bluuebunny/crossref_metadata_2025_split huggingface dataset:
Peripheral androgen levels in the male brush-tail possum (Trichosurus vulpecula)
Authors: Curlewis J. D. , Stone G. M. 
Published: December 2008

ABSTRACT
Radioimmunoassays were established for the measurement of total androgens and the specific measurement of testosterone and 5α-dihydrotestosterone in peripheral plasma of the brush-tail possum. Androgen concentrations were measured in blood collected from indwelling jugular cannulae (i) to determine whether the normal pattern of androgen secretion in this species was episodic and (ii) to attempt to relate total androgen and the pattern of testosterone secretion to the changes previously reported in prostatic, but not epididymal, weight in the breeding season. Blood was collected from restrained animals at varying time-intervals during daylight hours and darkness. Despite an apparent good adaptation to the sampling procedure there was generally a progressive decline in plasma androgen level during the collection period. This was true for animals bled during or out of the breeding season. There was no significant seasonal effect on the androgen concentration in the initial blood sample. When less restraint was used, two of three animals showed fluctuations in androgen levels over the 7-h sampling period. Testosterone levels in blood obtained by cardiac puncture were four- to nine-fold higher than those of 5α-dihydrotestosterone but levels of these androgens in samples obtained during the breeding season were not significantly different from those obtained out of season. The results do not argue for a pulsatile release of testosterone in the possum but do demonstrate a marked capacity for changes in the peripheral androgen concentration. There was a poor correlation between testosterone and 5α-dihydrotestosterone levels and prostatic weight.
J. Endocr. (1985) 105, 63–70
Supraoptic neurones in Brattleboro rats respond normally to changes in plasma osmotic pressure
Authors: Dyball R. E. J. , Leng G. 
Published: December 2008

ABSTRACT
Brattleboro rats homozygous for hypothalamic diabetes insipidus (DI rats) were anaesthetized with urethane. Extracellular recordings were made from antidromically identified neurones of the supraoptic nucleus. About half (77 out of 153) of the neurones recorded in DI rats showed phasic patterns of discharge activity similar to those which are characteristic of vasopressin-secreting neurones in normal rats during hyperosmotic stimulation. Significantly fewer neurones showed phasic activity in DI rats which had been pretreated with vasopressin tannate at a dose which significantly reduced urine volume, water intake and plasma osmolality. Acute systemic hyperosmotic stimulation, induced by an i.p. injection of 1 ml 1·5 m-NaCl, increased the discharge rate of each of 14 neurones from DI rats by 1–5 spikes/s. Hypo-osmotic stimulation, induced by an intragastric injection of 10 ml tap water, reduced the discharge rate of each of four neurones from DI rats by 50% or more.
We conclude that supraoptic neurones in DI rats respond normally to acute systemic osmotic stimuli despite the total absence of vasopressin in these rats and despite their chronically disturbed water balance. This implies that the osmoreceptor mechanism which drives the supraoptic nucleus does not adapt substantially during prolonged disturbance of water balance and functions outside the normal physiological range of plasma osmolality, and that the reported alteration of noradrenergic innervation of the neurones in DI rats does not affect their osmotic responsiveness.
J. Endocr. (1985) 105, 87–90
Stimulation of androgen and oestrogen concentrations in plasma of cows after administration of a synthetic glucocorticoid (flumethasone) at the end of gestation
Authors: Möstl E. , Choi H. S. , Bamberg E. 
Published: December 2008

ABSTRACT
Administration of flumethasone (3·5 mg i.m.) to six cows on day 260 of pregnancy induced parturition in only one animal. In the other five cows circulating concentrations of epitestosterone and conjugated oestrogens increased to reach maximum values (epitestosterone, 13·73 ± 2·81 nmol/l; conjugated oestrogens, 33·59 ± 6·87 nmol/l) 2–3 days after treatment. Concentrations of these steroids were raised as long as the synthetic glucocorticoid was present in the circulation (as judged by depression of cortisol concentrations). After clearance of the drug, concentrations of these steroids declined to values present in the control group. Concentrations of unconjugated oestrogens were only slightly raised after flumethasone.
In contrast to the effect observed after administration on day 260, treatment on day 270 induced parturition in four of six treated animals. In these cows, mean circulating concentrations of epitestosterone, unconjugated and conjugated oestrogens increased to 9·50 ± 2·96, 9·62 ± 1·48 and 36·51 ± 4·8 nmol/l respectively to reach concentrations observed in the control group at parturition. After parturition the concentrations of epitestosterone and oestrogens declined rapidly in all groups.
J. Endocr. (1985) 105, 121–126
The genetic background of circadian and ultradian rhythm patterns of 17-hydroxycorticosteroids: a cross-twin study
Authors: Reinberg A. , Touitou Y. , Restoin A. , Migraine C. , Levi F. , Montagner H. 
Published: December 2008

