bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of oestrogen treatment on gonadotroph function in adult male rats
Authors: Saade G. , London D. R. , Clayton R. N. 
Published: December 2008

ABSTRACT
The effect of oestradiol-17β on the hypothalamo-pituitary axis of intact adult male rats was studied. A single injection of oestradiol did not change the serum LH response to gonadotrophin-releasing hormone (GnRH) 48 h or 7 days after the injection, while administration of oestrogen over 66 days suppressed basal serum LH to <3·1 μg/l and did not enhance the LH response to GnRH at any time.
Treatment of ovariectomized rats with oestradiol capsules, however, enhanced the LH response to GnRH on days 3 and 14 of the treatment as compared with the control group (P<0·02 and P<0·05 respectively). Long-term treatment with oestradiol suppressed intrapituitary LH and FSH contents as well as pituitary GnRH receptors (P<0·0004, P<0·005 and P<0·001 respectively), whereas serum and intrapituitary prolactin levels were increased. To exclude the possible inhibitory effect of hyperprolactinaemia on LH responsiveness to GnRH, oestradiol-implanted rats were treated with bromocriptine. This prevented the rise in serum prolactin, but failed to enhance the LH response to GnRH.
Neither short- nor long-term treatment with oestradiol given under conditions shown to be effective in female animals stimulated the hypothalamo-pituitary-gonadotrophin axis in adult male rats.
J. Endocr. (1987) 114,95–101
Vasoactive intestinal peptide increases intracellular free calcium in rat and human pituitary tumour cells in vitro
Authors: Prysor-Jones R. A. , Silverlight J. J. , Jenkins J. S. 
Published: December 2008

ABSTRACT
Prolactin secretion by a human pituitary tumour cell line produced in our laboratory was stimulated by TRH, vasoactive intestinal peptide (VIP) and epithelial growth factor (EGF). All raised the intracellular concentration of free calcium (Ca2+i) of cells loaded with a fluorescent quinoline Ca2+ indicator in suspension, but the effect of TRH was much more rapid and less prolonged than that of VIP and EGF. Both TRH and VIP also increased Ca2+i in GH3 rat pituitary tumour cells, but in this cell line the effect of VIP was only found in attached cells grown on cover-slips. In both human and rat cell lines, the increase in Ca2+i produced by TRH was independent of extracellular calcium, whereas this was a requirement for the action of VIP and EGF. It is concluded that the prolactin secretogogues, VIP and probably EGF, increase Ca2+i through an effect on plasma membrane calcium channels and that this effect differs from that of TRH.
J. Endocr. (1987) 114, 119–123
Visualization of X-chromosome inactivation mosaicism of Tfm gene in XTfm/X+ heterozygous female mice
Authors: Takeda H. , Suzuki M. , Lasnitzki I. , Mizuno T. 
Published: December 2008

ABSTRACT
The testicular feminization (Tfm) locus, which produces a deficiency in androgen receptors, is located on the X-chromosome. Steroid autoradiographic techniques were used to demonstrate the mosaicism of the X-chromosome inactivation in two androgen target tissues of XTfm/X+ heterozygous female mice.
In the mesenchyme of urogenital sinuses of wild-type female fetuses (X+/X+), more than 95% of the cells were androgen-receptor positive (labelled with [3H]testosterone) while in that of heterozygous fetuses (XTfm/X+), about half of the cells were receptor positive (Tfm gene inactive). Statistical analysis of coherent clone size was applied to the heterozygous mesenchyme of the urogenital sinus and the coherent clone size of receptor-positive cells was estimated to be two or three cells per clone. This small clone size suggests that considerable cell mixing occurred in the tissue during embryonic development.
Androgen binding in the mammary gland rudiments was restricted to the mesenchymal cells only in close vicinity to the epithelial mammary bud. In the wild-type rudiments most of the mesenchymal cells beneath the epithelium were receptor positive, while in heterozygous rudiments, receptor-positive and -negative cells intermingled. This observation suggests that in the wild-type mammary gland rudiments the epithelial bud may induce the formation of androgen receptors in adjacent mesenchymal cells rather than attract pre-existing receptor-rich mesenchymal cells.
J. Endocr. (1987) 114, 125–129
Change of mosaic pattern by androgens during prostatic bud formation in XTfm/X+ heterozygous female mice
Authors: Takeda H. , Lasnitzki I. , Mizuno T. 
Published: December 2008

