bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of α-melanocyte-stimulating hormone on the cyclic AMP and phospholipid metabolism of rat adrenocortical cells
Authors: Hyatt P. J. , Bell J. B. G. , Bhatt K. , Chu F. W. , Tait J. F. , Tait S. A. S. , Whitley G. St J. 
Published: December 2008

ABSTRACT
Results on the effects of peptides on the phospholipid metabolism and steroid and cyclic AMP (cAMP) outputs of rat adrenal capsular cells (96% zona glomerulosa, 4% zona fasciculata) were obtained in a series of three batch experiments. Their significance was examined by analysis of variance. Incorporation of [32P] into phosphatidylcholine, phosphatidic acid and phosphatidylinositol was measured. Production of [3H]inositol-1 monophosphate, inositol-1,4 bis-phosphate and inositol-1,4,5 tris-phosphate was estimated after prelabelling with [3H]inositol followed by 1 min incubation with a steroidogenic stimulus. Angiotensin II (0·25 nmol/l to 0·25 μmol/l) highly significantly (P < 0·01) stimulated aldosterone and corticosterone outputs, [32P] incorporation into phosphatidic acid and phosphatidylinositol (but not into phosphatidylcholine) and the production of the three [3H]inositol phosphates. Aldosterone and corticosterone outputs were stimulated by α-MSH (above 0·1 nmol/l). However, incorporation of [32P] was not significantly increased until 10 μmol α-MSH/l but, unlike with angiotensin II, incorporation into phosphatidylcholine was also then stimulated. Also, the production of the inositol phosphates was not increased significantly (P > 0·05) by any dose of α-MSH (10 nmol/l, 1 μmol/l and 0·1 mmol/l) used. Therefore, it can be concluded that α-MSH does not stimulate phospholipase C in rat zona glomerulosa cells. In further experiments, it was also found that there were significant increases in cAMP as well as in steroid outputs above 1 nmol α-MSH/l (highly significant above 10 nmol α-MSH/l). There were plateaux of the outputs of both steroids and cAMP from 0·1 to 1 μmol α-MSH/l. However, there were further increases in steroid and cAMP outputs of the capsular cells at higher doses. Concomitant results on the stimulation of corticosterone output by zona fasciculata–reticularis cells indicate that this additional increase was mostly due to the stimulation of the contaminating zona fasciculata cells. It was also confirmed that α-MSH preferentially stimulates steroidogenesis by the zona glomerulosa. However, under our conditions, α-MSH highly significantly increased the output of cAMP by both zona fasciculata and glomerulosa cells.
J. Endocr. (1986) 110, 405–416
In-vitro conversion of thyroxine to tri-iodothyronine by chicken hepatic 5′-deiodinase: kinetic studies
Authors: Lam S. K. , Harvey S. 
Published: December 2008

ABSTRACT
In-vitro studies with chicken liver homogenates demonstrate that the conversion of thyroxine (T4) to tri-iodothyronine (T3) is dependent upon tissue concentration, time of incubation, pH, temperature, the presence of dithiothreitol (DTT) and the concentration of substrate (T4), and is heat-labile. The generation of T3 is inhibited by iopanoic acid and 6-n-propyl-2-thiouracil. The kinetics of conversion of T4 to T3, determined by Lineweaver–Burke analysis, indicated an apparent Michaelis–Menten constant (Km) of 1·16 μmol/l with a maximum velocity (Vmax) of 44·57 pmol T3 generated/mg protein per min from T4. Dithiothreitol appears to behave as a co-substrate for this system with an apparent Km of 98·5 μmol/l and a Vmax of 1·41 pmol T3 generated/mg protein per min at a T4 concentration of 5 μmol/l. These data suggest that the conversion of T4 to T3 in fowl proceeds by means of an enzymatic system, probably 5′-monodeiodinase, and is responsible for maintaining T3 levels in vivo.
J. Endocr. (1986) 110, 441–446.
Analysis of prostatic bud induction by brief androgen treatment in the fetal rat urogenital sinus
Authors: Takeda H. , Lasnitzki I. , Mizuno T. 
Published: December 2008

