bluuebunny/crossref_metadata_2025_split huggingface dataset:
Testicular steroid metabolism during development in the normal and hypogonadal mouse
Authors: Sheffield J. W. , O'Shaughnessy P. J. 
Published: December 2008

ABSTRACT
The patterns of testicular steroidogenesis were investigated during postnatal development in the normal mouse and in the hypogonadal (hpg) mouse from 20 days. The hpg mouse lacks GnRH and may be used to examine the function of this peptide in normal gonadal development. Testicular tissue was incubated with [3H]pregnenolone and metabolites were separated by thin-layer chromatography and high-performance liquid chromatography. In the normal mouse from 1 to 10 days, metabolism occurred predominantly through the Δ4 pathway, and progesterone, 17α-hydroxyprogesterone, androstenedione and testosterone were the main metabolites formed, together with significant amounts of an unidentified polar steroid. Between 15 and 25 days, androstenedione became the major metabolite formed from pregnenolone. There was also a marked increase in 5α-reductase activity during this age range, and 5α-dihydrotestosterone and 5α-androstane-3α, 17β-diol were significant metabolites. In normal animals older than 30 days, testosterone became the major metabolite, and between 30 days and adulthood the pattern of metabolism changed significantly due to increased formation of intermediates from the Δ5pathway. In the hpg mouse between 20 and 30 days, the pattern of steroid metabolism was unlike that of any age of the normal animal. Progesterone was the major metabolite formed and dehydroisoandrosterone was the major C19 steroid formed, although significant levels of androstenedione and testosterone were also formed. After 30 days there was a marked decrease in steroid metabolism, with androstenedione (the major androgen) being formed mainly through the Δ4 pathway. Addition of human chorionic gonadotrophin to tissue from normal or hpg animals had little effect on the pattern of metabolism, except in the 10- and 20-day-old normal animal where there was an increased accumulation of progesterone.
These results indicate that in the normal mouse the major testicular steroidogenic pathways show significant changes during development. In the hpg mouse the steroidogenic pathways are markedly different from those in normal animals, indicating the importance of the gonadotrophins in controlling the pattern of steroidogenesis. The change in the testicular steroidogenic pattern during development in the hpg mouse may also indicate, however, that these testes are under some stimulation during early postnatal development.
J. Endocr. (1988) 119, 257–264
Validation of a heterologous radioimmunoassay for insulin-like growth factor-I in bovine serum
Authors: Holland M. D. , Hossner K. L. , Niswender G. D. , Elsasser T. H. , Odde K. G. 
Published: December 2008

ABSTRACT
A quantitative, repeatable, heterologous radioimmunoassay (RIA) for insulin-like growth factor-I (IGF-I) was developed for bovine serum. Untreated serum could not be assayed due to interference by IGF-I-binding protein. Serum acidified to pH 3·6 in glycine–HCl (0·1 mol/l) for 24 h at 37 °C and neutralized with NaOH produced inhibition curves non-parallel to the [Thr59]-IGF-I standard. Neutralization by 40-fold dilution of acidified serum samples with assay buffer produced inhibition curves nearly parallel to the IGF-I standard. Complete parallelism was achieved by utilizing preprecipitated normal rabbit serum–sheep anti-rabbit γ-globulin to separate antibody-bound 125I-labelled IGF-I from free 125I-labelled IGF-I. Recovery of IGF-I (1·3–52·3 fmol) added to serum was quantitative. The sensitivity of the RIA (n = 6) was 8·25 ± 0·17 (s.e.m.) fmol. Intra- and interassay coefficients of variation were 3·03 and 4·95% respectively. Serum IGF-I levels measured in beef calves at weaning were positively correlated with weaning weight, total weight gain from birth to weaning and average daily weight gain. In conclusion, a heterologous RIA for IGF-I in beef serum which is sensitive, accurate, precise and repeatable has been developed.
J. Endocr. (1988) 119, 281–285
Electrophysiological correlates of fluid transport in cultured porcine thyroid cells
Authors: Pearson J. , Bourke J. R. , Manley S. W. , Huxham G. J. , Matainaho T. , Gerard C. , Verrier B. , Mauchamp J. 
Published: December 2008