ABSTRACT
The testicular feminization (Tfm) gene, which is characterized by a deficiency in androgen receptors, is located on the X-chromosome. Using steroid autoradiography, the mosaicism of the Tfm gene has been demonstrated in the androgen target tissues of XTfm/X+ heterozygous female mouse fetuses and the effects of androgens on the mosaic pattern analysed.
In the mesenchyme of urogenital sinuses of wild-type female fetuses (X+/X+), more than 95% of the cells were androgen-receptor positive (labelled with [3H]testosterone) while in that of heterozygous fetuses (XTfm/X+), only half of the cells were receptor positive (Tfm gene inactive), and receptor-positive cells and -negative cells formed small irregular patches. When the heterozygous sinuses were cultured in vitro in the presence of androgens, the sinuses underwent male sexual development and formed epithelial buds (prostate gland rudiments) projecting into the surrounding mesenchyme. Autoradiographic analysis revealed that the mosaicism of the mesenchyme disappeared around the developing epithelial buds: almost all the mesenchymal cells in close vicinity to the buds were receptor positive while in the outer layers receptor-positive and -negative cells coexisted. The proportion of receptor-positive cells was greatly increased in the mesenchyme beneath the non-budding area of the sinus epithelium. This androgen-induced increase was observed before the onset of bud formation. The results obtained in the thymidine incorporation experiments suggest that the increase of receptor-positive cells beneath the sinus epithelium might be explained by the migratory behaviour of the androgen-incorporating cells rather than by their selective proliferation.
J. Endocr. (1987) 114, 131–137
Patterns of LH and FSH in men during high-frequency blood sampling
Authors: Scheele F. , Lambalk C. B. , Schoemaker J. , van Kessel H. , de Koning J. , van Dieten J. A. M. J. , van Rees G. P. , de Vries Robles-Korsen T. J. M. 
Published: December 2008

ABSTRACT
The aim of the study was to test the hypothesis that in serial determinations of concentrations of LH and FSH involving blood samples taken every minute, the observed pulses of LH and FSH which last less than 3–4 min might not be a physiological phenomenon but part of the 'noise' of the radioimmunoassay or blood-sampling technique.
Blood was sampled every minute for a period of 90 min in six men. During the first 45 min, blood was sampled by means of vacuum tubes only. During the second 45 min, sampling took place with a syringe via a rubber stopper, either using a tourniquet (n = 3) or flushing the cannula with heparinized saline.
Three criteria were used to identify variations in the patterns of LH and FSH as true hormonal changes. First, a threshold was used which had to be exceeded by the difference between nadir and maximum values before a pulse could be identified. An average of approximately six pulses per 90 min was found in both the LH and FSH series. The majority of these pulses lasted less than 3–4 min. In two subjects, larger LH pulses of longer duration were measured. Secondly, differences between duplicate measurements of nadir and/or maximum values of more than one-third of the amplitude of a pulse were considered unacceptable. This involved about 75% of the pulses. Thirdly, the reproducibility of the hormone variations was estimated. In one subject, concentrations of LH were measured four times in four separate assays. Measurement of FSH concentrations in this subject and of LH and FSH in the samples from the other five subjects were repeated once again, but only in those parts of the series of samples which had shown hormone variations beyond the threshold composed of acceptable duplicate measurements. Only the larger variations of longer duration, as found earlier in two of the LH series, were reproducible.
The different blood-sampling techniques used had no significant influence on the frequency of pulses.
It was concluded that a rapid, small amplitude, pulsatile pattern of release of LH and FSH is probably not present in men or is obscured by limitations of current techniques of radioimmunoassay.
J. Endocr. (1987) 114, 153–160
Control of magnocellular oxytocin neurones by the region anterior and ventral to the third ventricle (AV3V region) in rats
Authors: Blackburn R. E. , Leng G. , Russell J. A. 
Published: December 2008

