bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of corticosterone on the hypothalamic-pituitary-gonadal system of male Japanese quail exposed to either short or long photoperiods
Authors: Deviche Pierre , Massa Renato , Bottoni Luciana , Hendrick Jean-Claude
Published: December 2008

Male quail were bred under short photoperiods of 8 h light: 16 h darkness (8L : 16D; SD) for the first 4 weeks of life and were then transferred to either long photoperiods of 16L : 8D (LD) or maintained under the SD regime. Both groups of birds were treated for 2 weeks with a daily dose of either 0·25 or 1·0 mg corticosterone. The conversion of [14C]testosterone in vitro into 5α- and 5β-dihydrotestosterone (5α- and 5β-DHT), 5α- and 5β-androstane-3α,17β-diol, and androstenedione was then measured in the pituitary and cloacal glands of all birds. In the hyperstriatum and posterior hypothalamus only 5β-reduced metabolites and androstenedione were detected.

Transfer to LD and injection of corticosterone affected the metabolism of testosterone only in the pituitary and cloacal glands. In the pituitary gland, exposure to LD increased the production of 5α-reduced metabolites but not of either 5β-reduced metabolites or androstenedione. In both SD and LD birds, injections of corticosterone enhanced the production of 5β-reduced steroids and decreased the production of androstenedione. In LD birds corticosterone also decreased the production of 5α-androstane-3α,17β-diol. Plasma levels of LH and FSH were higher in the LD than in the SD birds. In the SD birds treatment with corticosterone increased the level of LH after 14 days of treatment. Exposure to LD decreased the production of 5β-androstane-3α,17β-diol and androstenedione in the cloacal gland and increased the conversion of testosterone into 5α-DHT Treatment with corticosterone increased the production of androstenedione in the cloacal gland of LD birds but decreased it in that of SD birds. Corticosterone also partially blocked the photoinduced growth of the cloacal gland, but it slightly stimulated the growth of the gland in the SD birds. After 2 weeks of treatment SD (but not LD) corticosterone-treated birds had higher testicular weights than the corresponding controls.

It is suggested that treatment with corticosterone might affect the hypothalamic-pituitary-gonadal axis partly through changes in the metabolism of testosterone.
Regulation of immunoreactive β-endorphin release from rat pituitary cell culture
Authors: Daniel Susan G. , Ramsden D. B.
Published: December 2008

The release of immunoreactive β-endorphin from rat anterior pituitary cells in culture was studied by radioimmunoassay and gel-filtration chromatography. Two forms of immunoreactivity were detected corresponding to β-lipotrophin (β-LPH) and β-endorphin. Cells were found to release β-endorphin-like immunoreactivity (β-endorphin LIR) into the culture medium for up to 10 days with a trough in release occurring between days 2–4. The ratio of β-LPH to β-endorphin released remained constant during the course of culture. After 4 days in culture β-endorphin LIR release was constant and responsive to modulation. Incubation with lysine-vasopressin (0·1 units/ml) produced a two- to threefold increase in release and dexamethasone (10−6 mol/l) suppressed release to 33% of controls. Neither stimulation nor suppression resulted in a change in the ratio of β-LPH to β-endorphin released. Dexamethasone suppression was not overcome by removal of dexamethasone or addition of vasopressin.
Characteristics of thyrotrophin-stimulated cyclic AMP production in cultured human thyroid cells from thyrotoxic tissue and non-toxic goitres
Authors: Ollis C. A. , Munro D. S. , Tomlinson S.
Published: December 2008

We have described a system for the maintenance in culture of isolated human thyroid cells from both thyrotoxic tissue and non-toxic goitres. The cells isolated from the two thyroid tissue types showed similar cyclic AMP response characteristics to TSH with large increases in intracellular and extracellular cyclic AMP after 20-min incubations. Maximal responses were obtained with 50 mu. TSH/ml and half-maximal responses at 1·0 mu. TSH/ml. With cell passage the cyclic AMP responses to TSH decreased in magnitude and sensitivity. As with other thyroid cultures, growth of the cells with TSH induced arrangement into follicular structures, whereas cells grown in the absence of TSH remained as a monolayer. Basal intracellular cyclic AMP levels were increased in a dose-related fashion in cells grown in the presence of graded concentrations of TSH and the maximal response to further additions of TSH was not greater than in control cultures.
Multiple species of follicle-stimulating hormone exist within the anterior pituitary gland of male golden hamsters
Authors: Ulloa-Aguirre Alfredo , Chappel S. C.
Published: December 2008

Anterior pituitary glands were collected from immature and mature (intact and castrated) male hamsters. The various species of FSH present within these glands were separated by Concanavalin A (Con A) chromatography and polyacrylamide gel isoelectric focusing (PAG-IEF) and measured by a specific FSH radioimmunoassay (RIA) as well as a radioreceptor assay (RRA). Two distinct forms of FSH (Con A unbound and bound) were separated by Con A chromatography and detected by both RIA and RRA. These two populations of FSH were present within anterior pituitary glands of all three animal models tested. Castration before collection of anterior pituitary glands reduced the ratio of Con A unbound: bound immunoreactive FSH. When measured by RRA this reduction was not observed. When homogenates of anterior pituitary glands obtained from mature animals were separated by PAG-IEF, six distinct species of FSH were observed by RIA with isoelectric points (pI) of 6·0, 5·7, 5·3, 5·0, 4·7 and 4·2–3·8. Homogenates of anterior pituitary glands obtained from immature male hamsters did not contain one of these species of FSH (pI value, 4·7). The relative contribution of some of the species of FSH to the total amount of detectable FSH differed depending upon the endocrine status of the animal. The species with pI value of 4·2–3·8 did not show any receptor-binding activity in any of the three models studied. The overall ratio of the activity of FSH measured by RRA compared with RIA was highest in anterior pituitary glands from intact mature and immature hamsters and lowest in anterior pituitary glands obtained from castrated animals. The RRA: RIA ratio for each species of FSH in all models tested declined as the isoelectric point of that species decreased. Thus, these results demonstrated the presence of multiple species of FSH within the anterior pituitary glands of immature and mature male hamsters. The relative proportions and receptor-binding activities of these species differed according to the isoelectric point and the pattern of hormone secretion at the time of collection of pituitary glands. Gonadal and other endocrine factors may influence not only the relative amount of each species of FSH but also the receptor-binding capacity of the FSH species synthesized by the anterior pituitary gland.
Hyperprolactinaemia attenuates the gonadotrophin releasing hormone receptor response to gonadectomy in rats
Authors: Clayton R. N. , Bailey L. C.
Published: December 2008

