bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of a fragment of human growth hormone-releasing factor in normal and 'Little' mice
Authors: Clark R. G. , Robinson I. C. A. F. 
Published: December 2008

ABSTRACT
The 'Little' mouse is characterized by a body growth rate 60% of normal due to a defect in the synthesis and storage of GH in the anterior pituitary gland. We have now investigated the effects of GH releasing factor (GRF) in these mice and in normal animals. The pituitary GH content in Little mice was only 4% of that in normal C57: +/+ mice, and was not affected by twice daily i.p. injections of human (h) GRF1-29NH2 (0·2−2 μg) for 14 days. This treatment also had no effect on body growth. In anaesthetized normal mice, single i.v. injections of 0·1 or 2 μg hGRF1-29NH2 released large amounts of GH into the plasma, whereas this peptide was ineffective in Little mice, whether or not they had been pretreated with GRF. Therefore, although pituitaries of Little mice contain significant amounts of GH, this pool is not releasable by GRF. This suggests that the dwarfism in Little mice may be partly due to a pituitary defect in GRF receptors or their stimulus-secretion coupling, rather than a deficiency in hypothalamic GRF.
J. Endocr. (1985) 106, 1–5
Induction of selective release of FSH in castrated male rats bearing an ovarian transplant by the administration of human chorionic gonadotrophin
Authors: Watanabe G. , Taya K. , Sasamoto S. 
Published: December 2008

ABSTRACT
The present study was undertaken to determine whether hypothalamic differentiation is involved in the selective release of FSH during the periovulatory period using adult male rats castrated and implanted with an ovary.
Adult male rats (70–90 days old) were castrated and an ovary obtained from a prepubertal female rat (26 days old) was immediately grafted subcutaneously. Four weeks later, human chorionic gonadotrophin (hCG, 10 i.u.) was injected i.v. into the experimentally manipulated rats to induce ovulatory changes in the grafted ovaries. Another group of similarly prepared rats was injected with 0·9% (w/v) NaCl solution as controls. After injection of hCG, plasma concentrations of FSH increased significantly by 6 h, reached peak values at 12 h and declined to control levels at 36 h. On the other hand, plasma concentrations of LH were reduced by 6 h and decreased further during the next 36 h. An abrupt fall in plasma concentrations of oestradiol-17β occurred within 3 h of the administration of hCG. Histological examination revealed that ovulatory changes and luteinization of follicles were induced in grafted ovaries by 18 h after the injection of hCG. Thirty-six hours after treatment with hCG, a set of newly formed corpora lutea was observed in grafted ovaries and plasma concentrations of progesterone were raised. Treatment with oestradiol-17β did not inhibit the selective release of FSH after the administration of hCG, suggesting that the abrupt decrease in secretion of oestradiol-17β from the grafted ovary is not involved in the occurrence of the FSH surge.
These results indicate that a selective release of FSH can be induced in castrated male rats bearing an ovarian transplant probably due to decreased secretion of inhibin by the luteinized follicles in the grafted ovaries. Sex differentiation of the hypothalamus is not, therefore, involved in the selective surge of FSH.
J. Endocr. (1985) 106, 31–36
Antioestrogen inhibition of oestradiol-induced alterations in hypothalamic noradrenaline turnover
Authors: Hiemke C. , Poetz B. , Ghraf R. 
Published: December 2008

ABSTRACT
Long-term (4–6 weeks) ovariectomized rats were injected with either oestradiol benzoate (OB; 20 μg s.c.) or monohydroxytamoxifen (MTAM; 0·2 mg i.p.) plus OB. Oestradiol benzoate was administered at 12.00 h on day 0 and MTAM was given immediately before OB, followed by further injections twice daily to maintain sufficiently high antioestrogen levels. When given alone, OB reduced the serum levels of LH during the morning (08.00–09.00 h) and afternoon (17.30–18.30 h) hours of day 3 after priming. The feedback actions of OB on LH release were accompanied by time-dependent alterations of noradrenaline turnover in the preoptic–anterior hypothalamic brain area (POAH). On day 3 after priming the noradrenaline turnover rate was reduced in the morning and increased in the afternoon. The increase correlated with an enhanced sensitivity of the LH secretory system to progesterone. The antioestrogen MTAM blocked the OB-induced sensitization of LH release to the stimulatory action of progesterone and interfered with the stimulatory long-term effect of oestradiol on hypothalamic noradrenaline turnover.
The data strongly support the view that the oestrogen-induced afternoon increase of noradrenaline turnover in the POAH represents a pre-requisite for the induction of LH surges. The stimulatory effect of oestradiol on hypothalamic noradrenaline turnover seems to be mediated by a classical oestrogen receptor mechanism.
J. Endocr. (1985) 106, 37–42
Multiple molecular forms of prolactin during pregnancy in women
Authors: Pansini F. , Bergamini C. M. , Malfaccini M. , Cocilovo G. , Linciano M. , Jacobs M. , Bagni B. 
Published: December 2008