ABSTRACT
The androgen dependency of prostatic bud formation in fetal rat urogenital sinuses was studied using brief treatments with androgen, and the incorporation of androgens by the sinus mesenchyme was followed by steroid autoradiography.
Urogenital sinuses from 16·5-day fetuses of both sexes were grown in organ culture and treated with androgens for periods ranging from 4 to 72 h and then transferred to control medium. A minimum treatment of 24 h was required to induce prostatic buds in male sinuses and of 36 h in all female sinuses. This difference in response disappeared after more prolonged treatment. In both sexes the number of prostatic buds increased with the time of exposure to androgens. Prostatic bud formation continued for 24–36 h after transfer to control medium.
Steroid autoradiographic analysis showed that the labelled androgen was concentrated in the mesenchymal nuclei. The rate of incorporation rose steeply during the first 12 h and then more slowly. After transfer to control medium the amount of labelled androgen decreased rapidly to half within 12 h and then decreased more slowly. In the competition experiments a 200-fold excess of unlabelled testosterone or dihydrotestosterone in the labelling medium greatly reduced the nuclear labelling with [3H]testosterone.
J. Endocr. (1986) 110, 467–470
Are catechol oestrogens obligatory mediators of oestrogen action in the central nervous system? I. Characterization of pharmacological probes with different receptor binding affinities and catechol oestrogen formation rates
Authors: Pfeiffer D. G. , MacLusky N. J. , Barnea E. , Naftolin F. , Krey L. C. , Loriaux D. L. , Merriam G. R. 
Published: December 2008

ABSTRACT
In an attempt to define pharmacological probes with which to test the role of catechol oestrogen formation in the central nervous system, five oestrogens (oestradiol-17β, oestradiol-17α, 4-fluoro-oestradiol, 2-fluoro-oestradiol and moxestrol (11β-methoxy-17α-ethynyloestradiol) were studied for binding to oestrogen receptors and conversion to catechol metabolites. Binding to cytosol oestrogen receptors was measured in the hypothalamus–preoptic area–amygdala (HPA), pituitary gland and uterus of ovariectomized rats. Conversion to catechol oestrogens was tested in microsomes from the HPA, pituitary gland and liver, using a catechol-O-methyltransferase-coupled radioenzymatic assay. Oestradiol-17α was the only weak oestrogen receptor ligand. Binding affinities of the other compounds tested were much higher and comparable to those of oestradiol-17β. In contrast, oestradiol-17α was rapidly converted to catechol metabolites, while moxestrol was a relatively poor substrate for catechol oestrogen formation. 4-Fluoro-oestradiol could be 2-hydroxylated but not 4-hydroxylated. 2-Fluoro-oestradiol exhibited impaired 2-hydroxylation but normal 4-hydroxylation.
J. Endocr. (1986) 110, 489–497
Are catechol oestrogens obligatory mediators of oestrogen action in the central nervous system? II. Potencies of natural and synthetic oestrogens for induction of gonadotrophin release and female sexual behaviour in the rat
Authors: MacLusky N. J. , Krey L. C. , Parsons B. , Merriam G. R. , Loriaux D. L. , Pfeiffer D. G. , Naftolin F. 
Published: December 2008

ABSTRACT
The role of catechol oestrogen formation in the mechanism by which circulating oestrogens facilitate gonadotrophin release and female sexual behaviour was explored in adult female rats. The effects of oestradiol-17β were compared with those of a group of oestrogens with either a reduced affinity for oestrogen receptors (oestradiol-17α) or a reduced ability to act as substrates for catechol oestrogen formation (2-fluoro-oestradiol, 4-fluoro-oestradiol and moxestrol (11β-methoxy-17α-ethynyloestradiol)). Rats were ovariectomized on the evening of dioestrus day 1 of the 4-day oestrous cycle and implanted s.c. 12 h later with infusion pumps containing either one of the test oestrogens or vehicle alone. Infusion rates for oestradiol-17β, moxestrol, 2-fluoro-oestradiol and 4-fluoro-oestradiol were adjusted to give concentrations of nuclear oestrogen receptors in the brain and pituitary gland within the range of those found in intact female rats during pro-oestrus. Oestradiol-17α was infused at the same and at a tenfold higher rate than that of oestradiol-17β; neither of these treatments with oestradiol-17α significantly increased brain or pituitary gland nuclear oestrogen receptor levels. On the day after the pump was implanted, samples of tail vein blood were withdrawn at 12.00, 14.00, 16.00 and 18.00 h for LH assay. All animals were then injected s.c. with 1 mg progesterone in propylene glycol, and tested for feminine sexual behaviour 5 h later. Oestradiol-17β, moxestrol, 2-fluoro-oestradiol and 4-fluoro-oestradiol all elicited pronounced LH surges and facilitated progesterone-triggered proceptive and lordosis behaviours. In contrast, oestradiol-17α was without effect on LH secretion and sexual behaviours. These results are consistent with the hypothesis that catechol oestrogen biosynthesis is not an obligatory step in the mechanism by which circulating oestrogens induce LH release and feminine sexual behaviour in the rat.
J. Endocr. (1986) 110, 499–505
Effect of age on the 3,5,3′-tri-iodothyronine-induced increase in sugar uptake in rat thymocytes
Authors: Segal J. , Troen B. R. 
Published: December 2008

