bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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
Synthetic antagonists of the myometrial response to vasopressin and oxytocin
Authors: Melin P. , Trojnar J. , Johansson B. , Vilhardt H. , Åkerlund M.
Published: December 2008

With the aim of developing inhibitors of vasopressin-and oxytocin-induced uterine activity, 17 analogues of 1-deamino-oxytocin were synthesized by the solid-phase method. Modifications were made at positions 2, O-methyltyrosine (Tyr(OMe)) and O-ethyltyrosine (Tyr(OEt)),d-Tyr,d-Tyr(OEt),d-Trp; 4, Val,Thr and 8, Orn,Cit,Arg,d-Arg.

The analogues were tested for antiuterotonic activity in vitro and in vivo in the rat and in vitro on myometrial strips from non-pregnant women and pregnant women at term. Their selectivity was also investigated in blood pressure and antidiuretic bioassays in rats. Results were compared with those from an original antiuterotonic analogue 1-deamino-2-Tyr(OEt)-oxytocin (d(OEt)-oxytocin). In the rat in vitro and in vivo all analogues possessed higher antiuterotonic activity than d(OEt)-oxytocin. The negative logarithm of the molar concentration of the antagonist which reduced the effect of a dose of agonist to that of half the dose (pA2) was between 7·6 and 8·9 for all the new inhibitors compared with 7·2 for d(OEt)-oxytocin. The highest pA2 value was found for 1-deamino-2-Tyr(OMe)-8-Orn-oxytocin (8·9 ± 0·2, s.e.m.) and 1-deamino-2-Tyr(OEt)-4-Thr-8-Orn-oxytocin (8·9 ± 0·6). In myometrium from non-pregnant women the most potent peptide was 1-deamino-2-d-Tyr(OEt)-4-Th r-8-Orn-oxytocin (17·2 ± 2·0 times more potent that d(OEt)-oxytocin). In myometrium from pregnant women the inhibitory effects of the majority of the analogues were less pronounced. In the rat in vivo the most potent analogue 1-deamino-2-d-Trp-4-Val-8-Orn-oxytocin was 19·9 ± 2·5 times more active than d(OEt)-oxytocin. Exchanging l-tyrosine for the d form generally increased inhibitory activity as well as specificity of the analogues. Alkylation of the d-tyrosine residue did not appear to be necessary for inhibition. Substitution with d-tryptophan at position 2 gave analogues with high inhibitory potency in the rat in vitro and in vivo, but which exhibited weak effects in women in vitro. There was no correlation between the inhibitory effects on myometrium from non-pregnant and pregnant women nor between rat and human data. The high antiuterotonic activity of 1-deamino-2-d-Tyr(OEt)-4-Val-8-Orn-oxytocin and 1-deamino-2-d-Tyr(OEt)-4-Thr-8-Orn-oxytocin combined with low blood pressure and antidiuretic effects make these two analogues interesting for clinical studies.

J. Endocr. (1986) 111, 125–131
Methoxyindole production by the pineal gland appears to be dependent on the concentration of hydroxy precursors and their affinity for hydroxyindole-O-methyltransferase
Authors: Morton D. J.
Published: December 2008

Various pineal gland indole metabolites were separated by thin-layer chromatography after organ culture with tritiated serotonin. The amounts of methoxyindoles produced were remarkably constant and female rats in oestrus appeared to produce greater amounts than male rats. The results show a correlation between methylation and the concentration and affinity of the various hydroxyindoles for hydroxyindole-O-methyltransferase.