ABSTRACT
The distribution of isomorphic forms of prolactin in the serum of pregnant women was studied by gel filtration chromatography. Using this technique we were able to resolve three peaks, detected by radioimmunoassay: they were termed 'big-big', 'big' and 'little' prolactin in order of decreasing size, with approximate molecular weights > 100 000, 50 000 and 21 000 respectively. They displayed a comparable immunoreactivity to the antiserum employed in the radioimmunoassay, as determined in competition experiments. The relative amount of each hormone form in serum changed during the third trimester of pregnancy. At week 33 of pregnancy, 'little' prolactin accounted for 63·2 ± 7·7% of the total circulating hormone present in the serum of five normal pregnant women. During the progression of pregnancy, there was a gradual increase in the low molecular weight prolactin, so that, at the time of delivery, the larger forms of the hormone were present only in small amounts.
J. Endocr. (1985) 106, 81–85
Iodothyronine kinetics in the rabbit: an experimental model
Authors: Pearce C. J. , Byfield P. G. H. , Veall N. , Himsworth R. L. 
Published: December 2008

ABSTRACT
Turnover studies of thyroxine (T4), 3,5,3′-tri-iodothyronine (T3) and 3,3′,5′-tri-iodothyronine (rT3) have been performed in the rabbit. A novel modification of a conventional radioimmunoassay has been used to measure specific 125I-labelled iodothyronines in small volumes of plasma in the presence of other 125I-labelled metabolites. Kinetic analysis of plasma disappearance of tracer was performed by a new theoretical approach. For T4 the mean (±s.d.) plasma concentration, clearance and production rates were 34±12 nmol/l, 109±19 ml/kg per day and 3·7±1·4 nmol/kg per day respectively (n = 9). For T3 the corresponding values were 2·04±0·42 nmol/l, 1·52±0·29 litres/kg per day and 3·07±0·76 nmol/kg per day (n = 8), and for rT3 0·12±0·04 nmol/l, 5·7±1·7 litres/kg per day and 0·69±0·23 nmol/kg per day (n = 8). The combination of these two new methodologies affords a simple and convenient means of studying iodothyronine metabolism under normal and abnormal conditions. The techniques employed may be generally applied to turnover studies of other compounds of physiological interest which can be measured by radioimmunoassay.
J. Endocr. (1985) 106, 87–94
Age, sex and gonadal influences on oestrogen receptor content in the rat liver
Authors: Rochman H. , Rosner B. , Mathey B. , Getz G. E. , Hospelhorn V. 
Published: December 2008

ABSTRACT
Liver cytosol oestrogen receptor (OR) content of intact and gonadectomized male and female rats of defined age (1–18 months) was measured by the controlled pore glass bead assay. The OR content of animals of both sexes aged 3 weeks was low to insignificant (0·12±0·04 (s.e.m.) pmol/g wet wt liver). In the intact animal, liver OR reached maximum levels at an earlier age in the male (1·35±0·12 pmol/g at 28–32 weeks) than in the female (4·89±0·17 pmol/g at 44–52 weeks). In the mature female the OR is thus maintained at a level threefold greater than in males of comparable age.
Levels of OR in the gonadectomized male tended to be higher, at all ages, than those in the intact male but this difference was not statistically significant. Ovariectomy was associated with a decreased OR content in rats aged less than 6 months and an increase in the older rats, but these effects (of ovariectomy) were not statistically significant.
In the females, regression analysis of pooled data, combining all ages, indicated a significant positive correlation between OR and liver wet weight, independent of gonadal status; no such relationship was found with the males.
The results indicate that factors influencing liver cytosol OR content include maturity, age and sex whereas the gonads have little obvious effect. These findings lend further support to the concept that sex differences exist in the liver.
J. Endocr. (1985) 106, 95–102
Liver angiotensin II receptors in the rat: binding properties and regulation by dietary Na+ and angiotensin II
Authors: Sernia C. , Sinton L. , Thomas W. G. , Pascoe W. 
Published: December 2008