ABSTRACT
Circadian and ultradian rhythms in urinary excretion of 17-hydroxycorticosteroids were documented individually during an 8-day span in two pairs of young male twins. Studies were performed once at the age of 6 years for dizygotic twins and twice at the ages of 4·3 and 10·3 years for monozygotic twins. Four different methods were used for time-series analyses: chronograms (raw data), best-fitting curves resulting from cosinor analyses, power spectra and correlations of time-qualified data. Estimates of rhythm parameters (prominent periods, acrophases, etc.) as well as shapes of curves were closer in mono- than in dizygotic twins. Both similarities and small differences in rhythm characteristics of monozygotic twins were detected at both ages considered.
J. Endocr. (1985) 105, 247–253
Vasopressin-neurophysin II gene expression in the ovary: studies in Sprague–Dawley, Long–Evans and Brattleboro rats
Authors: Fuller P. J. , Clements J. A. , Tregear G. W. , Nikolaidis I. , Whitfeld P. L. , Funder J. W. 
Published: December 2008

ABSTRACT
The neurohypophysial hormones oxytocin and arginine vasopressin (AVP) have been identified on immunological criteria in the ovary. Confirmation of extraneuronal synthesis requires the demonstration in the tissue of the specific messenger RNA (mRNA) for the preprohormone. Using a synthetic pentadecamer nucleotide probe, highly specific for the 5′ region of rat neurophysin II (NPII), we have demonstrated the presence of AVP-NPII mRNA in the ovary of Sprague–Dawley, Long–Evans and Brattleboro rats, with an apparent molecular weight identical to that seen for hypothalamus. These findings, together with the presence of immunoreactive AVP in the ovaries but not hypothalami of Brattleboro rats, suggest that tissue-specific differences in AVP-NP II gene expression occur at the translational as well as transcriptional level.
J. Endocr. (1985) 105, 317–321
Antibiotics attenuate experimental hypertension in rats
Authors: Honour J. W. , Borriello S. P. , Ganten U. , Honour P. 
Published: December 2008

ABSTRACT
Hypertension was produced in Sprague–Dawley rats by intramuscular injections of either corticosterone or ACTH. Lower increases in blood pressure to these challenges were observed in Sprague–Dawley rats pretreated with neomycin or vancomycin which alone had no effect on blood pressure or growth. The development of high blood pressure in spontaneously hypertensive rats of a stroke-prone substrain was also attenuated by oral administration of neomycin. These results suggest that experimental hypertension can be modulated by the administration of antibiotics.
J. Endocr. (1985) 105, 347–350
Gonadotrophin excretion in fertile women: effect of age and the onset of the menopausal transition
Authors: Metcalf M. G. , Livesey J. H. 
Published: December 2008

ABSTRACT
In normal women the menopausal transition starts typically with a sudden break in regular menstrual cyclicity: gonadotrophin levels escape from the cyclical pattern characteristic of fertile women and increasingly rise into the postmenopausal range. An investigation was undertaken to determine whether this rise precedes the first appearance of ovarian dysfunction.
Weekly urine samples for the measurement of FSH, LH and pregnanediol were collected from 100 women, all of whom had regular 20- to 35-day menstrual cycles (504 samples from 48 women aged 20–39 years and 620 samples from 52 women aged 40–48 years; 96·8% of these cycles were shown to be ovulatory).
Excretion rates of FSH in excess of 5 i.u./24 h occurred more often in women aged ≥ 40 years than in younger women (incidence, 31·5 cf. 19·5%; P < 0·001). The difference was greatest at the time of the perimenstruum (7-day incidence, 32·5 cf. 13·9%) and declined to insignificance during the mid-cycle gonadotrophin surge (7-day incidence, 44·2 cf. 34·8%). Examination of the rank correlation between age and gonadotrophin excretion confirmed the age-related rise in FSH and identified a lesser but significant perimenstrual rise in LH. For both FSH and LH these changes were small compared with the increases observed in nine women presumed to have reached the menopausal transition during the trial (incidence FSH ≥ 5 i.u./24 h, 60·6%; incidence LH ≥ 5 i.u./24 h, 48·6%).
It is concluded that in fertile women there is evidence of an age-related rise in FSH which is distinct from the changes occurring at the start of the menopausal transition.
J. Endocr. (1985) 105, 357–362)
Vitamin D metabolites regulate osteocalcin synthesis and proliferation of human bone cells in vitro
Authors: Skjødt H. , Gallagher J. A. , Beresford J. N. , Couch M. , Poser J. W. , Russell R. G. G. 
Published: December 2008