J. Endocr. (1986) 111, 133–136
Corticotrophin-releasing factor in extra-hypothalamic brain of the mouse: demonstration by immunoassay and immunoneutralization of bioassayable activity
Authors: Nakane T. , Audhya T. , Hollander C. S. , Schlesinger D. H. , Kardos P. , Brown C. , Passarelli J.
Published: December 2008

Corticotrophin-releasing factor (CRF) bioactivity has been described in the extra-hypothalamic brain, but its relationship to hypothalamic CRF has remained questionable. Of the seven regions of the mouse brain examined, highest concentrations of CRF-like immunoreactivity (CRF-LI) and bioassayable CRF activity were present in the median eminence and hypothalamus. However, substantial CRF-LI and bioassayable CRF activity were also seen in brain extracts from the amygdala, thalamus, frontal cortex, pons medulla and cerebellum. Bioactivity was largely neutralized by prior incubation with heat-inactivated antiserum to ovine CRF. These findings, in conjunction with previous immunocytochemical evidence, strongly suggest that a substance closely resembling hypothalamic CRF is present in the extrahypothalamic brain of the mouse.

J. Endocr. (1986) 111, 143–149
Blood levels of ionized calcium, inorganic phosphorus, 1,25-dihydroxycholecalciferol and gonadal hormones in hens laying hard-shelled or shell-less eggs
Authors: Nys Y. , N'Guyen T. M. , Williams J. , Etches R. J.
Published: December 2008

The production of shell-less eggs was induced in hens to measure the effects of the high demands made by shell formation on the blood minerals and hormones whose concentrations change during egg formation. In control hens laying hard-shelled eggs, the concentration of ionized calcium in plasma decreased at the onset of shell formation, but no change was found in hens laying shell-less eggs. Total calcium concentrations in plasma decreased slightly throughout the ovulation cycle in both groups. Concentrations of inorganic phosphorus in the plasma were increased in the control group during the period of shell formation and decreased when calcification was suppressed. Finally, the concentrations of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) in plasma were significantly increased 16 and 20 h following an ovulation compared with 4 h after ovulation, or compared with the concentrations observed in hens laying shell-less eggs. The variations in the plasma concentrations of ionized calcium, inorganic phosphorus and 1,25-(OH)2D3 associated with egg formation were therefore absent in hens laying shell-less eggs demonstrating their direct link with shell calcification. On the other hand, suppression of shell production had no influence on the changes in the plasma concentrations of progesterone, oestradiol and testosterone which are associated with the normal ovulatory cycle. It is concluded that the increases in intestinal and uterine calcium transport and in 1,25-(OH)2D3 production which occur at the onset of egg production in hens are mainly controlled by factors involved in maintaining calcium homeostasis rather than by gonadal hormones.

J. Endocr. (1986) 111, 151–157
Dopaminergic inhibition of tyrosinase activity in hair follicular melanocytes of the mouse
Authors: Burchill S. A. , Thody A. J.
Published: December 2008

Bromocriptine, a dopamine agonist that blocks the secretion of MSH, inhibits melanogenesis in the hair follicular melanocytes of pubertal C3H–HeA*vy mice. However, since this effect cannot be explained by a reduction in circulating α-MSH, we have examined the possibility that dopaminergic mechanisms may have a direct inhibitory effect on these melanocytes.

Bromocriptine decreased tyrosinase activity in skin explants from 30- to 35-day-old mice that were growing dark hair. This decrease in tyrosinase activity was blocked by dopamine receptor antagonists, haloperidol or spiperone. The specific D2 agonist LY 171555 also inhibited tyrosinase activity in the skin explants in a dose-related manner and the effect was blocked by sulpiride, a D2-receptor antagonist. Neither bromocriptine nor LY 171555 had any effect on tyrosinase activity in skin explants taken from adult mice that were growing yellow hair. The D1-receptor agonist SKF 38393 had no effect on tyrosinase activity in skin explants from either group of mice.

The present results support the idea that dopamine D2-receptor agonists have a direct inhibitory effect upon tyrosinase activity of hair follicular melanocytes of the C3H–HeA*vy mouse. However, this effect was confined to periods of dark hair growth when the melanocytes produce eumelanin. The D2 agonists were ineffective in reducing tyrosinase activity during adult life when the melanocytes produce predominantly phaeomelanin. This suggests that different control mechanisms may operate in the hair follicular melanocytes during periods of eumelanin and phaeomelanin synthesis.