ABSTRACT
Recent evidence suggests that angiotensin II (AII) acts on the liver via specific receptors. The aims of this study were to examine the general binding properties of these receptors in the rat and to determine the role of dietary Na+ and AII in the regulation of AII receptors.
Binding of 125I-labelled Ile5-AII to liver membranes was saturable and behaved as a single class of sites with an affinity (Ka) of 2·9 l/nmol and a Hill coefficient of 0·99. Kinetic analysis of AII binding gave estimates for the rates of association and dissociation of 42 l/μmol per min and 1·5 × 10−2/min respectively. The binding of analogues exhibited the following order of potency: Val5-AII > Ile5-AII > AIII > Sar1-Ala8-AII > Sar1-Gly8-AII > AI > des-Asp-AI > C4−C8 pentapeptide > Phe1-Tyr8-AII > neurotensin > luteinizing hormone-releasing hormone. Binding was enhanced by Mg2+ and Ca2+ and inhibited by EDTA and the reducing agent dithiothreitol. Low dietary Na+ affected in a biphasic manner both the Ka and concentration (Ro) of liver AII receptors. Initially, Ro decreased from 25·9±3·8 (control) to 16±1·9 (s.e.m.) pmol/g tissue by 1·5 days but thereafter it rapidly increased to 47·3±8·7 pmol/g tissue (3·5 days) and remained elevated to the end of the experiment, 8·5 days later. The Ka initially increased from 2·7±0·3 (control) to 4·3±0·5 l/nmol (1·5 days) and then decreased steadily to 1·2±0·1 l/mol (8·5 days). The effect of AII was examined by infusing 24 pmol AII/kg per min for 5 days into the jugular vein by subcutaneous osmotic minipumps. The response was qualitatively similar to that for low dietary Na +. It was concluded that the rat liver has a high content of specific AII receptors that are responsive to changes in Na+ and AII.
J. Endocr. (1985) 106, 103–111
Prolactin permits the expression of a circadian variation in insulin receptor profile in hepatocytes of the golden hamster (Mesocricetus auratus)
Authors: Cincotta A. H. , Meier A. H. 
Published: December 2008

ABSTRACT
Insulin receptor profile was determined in freshly isolated hamster hepatocytes at two times (07.00 and 16.00 h) during a 14-h daily photoperiod (08.00–22.00 h). The hamsters were pretreated for 5 days with bromocriptine (to inhibit prolactin release), bromocriptine and prolactin replacement, or control saline injections. The insulin receptor profile was determined by Scatchard plot analysis. The insulin receptor number (high and low affinity) was three times greater at 07.00 than at 16.00 h among saline-injected controls. However, their affinities did not differ. Bromocriptine pretreatment reduced (70%) both the high and low affinity receptor numbers and increased the affinity of the high affinity receptor at 07.00 h. Prolactin replacement in bromocriptine-treated hamsters restored the receptor profile at 07.00 h to control values. These data indicate that prolactin facilitates the expression of a circadian variation in insulin receptor profile.
J. Endocr. (1985) 106, 177–181
Thyrotrophin stimulation of mitogenesis of the rat thyroid cell strain FRTL-5: a metaphase index assay for the detection of thyroid growth stimulators
Authors: Ealey P. A. , Emmerson J. M. , Bidey S. P. , Marshall N. J. 
Published: December 2008

ABSTRACT
Thyroid-stimulating hormone (TSH) has been shown to stimulate mitosis in cultures of the continuous thyroid cell strain FRTL-5, and this system may be used to quantify the growth-promoting effects of thyroid stimulators. Removal of TSH from the culture medium led to a progressive decline in the metaphase index (MI) to zero, after 7 days. Thus the cell culture conditions may be manipulated so that metaphases are absent in control cultures, i.e. in the absence of TSH. Restimulation with TSH caused an increase in mitosis only after a lag-phase of 20–24 h. A maximum MI was observed between 40 and 50 h, with a secondary peak between 70 and 75 h. An immunoglobulin G (IgG) preparation from a thyrotoxic patient with a small goitre which was a potent stimulator of adenylate cyclase in these cells produced a similar time-course. A dose–response relationship to TSH was obtained 47 h after addition of the hormone. Significant stimulation was observed with 10 mu. TSH/1, and maximal stimulation with 1 unit TSH/1; the highest dose tested (10 units TSH/1) slightly decreased the MI below the maximum. Stimulation of these cells appeared to be TSH specific, since FSH, human chorionic gonadotrophin, LH and isoproterenol did not induce mitosis. Epidermal growth factor under the experimental conditions employed was unable to induce mitosis. However, an increase in mitosis was observed with the adenylate cyclase stimulator forskolin. These experiments confirm the mitogenic properties of TSH and we describe a metaphase index assay for the detection of thyroid growth promotors.
J. Endocr. (1985) 106, 203–210
Intersexuality in five pigs, with particular reference to oestrous cycles, the ovotestis, steroid hormone secretion and potential fertility
Authors: Hunter R. H. F. , Cook B. , Baker T. G. 
Published: December 2008