ABSTRACT
The effects of six natural vitamin D metabolites of potential biological and therapeutic interest, 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), 25-hydroxyvitamin D3 (25-OH-D3), 24R,25-dihydroxyvitamin D3 (24R,25-(OH)2D3), 1,24R,25-trihydroxyvitamin D3 (1,24R,25-(OH)3D3), 25S,26-dihydroxyvitamin D3 (25S,26-(OH)2D3) and 1,25S,26-trihydroxyvitamin D3 (1,25S,26-(OH)3D3) on cell replication and expression of the osteoblastic phenotype in terms of osteocalcin production were examined in cultured human bone cells. At a dose of 5 × 10−12 mol/l, 1,25-(OH)2D3 stimulated cell proliferation, whereas at higher doses (5 × 10−9−5 × 10 −6 mol/l) cell growth was inhibited in a dose-dependent manner. The same pattern of effects was seen for the other metabolites in a rank order of potency: 1,25-(OH)2D3> 1,25S,26-(OH)3D3 = 1,24R,25-(OH)3D3>25S,26-(OH)2D3 = 24R,25-(OH)2D3 = 25-OH-D3. Synthesis of osteocalcin was induced by 1,25-(OH)2D3 in doses similar to those required to inhibit cell proliferation. Biphasic responses were observed for some of the metabolites in terms of osteocalcin synthesis, inhibitory effects becoming apparent at 5 × 10−6 mol/l. The cells did not secrete osteocalcin spontaneously. These results indicate that vitamin D metabolites may regulate growth and expression of differentiated functions of normal human osteoblasts.
J. Endocr. (1985) 105, 391–396
EVIDENCE FOR A NOVEL INHIBITION OF CALCIUM UPTAKE INTO CHICK BONE IN RESPONSE TO BOVINE PARATHYROID HORMONE (1-34) OR 16, 16-DIMETHYL PROSTAGLANDIN E2 IN VIVO
Authors: Shaw A.J. , Dacke C.G. 
Published: December 2008

ABSTRACT
Mechanisms of initial hypercalcaemic responses to parathyroid hormone (PTH) and 16, 16-dimethyl prostaglandin (PG) E2 have been investigated in 10-to 12-day-old chicks in vivo using a combination of acute 45Ca injection and microwave fixation to stabilize tissue isotope levels.
Single i.v. injection of 16, 16-dimethyl PGE2 (20 μg/100 g body wt) caused an approximately 100% increase in soft tissue 45Ca levels compared with vehicle control injected chicks at 30 min. 45Ca levels were lowered in calvarium by 26% and in femur by 60% with this treatment. Bovine PTH (1-34) (3.3 μg/100 g body wt) had no effect on soft tissue 45Ca levels, but in calvarium it had a similar effect to the PG. In femur this dose of PTH lowered 45Ca by 19%. When expressed on an absolute basis (c.p.m./ 100 mg tissue wt), responses to the PG in soft tissue were only 3 and 10% respectively of those in femur and calvarium.
The duration of inhibitory responses in bone were examined and those to PTH found to be transient (< 45 min) compared with the responses to the PG (> 135 min). Dose-response curves for PTH- and PG-induced inhibition of 45Ca uptake into femur at 15 min were essentially parallel and indicated that the lowest doses of PTH and PG used (0.74 μg and 1.1 μg/100 body wt respectively) produced significant responses.
In a separate experiment it was found that inhibition of 45Ca uptake into femur was evident as early as 3 min following PTH or PG injection.
The experiments described in this paper collectively indicate a higherto unrecognized action of PTH and PGE in the regulation of Ca metabolism in chicks which is to inhibit entry of Ca into bone.
Measurement of low concentrations of bovine thyrotrophin by iodide uptake and organification in porcine thyrocytes
Authors: Reader S. C. J. , Davison B. , Ratcliffe J. G. , Robertson W. R. 
Published: December 2008