Measurement of pituitary gonadotrophin releasing hormone (Gn-RH) receptor content provides a qualitative index of prior exposure of the pituitary gland to endogenous Gn-RH. The effect of moderate hyperprolactinaemia (serum prolactin = 95–250 μg/l), achieved with three pituitary grafts beneath the renal capsule, on the pituitary Gn-RH receptor content and serum LH responses to gonadectomy of adult rats has been studied. In males the presence of hyperprolactinaemia for 7 days completely prevented the increase in Gn-RH receptor content 3 days after castration and inhibited the serum LH rise by 45%. By 6 days after castration, Gn-RH receptors had increased in the hyperprolactinaemic castrated animals but values were 33% lower than in sham-grafted controls, while the serum LH increase was attenuated by 30%. Pituitary LH content was also lower in grafted castrated animals 6 days after castration. Hyperprolactinaemia for 3 weeks had no effect on Gn-RH receptors or pituitary LH content of intact male rats, although basal serum LH was decreased by 50%. Hyperprolactinaemia also attenuated the increases in Gn-RH receptors, serum LH and pituitary LH which occurred 6 days after ovariectomy in female rats. In all experiments the pituitary content of prolactin was reduced by 80–90% in animals bearing pituitary grafts. These results suggest that hyperprolactinaemia restricts the Gn-RH receptor response to gonadectomy by decreasing endogenous hypothalamic Gn-RH secretion.
A study of carbohydrate metabolism in 'delayed' and 'activated' mouse blastocyst and uterus
Authors: Sakhuja Deepa , Sengupta Jayasree , Manchanda S. K.
Published: December 2008

Several regulatory enzymes of carbohydrate metabolism were studied in blastocysts and uteri of mice in which implantation had been delayed and of oestrogen-activated mice, and compared with those of normal mice just before implantation on day 4 of pregnancy. A significant increase in the activities of phosphofructokinase and pyruvate kinase was observed but the level of lactate dehydrogenase declined in delayed blastocysts. Carbohydrate metabolism in the uterus remained essentially unchanged during the delay period. A study of uterine mitotic patterns showed a steady increase in stromal mitosis after administration of oestradiol to animals in which implantation had been delayed.
Inhibition of prostatic growth in rats by 6-methylene-4-pregnene-3,20-dione
Authors: Petrow Vladimir , Padilla G. M. , Kendle Keith , Tantawi A.
Published: December 2008

6-Methylene-4-pregnene-3,20-dione, a potent irreversible inhibitor of rat prostate 5α-reductase in vitro, markedly inhibited the growth of the ventral prostate and seminal vesicles in immature rats when administered s.c. in a daily dose of 100 mg/kg body weight for 35 days. Kidney and testes weights were reduced, together with some reduction in body weight. In the mature rat treated with this steroid in a dose of 40 mg/kg body weight per day for 11 days, marked regression in ventral prostate and seminal vesicles was observed.
Immediate in-vivo effect of corticosterone on glucose-induced insulin secretion in the rat
Authors: Billaudel B. , Sutter B. Ch. J.
Published: December 2008

The effect of infused corticosterone (300 μg/h per kg body wt) on the concentrations of insulin in the plasma of the rat was examined (1) when glucose concentration was basal, (2) at standardized glucose levels attained by modulated glucose infusion and (3) in response to a standard or a modulated glucose pulse. There was no effect of corticosterone on the levels of plasma insulin when the glucose concentrations were either basal or raised in response to the standard pulse of glucose. However, when glucose was infused a significantly reduced plasma level of insulin was detected after 60 min when the glucocorticoid was present and this level remained significantly reduced after the modulated pulse of glucose. Thus the infusion of corticosterone leads to an acute depression of the concentrations of insulin in the plasma and of their response to a glucose pulse only when the hormone acts in the presence of a concentration of glucose in the plasma that is insulin-stimulatory.
Reciprocal changes in serum 3,3′,5′-tri-iodothyronine concentration and the peripheral thyroxine inner ring monodeiodination during food restriction in the young pig
Authors: Ślebodziński A. B. , Brzezińska-Ślebodzińska E. , Drews R.
Published: December 2008