ABSTRACT
The involvement of the region anterior and ventral to the third ventricle (AV3V region) in the control of oxytocin release was investigated using electrical stimulation and electrolytic lesioning techniques in the rat. Electrical stimulation (0·5 mA, 50 Hz, 15–25 s) of the AV3V region of lactating rats evoked a reproducible rise in intramammary pressure equivalent to that induced by 0·25–0·5 mu. oxytocin (i.v.). Increases in circulating concentrations of oxytocin, as determined by specific radioimmunoassay, confirmed that AV3V stimulation released oxytocin in both lactating and non-lactating rats. The increases in plasma oxytocin concentration evoked by electrical stimulation of the AV3V region were dependent upon intensity and frequency of stimulation, and electrode position. A significant (P<0·05) increase followed stimulation at 25 Hz and 0·1 mA, and a maximal response was obtained with 50 Hz and 1·0 mA. Stimulation of the area in and around the nucleus medianus produced the greatest rise in oxytocin secretion.
The milk-ejection reflex was not abolished after acute electrolytic ablation of the AV3V region in urethane-anaesthetized lactating rats, but electrolytic lesion of the AV3V region prevented the increase in plasma oxytocin concentration which normally followed an osmotic stimulus (1 ml 1·5 mol NaCl/l, i.p.),
These studies provide evidence that the AV3V region is a major source of excitatory afferents to oxytocin neurones; this input is essential for the osmoresponsiveness of these neurones but plays little role in the control of such neurones during reflex milk ejection.
J. Endocr. (1987) 114, 253–261
Thyroid hormone modulation of thyrotrophin-releasing hormone (TRH) and TRH-Gly levels in the male rat reproductive system
Authors: Pekary A. E. , Bhasin S. , Smith V. , Sugawara M. , Swerdloff R. S. , Hershman J. M. 
Published: December 2008

ABSTRACT
Thyrotrophin-releasing hormone (TRH) occurs in high concentrations in the rat ventral prostate and its concentration is regulated in a positive dose–response manner by testosterone in castrated rats. α-Amidation of the tetrapeptide precursor, TRH-Gly, is a rate-limiting step in TRH biosynthesis. To investigate further the hormonal regulation of TRH biosynthesis in prostatic tissue, Sprague–Dawley rats of approximately 250 g were injected s.c. with either physiological saline or 3 mg propylthiouracil (PTU) daily for 5 days. The reproductive tissues were boiled in acetic acid (1 mol/l), dried and extracted with methanol. The methanol extracts were measured for TRH immunoreactivity (TRH-IR) and TRH-Gly-IR by radioimmunoassay. Hypothyroidism induced by PTU significantly increased TRH-IR and TRH-Gly-IR levels in prostate and testis and reduced these levels in epididymis but did not affect the serum concentrations of testosterone compared with those of controls. Corresponding changes in TRH and TRH-Gly in the rat prostate were established by high-pressure liquid chromatography. To control for possible pharmacological effects of PTU on TRH biosynthesis, additional experiments were carried out on castrated rats receiving testosterone replacement and treatment with PTU plus methimazole. Treatment with thyroxine (T4) significantly reduced the increase in prostatic TRH levels due to hypothyroidism, despite the drug-induced blockade of the conversion of T4 to tri-iodothyronine. These effects parallel similar observations made in rat spinal cord and pancreas. This study demonstrates that in the male rat reproductive system the levels of TRH and its immediate biosynthetic precursor, TRH-Gly, are regulated by thyroid hormones.
J. Endocr. (1987) 114, 271–277
Receptors for lactogenic hormones in the ovine corpus luteum. III: Inhibition of 125I-labelled human growth hormone binding by a high molecular weight factor in ovine corpus luteum cytosol
Authors: Bramley T. A. , Menzies G. S. , McNeilly A. S. , Friesen H. G. 
Published: December 2008

ABSTRACT
Ovine luteal cytosol fractions inhibited the specific binding of 125I-labelled human GH and ovine prolactin (oPRL) to ovine luteal microsomes in a dose-dependent fashion. Inhibition was dependent on divalent cation concentrations, and was abolished by divalent metal ion chelating agents or by boiling. Inhibition was not due to ionic strength or salt effects on hormone binding, the release of endogenously bound oPRL into the cytosol fraction during tissue disruption and fractionation, or the presence of a soluble (or solubilized) lactogenic receptor in ovine cytosol preparations. Gel chromatography of cytosol fractions gave a molecular weight for the inhibitor of approximately 50 000.
J. Endocr. (1987) 114, 383–389
Long-term in-vitro maintenance of growth hormone secretion from human somatotrophinomas with cortisol, and its effects on growth hormone-releasing factor
Authors: Daniels M. , White M. C. , Kendall-Taylor P. 
Published: December 2008