ABSTRACT
Confluent monolayers of cultured porcine thyroid cells transport fluid from the apical to the basal surface, forming circumscribed zones of detachment from the culture dish substrate (domes). The transepithelial potential (TEP), positive on the basal side, was 12·9 ± 0·4 (s.e.m.) mV (n = 93) under control conditions, increasing to 38·9 ± 0·3 mV (n = 281) when fluid transport was stimulated by prostaglandin E2 (PGE2; 1 μmol/l). Forskolin (1 μmol/l) and 8-(4-chlorophenylthio) adenosine 3′,5′-cyclic monophosphate (0·5 mmol/l) were also effective in increasing TEP. Addition of amiloride in concentrations sufficient to block fluid transport (100 μmol/l) reduced the TEP to 5·8 ± 0·3 mV (n=76). Substitution of N-methyl-d-glucamine for sodium in the medium reduced the PGE2-stimulated TEP to 13·4 ± 0·8 mV (n = 32). Substitution of gluconate for chloride increased the TEP to 40·3 ± 0·4 mV (n = 160). Removal of bicarbonate or potassium from the medium, or addition of ouabain (200 μmol/l) were also effective in reducing the TEP. In media of low bicarbonate concentration (1 mmol NaHCO3/l), acetazolamide (1 mmol/l) reduced the TEP. Fluid transport by the monolayer as measured by the change in height of domes was increased by PGE2 (1 μmol/l). PGE2-stimulated fluid transport was inhibited by sodium or chloride ion substitution, bicarbonate removal or the addition of ouabain (200 μmol/l) or amiloride (100 μmol/l). It was concluded that fluid transport in thyroid monolayers is mediated by rheogenic sodium transport with chloride transport being passive, electrogenically coupled to sodium transport. Sodium entry to the apical pole of the cells occurs by an amiloride-sensitive mechanism, and sodium extrusion at the basal pole depends on the Na+/K+ ATPase.
J. Endocr. (1988) 119, 309–314
Plasma clearance in the rat of the LH bioactivity of two human LH standards of differing molecular composition
Authors: Storring P. L. , Khan S. A. , Mistry Y. G. , Diczfalusy E. 
Published: December 2008

ABSTRACT
The LH biological potency of the International Reference Preparation (IRP) of Human Pituitary LH for Immunoassay (IRP 68/40) relative to that of the 2nd IRP of Human Pituitary FSH and LH for Bioassay (IRP 78/549) is markedly greater when estimated by in-vitro interstitial cell testosterone production (TICT) bioassay than by in-vivo bioassay, and by the 4-h ovarian ascorbate depletion (OAAD) assay than by the 4-day seminal vesicle weight gain assay. Other preparations of human LH which, like IRP 68/40, were highly purified, showed a similar spectrum of bioactivity in these assay systems and also contained a higher proportion of more basic LH isoforms than are found in crude pituitary extracts such as IRP 78/549.
In an attempt to explain these differences, a comparison was made of the plasma survival in rats of the LH bioactivity (by TICT assay) of these two preparations. Contrary to expectation, their relative plasma clearance rates over a 4-h period did not account for their differing bioactivities. The plasma half-life of the LH bioactivity (with 95% confidence limits) was estimated to be 42·4 (35·3–49·5) min for IRP 68/40 and 41·3 (31·5–51·0) min for IRP 78/549.
Furthermore the time-course of action in vivo of IRP 78/549 did not appear to be more prolonged than that of IRP 68/40. Thus their plasma testosterone responses during the course of these 4-h plasma clearance studies were similar, and estimates of the LH potency of IRP 68/40 relative to that of IRP 78/549 were no greater by 2-h than by 4-h OAAD assay.
The more basic isoforms of LH present in IRP 68/40 and in other purified human LH preparations may therefore differ from those in crude pituitary extracts, such as IRP 78/549, in their intrinsic activity to stimulate the different target cells in these assay systems rather than in their bioavailability in vivo.
J. Endocr. (1988) 119, 327–334
A sensitive and specific two-site enzyme-immunoassay for human calcitonin using monoclonal antibodies
Authors: Seth R. , Motté P. , Kehely A. , Wimalawansa S. J. , Self C. H. , Bellet D. , Bohuon C. , MacIntyre I. 
Published: December 2008