Utilizing the difference in pH optima between two distinct enzyme systems responsible for the thyroxine (T4) inner and outer ring monodeiodination, and a specific radioimmunoassay for iodothyronines, the net T4 conversion to 3,3′,5′-tri-iodothyronine (rT3) and 3,5,3′-tri-iodothyronine (T3) in growing pigs kept under various food restrictions was determined in vitro. It has been found that fasting lowers deiodination of T4 to T3 by liver and kidney homogenates. The conversion of T4 to rT3 was reduced in the liver but not in the kidney, unless the animals were completely fasted. During food restriction serum T4 and T3 decreased whereas rT3 increased, which indicated that the serum rT3 level is not a good reflection of T4 to rT3 converting activity in the liver or kidney. The data suggest that a rise in rT3 reflects a lowered degradation rate of the hormone or an increased secretion by the thyroid gland rather than changes in rT3 neogenesis in the periphery.
Preparation and steroidogenic properties of purified zona fasciculata and zona reticularis cells from the guinea-pig adrenal gland
Authors: Hyatt P. J. , Bell J. B. G. , Bhatt K. , Tait J. F.
Published: December 2008

Mixtures of zona fasciculata (ZF) and zona reticularis (ZR) cells, obtained by enzyme dispersion of decapsulated guinea-pig adrenal glands, were separated either by unit gravity sedimentation or by equilibrium density sedimentation. There was no evidence of deleterious effects on ultrastructural integrity or the ability of cells to respond to (1–24)ACTH (Synacthen) after either separation technique. Unit gravity sedimentation gave one fraction in which 90% of the cells were from the ZR and another fraction in which 70% of the cells were from the ZF. Equilibrium density sedimentation of cell mixtures on Percoll gradients gave fractions containing either 90% pure ZR or 95% pure ZF cells.

Cortisol, 11-deoxycortisol, corticosterone, deoxycorticosterone, 11 β-hydroxyandrostenedione and androstenedione were all formed from [14C]pregnenolone on incubation with purified preparations of both types of cell. No product was seen to be unique to either cell type although ZR cells appeared deficient in 11β-hydroxylase activity relative to ZF cells. The ratio of androstenedione to cortisol (formed either from labelled pregnenolone or from endogenous precursors) was higher for ZR cells than for ZF cells. When the purer cells obtained by equilibrium density sedimentation were studied, it was found that (1–24)ACTH stimulated greater steroid production (both androstenedione and cortisol) by the ZF cells compared with the ZR cells.
Effect of porcine follicular fluid preparations on gonadotrophin secretion by the mouse pituitary gland in vitro
Authors: Kato K. , Sairam M. R. , Ramasharma K.
Published: December 2008

The acute effects of pooled porcine follicular fluid (PFF), before and after various methods of processing to eliminate steroids, were studied on the luteinizing hormone releasing hormone (LH-RH)-induced release of FSH and LH by whole pituitary glands, from 34-day-old mice, incubated in vitro for 3–4 h. Charcoal treatment of PFF eliminated the steroids and reduced the inhibitory potency on gonadotrophin secretion. On the other hand, dialysis or ultrafiltration (mol. wt > 10 000) did not reduce the inhibitory activity on gonadotrophin secretion.

Of the three steroids tested, only oestradiol at a concentration of 10−10 mol/l inhibited FSH and LH secretion in vitro. This inhibitory effect was counteracted by the inclusion of the oestrogen antagonist tamoxifen in the incubation medium. The presence of tamoxifen did not decrease the suppression of FSH and LH induced by PFF, suggesting that the inhibition observed under the conditions of incubation was not due to oestrogen. Preincubation of mouse pituitary tissue for 1 h with PFF reduced the subsequent release of bioactive FSH and LH induced by LH-RH. The inhibitory effect of PFF was rapid and sustained. The continuous presence of PFF throughout the incubation period was not necessary for manifestations of the inhibitory effects on gonadotrophin release. The suppression of gonadotrophin secretion was related to the dose of PFF with the curve showing a biphasic pattern. The degree of FSH suppression was uniformly greater than that of LH, showing the preferential nature of the inhibitory effect of PFF. At high doses of PFF, the degree of FSH suppression was decreased significantly. This effect on LH release was less pronounced.

The inhibition caused by PFF in the in-vitro incubation procedure was not due to destruction of LH-RH or the released gonadotrophins.
Oestrogen secretion by in-vitro perfused testes: species comparison and factors affecting short-term secretion
Authors: Thompson D. L. , Ewing L. L. , Lasley B. L.
Published: December 2008

Testes from mature rats, rabbits, hamsters, guinea-pigs and dogs were perfused in vitro with added gonadotrophins to study the qualitative and quantitative aspects of oestrogen secretion by these species. After separation by high performance liquid chromatography (HPLC), the major oestrogen secreted by the testes of all five species was oestradiol-17β; lesser amounts of oestrone were also detected for all species. Secretion rates of oestradiol and testosterone were determined for one testis from each of six animals of each species after purification by HPLC. Oestradiol and testosterone secretion varied (P < 0·05) among species on both per testis and per gram of testis bases. The rabbit, which was a high secretor of oestradiol, was used in subsequent experiments to study the factors which affect short-term oestradiol secretion by perfused testes. Luteinizing hormone (NIAMDD-LH-S21) at 100 ng/ml significantly stimulated oestradiol secretion by 2·9-fold and increased testosterone secretion by 155-fold. Follicle-stimulating hormone (NIH-FSH-S11) had no significant effect on secretion of either steroid. In a time-course study in which LH stimulation was started after 45 min of control perfusion, the rates of increase in oestradiol and testosterone secretion over time were similar. Increasing amounts of testosterone added directly to the arterial perfusion medium (0–10 μg/ml) resulted in an increase in oestradiol secretion in the absence of gonadotrophins. Oestradiol secretion increased in a dose-dependent manner up to 1·0 μg testosterone/ml; there was no further stimulation of oestradiol secretion at 10 μg testosterone/ml. When testes were perfused with saturating concentrations of testosterone (10 μg/ml) neither LH nor FSH at 100 ng/ml increased oestradiol secretion above control values. It appears that the major factor affecting oestradiol secretion by in-vitro perfused rabbit testes is the amount of substrate (testosterone) available for aromatization.
Time-course of release and synthesis of luteinizing hormone, follicle-stimulating hormone and prolactin from rat pituitary glands in vitro
Authors: Apfelbaum Marta E.
Published: December 2008

To study the time-course of release and synthesis of LH, FSH and prolactin, anterior pituitary glands from ovariectomized rats were incubated for different time-intervals between 0 and 4 h.