ABSTRACT
The effect of cortisol (206 nmol/l) on GH secretion from enzymatically dispersed human somatotrophinoma cells in long-term culture was studied using adenomas from 13 patients with acromegaly. Basal GH secretion from cultures of three out of five tumours measured during periods of 4 hours declined to < 10 μu. GH/culture within 21 days. Secretion from two other tumours measured during 24 h also declined but GH concentrations were still readily detectable (> 100 μu./culture) by 28 or 58 days after cell dispersal. The decline in GH secretion was reversed in all seven tumours when cultures were maintained in cortisol-supplemented medium (CM), 4-h secretion rates being increased or retained at ≥ 100 μu./culture for as long as the studies were continued (range 18–291 days), and 24-h secretion rates at > 1000 μu./culture (range 28–58 days). GH secretion and content from cultures of two additional somatotrophinomas were increased by treatment with cortisol for 5 or 9 days but there was no concomitant effect on cell number.
During long-term maintenance of cultures in CM (range 5–40 days), cortisol partially or completely blocked the 4-h GH response to a test dose of GH-releasing factor (GRF) (20 nmol/l) in five out of six tumours, and to a dose range of GRF (0·01–20 nmol/l) in two of them. However, when cultures maintained in this way (range 7–89 days) were rinsed and acute studies performed in medium without added cortisol, a significant (P < 0·05) stimulatory effect of GRF either at a test dose of 20 nmol/l or with a dose range (0·02–20 nmol/l) was observed in all six tumours tested.
In conclusion, long-term maintenance of human somatotrophinoma cells in medium supplemented with cortisol (206 nmol/l) prevents the early decline in GH secretion and extends their functional lifespan for several weeks or months. However, the stimulatory effects of GRF during such treatment are usually partially or completely blocked in the presence of medium containing cortisol but restored when cortisol is excluded from the medium.
J. Endocr. (1987) 114, 503–509
ACTH and adrenal aerobic glycolysis. I: Effects of O-nitrophenylsulphenyl and other ACTH analogues, vasoactive intestinal peptide and human parathyroid hormone(1–34) on lactic acid, steroid and cyclic AMP production by mouse adrenocortical cells
Authors: Hinson J. , Birmingham M. K. 
Published: December 2008

ABSTRACT
The structural requirements in the ACTH molecule for evocation of the glycolytic response in suspensions of mouse adrenal cells were investigated by examining the effects of analogues containing modifications at positions 8,9 and 10 and of peptides containing homologies with the amino-terminal segment of ACTH. Introduction of a nitrophenylsulphenyl (NPS) group into the tryptophan moiety at position 9 of ACTH(1–24) greatly reduced both the potency and the capacity for maximal glycolytic response. It also virtually abolished cyclic AMP formation. In contrast, the capacity for a maximal steroidogenic response remained unimpaired in the NPS derivative, although steroidogenic potency was reduced to 0·4% of that of ACTH(1–24).
Replacement of the tryptophan moiety with phenylalanine had intermediate inhibitory effects on glycolysis and steroid output; replacement with alanine virtually abolished both these responses. Replacement of arginine in position 8 with lysine in the Phe9 analogue caused a fifty-fold increase in glycolytic potency, but rendered it steroidogenically inactive. Cyclic AMP production was abolished in the Ala9 analogue and greatly impaired in the Phe9 and Lys8,Phe9 analogues. Replacement of the glycine moiety in position 10 with l-alanine, d-alanine, β-alanine or α-aminoisobutyric acid had little or no effect on steroidogenic or glycolytic capacity, although potency was reduced with all substitutions excepting l-alanine.
Vasoactive intestinal peptide, which contains homologies with positions 3, 7, 15 and 16 of ACTH, proved completely inactive in dispersed mouse adrenal cells under our experimental conditions, in contrast to human parathyroid hormone(1–34) (hPTH (1–34)) which contains homologies with positions 3, 4, 5, 9 and 11 and was steroidogenic at the lowest concentration tested (0·1 nmol/l), eliciting an eleven-fold increase in steroid production, a response which might be physiologically relevant. It induced near maximal steroidogenesis at a concentration of 10 nmol/l, without affecting cyclic AMP production, and stimulated glycolysis at concentrations above 10 nmol/l, accompanied by a slight rise in cyclic AMP levels.
The examples of dissociation between glycolysis and steroidogenesis suggest that different receptors may mediate the two responses. The examples of increased steroidogenesis unaccompanied by a rise in cyclic AMP accord with the concept that cyclic AMP is not an obligatory second messenger for the steroidogenic response.
J. Endocr. (1987) 115, 61–69
Intratesticular injection of glycerol as a model for studying the quantitative relationship between spermatogenic damage and serum FSH
Authors: Weinbauer G. F. , Drobnitzky F. , Galhotra M. M. , Nieschlag E. 
Published: December 2008