ABSTRACT
The effect of age on the responsiveness of rat thymocytes to 3,5,3′-tri-iodothyronine (T3) was studied. It has been demonstrated previously that the plasma membrane-mediated effect of T3 to increase sugar uptake by rat thymocytes is influenced by age and sex. In both sexes, T3 given in vitro stimulated sugar uptake in cells from animals of 15 days of age, had no effect at 21 days and was again effective at 26 days. In the male, thymocytes from animals of 40 days of age and older were refractory to T3. However, in the female, T3, although less effective than in cells from 26-day-old animals, remained stimulatory in cells from 40- and 60-day-old rats. T3 had no effect in cells from animals of 90 days of age and older. In in-vivo studies in which female rats of 26, 60 and 90 days of age were first injected with T3 and 1 h later with [3H]2-deoxyglucose, the responsiveness of thymocytes to T3 also declined progressively with advancing age; T3 was most effective in cells from 26-day-old animals, less stimulatory in 60-day-old and essentially without effect in cells from 90-day-old animals. From these observations we have concluded that in both male and female rats the responsiveness of thymocytes to T3 declines progressively with age, and that this decline occurs at an earlier age in cells obtained from males.
J. Endocr. (1986) 110, 511–515
Neonatal exposure to Δ9-tetrahydrocannabinol enhances sexual responses in the adult male mouse
Authors: Shrenker P. , Stegar R. , Bartke A. 
Published: December 2008

ABSTRACT
From day 1 post partum to postnatal day 5, lactating female mice were given daily oral doses of 25 μl sesame oil, 0·5 mg tetrahydro-6,6,9-trimethyl-3-pentyl-6H-dibenzo(b,d)pyran-1-ol (Δ9-tetrahydrocannabinol; THC)/kg or 50 mg THC/kg in 25 μl oil. Additionally, the pups were given 20 μl oil, 10 μg testosterone or 20 μg testosterone in 20 μl oil s.c. from days 1 to 5 of age. This regimen resulted in nine treatment groups. At 60 days of age, all males were castrated and their testes weighed. After castration, each mouse was implanted s.c. with a 5 mm length of testosterone-filled silicone elastomer capsule. When adult they were tested for male copulatory behaviour. Following behavioural testing the animals were bled by cardiac puncture for measurement of plasma testosterone levels, and their hypothalami removed and assayed for dopamine, noradrenaline, 5-hydroxytryptamine (5-HT) and LH-releasing hormone (LHRH). In addition, another two groups of pregnant females were given daily oral doses of 0·5 or 50 mg THC/kg or oil during the first 3 or 5 days of lactation. The male pups were either decapitated for collection of trunk blood or homogenized for determination of serum or whole body testosterone concentrations. Neonatal administration of THC altered adult male sexual responses and had no effect on hypothalamic noradrenaline, 5-HT and LHRH concentrations. There were large increases in serum testosterone concentrations in neonates after maternal THC treatment, although these differences were not significant. Additionally, THC did not influence the testosterone content of neonatal tissue or the testosterone concentration of adult plasma.
These results suggest strongly that the effect of THC on male sexual responses is not mediated by its effect on adult hypothalamic neurotransmitter concentrations. Some other potential mechanisms are discussed.
J. Endocr. (1986) 110, 517–523
Olfactory recognition in the male hamster: effect of non-aromatizable androgens, 17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (R1881) and 5α-dihydrotestosterone, in combination with oestrogen
Authors: Steel E. , Hutchison J. B. 
Published: December 2008