Comparable patterns of release and synthesis of LH and FSH as a function of the incubation time were observed. It was possible to distinguish two phases in the profiles of secretion of both gonadotrophins. During the first phase, from 0–2 h, release was associated with a corresponding decrease of the hormone concentrations within the gland but no overall changes in total LH and FSH production. During the second phase, between 2 and 4 h, a progressive reaccumulation of both gonadotrophins occurred in spite of the continuous release of hormones into the medium, reflecting formation of new immunoassayable material. These results suggest that the increased synthesis ensues as a secondary phenomenon arising from the release of the hormones from the tissue. The time-course of release and synthesis of prolactin showed different dynamics during the course of incubation. High levels of prolactin were released and synthesized when the adenohypophysis was incubated in vitro. Considerably larger amounts of this hormone were found in the medium than in the tissue from the first hour of incubation. After a lag of about 40 min synthesis of prolactin was increased in parallel with its release. This led to the assumption that both prolactin synthesizing and releasing processes occurred simultaneously from the early stages of the incubation. Comparatively, prolactin-secreting cells had a very fast and LH-secreting cells a low rate of turnover; FSH-secreting cells were intermediate between the two.

These results indicate that (1) the increase in release of LH, FSH and prolactin into the medium precedes that of hormone synthesis and (2) the initial depletion of the pituitary gland as a result of hormone release could act as a stimulus for synthesis, leading to the reestablishment of hormonal storage levels.
Bovine growth hormone fragment (1–133) has in-vitro somatomedin-like activity
Authors: Liberti J. P. , Durham L. A.
Published: December 2008

Thrombin digestion of bovine growth hormone (1–191) resulted in cleavage of the peptide bond between amino acid residues 133 and 134. Native growth hormone and purified peptides (1–133) and (134–191) were assayed for somatomedin-like activity. Peptide (1–133), ranging in concentration from 0·15–15 nmol/l, stimulated in-vitro uptake of [3H]thymidine by rat costal cartilage. None of the other peptides was biologically active.
Receptors for insulin and insulin-like growth factor in cultured arterial smooth muscle cells depend on their growth state
Authors: Pfeifle B. , Ditschuneit H.
Published: December 2008

The binding of 125I-labelled insulin and 125I-labelled insulin-like growth factor (IGF) to cultured arterial smooth muscle cells from rats was studied during various growth states of the cells. The level of binding of 125I-labelled insulin to the cells was low in growing cells and high in stationary cells. The level of 125I-labelled IGF binding to the cells was high in growing cells and low in stationary cells. In addition, the effect of unlabelled IGF and insulin on the binding of both 125I-labelled hormones to the cells was examined during various growth states. In growing cells insulin displaced 125I-labelled insulin from its binding sites; IGF competed weakly with 125I-labelled insulin for the binding sites. In parallel, IGF displaced 125I-labelled IGF binding whereas insulin competed weakly with 125I-labelled IGF for the binding sites. In stationary cells both hormones displaced 125I-labelled IGF binding. Insulin-like growth factor also displaced 125I-labelled insulin binding whereas insulin could not significantly displace 125I-labelled insulin from the binding sites. Insulin only competed with 125I-labelled insulin for the binding sites after removal of the fetal calf serum from the culture medium.
Serum somatomedin C concentrations in the fetal sheep increase markedly during gestation
Authors: Handwerger S. , D'Ercole A. J. , Underwood L. E. , Gluckman P. , Liggins G. C.
Published: December 2008

Serum somatomedin C concentrations in fetal sheep and pregnant ewes from days 51 to 149 of gestation were determined by specific radioimmunoassay. In the fetus (n = 61 samples) serum somatomedin C concentrations, fitted to a regression curve, increased significantly with advancing gestation from 0·44 units/ml at 51 days to 3·99 units/ml at 149 days, an increase of 806% (P < 0·001). In the pregnant ewes (n = 14 samples), serum somatomedin C did not change during gestation. The temporal relationship between the marked increase in fetal somatomedin C concentrations and the acceleration of fetal growth is consistent with the hypothesis that somatomedin is important in the stimulation of fetal growth.
The corticotrophic cells of the canine pituitary gland in pituitary-dependent hyperadrenocorticism
Authors: McNicol A. M. , Thomson H. , Stewart C. J. R.
Published: December 2008

The distribution of specifically stained corticotrophic cells has been studied in the pituitary glands of 11 dogs with pituitary-dependent hyperadrenocorticism. The results suggest that the disease is not a single entity, and that some cases are caused by primary abnormality of the pituitary gland whereas others appear to be the result of dysfunction of the hypothalamus or central nervous system.

