bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of hypobaric hypoxia on the Leydig cell population of the testis of the rat
Authors: Gosney J. R. 
Published: December 2008

ABSTRACT
A group of ten young adult male Wistar albino rats was exposed to hypobaric hypoxia at a barometric pressure of 380 mmHg for 28 days. After this period their testes were of smaller weight (and volume) in comparison with matched controls (1·220 vs 1·553 g; P < 0·005). Histological examination revealed degeneration and sloughing of spermatogenic cells in occasional tubules. Quantitative methods also revealed a marked difference in the volume of the testis occupied by Leydig cells. These were of a significantly smaller total volume in the hypoxic animals (0·046 vs 0·083 ml; P < 0·001) and this could not be accounted for merely by the smaller overall testicular volume.
J. Endocr. (1984) 103, 59–62
Dopaminergic inhibition of prolactin release from pituitary glands of the domestic fowl incubated in vitro
Authors: Hall T. R. , Chadwick A. 
Published: December 2008

ABSTRACT
Anterior pituitary glands from broiler fowl were incubated by themselves, with hypothalamic tissue or with thyrotrophin releasing hormone (TRH) in medium containing dopamine and its antagonist pimozide. The presence of hypothalamic tissue or TRH resulted in a stimulation of release of prolactin. Neither dopamine nor pimozide affected prolactin release directly from the pituitary gland. Dopamine inhibited the release of prolactin stimulated by hypothalamic tissue or TRH, in a concentration-dependent fashion. Pimozide diminished the response to dopamine. After pituitary glands were preincubated for 20 h in medium containing oestradiol-17β, the basal release of prolactin was enhanced as was the response to TRH. Both basal and TRH-stimulated release of prolactin from the oestrogen-primed pituitary glands was inhibited by dopamine, an effect blocked by pimozide. Hypothalami from broiler fowl were incubated for up to 8 h in medium containing dopaminergic drugs and pituitary glands were incubated in this medium, alone or with pimozide. As indicated by the prolactin released by the pituitary glands, the hypothalami appeared to secrete prolactin-releasing activity in a time-related fashion. Dopaminergic activity was also present in the hypothalami, since pimozide enhanced the prolactin-releasing activity of the medium. Dopamine apparently inhibited and pimozide stimulated the secretion of releasing activity from the hypothalamus. These results suggest that dopamine inhibits release of prolactin directly from the pituitary gland only when prolactin secretion is high. The hypothalamus secretes at least two factors regulating prolactin secretion, a prolactin-releasing factor and a dopaminergic prolactin-inhibiting factor. Dopamine may also play an inhibitory role in the regulation of secretion of the prolactin-releasing factor.
J. Endocr. (1984) 103, 63–69
Progesterone, androstenedione and oestradiol content of theca and granulosa tissues of the four largest ovarian follicles during the ovulatory cycle of the hen (Gallus domesticus)
Authors: Etches R. J. , Duke C. E. 
Published: December 2008

ABSTRACT
The progesterone, androstenedione and oestradiol contents of the theca and granulosa tissues of the four largest follicles in the ovarian hierarchy of the hen were determined. The granulosa tissue contained significantly (P < 0·05) more progesterone and less androstenedione and oestradiol than the theca tissue. The content of progesterone was greatest in the granulosa tissue of the first three follicles in the hierarchy and in each of these follicles there was a peak in progesterone content of the granulosa 4 h before ovulation. The theca of the second, third and fourth follicles and the granulosa of the third and fourth follicles contained significantly (P < 0·05) more androstenedione than either tissue in the largest follicle. The content of androstenedione was maximal approximately 8 h before ovulation in both tissues of the second and third follicles. The content of oestradiol in the granulosa did not vary as follicles changed position within the hierarchy or during the ovulatory cycle. The oestradiol content of the theca tissue remained constant during the third and fourth positions in the hierarchy and declined throughout the second and first positions until a nadir was observed approximately 20 h before ovulation.
It was concluded that the synthesis of androstenedione and oestradiol ceases in both follicular tissues after the follicle is exposed to the penultimate preovulatory surge of LH and that progesterone production is stimulated in the granulosa of the three largest follicles at the time of the preovulatory release of LH.
J. Endocr. (1984) 103, 71–76
Presence of a neurophysin-like precursor in the green turtle (Chelonia mydas)
Authors: Licht P. , Pickering B. T. , Papkoff H. , Pearson A. , Bona-Gallo A. 
Published: December 2008