ABSTRACT
Intact male hamsters show olfactory behaviour (sniffing and licking) to novel females. After exposure to female vaginal secretions, they show less sniffing towards a novel female if she does not match previously encountered odours (Steel, 1984). Male hamsters, castrated and injected s.c. with various steroids, were tested for the amount of sniffing they directed towards novel and mismatching females.
5α-Dihydrotestosterone propionate (DHTP),17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (methyltrienolone, R1881) and oestradiol benzoate alone did not influence olfactory behaviour, while testosterone propionate (TP), DHTP plus oestradiol and R1881 plus oestradiol all increased sniffing to a novel female over the levels shown by saline-treated, castrated controls. Our results also indicated that only the aromatizable androgen (TP) or non-aromatizable androgens DHTP and R1881, in combination with oestradiol, reduced sniffing directed to a mismatching female after exposure to vaginal odour.
We conclude that both androgenic and oestrogenic actions are required not only for olfactory behaviour, but also for olfactory recognition as indicated by a reduction in sniffing directed towards mismatching females. This suggests that aromatization of testosterone may be involved in the control of olfactory processes associated with reproductive behaviour.
J. Endocr. (1986) 110, 525–531
Suppression of ovine plasma FSH by bovine follicular fluid: neutralization by plasma from ewes immunized against an inhibin-enriched preparation from bovine follicular fluid
Authors: Al-Obaidi S. A. R. , Bindon B. M. , Hillard M. A. , O'Shea T. , Piper L. R. 
Published: December 2008

ABSTRACT
Adult Merino ewes were immunized against an inhibin-enriched preparation (bFFI) obtained by affinity chromatography of bovine follicular fluid (bFF). Plasma was obtained in early luteal phase from these ewes and from control ewes immunized against bovine serum albumin.
Ten months after ovariectomy the plasma concentration of FSH, but not LH, in control ewes was decreased by four s.c. injections of 8 ml bFFI (17 500 units inhibin/injection). There was no decrease in plasma concentrations of FSH or LH in immunized ewes with the same dose of bFFI. In a second study with long-term ovariectomized ewes, four injections of 20 ml plasma from the immunized ewes significantly reduced the decrease in FSH concentration caused by four injections of steroid-free bFF (2500 units inhibin/injection) in comparison with similar ewes injected with plasma from control ewes.
These results show that the plasma of ewes immunized against bFFI contains substances, presumably antibodies, which neutralize the FSH-suppressive effects of bFF and bFFI in ovariectomized ewes.
J. Endocr. (1986) 111, 1–5
Hyperglucagonaemia: effects on active nutrient uptake by the rat jejunum
Authors: Thompson C. S. , Debnam E. S. 
Published: December 2008

ABSTRACT
The effects of chronic (72 h) glucagon treatment on active nutrient uptake by the rat jejunum have been determined using in-vitro electrophysiological and autoradiographic methods together with an in-vivo technique which measures absorption across a cannulated segment of upper jejunum. Glucagon caused a marked increase in the potential difference across the brush border membrane from a mean value of − 47·6 mV under control conditions to − 54·2 mV following treatment with the hormone (P<0·025). A similar hyperpolarization was also noted after 24 h glucagon administration. The magnitude of the depolarization induced by the addition of d-galactose (4 mmol/l) to the mucosal fluid was increased from 6·0 to 14·3 mV following 72 h glucagon treatment (P<0·05). Phloridzin (0·1 mmol/l) abolished the galactose-induced depolarization in both control and treated animals. Glucagon induced significant increases of 49·9 and 61·0% respectively for glucose and galactose absorption measured under in-vivo conditions. Autoradiographic studies revealed that following glucagon treatment, l-valine uptake occurred earlier during enterocyte migration along the villus. This resulted in an enhanced accumulation of the amino acid at the villus tip. We conclude that glucagon increases nutrient transport across the small intestine. The raised electrical gradient for Na+coupled nutrient entry into the enterocyte is likely to be a major factor in the transport response.
J. Endocr. (1986) 111, 37–42
Effects of constant infusion of gonadotrophin-releasing hormone in ovariectomized ewes with hypothalamo-pituitary disconnection: further evidence for differential control of LH and FSH secretion and the lack of a priming effect
Authors: Clarke I. J. , Burman K. J. , Doughton B. W. , Cummins J. T. 
Published: December 2008