The patterns correspond closely to those demonstrated in the human pituitary gland in Cushing's disease, and confirm that the canine disease is a useful model for the study of the pathogenesis of the variants of the condition.
Influence of streptozotocin-induced diabetes in pregnant rats on plasma corticosterone and progesterone levels and on cytoplasmic glucocorticoid receptors in fetal tissues
Authors: Mulay S. , Solomon S.
Published: December 2008

Administration of a dose of 45 mg streptozotocin/kg on day 2 of gestation produced a diabetic state in pregnant rats and was associated with fetal hyperinsulinaemia. Although there was no evidence of fetal macrosomia, the ratio of fetal liver and lung weight to body weight was greater in fetuses of diabetic rats, suggesting an increase in the size of these organs relative to the body weight.

Maternal and fetal plasma corticosterone levels of diabetic rats between 19 and 22 days of gestation was significantly lower than the corresponding control values. Maternal plasma progesterone levels of diabetic rats were lower than controls on days 19 and 20 of gestation, but higher than controls on day 21 of gestation. The absence of pregnancy-related changes in maternal and fetal plasma corticosterone levels and maternal progesterone levels in diabetic rats suggest that adrenocortical function as well as ovarian and/or placental function may be impaired, which may in turn be related to the observed delay in parturition of approximately 18 h as well as to the low survival rate of the pups.

There was a small increase in the cytoplasmic glucocorticoid receptor concentration in the lung but not in the liver of fetuses of diabetic mothers when compared with fetuses of controls, suggesting that the increased receptor concentration may be a compensatory mechanism to overcome the effect of decreased corticosterone levels and increased insulin levels in the fetuses of diabetic rats.
Radioimmunoassays for individual rat neurophysins
Authors: North W. G. , LaRochelle F. T. , Hardy G. R.
Published: December 2008

Radioimmunoassays are described for vasopressin-associated rat neurophysin (VP-RNP), oxytocin-associated rat neurophysin (OT-RNP) and a major metabolic derivative of oxytocin-associated rat neurophysin (OT-RNP′). The cross-reactions in the radioimmunoassay for VP-RNP with preparations of OT-RNP and OT-RNP′ were 4 and 2%. However, the very small values found for VP-RNP using this radioimmunoassay in concentrated extracts of neural lobes from rats homozygous for the condition of hypothalamic diabetes insipidus (DI) indicate that the sum of the cross-reactions of OT-RNP and OT-RNP′ in the assay is <0·02%. The radioimmunoassay for OT-RNP showed a 100% cross-reaction with OT-RNP′ and a 4% cross-reaction with VP-RNP, while cross-reactions in the radioimmunoassay for OT-RNP′ with OT-RNP and VP-RNP were 17 and 3%. All three radioimmunoassays had a range of measurement from 20 to 1280 pg protein (2–132 fmol). The radioimmunoassays for VP-RNP and OT-RNP were used to measure neurophysin levels in the neural lobes and serum of Long–Evans rats and rats homozygous and heterozygous for DI. Neurophysin values in neural lobes were compared with values for oxytocin and vasopressin obtained by radioimmunoassay. On a molar basis the storage levels of vasopressin in Long–Evans rats were similar to those of VP-RNP; oxytocin levels were similar to the levels of total OT-RNP (OT-RNP + OT-RNP′). The storage levels in oxytocinergic and vasopressinergic neurones were similar. Total OT-RNP and oxytocin levels were similar in homozygous DI rats, while vasopressin and VP-RNP in these animals were <0·013 and <0·1% of the oxytocin and OT-RNP levels respectively. Long–Evans rats given 2% NaC1 for 96 h had drastically reduced storage of all four neurohypophysial peptides, but there was no significant change in their subcellular distribution when compared with control animals. This is taken as evidence that the readily releasable pool is not extragranular. Oxytocin and total OT-RNP were reduced to about 50% by depriving homozygous DI rats of water for 24 h. The storage levels of oxytocin and OT-RNP in female homozygous DI rats were twice those of their male counterparts. Normal serum values of VP-RNP and OT-RNP were 221±41 and 312±43 ng/l for males, and 280 ± 40 and 462±116 ng/l for females. Heterozygous DI rats (all female) had serum values of 165 ± 5 ng VP-RNP/1 and 1130±136 ng OT-RNP/1. In the serum of homozygous DI rats VP-RNP levels were below detectable limits; OT-RNP levels of rats with free access to water were 442± 37 ng/l for males and 959 ± 121 ng/l for females. These values are approximately twice those in Long–Evans rats. In water-deprived homozygous DI rats values of OT-RNP were increased threefold to 1202± 87 ng/l in males and twofold to 1822± 259 ng/l in females. Data indicate that female DI rats have twice the production/release rate of OT-RNP as males.
Prolonged oestrogen treatment inhibits growth hormone-induced growth in hypopituitary dwarf mice
Authors: Holder A. T. , Clark R. G. , Preece M. A.
Published: December 2008

This paper presents an investigation into the effects of prolonged oestrogen treatment (20 days) on basal growth and on growth stimulated by GH in hypopituitary dwarf mice. Body 35SO42− weight and tail length were measured during the treatment period and uptake of S04 into costal cartilage in vivo at the end of the treatment period. This study confirmed that treatment with human GH promotes a dose-dependent increase in body weight, tail length and uptake of 35SO42− in vivo; there was a highly significant correlation between these responses. Treatment with oestrogen alone had no significant effect on any of the parameters measured. All groups receiving combined oestrogen and human GH treatment showed a significant increase in body weight and tail length compared with animals receiving the same dose of oestrogen alone. However, the increase in body weight and tail length was significantly less in animals given the highest dose of oestrogen plus human GH than that observed in animals treated with the same dose of human GH alone. Treatment with oestrogen had no significant effect on the uptake of 35SO42− stimulated by human GH. Possible mechanisms for the growth-inhibiting effects of oestrogens are discussed.
Effects of oestradiol-17β and diethylstilboestrol on progesterone-induced protein (avidin) production in chick oviduct: evidence for differences in the actions of steroidal and non-steroidal oestrogens
Authors: Niemelä A. O. , Elo H. A.
Published: December 2008