ABSTRACT
A highly sensitive, specific and rapid two-site enzyme-immunometric assay (EIA) for the measurement of immunoreactive (ir) human calcitonin (hCT) in human plasma was developed using high-affinity monoclonal antibodies. The assay was validated in terms of sensitivity, specificity and reproducibility and its performance compared with that of a radioimmunoassay (RIA) employing a polyclonal antiserum. The sensitivity of the overnight EIA (2 pmol/l) was comparable with the long-incubation (7 days) RIA. The overnight RIA had a sensitivity of 10 pmol/l. The inter- and intra-assay variations of the EIA were less than 12%. Some related and non-related peptides were compared with synthetic hCT for cross-reactivity in the assay and were found to be negative. The mean recovery of added synthetic hCT from plasma of normal volunteers was 96%. Both RIA and EIA have been applied to the measurement of ir-hCT in normal volunteers and in patients with medullary carcinoma of the thyroid. In both groups, the level of ir-hCT measured by EIA was found to be lower than that measured by RIA, presumably due to the ability of the more specific EIA to detect only the 'mature' form of the hormone. EIA offers an attractive alternative to the more cumbersome and lengthy RIA in current usage, with the added advantage of employing a non-isotopic label.
J. Endocr. (1988) 119, 351–357
Effects of thyroxine on oestrogen receptor concentrations in anterior pituitary and hypothalamus of hypothyroid rats
Authors: Altschuler L. R. , Ceppi J. A. , Ritta M. N. , Calandra R. S. , Zaninovich A. A. 
Published: December 2008

ABSTRACT
The effects of thyroxine (T4) were studied on the concentration of oestrogen receptors in the anterior pituitary gland and hypothalamus of ovariectomized euthyroid and hypothyroid rats. A group of rats was made hypothyroid by the administration of I. Seven days after ovariectomy, animals were separated into five groups: I, euthyroid controls; II, hypothyroid controls; III, hypothyroid and injected with oestradiol benzoate (10 μg/day for 10 days); IV, hypothyroid and injected with T4 (4 μg/day for 10 days) and V, hypothyroid and injected with both oestradiol and T4 as described above. In group I, oestrogen receptor levels in pituitary cytosol were 44·4 ± 3·4 (s.d.) fmol/mg protein and in the nucleus 47·7 ± 4·0 fmol/mg DNA. In group II the respective values were 12·8 ± 1·7 fmol/mg protein (P <0·01) and 12·7 ± 1·7 fmol/mg DNA (P <0·01 compared with group I). In group III, cytosolic receptor concentrations decreased when compared with those in group II (P <0·05), whereas nuclear receptor concentrations rose significantly (P <0·01). Group IV had both pituitary cytosolic and nuclear receptors increased (P <0·01 compared with group II). In group V there were no changes in cytosolic receptor concentrations but a significant (P <0·01) rise in nuclear receptors as compared with group II. Hypothalamic oestrogen receptors in untreated hypothyroid rats (group II) were unchanged in the cytosol and diminished (P <0·01) in the nucleus in relation to euthyroid controls (group I). Thyroxine, but not oestrogen, was effective in increasing the concentration of cytosolic receptors (P <0·05). Neither hormone caused changes in nuclei. The results show that there is a pronounced decrease in pituitary and hypothalamic (nuclei) oestrogen receptors in untreated hypothyroid rats and that this decrease can be reversed by T4 treatment.
J. Endocr. (1988) 119, 383–387
In-vitro control of growth hormone secretion by synthetic releasing factors in young and adult ducks (Anas platyrhynchos)
Authors: Foltzer-Jourdainne C. , Harvey S. , Mialhe P. 
Published: December 2008

ABSTRACT
Release of GH from perifused duckling hemipituitaries was stimulated, in a biphasic manner, by synthetic TRH and human pancreatic GH-releasing factor (GRF). At all effective concentrations, the level of GH release was increased within 5 min of TRH or GRF perifusion and was maximal after 10 min of TRH perifusion and after 20 min of GRF perifusion. Although TRH was perifused for 20 min the level of GH release declined during the last 10 min. The most effective dose of TRH (1·0 μg/ml; 2·7 μmol/l) and GRF (0·5 μg/ml; 110 nmol/l) provoked similar (250– 300%) increases in the level of GH release. However, since the effect of TRH was only of short duration, the total release of GH induced by GRF was higher than that elicited by TRH, especially with the low dose. The increase in release of GH induced by TRH or GRF was blunted when pituitaries from adult ducks were used. As in young ducks, the GH response to GRF was higher, whereas the response to TRH was very low. The GH response of perifused adult pituitaries to GRF was, however, potentiated when TRH was perifused simultaneously. The basal release of GH from both young and adult pituitary glands was unaffected by perifusion with somatostatin-14 (SRIF-14) at doses of 1 and 2 μg/ml. The perifusion of hemipituitary glands with similar doses of SRIF-14 was also unable to suppress the stimulation of GH release induced by prior perifusion with GRF, although when SRIF-14 and TRH were simultaneously perifused TRH-induced GH release was markedly suppressed.
These results demonstrate direct effects and interactions of TRH, GRF and SRIF on the release of GH from duck pituitary glands. GRF is the most potent releasing factor for GH in both young and adult ducks although in adult ducks it is less effective. These results also provide evidence that the age-related decline in the in-vivo GH response to TRH is due to a desensitization of pituitary somatotrophs.
J. Endocr. (1988) 119, 421–429
Oestradiol synergizes with 5α-dihydrotestosterone or 3α- but not 3β-androstanediol in inducing sexual behaviour in castrated rats
Authors: Södersten P. , Eneroth P. , Hansson T. 
Published: December 2008