ABSTRACT
A glycoprotein of neurohypophysial origin was found to have cofractionated with FSH prepared from pituitary glands of the green turtle, Chelonia mydas. Antiserum raised against this preparation contained high antibody titres and affinity for the neurohypophysial component and allowed development of a specific radioimmunoassay to monitor its purification and distribution in the brain. Immunocytochemistry revealed that the glycoprotein was concentrated in the pars nervosa and associated nerve tracts passing through the median eminence to the supraoptic and paraventricular nuclei; similar distributions were observed in turtles and rats. The antiserum to the turtle material bound radiolabelled rat vasopressin (VP)-neurophysin and precipitated precursors of this neurophysin, but it did not cross-react with rat oxytocin-neurophysin. An amino-terminal alanine was also consistent with the structure of rat VP-neurophysin, but the turtle molecule was larger than the corresponding rat molecule. Limited tryptic digests of the turtle glycoprotein contained two components, one of which bound to lysine VP.
Both components contained carbohydrate, but only the one which bound to VP cross-reacted in a radioimmunoassay for rat VP-neurophysin. The apparent surge in plasma immuno-FSH at the time of oviposition previously described in the turtle probably represented release of a neurophysin-like 'carrier' molecule associated with secretion of the neurohypophysial hormone (e.g. arginine vasotocin; AVT) responsible for oviduct contractility. These data suggest that the neurohypophysial glycoprotein represents a partially processed AVT precursor and provide the first biochemical evidence of a mammalian-like biosynthetic pathway for neurohypophysial hormones in a non-mammalian species.
J. Endocr. (1984) 103, 97–106
Lack of binding of serum glycoprotein hormone α subunit to Concanavalin A–Sepharose reflects increased branching of the oligosaccharide chains
Authors: Chapman A. J. , Gallagher J. T. , Beardwell C. G. , Shalet S. M. 
Published: December 2008

ABSTRACT
The lectin-binding properties of serum α subunit were studied by lectin affinity chromatography. Normal individuals and most patients with pituitary tumours produced α subunit which bound specifically to Concanavalin A–Sepharose (Con A). Some patients with pituitary tumours produced both Con A-reactive α subunit and α subunit which did not bind to Con A. Concanavalin A–Sepharose-binding α subunit from all sources bound strongly to Ricinus communis agglutinin–Sepharose after treatment with neuraminidase. Serum α subunit from those patients with pituitary tumours, which did not bind to Con A, bound to wheat germ agglutinin–Sepharose, exhibiting both weakly binding and strongly binding forms. Serum α subunit from both patients and controls, which did bind to Con A, showed only weak affinity for wheat germ agglutinin–Sepharose. Neither the low affinity nor the high affinity of serum α subunit from any source for wheat germ agglutinin–Sepharose was affected by neuraminidase. These findings show that (a) the predominant pattern of glycosylation of serum α subunit from normal controls is a Con A-reactive, biantennate complex oligosaccharide and (b) that the structural alteration which results in serum α subunit which does not bind to Con A in some patients with pituitary tumours is not an absence of carbohydrate, rather the α subunit contains highly branched, either complex or hybrid oligosaccharides.
J. Endocr. (1984) 103, 111–116
Variation in the core and branch carbohydrate sequences of serum glycoprotein hormone α subunit as determined by lectin affinity chromatography
Authors: Chapman A. J. , Gallagher J. T. , Beardwell C. G. , Shalet S. M. 
Published: December 2008