ABSTRACT
Intratesticular injection of glycerol (1,2,3-trihydroxypropane) was evaluated as an experimental approach for studying the relationship between spermatogenic activity, i.e. relative proportion of euspermatogenic and aspermatogenic tubules in the testis, and serum concentrations of FSH. Adult rats received a single intratesticular injection of either 400 μl distilled water or five different doses of glycerol, ranging from 25 to 400 μl, and were killed after 1 or 4 weeks respectively. Injection of glycerol caused focal destruction, so that the same testes contained intact tubules, tubules with spermatogonia and Sertoli cells only, and tubules devoid of cellular material. There was a close correlation (r=−0·896) between the frequency of intact tubules and the dose of glycerol, and a similarly strong correlation (r= −0·908) between acellular tubules and the dose of glycerol. A correlation existed between FSH and euspermatogenic tubules (r= −0·758, n=122) and, conversely, between FSH and acellular tubules (r=0·820, n=122), while the correlation for tubules containing spermatogonia and Sertoli cells was only marginal (r=− 0·055). The exact relationship between FSH and spermatogenic activity in the testis was used to estimate the minimal amount of spermatogenic tissue necessary for maintaining normal serum concentrations of FSH. Only the disruption of spermatogenesis in more than 30% of seminiferous tubules in each testis caused increased serum concentrations of FSH. Serum concentrations of FSH reached the range found in castrated rats when less than 1 % of tubules were intact.
These findings demonstrate (1) that a single intratesticular injection of glycerol is suitable for the study of the relationship between spermatogenic activity in the testis and FSH and (2) that a quantitative relationship exists between the extent of spermatogenic damage and serum concentrations of FSH. The observation that, in the rat, serum FSH has a diagnostic value for the extent of spermatogenic damage may be of importance for clinical evalution of testicular disorders.
J. Endocr. (1987) 115, 83–90
Structural plasticity in the rat supraoptic nucleus during gestation, post-partum lactation and suckling-induced pseudogestation and lactation
Authors: Montagnese C. M. , Poulain D. A. , Vincent J.-D. , Theodosis D. T. 
Published: December 2008

ABSTRACT
In the supraoptic nucleus (SON) of parturient and lactating rats, large portions of the surface membranes of almost all oxytocinergic neurones are directly juxtaposed with no glial interposition. A significant number of the same neurones are also contacted by the same presynaptic terminal ('double' synapses).
Our present observations have revealed that direct appositions between adjacent neurones in the SON increase quite rapidly during the day before parturition. 'Double' synapses also become visible during late gestation, but they appear more progressively. Earlier studies have shown that 1 month after weaning, as in virgin rats, there are again very few appositions and 'double' synapses in the nucleus. We show here that the SON can remain structurally modified, and to the same degree, beyond normal weaning time so long as lactation is prolonged by renewing suckling litters. However, if the mothers are deprived of their pups immediately after birth, neuronal appositions disappear within 2 days and 'double' synapses by 10 days. In non-pregnant primiparous rats, continuous exposure to suckling litters leads to pseudogestation and eventually lactation (in 16–22 days). Examination of the SON in such animals revealed that the oxytocinergic system is already modified by day 12 of dioestrus; during suckling-induced lactation, the anatomical changes are identical to those seen during a normal post-partum lactation.
These observations indicate that neither gestation nor suckling alone are indispensable for the anatomical reorganization of the SON apparent at lactation. However, suckling is important in maintainingthe structural changes during prolonged lactation, and can lead to restructuring of the nucleus by inducing pseudogestation and lactation in non-pregnant animals. Taken together with earlier data, these results suggest that hormonal factors, especially oxytocin and gonadal steroids, may act singly or, more probably, in synergy to produce the structural plasticity of the adult oxytocinergic system.
J. Endocr. (1987) 115, 97–105