ABSTRACT
Castrated male rats were treated with constant-release implants filled with testosterone, oestradiol-17β, 17β-hydroxy-5α-androstan-3-one (5α-dihydrotestosterone; DHT), 5α-androstane-3α,17β-diol (3α-Adiol) or 5α-androstane-3β,17β-diol (3β-Adiol). Only testosterone activated the sexual behaviour of the rats. If combined with oestradiol, DHT or 3α-Adiol induced the behaviour, but 3β-Adiol failed to have this effect. Oestradiol inhibited the in-vitro formation of [14C]Adiols from [14C]DHT by combined preoptic and hypothalamic tissue, but only when given in high doses. No effect on the formation of [14C]Adiols from [14C]DHT was found in rats treated in vivo with DHT or with the combination of DHT and oestradiol which effectively stimulated sexual behaviour. These results do not support the suggestion that oestradiol may synergize with androgens to induce sexual behaviour in castrated rats by inhibiting androgen metabolism.
J. Endocr. (1988) 119,461–465
Precopulatory behaviour in the male hamster: effect of the 5α-reductase inhibitor 17β-N,N-diethylcarbamoyl-4-aza-5α-androstan-3-one
Authors: Steel E. , Hutchison J. B. 
Published: December 2008

ABSTRACT
Three independent components of hamster masculine behaviour (approaching, leaving and sniffing the female) have been shown to depend on both androgenic and oestrogenic action. The behavioural role of 5α-reduced androgens was assessed by blocking 5α-reduction of testosterone by means of 17β-N,N-diethylcarbamoyl-4-aza-5α-androstan-3-one (4-MA) through slow-release silicone elastomer implants. Three dose levels of 4-MA were given to intact, sexually active males. The probability of approaching the female and the amount of sniffing directed to her were both decreased, while the probability of leaving the female was increased. Sniffing and the tendency to approach were affected at lower dose levels than was the tendency to leave. The higher dosage of 4-MA also abolished odour-based discrimination between females shown by normal males. These effects of 4-MA on behaviour were confirmed in castrated hamsters maintained on testosterone. The suppressive effects of 4-MA on behaviour were reversed by treatment with 5α-dihydrotestosterone (DHT). We conclude that testosterone maintains sociosexual behaviour in part by conversion to its 5α-reduced metabolites; components of this behaviour differ in their relative dependence on DHT. In this species, DHT is likely to be a behaviourally active metabolite of testosterone involved in the fine control of behaviour.
J. Endocr. (1988) 119, 483–491
SECRETION OF BIOACTIVE INHIBIN BY THE OVARY OF THE BOOROOLA MERINO EWE WITH OR WITHOUT A COPY OF THE FECUNDITY (F) GENE.
Authors: Tsonis C. G. , Baird D. T. , Campbell B. K. , Downing J. A. , Scaramuzzi R. J. 
Published: December 2008

ABSTRACT
The secretion rates of bioactive inhibin, oestradiol and progesterone were measured during the mid-luteal phase and at various times during the follicular phase of the cycle by a sensitive bioassay using sheep pituitary cells in culture in 12 Booroola ewes with and without copies of the Fecundity (F) gene in which the left ovary had been auto-transplanted to the neck.
Inhibin secretion was high during the luteal phase and fell in the early follicular phase in all genotypes (P < 0.01). In Booroola ewes with a F/- genotype, inhibin secretion then increased again, towards luteal rates, in the mid and late follicular phases. In Booroola ewes without a copy of the F gene (+/+) inhibin secretion remained low at all three sampling times in the follicular phase. The secretion rate of inhibin at 36 h (P < 0.1) and 48 h (P < 0.01) were significantly lower in ewes from the +/+ (no copy of the gene) ewes than in F/(one copy of the gene) ewes. Oestradiol secretion was low during the luteal phase and increased steadily during the early (24 h) to a plateau in the mid (36 h; P < 0.01) and late (48 h; P < 0.05) follicular phase. Progesterone secretion was high during the luteal phase, and decreased to a very low rate by 24 h after prostaglandin (PG) treatment (P < 0.001) and remained low. At 24 h after PG the concentration of FSH was significantly lower (P < 0.01) than that during the luteal phase and remained suppressed until the onset of the LH surge. There were no significant differences in LH concentrations. We conclude that (1) the secretion of inhibin by the ovary is highest in the luteal phase and (2) inhibin secretion is significantly raised during the mid to late follicular phase in Booroola ewes with a copy of the Fecundity gene compared with those without.
Feedback regulation by progesterone of stress-induced prolactin release in rats
Authors: Deis R. P. , Leguizamon E. , Jahn G. A. 
Published: December 2008