The effects of diethylstilboestrol (DES) and oestradiol-17β on the production of a progesterone-induced protein (avidin) in the chick oviduct were studied. Chicks were pretreated with DES or oestradiol-17β daily for 3–28 days and progesterone (10 or 20 mg/kg) was administered 24 h after the last oestrogen injection. Diethylstilboestrol (2–20 mg/kg) administered with progesterone to chicks pretreated with DES increased avidin production after 16 h compared with that induced by progesterone alone. The potentiation of avidin production appeared even when DES was administered between 6 h before and 13 h after progesterone injection. The length of DES pretreatment did not affect the potentiation. The amount of avidin induced by progesterone in the chicks pretreated with oestradiol-17β was similar to that in the chicks pretreated with DES. Oestradiol-17β (2–20 mg/kg) administered with progesterone, however, did not affect avidin production. The results suggest that DES may have some non-oestrogenic effects on the production of progesterone-induced proteins.
Neurotensin release from rat hypothalamus in vitro
Authors: Shennan K. I. J. , Sheppard M. C.
Published: December 2008

Neurotensin is a hypothalamic peptide which inhibits secretion of TSH in the rat in vivo. We have demonstrated a calcium-dependent release of neurotensin from incubated rat hypothalamus in response to depolarizing stimuli, as well as a dose-dependent stimulatory effect of tri-iodothyronine (T3) on neurotensin secretion. We suggest that part of the neuroendocrine control of TSH secretion involves the interaction of T3, neurotensin and TSH; the presence of neurotensin in extracts of anterior pituitary gland is further evidence for its hypophysiotrophic role.
Effects of acetazolamide on iodide transport, electrolyte distribution and activities of carbonic anhydrase, Na+,K+-ATPase and HCO3−-ATPase in mouse, rat and turtle thyroid glands
Authors: Chow S. Y. , Kemp J. W. , Woodbury D. M.
Published: December 2008

The effects of acute (200 mg/kg) and chronic (20 mg/kg per day for 7 days) administration of acetazolamide on iodide transport, electrolyte distribution, and on carbonic anhydrase (CA), Na+,K+-ATPase and HCO3−-ATPase activities were evaluated in mouse thyroid glands. The effects of withdrawal from chronic administration of acetazolamide were also assessed. A single injection of a large dose of acetazolamide increased iodide uptake and completely inhibited CA activity. Chronic administration of acetazolamide only slightly increased iodide uptake; CA inhibition was also less marked than after acute administration. After withdrawal of acetazolamide, iodide uptake decreased and CA activity recovered rapidly to the control levels. Chronic treatment with acetazolamide decreased the content of water and increased the contents of protein and DNA in thyroid tissues. Withdrawal of the drug resulted in an increase in Na+ and K+ contents and a decrease in water content of this gland. These data demonstrate that CA activity has an inverse relation to the iodide transport and a direct relation to Cl− content in the thyroid. Chronic administration of acetazolamide also increased iodide uptake by the thyroid glands of hypophysectomized rats and of turtles.
Differential effects of ornithine on placental lactogen and growth hormone secretion in the pregnant ewe and fetus
Authors: Grandis A. S. , Handwerger S.
Published: December 2008

The intravenous infusion of ornithine (0·5–0·9 g/kg) into five fetal sheep of 116–141 days gestation caused no significant change in concentrations of fetal plasma placental lactogen (PL) or GH as determined by specific homologous radioimmunoassays. In contrast, the intravenous infusion of ornithine (0·3–0·5 g/kg) into three of the ewes caused a 144·5 ± 74·7 (s.e.m.)% increase in maternal plasma PL concentrations and a 255·2 ± 55·0% increase in maternal GH concentrations. Fetal PL concentrations remained unchanged despite the large increase in maternal PL concentrations. This study, which indicates a differential effect of ornithine on PL and GH secretion in the mother and fetus, suggests that the factors regulating PL and GH secretion in the mother and fetus are distinct.
Interrelationship between pituitary-testicular axis activity and raised environmental temperature in the rat
Authors: Chap Z. , Bedrak E.
Published: December 2008

The relationship between the testes and the adenohypophysis in rats exposed to heat was assessed by (1) the determination of adenohypophysial concentrations of FSH, LH and prolactin as well as serum levels of prolactin and testosterone in rats maintained at 35 °C for various periods of time and (2) the elucidation of the responsiveness to stimulation with gonadotrophin releasing hormone (GnRH) or human chorionic gonadotrophin (hCG) of the rat acclimatized for 40 days to a temperature of 35 °C. The results demonstrated that while heat exposure caused a transient change in the concentration of FSH and LH in the adenohypophysis, the level of prolactin increased by twofold within 24 h and remained significantly higher than in control animals. A concurrent significant decrease in the concentrations of prolactin and testosterone in the serum of rats exposed to heat was also observed. Challenging the rat with exogenous GnRH resulted in a significant increase in serum LH and FSH concentrations in control rats and rats exposed to heat, but the magnitude of the rise in LH was greater in the latter group. However, this phenomenon was not accompanied by a rise in serum testosterone concentration in the rat exposed to heat. Challenging the animals with hCG provoked an increase in serum testosterone, but the magnitude of the rise was greater by far in the control rats. It is concluded that exposure of the intact rat to increased environmental temperatures is accompanied by accumulation of prolactin in the lactotrophs, reduced serum prolactin concentration, decreased capacity of the testes to synthesize testosterone and consequently reduced serum testosterone concentration. These phenomena are independent of the capacity of the adenohypophysis to synthesize LH.
Plasminogen activator in rat ovary during the ovulatory process: independence of prostaglandin mediation
Authors: Shimada Hayato , Okamura Hitoshi , Noda Yōichi , Suzuki Akira , Tōjō Shimpei , Takada Akikazu
Published: December 2008