ABSTRACT
Thyrocytes isolated from porcine thyroids by mechanical and enzymatic dispersion and cultured in Eagle's minimal essential medium, supplemented with 5% (v/v) fetal calf serum, glutamine and cortisol, formed a continuous monolayer within 48 h. This monolayer was without cytochemical peroxidase and diaphorase (NADPH reoxidation) activity. In the presence of bovine thyrotrophin (bTSH; 50 mu./l) the cells developed a follicular-like architecture which was maximal at 4 days before reverting back to a uniform monolayer at 6 days. There were no detectable changes in the total DNA content over this period. The follicular structures had marked diaphorase and peroxidase activity, the latter being apically distributed. Concomitant with follicle formation bTSH induced uptake and organification of iodide presented to the cells during the last 6 h of culture. The extent of this process depended on the dose of bTSH and the duration of stimulation. The most sensitive effects for both iodide uptake and organification occurred with 1 mu. bTSH/1 and were maximal with 100 mu./l. Uptake and organification were increased 20±8-fold and 9·6±2- fold (n = 10) respectively over the control with 100 mu./l and the doses of bTSH at which a half maximal response was seen (ED50) were 15±2 and 7±1 (s.d) mu./l (n = 10) respectively.
On changing the culture medium to a serum-free system using HB101 culture medium the stimulation time for the most sensitive bTSH effect was reduced to 2·5 days. Moreover the sensitivity of iodide uptake to bTSH was dramatically increased being significantly stimulated by 0·1 mu./l, saturated with 10 mu./l, and having an ED50 of 7 ± 0·2 mu. bTSH/1 (n = 7). Over the dose range 0·1–10 mu. bTSH/l intra- and interassay coefficients of variation were 7%±1·5 (n = 15) and 11% ± 2·5 (n = 15) respectively. Cyclic AMP production in cultures incubated under similar conditions (i.e. after chronic TSH stimulation) was also stimulated by bTSH doses in the range 15·6–125 mu./l. Cells stimulated for 2·5 days with dibutyryl cyclic AMP (range 1 μmol/1–2 mmol/l) also actively concentrated iodide in a dose-dependent fashion.
The presence of normal human serum in the medium yielded a progressive and dose-related decrease in TSH-stimulated iodide uptake. This inhibitory effect occurred with serum concentrations as low as 0·1%.
In conclusion, a porcine cell culture system is described in which iodide uptake is significantly stimulated by 0·1 mu. bTSH/l, a sensitivity inferior only to that reported with the cytochemical bioassay.
J. Endocr. (1985) 106, 13–20
The role of neonatal and pubertal gonadal hormones in regulating the sex dependence of the hepatic microsomal testosterone 5-reductase activity in the rat
Authors: Pak R. C. K. , Tsim K. W. K. , Cheng C. H. K. 
Published: December 2008

ABSTRACT
Hepatic microsomal testosterone 5-reductase activity was approximately fourfold higher in adult female rats than in males. This discrepancy was only partly androgen-dependent since gonadectomy of male rats at 68 days of age resulted in only a partial increase of the enzyme activity. This increase was reversible by the administration of testosterone. Similar treatment, however, produced no effect in the female rat, indicating that there is a sex difference in testosterone responsivity. Castration of newborn male rats resulted in a marked increase in the basal enzyme activity. This increase was not affected by treating the adults with testosterone. Giving testosterone to male rats immediately after neonatal gonadectomy, or to newborn female rats, did not produce the male pattern of both the basal enzyme activity and the testosterone responsivity in adulthood. These results suggest that a brief exposure to neonatal androgen is not critical for the expression of the male type of enzyme activity, but that the continuous presence of the male gonads up to and including the pubertal period is essential. Exposure of pubescent female rats to testosterone during the period from 35 to 50 days of age resulted in a significant increase in testosterone sensitivity when tested at 90 days of age, suggesting that pubertal exposure to androgen is important for the expression of testosterone responsivity in adulthood. The sensitivity was potentiated when the animals were ovariectomized before puberty. Furthermore, the enzyme activity in prepubertally ovariectomized female rats was significantly lower than that in adult gonadectomized animals. The decreased level of activity returned to the control value when oestrogen was replaced during puberty, indicating that peripubertal oestrogen exposure is required for maintaining the high level of activity found in adult female rats. The present findings suggest that the pubertal period represents a sensitive phase during which sex hormones act to regulate the sexual differentiation of testosterone 5-reductase activity in the rat.
J. Endocr. (1985) 106, 71–79
Effect of immunoneutralization of thyrotrophin-releasing hormone on the release of thyrotrophin and prolactin during suckling or in response to electrical stimulation of the hypothalamus in the anaesthetized rat
Authors: Sheward W. J. , Fraser H. M. , Fink G. 
Published: December 2008