J. Endocr. (1986) 111, 233–237
Cholinergic agonist and antagonist drugs modulate the growth hormone response to growth hormone-releasing hormone in the rat: evidence for mediation by somatostatin
Authors: Locatelli V. , Torsello A. , Redaelli M. , Ghigo E. , Massara F. , Müller E. E.
Published: December 2008

Recently, data have been presented showing that muscarinic cholinergic agonists or antagonists can modulate, in opposite ways, GH-releasing hormone (GHRH)-induced GH release in man. The aim of the present study was, first, to confirm these findings in the rat and, secondly, if confirmed, to investigate the mechanism(s) subserving the effect of cholinergic drugs.

In adult male rats bearing chronic indwelling atrial cannulae, pretreatment with the cholinergic antagonists pirenzepine (0·5 mg/kg, i.v.) or atropine (0·5 mg/kg, i.v.) significantly reduced the rise in plasma GH induced by GHRH (2 μg/kg, i.v.), while pretreatment with the cholinergic agonist pilocarpine (3 mg/kg, i.v.) potentiated it. In rats with hypothalamic somatostatin (SRIF) depletion, i.e. rats with anterolateral deafferentation of the mediobasal hypothalamus or rats treated with cysteamine, the modulatory action of cholinergic drugs on the neuroendocrine effect of GHRH was completely lacking. In these two experimental models, an antiserum raised against SRIF failed to elicit a rise in plasma GH and measurement of hypothalamic SRIF content revealed a clear-cut reduction of the neuropeptide. Atropine (1 μmol/l) and pilocarpine (1 μmol/l), added to pituitary cells in vitro, failed to alter GHRH-induced GH release. The present results indicate that muscarinic cholinergic agonists and antagonists modulate GHRH-induced GH release in the rat and suggest that the effect of cholinergic modulation takes place through SRIF.

J. Endocr. (1986) 111, 271–278
Changes in FSH and the pulsatile secretion of LH during treatment of ewes with bovine follicular fluid throughout the luteal phase of the oestrous cycle
Authors: Wallace J. M. , McNeilly A. S.
Published: December 2008

Treatment of Damline ewes with twice-daily i.v. injections of bovine follicular fluid during the luteal phase for 10 or 2 days before prostaglandin-induced luteolysis resulted in a delay in the onset of oestrous behaviour and a marginal increase in ovulation rate. During the treatment cycle, blood samples were withdrawn at 15-min intervals for 25 h from 08.00 h on days 1, 6 and 10 (day 0 = oestrus). At all three stages of the luteal phase, plasma FSH concentrations were suppressed relative to controls 3 h after the 09.00 h injection of follicular fluid and remained low until

06.00 h on the following day. In the 10-day treatment group LH pulse amplitude was significantly greater than that of controls on days 6 and 10. Pulse frequency remained high throughout treatment and was significantly higher relative to controls on day 10 despite normal progesterone levels. The results suggest that the higher pulsatile LH secretion during the luteal phase is due to reduced negative feedback effects of oestradiol occurring as a result of the follicular fluid-induced reduction in FSH.

J. Endocr. (1986) 111, 317–327
Regression of redundant lactotrophs in rat pituitary gland after cessation of lactation
Authors: Haggi E. S. , Torres A. I. , Maldonado C. A. , Aoki A.
Published: December 2008

Regressive changes occurring in the pituitary gland of the rat after removal of litters were studied. Pituitary glands of lactating rats were characterized by the presence of numerous hypertrophied lactotrophs. Interruption of lactation caused a blockade of prolactin synthesis and secretion, followed by degeneration of lactotrophs. Morphometric analysis of pituitary glands revealed that lactotrophs accounted for about 50% of the total hypophysial cell count in lactating rats. This percentage decreased progressively and reached pre-pregnant levels 7 days after removal of litters; the decrease was inversely correlated with an increase in the number of degenerating lactotrophs which comprised 30% of all lactotrophs 72 h after removal of litters. The morphological changes found in lactotrophs were closely related to changes in the prolactin content of serum and the pituitary gland. Regression of lactotrophs appeared to be the most important cause inducing the reversal of hypophysial lactotrophic activity to pre-pregnant conditions.