To elucidate the possible roles of increased plasminogen activator (PA) in follicular rupture and to investigate whether prostaglandins participate in ovarian PA synthesis in vivo, enzyme activities were sequentially measured by a method using the chromogenic substrate S-2251 in immature rat ovaries primed with pregnant mare serum gonadotrophin (PMSG) followed by human chorionic gonadotrophin (hCG) either alone or with a concurrent injection of indomethacin.

Before hCG injection PA activity was 0·006 ± 0·006 (s.d.) μmol/1·6 mg ovarian tissue (wet wt) per 30 min: PA activity of a saline-treated group remained at low levels (<0·018 ± 0·003 μmol/1·6 mg tissue per 30 min). In contrast, PA activity of animals given hCG alone increased after the treatment, reaching a peak value of 0·112 ± 0·071 μmol/1·6 mg tissue per 30 min 12 h later, before decreasing to 0·023 ± 0·014 μmol/1·6 mg tissue per 30 min at 32 h. Contrary to expectations, a dose of indomethacin which completely blocked ovulation had no effect on either the magnitude or the time-course of PA synthesis after hCG administration (P>0·05).

These results indicate that prostaglandins are not involved in the preovulatory synthesis of PA induced by hCG in rat ovaries and that PA is not a primary proteolytic enzyme for follicular rupture. It is suggested that PA has possible roles in cumulus detachment and/or proliferation of granulosa cells during the ovulatory process.
Incidence of ovulation in the years after the menarche
Authors: Metcalf M. G. , Skidmore D. S. , Lowry G. F. , Mackenzie J. A.
Published: December 2008

Urine for the analysis of pregnanediol was collected weekly for 3 months from 209 menstruant women aged 11–24 years who lived with their parents and from 59 women aged 17–23 years who had left the parental home. Menstrual cycles were classed as ovulatory if the 24-h pregnanediol output in the 12 days preceding menstruation was ≥ 5 μmol on a single occasion or if the total excreted on 2 days, 1 week apart, was ≥ 7 μmol.

In the first group, ovulatory incidence increased with menarchal age. Unfailing ovulation occurred in 22·9, 25·0,44·8,42·9, 63·2, 71·8 and 82·6% of those who were < 1, 1−<2, 2−<3, 3−<4, 4−< 5, 5–8 and 9–12 years from menarche. Comparable figures for the women who lived in flats and hostels were 40·0% (menarchal age, 5–8 years) and 78·6% (9–12 years).

It is concluded that a regular pattern of ovulatory menstrual cycles is established in most young women within 5 years of the menarche, and that departure from the family home is often associated with a regression to a juvenile pattern of anovulatory menstrual cycles.
Cell-density dependence of the rate of prolactin secretion from perifused rat anterior pituitary cells
Authors: Bentley A. M. , Wallis M.
Published: December 2008

Anterior pituitary glands from female rats were dispersed enzymically in the absence of dopamine. Dispersed cells (106–107) were layered onto columns containing Bio-Gel P-2 and were then perifused for 3 h with Dulbecco's Modified Eagle's Medium. The prolactin content of the perifusate and cell homogenates was determined by radioimmunoassay. Prolactin secretion during the third hour of perifusion increased as the loading of cells increased. However, the increase was not linear, and when secretion rate per 106 cells was calculated it was found that increased loading decreased the rate, which fell to a plateau of 1·3 ± 0·1 (s.e.m.) ng/min per 106 cells at a loading of about 8 × 106 cells from 3·8 ± 0·1 ng/min per 106 cells for a loading of 106 cells. This cell-density dependence of the rate of prolactin secretion in the perifusion system may be due to intercellular contact since the isolation of the tissue removes the influence of hypothalamic factors, while localized build up of prolactin (potentially causing direct autoregulation on the lactotroph) seems unlikely because of the continuous flow of medium.
Plasma somatomedin-C in fasted and refed rats: close relationship with changes in liver somatogenic but not lactogenic binding sites
Authors: Maes M. , Underwood L. E. , Ketelslegers J.-M.
Published: December 2008

Circulating levels of somatomedins in man and rats are reduced by fasting and restored by refeeding. To determine the mechanisms for these alterations in somatomedin levels, the affinities and binding capacities of 125I-labelled bovine GH (somatogenic binding sites) and of 125I-labelled ovine prolactin (lactogenic binding sites) were assessed in liver homogenates from fasted and refed rats. Correlations were made with plasma immunoreactive somatomedin-C (Sm-C) and plasma insulin.

During fasting and refeeding there was a close temporal relationship between the fall and the rise of plasma levels of Sm-C and insulin, and the number of hepatic GH binding sites. After fasting for 1 day, plasma Sm-C dropped by 68% and plasma insulin by 76% when compared with values before fasting. At the same time, GH binding capacity was significantly reduced (7·3 ± 2·8 (s.e.m.) pmol/liver v. controls, 20·3 ± 2·1 pmol/liver; P < 0·01). Refeeding for 24 h normalized plasma insulin levels and restored GH binding capacity to values before fasting (13·2 ± 2·4 v. 20·3 ± 2·1 pmol/liver; P > 0·05). Plasma Sm-C rose significantly with refeeding and returned to initial values at day 4 of refeeding (0·82 ± 0·10 v. 0·77 ± 0·07 units/ml; P > 0·05).