ABSTRACT
The aim of the present study was to use the technique of immunoneutralization with anti-thyrotrophin-releasing hormone (anti-TRH) serum to investigate the role of TRH in mediating the TSH and prolactin responses to electrical stimulation of the hypothalamus and the prolactin response to suckling in lactating rats. Electrical stimulation of either the median eminence or paraventricular nuclei of male or female rats anaesthetized with urethane resulted in significant increases in the plasma concentrations of both TSH and prolactin. Injection of sheep anti-TRH serum blocked the rise in plasma TSH concentration in response to stimulation of either brain area, but did not block the increase in plasma prolactin concentration. In anaesthetized, lactating female rats, the suckling stimulus produced a significant increase in the plasma prolactin concentration, but did not alter the plasma TSH concentration. Injection of anti-TRH serum, but not control non-immune or anti-bovine serum albumin, significantly decreased the basal release of TSH but did not abolish the prolactin response to suckling. These results show that TRH is the principal mediator of the neural control of TSH release in the rat, but is not crucial for the release of prolactin in response to either hypothalamic stimulation or suckling.
J. Endocr. (1985) 106, 113–119
FSH secretion in pinealectomized rams subjected to artificial photoperiods
Authors: Barrell G. K. , Lapwood K. R. , Elgar H. J. 
Published: December 2008

ABSTRACT
Eight mature Romney rams which had been pinealectomized and another eight sham-operated rams were allocated equally to one of two contrasting lighting regimes. They were housed indoors with the temperature held constant, offered a constant diet and plasma samples were collected each week for 9 months.
Changes in plasma FSH in pinealectomized and sham-operated rams were similar when the rams were subjected to normal seasonal changes in photoperiod, with lower FSH levels recorded under increasing daily photoperiods than during the phase of decreasing (stimulatory) photoperiods. In contrast a reversed pattern of changes in lighting advanced the increase of plasma levels of FSH in the case of sham-operated rams, because the period of decreased daily photoperiods occurred earlier in this situation. In this case, however, pinealectomized rams did not behave like the control animals, but had raised plasma FSH levels at the same time as rams on the normal lighting regime.
These results demonstrate that the pineal-mediated effects of photoperiod on reproduction in sheep directly involve FSH secretion and that seasonal cyclic changes in FSH secretion persist even after pinealectomy.
J. Endocr. (1985) 106, 167–171
Inhibition by prostaglandin E2of the release of vasopressin and β-endorphin from rat pituitary neurointermediate lobe or medial basal hypothalamus in vitro
Authors: Knepel W. , Nutto D. , Vlaskovska M. , Kittel Ch. 
Published: December 2008

ABSTRACT
The present study was performed to examine the effect of the cyclo-oxygenase inhibitor, indomethacin, and that of various prostaglandins on the release of vasopressin and β-endorphin-like immunoreactivity (β-EI) from the rat neurointermediate lobe of the hypophysis, which was superfused in vitro. Indomethacin (2·8 and 28 μmol/l) changed neither basal secretion of vasopressin nor that evoked by electrical stimulation, whereas the resting release of β-EI was enhanced by indomethacin (28 μmol/l). Prostaglandin (PG) E2 did not influence resting release of vasopressin but markedly inhibited (by about 50%) electrically induced release of vasopressin (least effective concentration: 300 nmol/l) as well as spontaneous secretion of β-EI (least effective concentration: 100 nmol/l) in the presence of indomethacin (28 μmol/l). Prostaglandin F2α (5 μmol/l) also inhibited the evoked release of vasopressin, whereas PGD2 (5 μmol/l) did not. Prostaglandin F2α (5 μmol/l), D2 and I2 (1·5 μmol/l each) produced no effects on β-EI release. As observed in the neurohypophysis, PGE2 inhibited the electrically induced release of vasopressin from the medial basal hypothalamus in vitro. We conclude that prostaglandins (especially PGE2) can inhibit (1) the stimulated release of vasopressin when acting on vasopressin-containing nerve terminals of either neurosecretory system (neurohypophysis, median eminence region), and (2) the secretion of β-EI and, as can be inferred, α-MSH, by a direct action on intermediate lobe cells.
J. Endocr. (1985) 106, 189–195