ABSTRACT
Reproductive tissues, steroid hormone secretion, and sexual behaviour have been examined in five gilts, in each of which the right gonad was an ovotestis. Although from different females, these animals were sired by the same boar and each possessed an XX sex chromosome constitution as determined by karyotype analysis of blood cells. Despite variable amounts of testicular tissue in the ovotestis and unilateral development of a prominent epididymis, four of the animals had oestrous cycles of normal duration (20–22 days) and extended periods of standing oestrus (3–6 days). The fifth animal did not have detectable oestrous cycles but was extremely aggressive in the presence of a mature boar. Two of the gilts were mated, and there were small numbers of embryos in each uterine horn 23 and 26 days later. Removal of the ovary did not prompt compensatory hypertrophy in the ovarian portion of the ovotestis, nor did injection of pregnant mare serum gonadotrophin stimulate detectable follicular growth in ovarian tissue adjoining testicular tissue.
Concerning the aetiology of this intersex condition, the unilateral appearance of an ovotestis precludes any simple involvement of a translocated portion of the Y chromosome or systemic effects of unusual titres of the putative H–Y antigen. However, bearing in mind a predisposition to gonadal asymmetry in eutherian mammals, a case is advanced for apposition or incorporation of adrenocortical tissue in the right embryonic ovary. The resultant virilization of neighbouring reproductive tissues would stem from adrenocortical androgen synthesis.
J. Endocr. (1985) 106, 233–242
Prolactin in cerebrospinal fluid increases the synthesis and release of hypothalamic γ-aminobutyric acid
Authors: Locatelli V. , Apud J. A. , Gudelsky G. A. , Cocchi D. , Masotto C. , Casanueva F. , Racagni G. , Müller E. E. 
Published: December 2008

ABSTRACT
The effect of intracerebroventricularly (i.v.t.)-injected rat prolactin (2 μg/rat) on the function of tuberoinfundibular γ-aminobutyric acid (GABA)ergic neurones was assessed in adult male rats by measuring the activity of glutamic acid decarboxylase (GAD) in the mediobasal hypothalamus (MBH) and the concentrations of GABA in hypophysial portal plasma and in the anterior pituitary gland. Fourteen hours after i.v.t. injection of rat prolactin the activity of GAD in the MBH was significantly (P <0·05) increased and it remained elevated for at least 16 h after injection.
The mean concentrations of GABA in hypophysial portal plasma and in the anterior pituitary were twice those found in vehicle-treated controls 16 h after administration of rat prolactin; no significant effects were observed at earlier time-periods. A significant (P <0·01) and long-lasting decrease in endogenous plasma prolactin concentrations was detected 2 h after the i.v.t. injection of rat prolactin and the concentrations remained suppressed for up to 16 h. The present results are consistent with the concept that the activity of tuberoinfundibular GABAergic neurones is regulated, at least in part, by circulating prolactin. The ability of prolactin to accelerate the synthesis and release of GABA in the MBH might constitute a short loop feedback system by which the hormone regulates its own secretion.
J. Endocr. (1985) 106, 323–328
Binding of glucocorticoid to the androgen receptor of mouse submandibular glands
Authors: Maruyama S. , Sato S. 
Published: December 2008

ABSTRACT
An increase in esteroprotease activity, a known cytodifferentiating response to androgen in the submandibular gland, occurred after cortisol acetate, dexamethasone or methyltrienolone (R1881) treatment in castrated genetically normal male (X/Y-castrated) mice, but not in normal male (X/Y) and testicular feminized male (Tfm/Y) mice. A peak with specific binding for [3H]cortisol appeared in sucrose density gradient patterns of extracts from X/Y-castrated mice and in almost the same fraction number as that for [3H]R1881 binding. However, peaks specific for neither [3H]cortisol nor [3H]R1881 binding were observed in Tfm/Y mice. The peak binding [3H]cortisol in extracts from X/Y-castrated mice, as well as the one binding [3H]R1881, were inhibited by unlabelled R1881 and cyproterone acetate, an antiandrogen; the peak was not, however, affected by unlabelled oestradiol-17β. The binding capacity of [3H]cortisol determined by Scatchard analysis was similar to that of [3H]R1881 (103 and 106 fmol/mg protein respectively). The Kd value of [3H]cortisol, however, was about 13·6-fold higher than that of R1881. These results suggest that cortisol has the ability to promote androgenic cytodifferentiating action in the mouse submandibular gland by binding to its androgen receptors, if androgens are absent or deficient.
J. Endocr. (1985) 106, 329–335
31P-Nuclear magnetic resonance spectroscopy of rat pituitary tumours in vivo
Authors: Prysor-Jones R. A. , Silverlight J. J. , Jenkins J. S. , Stevens A. N. , Rodrigues J. L. , Griffiths J. R. 
Published: December 2008