J. Endocr. (1986) 111, 367–373
Met-enkephalin stimulates secretion of ACTH in sheep
Authors: Wang X.-M. , Coghlan J. P. , Congiu M. , Scoggins B. A. , Wintour E. M.
Published: December 2008

The ability of opioid peptides to affect plasma immunoreactive ACTH concentrations was examined in conscious sheep. Plasma concentrations of ACTH were significantly increased by an i.v. infusion of Met-enkephalin and its analogue (FK-33824). There was a dose-dependent increase in plasma concentrations of ACTH with a graded administration of FK-33824. The combined effect of Met-enkephalin and ovine corticotrophin-releasing factor (oCRF) or FK-33824 and oCRF on plasma concentrations of ACTH was greater than the effect of each peptide when given individually. This study demonstrates that Met-enkephalin and its analogue stimulate ACTH release in sheep.

J. Endocr. (1986) 111, 463–467
Characterization by high-performance liquid chromatography of circulating growth hormone-releasing factors in normal subjects
Authors: Penny E. S. , Sopwith A. M. , Patience R. L. , Wass J. A. H. , Besser G. M. , Rees L. H.
Published: December 2008

Four forms of circulating immunoreactive human GH-releasing factor (ir-hGRF) have been identified in each of four normal subjects, with a mean increase in total ir-hGRF of twofold over basal levels following a mixed meal. Plasma samples (200 ml) from each individual were subjected to large-scale Vycor extraction with initial purification by high-performance liquid chromatography on a reversed-phase C18 column, followed by analytical separation of the ir-hGRF components using a C3 wide-pore reversed-phase column, and subsequent radioimmunoassay of the fractions. The mean recovery of total ir-hGRF from the plasma (fasted and non-fasted) was 76±16% (2×s.e.m.). Analytical separation of the ir-hGRF revealed four components which co-eluted with synthetic hGRF-37, hGRF-40 and hGRF-44, and a peak eluting between hGRF-40 and -44 which may represent hGRF-42. The hGRF-40 was shown to be the predominant circulating molecular form in the fasted state in each subject, and in three out of four subjects following a mixed meal. The hGRF-44 showed the greatest percentage increase over basal in all four individuals.

J. Endocr. (1986) 111, 507–511
Differentiation of granulated metrial gland cells in ovariectomized mice given ovarian hormones
Authors: Stewart I.
Published: December 2008

A study has been made of the differentiation of granulated metrial gland (GMG) cells in ovariectomized mice given progesterone and oestradiol at a time equivalent to the first 6 days of pregnancy. By varying the hormone regime, it was shown that progesterone is the ovarian hormone likely to be involved in stimulating GMG cell differentiation in the early pregnant uterus. Progesterone, however, failed to maintain, or allow further differentiation, of GMG cells during stages equivalent to the early post-implantation period, suggesting that the progesterone is not directly stimulating this cell population. The hypothesis that the differentiation and maintenance of GMG cells is under the control of activated stromal cells in the preimplantation period is supported by these results.

J. Endocr. (1987) 112, 23–26
Blockade of the final phase of ovulation has no effect on the post-ovulatory surge of serum FSH in the rabbit
Authors: Bolet G. , Meunier M. , Blanc M.R. , Martinet L. , Poirier J.C.
Published: December 2008

Mating induces a surge of both LH and FSH in the blood of female rabbits, followed 10–12 h later by a surge of FSH only, which begins at the time of ovulation. We have studied the effect of suppression of ovulation on the post-ovulatory surge of FSH. In the first experiment, follicular fluid and oocytes were withdrawn from the largest follicles 8 h after coitus. In the second experiment, ovulation was inhibited by injecting the rabbits with 25 mg indomethacin/kg body weight 7·5 h after mating. Levels of serum FSH and LH were measured for 24-48 h after mating. Control rabbits ovulated normally in both experiments. The treatments did not significantly affect the levels of serum FSH in either experiment, although the second surge of FSH was slightly higher after fluid had been aspirated from the preovulatory follicles. These observations show that the post-ovulatory surge of serum FSH is not dependent upon the completion of ovulation and that it is programmed before 7·5–8 h post coitum.

