bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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

ABSTRACT
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