ABSTRACT
31P-Nuclear magnetic resonance (NMR) spectra were obtained in the living rat from 19 implanted prolactin-secreted pituitary tumours. Seven major peaks were found including those arising from the high energy phosphorus metabolites ATP and phosphocreatine. Intracellular pH of the tumours was measured and a relationship with prolactin secretion was observed, the highest plasma prolactin concentrations being associated with an intracellular pH >7·18. Repeated NMR measurements in three tumours over periods of up to 21 days revealed progressive changes with age, shown by an increase in inorganic phosphate, a decrease in high energy phosphorus metabolites and a decrease in prolactin secretion. It is concluded that NMR spectroscopy provides a useful method of studying intracellular events which accompany hormone secretion in vivo.
J. Endocr. (1985) 106, 349–353
Effects of LH-releasing hormone antagonist or lesions of the medial basal hypothalamus on periovulatory gonadotrophin release in female rats
Authors: Rush M. E. 
Published: December 2008

ABSTRACT
Follicle-stimulating hormone release on the morning of oestrus was examined by using two different techniques which eliminate LH-releasing hormone (LHRH) stimulation of the pituitary gland. Cyclic female rats were given a potent LHRH antagonist (ALHRH) or were subject to electrolytic lesions of the medial basal hypothalamus (MBH) before or after the pro-oestrous phase of FSH release. Administration of ALHRH at 14.00, 15.30 and 17.00 h or lesioning of the MBH between 11.30 and 13.00 h on pro-oestrus entirely blocked the preovulatory LH surge and both phases of FSH release. Ovulation was abolished in all of these animals. However, when ALHRH was given at 20.30, 22.00 and 23.30 h or lesions of the MBH made between 20.00 and 21.30 h on pro-oestrus after the prooestrous FSH and LH surges had occurred, the oestrous phase of FSH release was indistinguishable from that of saline-treated control rats. Ovulation occurred in all of these animals, and the mean number of ova shed was eight/rat. The conclusions are that (1) the pro-oestrous phase of FSH release is dependent upon the hypothalamic hormonal stimulation by LHRH and (2) the oestrous phase of FSH release is entirely independent of direct LHRH stimulation, or any hypothalamic stimulus.
J. Endocr. (1985) 106, 361–366
Effects of photoperiod, pinealectomy and castration on body weight and daily torpor in Djungarian hamsters (Phodopus sungorus)
Authors: Vitale P. M. , Darrow J. M. , Duncan M. J. , Shustak C. A. , Goldman B. D. 
Published: December 2008

ABSTRACT
During the autumn and winter Djungarian hamsters (Phodopus sungorus) exhibit regression of the gonads, development of a white winter pelage, loss of body weight and daily torpor. These seasonal events are largely regulated by changes in photoperiod. The present experiments were designed to examine the role of the testes and the pineal gland in photoperiodically induced daily torpor and body weight loss. Hamsters displayed a loss of body weight and daily torpor when exposed to a short-day photoperiod in a cold environment, but these phenomena did not occur in hamsters exposed to long days and cold. Testicular regression is probably a precondition for the display of torpor, since daily torpor was almost totally inhibited in hamsters which were exposed to short days and in which testosterone was administered from subcutaneous silicone elastomer implants. Nevertheless, decreased testosterone secretion alone is not a sufficient condition for induction of daily torpor, since torpor was rarely observed in hamsters exposed to long days, even after castration. In addition to decreased testicular activity, the pineal gland is also involved in establishing conditions for torpor. Thus, pinealectomy prevented the display of torpor by castrated hamsters exposed to short days. Body weight changes were also found to be influenced by both testicular hormone and pineal activity. These observations indicate that the pineal gland is involved, as a part of the photoperiodic mechanism, in regulating a variety of physiological events and that some of these actions of the pineal are independent of its extensively described actions on the reproductive axis.
J. Endocr. (1985) 106, 367–375