J. Endocr. (1987) 112, 57–61
Osmoregulatory actions of growth hormone in rainbow trout (Salmo gairdneri)
Authors: Bolton J. P. , Collie N. L. , Kawauchi H. , Hirano T.
Published: December 2008

The seawater-adapting actions of GH, which are independent of growth, were studied in juvenile rainbow trout (Salmo gairdneri). Hormones examined were chum salmon (Oncorhynchus keta) GH (sGH) and prolactin (sPRL), and ovine GH (oGH). Plasma Na levels of freshwater-adapted fish peaked 24 h after transfer to 67% seawater and remained high for at least 48 h. Twenty-four hours after transfer, plasma Na levels were inversely correlated to body weight. In order to limit size and growth effects in all subsequent experiments, fish having a narrow range of body weights, fed a fixed diet, and injected with hormones over a short time-period were used. Plasma Na levels 24 h after transfer to 80% seawater were reduced significantly by sGH (0·25 and 2·5 μg/g) and oGH (2·5 μg/g) compared with saline injections, whereas sPRL (2·5 μg/g) had no significant effect. All the GH-treated fish had lower plasma Mg levels than controls; Ca levels were significantly reduced by the high dose of sGH. Salmon prolactin had no effect on concentrations of divalent ions. When the effects of a range of doses (0·01–1·25 μg/g) of sGH on plasma ion levels was tested, 0·25 μg/g was the most potent in reducing Na and Mg levels, while 1·25 μg/g alone reduced plasma Ca concentrations significantly. These studies show that the seawater-adapting actions of GH in trout are specific to that hormone and are not consequent to an increase in size.

J. Endocr. (1987) 112, 63–68
Effect of adrenaline on basal and ovine corticotrophin-releasing factor-stimulated ACTH secretion in man
Authors: Al-Damluji S. , Cunnah D. , Grossman A. , Perry L. , Ross G. , Coy D. , Rees L. H. , Besser G. M.
Published: December 2008

Six normal male subjects were given, in single blind random order on six separate occasions, i.v. bolus doses of synthetic ovine corticotrophin-releasing factor-41 (oCRF-41; 25 and 50 μg) with and without adrenaline (3 μg/min) i.v. for 150 min, the adrenaline infusions alone and saline placebo. The adrenaline infusions resulted in plasma adrenaline concentrations of 4·33 ± 0·82 (s.e.m.) nmol/l and were associated with an increase in blood glucose, heart rate and systolic blood pressure and a reduction of diastolic blood pressure. Despite these evident biological effects at several sites, there was no stimulation of plasma ACTH or cortisol by adrenaline in comparison with the effect of saline, and no enhancement of the stimulatory effect of either dose of oCRF-41 on ACTH or cortisol secretion. The ACTH response to 50 μg oCRF-41 was greater than that to 25 μg, indicating that the 25 μg dose of oCRF-41 was sub-maximal and capable of further enhancement. As the plasma adrenaline concentrations during the adrenaline infusions reached the upper limit of the physiological range of plasma adrenaline in man, yet failed to enhance the ACTH or cortisol responses to a sub-maximal dose of oCRF-41, we conclude that circulating adrenaline neither exerts a direct stimulatory effect on pituitary corticotrophs nor enhances the effect of CRF under physiological circumstances. The adrenaline infusions attenuated the ACTH and cortisol responses to oCRF-41 and were associated with a transient reduction of basal concentrations of both hormones.