In contrast, changes in prolactin binding sites correlated poorly with changes in plasma Sm-C. There was a modest decline with fasting significant only after 72 h (6·8 ± 0·6 v. 13·9 ± 3·2 pmol/liver; P < 0·05), and refeeding for 24 h did not restore prolactin binding (5·7 ± 1·2 pmol/liver).

Since a number of reports suggest that fasting induces a state of tissue insensitivity to GH, our findings suggest that the reduction in hepatic GH binding capacity might be a mechanism for the fasting-induced reduction in Sm-C. The reduction in plasma insulin, which accompanies fasting, might play a permissive role in the intracellular metabolic events involved in Sm-C and GH receptor regulation.
Measurement of immunoreactive α-melanocyte-stimulating hormone in the blood of rainbow trout kept under various conditions
Authors: Bowley T. J. , Rance T. A. , Baker B. I.
Published: December 2008

Initial attempts to measure α-MSH in trout blood by radioimmunoassay proved unsuccessful due to apparent losses of immunoreactive hormone, especially in the plasma of trout adapted to a black background. An extraction protocol for α-MSH from plasma is described. Subsequent radioimmunoassay revealed progressive increases in immunoreactive α-MSH as trout became adapted to a black background. Plasma α-MSH titres were raised during fungal infection, and also showed significant differences in fish obtained from different fish farms.
Plasma concentrations of progesterone, oestradiol-17β and 13,14-dihydro-15-oxo-prostaglandin F2α in the pregnant wallaby (Macropus rufogriseus rufogriseus)
Authors: Walker M. T. , Gemmell R. T.
Published: December 2008

The concentrations of progesterone and oestradiol-17β in the maternal plasma of Bennett's wallaby, Macropus rufogriseus rufogriseus, were measured daily throughout gestation after reactivation of the diapausing corpus luteum by removal of the suckling pouch young (RPY). Progesterone increased from mean concentrations of 382–424 pmol/l (120–133 pg/ml) during lactation to reach peak concentrations of 908 ± 172 (s.e.m.) pmol/l (285 ± 54 pg/ml) (n = 8) 4 days after RPY and 971 ± 220 and 971 ± 229 pmol/l (305 ± 69 and 305 ± 72 pg/ml) (n = 7) 24 and 25 days after RPY respectively. The mean gestation length (RPY to birth) was 26·8 ± 0·6 (s.d.) days (n = 6, range 25·75–27·50 days). Immediately after birth the plasma progesterone concentration declined to 299 ± 51 (s.e.m.) pmol/l (94 ± 16 pg/ml) (n=6). Oestradiol-17β increased from mean concentrations of 291–553 pmol/l (80–152 pg/ml) during lactation to reach a peak concentration of 967 ± 331 pmol/l (266 ± 91 pg/ml) (n = 9) 1 day after RPY. The concentration declined from 7 days after RPY and fluctuated between mean concentrations of 273 and 480 pmol/l before reaching a minimum of 207 ± 69 pmol/l (57 ± 19 pg/ml) (n = 6) 19 days after RPY. A transient increase to 542 ± 207 pmol/l (n = 7) occurred at 22 days after RPY. Plasma concentrations declined to a low of 156 ± 55 pmol/l (43 ± 15 pg/ml) (n = 6) 5 days after parturition. The mean concentration of plasma 13,14-dihydro-15-oxo-prostaglandin F2α was less than 2·8 nmol/l (1 ng/ml) for all samples from 13 days after RPY until 4 days after parturition. The results suggest that oestradiol-17β may be important in the early stages of blastocyst reactivation to synergize with progesterone in stimulating uterine secretions. 13,14-Dihydro-15-oxo-prostaglandin F2α is unlikely to be involved in the birth process and any luteolytic effect is likely to be from a local production of PGF2α.
Is hirsutism an evolving syndrome?
Authors: Toscano Vincenzo , Adamo M. V. , Caiola Stefania , Foli Sonia , Petrangeli Elisa , Casilli Daniela , Sciarra Francesco
Published: December 2008

The possibility that hirsutism is an evolving syndrome rather than a static condition involving only one gland has been considered. To assess this proposal 60 untreated hirsute patients aged 12–32 years were divided into five groups according to the duration of the hirsutism (< 1, 1–2, 2–3, 3–5 and > 5 years).

Peripheral plasma concentrations of LH and FSH, androstenedione, dehydroepiandrosterone sulphate, testosterone, 5α-dihydrotestosterone, 5α-androstane-3α, 17β-diol, 5α-androstane-3β, 17β-diol, cortisol, oestradiol-17β and oestrone were determined by radioimmunoassay. When the values obtained were compared with those from normal menstruating women, the results showed that in group I there was a significant increase only in the mean plasma 5α-androstane-3α, 17β-diol concentration. The mean concentration of this steroid was also raised in all other groups. In groups II and III mean basal levels of plasma dehydroepiandrosterone sulphate were also significantly increased and showed a marked increase after ACTH stimulation (1 mg tetracosactide acetate, i.m.) as did the concentrations of androstenedione and 17α-hydroxyprogesterone. Finally, in groups IV and V, a significant increase in mean plasma concentrations of LH, androstenedione, oestrone and testosterone was found in the basal condition. The clinical picture also became gradually more severe from group I to group V.

These data suggest that hirsutism could be an evolving syndrome progressively involving peripheral androgen metabolism, the adrenal gland and finally the ovary possibly through alterations of hypothalamic-pituitary function.