ABSTRACT
We have previously found that modifications to serum progesterone concentration have profound inhibitory effects on prolactin release in response to ether stress. The objective of the present study was to determine the effect of ether stress on progesterone secretion and the role of this steroid in ether-induced prolactin release.
Serum progesterone concentration, 5 min after ether stress had been applied over a 2-min period, was consistently increased in male rats, in cyclic rats on the mornings of pro-oestrus and oestrus, and in androgenized rats in permanent oestrus. Ovariectomized androgenized rats showed the same response. Adrenalectomy of male and female rats abolished the progesterone increase induced by stress. Thus, the progesterone secreted by stressed rats is mostly of adrenal origin.
In groups of male and pro-oestrous rats, circulating concentrations of prolactin and progesterone were measured from 5 to 60 min after stress. In both sexes the serum prolactin concentration was significantly increased at only 5 and 10 min after stress when compared with control values. In pro-oestrous rats the serum progesterone concentration was significantly higher than in controls at 5, 10 and 20 min after stress, whilst in male rats the concentration remained significantly higher at 30 min.
Thirty minutes after the first stress, male and pro-oestrous rats were etherized for 2 min, and bled 5 min after removal from the ether container. In female rats this second stress produced only a slight but significant increase in serum prolactin concentrations, whereas in male rats prolactin concentrations did not increase. The second stress was still capable of significantly increasing circulating progesterone concentrations to levels similar to those obtained after the first stress in animals from all groups. Thus, an increased circulating progesterone concentration did not lead to regulation of further progesterone secretion. To find whether this type of response was due to a blocking effect of the previously released progesterone, animals were injected with the anti-progesterone RU 38486 (17β-hydroxy-11β-(4-dimethylaminophenyl)-17α-propinyl-oestra-4,9-dien-3-one) or with a specific antibody raised against progesterone. In both groups of treated rats the second stress induced a significant increase in serum prolactin and progesterone concentrations to give values similar to those obtained after the first stress. When the second stress was applied to female rats 60 min after the first the prolactin response was comparable to that obtained after the first exposure to ether.
In conclusion, we have demonstrated that serum prolactin and progesterone concentrations are significantly increased after ether stress, and that the latter hormone exerts an inhibitory regulatory feedback on prolactin secretion. These results provide an important new insight into the role of progesterone in the regulation of prolactin release.
Journal of Endocrinology (1989) 120, 37–43
Androgen regulation of major mRNAs for proteins of the immature and adult mouse vas deferens
Authors: Martinez A. , Berger M. , Jean Cl. 
Published: December 2008

ABSTRACT
When total RNA and poly (A)+ RNA extracted from the adult mouse vas deferens were translated in the rabbit reticulocyte lysate protein synthesizing system, they showed a similar electrophoretic pattern of about 20 protein bands of widely varying molecular weights. Within the total mRNA population, three functional mRNAs coding for proteins with molecular weights of 24, 34·5 and 36 kDa showed marked changes after 1 month of castration. The time-course of the response of the translatable proteins showed that while 3 days after castration the 24 and 36 kDa bands were missing, the mRNA coding for the 34·5 kDa band was markedly reduced only 20 days after castration. The negative effect of castration on the three mRNAs could be completely reversed by treatment with testosterone. When total RNA extracted from the immature mouse vas deferens was translated, the 24, 34·5 and 36 kDa protein bands were detectable in 10-day-old males and were synthesized in significant amounts between 10 and 20 days (24 and 36 kDa bands) or between 20 and 30 days (34·5 kDa band). Based on its electrophoretic and immunological properties, the 34·5 kDa protein band, which is predominant in the translation products, was identified as the major androgen-dependent protein previously described in vivo.
Journal of Endocrinology (1989) 120, 67–74