ABSTRACT
Serum α subunits from patients with pituitary tumours and from normal controls were studied for their ability to bind to Lens culinaris agglutinin–Sepharose (LCA), l-phytohaemagglutinin–agarose (l-PHA) and soybean agglutinin–Sepharose (SBA). Serum α subunits from normal controls which had previously been shown to bind to Concanavalin A–Sepharose (Con A) were not retained by LCA. In contrast, Con A-reactive α subunits from patients with pituitary tumours bound specifically to LCA. Non-Con A-reactive α subunits from patients with pituitary tumours were also largely not bound to LCA, but were retained by l-PHA. No α subunits from any source bound to SBA.
These results indicate that the structural alterations resulting in non-Con A-reactive serum α subunits include highly branched complex oligosaccharides in addition to the hybrid-type glycans previously described. The increased branching appears to be associated with fucosylation in the core region of the oligosaccharides. Serum α subunit from any source appears to be devoid of terminal N-acetylgalactosamine residues. These structural modifications may be related to the variable biological activity of α subunit which has been reported.
J. Endocr. (1984) 103, 117–122
Circadian rhythms of lipogenic and hypoglycaemic responses to insulin in the golden hamster (Mesocricetus auratus)
Authors: Cincotta A. H. , Meier A. H. 
Published: December 2008

ABSTRACT
Lipogenesis and blood glucose concentrations were determined at 4-hourly intervals in control and insulin-treated golden hamsters maintained on 14-h daily photoperiods (08·00–22·00 h). Lipogenesis was studied by measuring the incorporation of label into liver and fat pad lipids in animals killed 30 min after i.p. [3H]acetate injection and 2 h after insulin or saline (control) injections. Circadian rhythms of lipogenesis and plasma glucose concentration were present in both control and insulin-treated hamsters. In control animals most lipogenic activity occurred during the dark period and early during the daily photoperiod (14 h light: 10 h darkness). There were dramatic differences in the lipogenic (fat pad) and hypoglycaemic responses to insulin which varied as a function of the time of day at which insulin was injected. Insulin stimulated fivefold increases in lipid deposition (fat pad incorporation) when injected late during the dark period but had little or no effect 4–8 h after the onset of light. Daily injections for 8 days also produced variable cumulative effects on body fat stores as a function of the time of day. Insulin injected late during the dark period stimulated a 40% increase in abdominal fat weight over controls, whereas insulin injected at 4 and 12 h after the onset of light had no effect on abdominal fat weight. Insulin decreased plasma glucose concentrations markedly at 8 and 20–24 h after the onset of light but had no apparent hypoglycaemic activity (120 min after its injection) at 4 h after the onset of light. These response rhythms coupled with rhythms of insulin secretion provide a basis for temporal synergisms which could produce a spectrum of physiological conditions as a function of the phase relations between the rhythms.
J. Endocr. (1984) 103, 141–146
Androgen regulation of secretions in the sebaceous-like uropygial gland of the male Japanese quail
Authors: Abalain J. H. , Amet Y. , Daniel J. Y. , Floch H. H. 
Published: December 2008

ABSTRACT
The uropygial gland of the male quail is a sebaceous-like, androgen-dependent structure. The waxes secreted by this gland consist of fatty acids esterified by alkane-2,3-diols. In adult male quail the relative concentrations of all fatty acids were not affected by castration and testosterone treatment; but in contrast, the relative concentration of dodecane diol was found to be correlated with the androgen levels. In castrated quail administration of testosterone induced an increase in the dodecane diol percentage which was blocked by protein-synthesis inhibitors. Furthermore, the effects of testosterone were found to be neutralized by the administration of cyproterone acetate. Consequently it may be stated that the relative concentration of dodecane diol is indeed a very good marker for androgenicity in the uropygial gland of the male quail. This experimental model seems well suited for evaluating the stimulators and inhibitors of the activity of the sebaceous gland.
J. Endocr. (1984) 103, 147–153
Alteration by thyrotrophin-releasing hormone of heterogeneous components associated with thyrotrophin biosynthesis in the rat anterior pituitary gland
Authors: Mori M. , Murakami M. , Iriuchijima T. , Ishihara H. , Kobayashi I. , Kobayashi S. , Wakabayashi K. 
Published: December 2008