J. Endocr. (1987) 112, 145–150
Neuroendocrine studies in hyperprolactinaemic male mice
Authors: Bartke A. , Morgan W. W. , Clayton R. N. , Banerji T. K. , Brodie A. M. , Parkening T. A. , Collins T. J.
Published: December 2008

In several species, including man and the rat, hyperprolactinaemia is associated with suppression of gonadotrophin release and male sexual behaviour. However, in the hyperprolactinaemic male mouse, plasma LH and FSH levels and copulatory behaviour are increased rather than suppressed. In an attempt to identify mechanism(s) which may be responsible for these effects of hyperprolactinaemia in the mouse, we have examined the effects of two ectopic pituitary isografts on several indices of hypothalamic and pituitary function in adult DBA/2J males. Animals with pituitary grafts had markedly increased plasma concentrations of prolactin, LH and FSH and enlarged seminal vesicles, whereas testicular and pituitary weights were not affected. Content of LHRH receptors and activity of aromatase in the pituitary, as well as dopamine-β-hydroxylase activity in the hypothalamus were nearly identical in pituitary-grafted and sham-operated males. Biosynthesis of dopamine and turnover of noradrenaline in the median eminence were significantly increased in grafted males. We suggest that the increase in the activity of hypothalamic noradrenergic neurones may mediate stimulatory action of hyperprolactinaemia on LH and FSH release in the mouse. Comparison of these results with those obtained previously in the rat suggests that species differences in the effects of prolactin on gonadotrophin release may be related to its divergent effects on noradrenaline turnover.

J. Endocr. (1987) 112, 215–220
Ethan-1,2-dimethanesulphonate reduces testicular oxytocin content and seminiferous tubule movements in the rat
Authors: Nicholson H. D. , Worley R. T. S. , Guldenaar S. E. F. , Pickering B. T.
Published: December 2008

An oxytocin-like peptide is present in the interstitial cells of the testis, and testicular concentrations of oxytocin have been shown to increase seminiferous tubule movements in vitro. We have used the drug ethan-1,2-dimethanesulphonate (EDS), which depletes the Leydig cell population of the adult rat testis, to examine further the relationships between the Leydig cell, testicular oxytocin and tubular movements. Adult rats were injected i.p. with a single dose of EDS (75 mg/kg) or of vehicle (25% dimethyl sulphoxide). Histological study 3 and 10 days after treatment with EDS showed a reduction in the number of interstitial cells, and levels of oxytocin immunoreactivity were undetectable by radioimmunoassay. Immunostaining revealed very few oxytocin-reactive cells. Spontaneous contractile activity of the seminiferous tubules in vitro was also dramatically reduced, but could be restored by the addition of oxytocin to the medium. Four weeks after EDS treatment, the interstitial cells were similar to those in the control animals both in number and in immunostaining; immunoassayable oxytocin was present and tubular movements were normal. The EDS effect, seen at 3 and 10 days, was not altered by daily treatment with testosterone. However, repopulation of the testes with oxytocin-immunoreactive cells was not seen until 6 weeks in the testosterone-treated animals.

We suggest that the Leydig cells are the main source of oxytocin immunoreactivity in the testis and that this oxytocin is involved in modulating seminiferous tubule movements and the resultant sperm transport. The results also imply that testosterone does not play a major role in controlling tubular activity in the mature rat.

J. Endocr. (1987) 112, 311–316
Oestrogen receptor in the granulosa cell during postnatal development of the rat ovary
Authors: Kudolo G. B. , Elder M. G. , Myatt L.
Published: December 2008

Numbers of granulosa cells obtained from follicles of immature rats increased from 1·6 × 105 cells/ovary on day 8 to 7·1 × 106 cells/ovary on day 40 of age, the day of vaginal opening and first pro-oestrus. Very high levels of cytosol oestrogen receptor were found on day 8 (175 000 sites/cell) but by day 19 20 000 sites/cell were found. Nuclear receptor concentrations were highest on day 12(5400 ± 1470 (s.d.) sites/cell) and again on day 21 (5400 ± 2300 sites/cell). After day 21 both cytosol and nuclear oestrogen receptor concentrations fell and remained low until nuclear concentrations rose at day 40. Two consecutive daily injections of FSH/LH (5 i.u.) increased cell number over control in animals killed on day 22, gave no significant alteration in animals killed on day 26 or 28 but decreased numbers in animals aged 32 and 35 days. Only on day 22 was the increase in cell number associated with an increase in nuclear oestrogen receptor concentrations. Indeed on days 32 and 35 increased nuclear receptor concentrations were associated with a decreased cell number.