ABSTRACT
Experiments were conducted in ovariectomized ewes after hypothalamo-pituitary disconnection (HPD) (a) to examine LH and FSH secretion during constant infusion of gonadotrophin-releasing hormone (GnRH) or physiological saline and (b) to determine whether or not a constant GnRH background enhances or diminishes pituitary responsiveness to GnRH pulses. Whereas pulsatile GnRH infusions maintained LH and FSH secretion, constant infusions (125 or 250 ng/h) led to the complete cessation of LH secretion and reduced FSH secretion. The rate of decline of plasma FSH concentrations was significantly (P<0·01) greater in animals receiving 250 ng GnRH/h than in saline-treated animals, whereas that in animals receiving 125 ng/h was not significantly different. When GnRH pulses were administered during constant GnRH infusion, the plasma LH pulse amplitudes were similar to those seen without the GnRH background. These data show that, in ovariectomized-HPD ewes (a) FSH secretion does not require GnRH pulses and may merely reflect ongoing FSH synthesis and (b) a constant low background of GnRH does not affect pituitary responsiveness to GnRH pulses.
J. Endocr. (1986) 111, 43–49
Effects of an LH-releasing hormone antagonist on the secretion of LH, FSH, prolactin and ovarian steroids at different stages of the luteal phase in the stumptailed macaque (Macaca arctoides)
Authors: Fraser H. M. , Abbott M. , Laird N. C. , McNeilly A. S. , Nestor J. J. , Vickery B. H. 
Published: December 2008

ABSTRACT
The role of the pituitary gonadotrophins in controlling luteal function in the stumptailed macaque has been investigated by examining profiles of serum concentrations of LH, FSH, progesterone and oestradiol in daily blood samples from 13 monkeys during the menstrual cycle, and in blood samples taken at hourly intervals between 09.00 and 21.00 h on different days of the luteal phase in 13 cycles. The effects of acute withdrawal of gonadotrophins was investigated by administering a single injection of 300 μg LHRH antagonist/kg body weight at different stages of the luteal phase during 28 cycles.
Although there were high basal values and marked fluctuations of bioactive LH during the first 4 days after the LH peak, progesterone profiles showed no corresponding short-term changes, there being a slow and steady rise in progesterone concentrations during the sampling periods. After day 5, basal LH secretion decreased, but high amplitude LH pulses were identified which were associated with episodes of progesterone secretion.
Administration of the LHRH antagonist caused a suppression of bioactive LH and progesterone concentrations at all stages of the luteal phase, although some basal secretion of progesterone was maintained through the 24-h period of effective antagonist gonadotroph blockade. Luteal function recovered apparently normally in all monkeys treated in the early–mid-luteal phase.
Serum concentrations of FSH and oestradiol fluctuated comparatively less during the 12-h sampling periods, and the antagonist had less suppressive effects on the concentrations of these hormones. The LHRH antagonist had no apparent effect on prolactin release.
It appears that the corpus luteum is relatively unresponsive to the high serum LH concentrations during the early luteal phase, but that responsiveness increases as the corpus luteum develops. The corpus luteum is, however, susceptible to withdrawal of LH not only in the mid–late luteal phase when the relationship with LH is apparent, but also during the early luteal phase.
J. Endocr. (1986) 111, 83–90
Prostaglandin in the peripheral plasma of tammar wallabies during parturition
Authors: Lewis P. R. , Fletcher T. P. , Renfree M. B. 
Published: December 2008

ABSTRACT
Tammar wallabies (Macropus eugenii) were observed for 7 days, 24 h/day, at the expected time of birth in two consecutive breeding seasons. Blood was collected from the lateral tail vein 1–2 days before birth, then at 10- to 20-min intervals in the peripartum period and less frequently to 30-h post partum. Plasma was assayed for the prostaglandin metabolite 13, 14-dihydro-15-oxo-prostaglandin F2α (PGFM), progesterone and LH. An assay for PGFM was validated which allows direct measurement in 100 μl unextracted plasma with a sensitivity of 0·14 nmol/l (50 pg/ml).
There was a short-lived peak of PGFM immediately before or at birth (7·15 ± 2·52 nmol/l; 2536± 892 pg/ml) which declined to less than 0·28 nmol/l (100 pg/ml) within 2-h post partum. Progesterone concentrations declined about the time of birth, coincident with the peak of PGFM, and reached levels observed in lactationally quiescent animals by 16-h post partum, which was also the time of the LH peak. The transient prostaglandin pulse was detected only by frequent sampling and suggests that, as in other mammals, prostaglandin is important in parturition.
J. Endocr. (1986) 111, 103–109