ABSTRACT
An influence of thyrotrophin-releasing hormone (TRH) on TSH heterogeneity in close association with de-novo biosynthesis was studied in rat anterior pituitary glands. Hemipituitary glands from adult male rats were incubated in Krebs–Henseleit–glucose media containing [3H]glucosamine and [14C]alanine for 3 and 6 h in the presence or absence of 10 ng TRH per ml. Fractions of TSH in the pituitary extracts were obtained using affinity chromatography coupled with an anti-rat TSH globulin. These TSH fractions were analysed by isoelectric focusing. The control pituitary glands were composed of four component peaks (isoelectric point (pI) 8·7, 7·8, 5·3 and 2·5) of [3H]glucosamine and [14C]alanine incorporated into TSH, and the amounts of radioactivity of these components were increased with the incubation time. Of these peaks, radioactive components of pI 8·7 and 7·8 coincided with the non-radioactive TSH components measured by radioimmunoassay. Addition of TRH increased incorporation of [14C]alanine into TSH in each of the components to a greater extent than that of [3H]glucosamine. In addition, new components with pI 7·2, 6·5 and 6·2, each component corresponding to each unlabelled TSH component, were demonstrated in the presence of TRH. Because addition of TRH did not change the amounts of [14C]alanine-labelled TSH in the media, the newly formed components were assumed to be connected with protein synthesis occurring in the anterior pituitary gland, which may be specific substances in response to TRH administration. These results indicate that TRH principally elicits an increase in protein synthesis in TSH at the anterior pituitary level, resulting in an alteration of TSH heterogeneity.
J. Endocr. (1984) 103, 165–171
Comparative rates of formation, in vivo, of 16-androstenes, testosterone and androstenedione in boar testis
Authors: Hurden E. L. , Gower D. B. , Harrison F. A. 
Published: December 2008

ABSTRACT
Three mature Large White boars were anaesthetized and received [7(n)-3H]pregnenolone by continuous infusion into right and left spermatic arteries for up to 180 min. Spermatic venous blood flow was measured by separate timed collections of completely diverted outflow from each testis and blood not sampled was returned to the peripheral circulation.
The total radioactivity in plasma from each testis increased markedly during the first 60 min of infusion to reach a plateau from 80 to 180 min. Radiolabelling of 5α-androst-16-en-3-one, 5α-androst-16-en-3β-ol and -3α-ol showed similar patterns with ratios of mean radioactivity of 5:3:1 respectively between 80 and 180 min. In comparison, the amounts of tritiated 4,16-androstadien-3-one formed were very small. The radiolabelling of testosterone and 4-androstenedione occurred more rapidly than that of the 16-androstenes and reached maxima by 30 min. However the amounts were only one-fifth (testosterone) and one-tenth (4-androstenedione) those of the combined quantities of tritiated 16-androstenes.
Addition of human chorionic gonadotrophin (hCG) to the infusate to one testis in each animal (so that 5000 i.u. hCG were delivered in 15–20 min) produced no change in the outputs of radiolabelled steroids although radioimmunoassay of spermatic venous plasma in samples from the third experiment showed a transient increase in the concentration of 4-androstene-3,17-dione during the hCG infusion. It is suggested the lack of response to hCG could be produced by saturation and down regulation of binding sites by the very high local concentrations of hCG.
J. Endocr. (1984) 103, 179–186
Inverse changes in plasma prolactin and LH concentrations in female canaries after disruption and reinitiation of incubation
Authors: Goldsmith A. R. , Burke S. , Prosser J. M. 
Published: December 2008

ABSTRACT
Prolactin and LH concentrations were measured in the plasma of female canaries sampled during the breeding cycle and after disruption and reinitiation of incubation behaviour. The late incubation period was characterized by low LH and high prolactin concentrations, and canaries separated from their nests at this stage showed an increase in LH and a decline in prolactin within 3 h. In one experiment mean (±s.e.m.) concentrations before and 24 h after nest deprivation were: prolactin 397 ± 86 and 18 ± 5 μg/l; LH 1·04±0·21 and 2·03±0·17 μg/l. Female canaries which abandoned their nests after the eggs had been removed also showed an increase in LH together with a fall in prolactin 24 h after egg removal. When nest-deprived canaries were allowed to resume incubation, plasma prolactin increased again within 5 h and after 2 days had reached levels normal for incubating birds (398± 46 μg/l). Concentrations of LH changed more gradually but had decreased 2 days after the resumption of incubation. Thus prolactin and LH show inverse changes after the disruption and reinitiation of incubation behaviour; it is not clear, however, if the change in one is dependent on the other or if both hormones are responding to the same external stimulus.
J. Endocr. (1984) 103, 251–256
Mechanism of the regulation of the 1α,25-dihydroxyvitamin D3 receptor in the rat jejunum by glucocorticoids
Authors: Chan S. D. H. , Chiu D. K. H. , Atkins D. 
Published: December 2008