J. Endocr. (1987) 112, 333–338
Protective effect of 4,6-O-ethylidene glucose against the cytotoxicity of streptozotocin in pancreatic β cells in vivo: indirect evidence for the presence of a glucose transporter in β cells
Authors: Kawada J. , Okita M. , Nishida M. , Yoshimura Y. , Toyooka K. , Kubota S.
Published: December 2008

Ethylidene glucose (4,6-O-ethylidene glucose; EG) is known to bind the outer surface of the glucose transporter in the membranes of human erythrocytes and other mammalian cells. If a glucose transport system is present on pancreatic β cells and recognizes the glucose moiety of streptozotocin (STZ), EG should protect β cells from the cytotoxicity of STZ when it is administered with STZ. This possibility was examined in in-vivo experiments in rats. When EG and STZ were injected into rats together the animals did not become diabetic, as judged by (1) their blood glucose levels, (2) response in a glucose-tolerance test, and (3) insulin secretion in response to feeding. These results suggest that there is a glucose transporter present in β cells and also the transport of streptozotocin into β cells through this system.

J. Endocr. (1987) 112, 375–378
1,25-Dihydroxycholecalciferol regulates salivary phosphate secretion in cattle
Authors: Riad F. , Lefaivre J. , Barlet J.-P.
Published: December 2008

The influence of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) on salivary inorganic phosphorus (Pi) concentration and secretion was studied in two groups of four heifers, the right parotid ducts of which were chronically fitted with a re-entrant cannula.

In four heifers i.v. Pi loading (5 mmol/min for 2 h) induced hyperphosphataemia associated with a decrease in plasma 1,25-(OH)2D concentration and an increase in salivary Pi concentration and secretion. In four other heifers, daily 1α-hydroxycholecalciferol injections (1 μg/kg body wt per day for 3 days) induced hyperphosphataemia associated with an increase in plasma 1,25-(OH)2D concentration and a decrease in salivary Pi concentration and secretion. These treatments had no significant effect on salivary calcium concentration and secretion.

Our results indicate that plasma 1,25-(OH)2D concentrations rather than phosphataemia regulate salivary Pi concentration and secretion in cattle.

J. Endocr. (1987) 112, 427–430
Response of adrenal cells to parathyroid hormone stimulation
Authors: Rosenberg J. , Pines M. , Hurwitz S.
Published: December 2008

Dispersed adrenal cells of avian and bovine origin were incubated with human (h) 1–34 parathyroid hormone (PTH(1–34)), bovine (b) PTH(1–84), bPTH(3–34), avian (a) PTH, and with ACTH. Kidney tubular cells, the established target cells for PTH, were used for comparison. Cyclic AMP (cAMP) accumulation and steroid hormone (aldosterone and corticosterone) secretion were measured in response to the hormones.

In the bovine adrenocortical cells PTH of both bovine and avian origin stimulated cAMP production, but the aPTH action was more pronounced. The maximal cAMP response of avian adrenocortical cells to aPTH was 15-fold greater than that of ACTH, but a 20-times higher concentration of aPTH was required to reach half-maximal response. Avian PTH stimulated steroid hormone secretion in the chick adrenocortical cells, but the induced secretion was similar to that induced by ACTH, despite the difference in cAMP accumulation. Human PTH(1–34) and bPTH(1–84), which stimulated cAMP production in kidney cells, and the conventional antagonist bPTH(3–34) inhibited aPTH stimulation of cAMP accumulation in avian adrenocortical cells, but did not interfere with ACTH action. Furthermore, cAMP stimulation by aPTH and ACTH in avian adrenal cells was additive.

