. , Coles R. , Sesay A. , Earley B. , Jacobs H. S. , Ekins R. P.
Published: December 2008

A previously described in-vitro rat granulosa cell plasminogen activator bioassay for FSH has been modified and applied in the assay of human serum. This modified method consists of exposing the diethylstilboestrol-stimulated granulosa cells from 25- to 26-day-old rats to FSH or test substance for 3·5 h in wells coated with 125I-labelled fibrinogen and treated with thrombin. Following stimulation with FSH, the dose-related production of plasminogen activator was measured as the degree of 125I-labelled fibrinolysis in the presence of added plasminogen. Using the urinary FSH/LH bioassay reference preparation as the assay standard, the useful range of the assay was 0·3–15IU/l, with an assay sensitivity of 0·3 IU/l. As determined using purified glycoprotein hormone preparations, the assay was highly specific for FSH. The minor degree of FSH bioactivity measured in some of the hormone preparations was accounted for by the amount of FSH contamination in these preparations. To abolish interference caused by unknown serum factors, we heat-treated the serum samples for 15 min at 56 °C before the assay. The results indicated that neither immunoreactivity nor bioactivity was affected by this treatment. Furthermore, heat-treated human sera gave responses parallel to the standard curve at the three dose levels (2, 4 and 8 μl) studied. We used this bioassay to estimate the FSH-like bioactivity in 15 human serum samples. The estimates of immunoreactive FSH in these samples correlated well with the corresponding FSH bioactivity (r = 0·745, n = 15 and P < 0·05).

The results indicate that with this sensitive and rapid (completed within 24 h) bioassay, it should be possible to measure FSH bioactivity in heat-treated human serum samples.

Journal of Endocrinology (1990) 126, 159–168
Glucagon-like peptide-1 (7–36)-NH2: a physiological inhibitor of gastric acid secretion in man
Authors: O'Halloran D. J. , Nikou G. C. , Kreymann B. , Ghatei M. A. , Bloom S. R.
Published: December 2008

Glucagon-like peptide (GLP)-1 (7–36)-NH2 is a peptide found in the mucosal endocrine cells of the intestine, and plasma levels of GLP-1 (7–36)-NH2 immunoreactivity show a rise after the ingestion of a fat or mixed-component meal. We investigated the effects of physiological infusion of GLP-1 (7–36)-NH2 on a submaximal gastric acid secretion in healthy volunteers at a rate known to mimic the observed postprandial rise in plasma concentrations. Corrected gastric acid output decreased to less than 50% and volume output to 33% of stimulated values. After the infusion, the secretion of gastric acid recovered immediately to preinhibition values. These results suggest a novel role for GLP-1 (7–36)-NH2 as a physiological inhibitor of gastric acid secretion in man.

Journal of Endocrinology (1990) 126, 169–173