ABSTRACT
The distribution of 1α,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptors in isolated jejunal villous and crypt cells was investigated in normal and adrenalectomized male rats, and also in animals treated with the synthetic glucocorticoid, dexamethasone, and/or the glucocorticoid antagonist, 11-deoxycortisol. Adrenalectomy caused an increase in 1,25-(OH)2D3 receptors whilst dexamethasone treatment led to a reduction in receptor number. 11-Deoxycortisol was able to reverse the 'down-regulation' effect caused by glucocorticoids. In all cases, the changes in receptor numbers were more pronounced in crypt cells. The data suggest that, in the small intestine, glucocorticoids may control the synthesis of 1,25-(OH)2D3 receptors via the mediation of a glucocorticoid receptor, and that the adrenal hormones mainly express their effect in crypt cells. It is proposed that this phenomenon may, in part, explain the reduction in calcium absorption which occurs in man after chronic glucocorticoid treatment.
J. Endocr. (1984) 103, 295–300
Effects of acute administration of 2-hydroxylated metabolites of oestrogens on LH and prolactin secretion in male and female prepubertal rats
Authors: Brar A. K. , Fink G. 
Published: December 2008

ABSTRACT
The effects of catechol oestradiol and catechol oestrone on the release of LH and prolactin were investigated in immature male and female Wistar rats. In male rats both catechol oestradiol and catechol oestrone significantly increased the plasma concentration of LH, and catechol oestradiol but not catechol oestrone significantly increased the plasma concentration of prolactin and decreased the pituitary concentration of LH. The parent oestrogens, oestradiol-17β and oestrone, had no effect on plasma LH concentrations, but both increased significantly the plasma concentration of prolactin, and oestrone but not oestradiol-17β increased the pituitary concentration of LH. In immature female rats, catechol oestradiol inhibited the surge of LH and the increase in uterine weight induced by injecting pregnant mare serum gonadotrophin (PMSG). The injection of oestrone induced an increase in the plasma concentration of LH which was about nine times greater than that produced by oestradiol-17β. There were no significant differences in the effects of these steroids on plasma prolactin concentration. These results (i) confirm that in the immature male rat catechol oestrogens can stimulate LH release and show that catechol oestradiol can increase prolactin release, (ii) show that catechol oestradiol can inhibit the stimulatory effects of PMSG on LH release and uterine weight in the immature female rat, and (iii) demonstrate that oestrone can stimulate LH release in the immature female rat.
J. Endocr. (1984) 103, 317-325
Secretion of oxytocin and milk removal as affected by milking cows with and without manual stimulation
Authors: Mayer H. , Schams D. , Worstorff H. , Prokopp A. 
Published: December 2008

ABSTRACT
Milking cows with a 1-min manual stimulation (treatment 1) and without any udder preparation (treatment 2) was compared by application of an improved, highly sensitive radioimmunoassay for oxytocin and recordings of milk-flow curves. Both treatments caused the release of oxytocin, but treatment 2 generally seemed to be less efficient. Milking characteristics supported the advantage of manual stimulation; milk yield and milk flow were significantly higher, while 'machine-on' time was shorter. This clearly indicates the importance of the right timing of release of oxytocin before commencement of milking. Substitution of stimulation by an i.v. injection of 0·5 i.u. oxytocin (treatment 3) resulted in milking parameters very similar to those of treatment 2. This implies that manual stimulation has other effects besides the secretion of oxytocin which are also responsible for optimal milk removal.
J. Endocr. (1984) 103, 355–361