The results establish the adrenal as a target organ for PTH, and suggest that the PTH acts through specific receptors, distinct from those for ACTH.

J. Endocr. (1987) 112, 431–437
THYROIDECTOMY OF NESTLING STARLINGS APPEARS TO CAUSE NEOTENOUS SEXUAL MATURATION
Authors: Dawson A. , Williams T.D. , Nicholls T.J.
Published: December 2008

Nestling starlings (Sturnus vulgaris) were thyroidectomized, in the wild, when 8 days old. They were later brought into captivity and hand reared on a daylength of 16 h light: 8 h darkness per day.

Thyroidectomy dramatically affected somatic development so that even at 23 weeks of age these birds retained the physical characteristics of approximately 3-week-old euthyroid birds. Nevertheless, they appeared to be healthy and were active. Despite retaining juvenile features, these thyroidectomized birds became sexually mature. In males, testicular growth began at 8 weeks of age and by 23 weeks both males and females had well developed gonads.
Insulin release from a cloned precursor beta cell line
Authors: Ng K. W. , Gummer P. R. , Grills B. L. , Michelangeli V. P. , Dunlop M. E.
Published: December 2008

This paper describes the establishment in long-term tissue culture of a functional, clonal beta (B) cell line UMR 407/3 derived from neonatal rat pancreas. Immunofluorescence demonstrated specific and uniform staining for insulin. Transmission electron microscopy showed the presence of microvilli and cytoplasmic granules. The doubling time in culture was approximately 60 h in 2% (v/v) fetal calf serum with inhibition of growth at confluence. Biochemical studies demonstrated the incorporation of [3H]leucine into proinsulin and insulin, with insulin comprising 43·6% of the total radioactivity incorporated into immune complexes. When incubated at 37 °C for 30 min with Krebs–Ringer bicarbonate buffer (pH 7·4), the amount of insulin released on stimulation by 16·7 mmol glucose/l, 20 mmol dl-glyceraldehyde/l or 20 mmol α-ketoisocaproate/l was significantly higher compared with 5·6 mmol glucose/l. The mean insulin content was equivalent to 99±0·4 fmol (s.e.m.)/5 × 105 cells. Regulated insulin release was maintained through at least 15 passages in culture. The cells showed morphological evidence of senescence after passage 26 and this was associated with significant reduction in stimulated insulin release as well as insulin content. The ability of the cells of this clonal line to grow in soft agar suggests that it is a precursor cell line. The clonal B cell lines isolated so far may thus represent variably committed rather than fully differentiated B cells in culture. These clonal non-neoplastic cell lines will be useful models with which to study the regulation of maturation/differentiation of B cells and insulin gene expression. Finally, the method described for the isolation of clonal B cell lines can be used to establish, in culture, precursor clonal lines from other normal tissues.

J. Endocr. (1987) 113, 3–10
Possible role of dopamine and noradrenaline in the regulation of prolactin secretion from an ectopic anterior pituitary gland in female rats
Authors: Fernández-Ruiz J. J. , Cebeira M. , Agrasal C. , Tresguerres J. A. F. , Bartke A. , Esquifino A. I. , Ramos J. A.
Published: December 2008

It was recently reported that anterior pituitary tissue transplanted to an ectopic site contains measurable amounts of dopamine and noradrenaline. To examine the possibility of local catecholaminergic control of prolactin secretion from ectopic pituitaries, pituitary grafted and sham-operated female rats were submitted to several pharmacological treatments modifying catecholamine synthesis. Administration of a single dose of α-methyl-p-tyrosine (α-MPT) significantly reduced dopamine content in the graft, while noradrenaline content was not modified. Similar changes in the contents of dopamine and noradrenaline after α-MPT administration were observed in the hypothalamus and in the in-situ pituitary in both grafted and sham-operated rats. Plasma concentrations of prolactin were increased in both grafted and sham-operated rats after administration of α-MPT. A single injection of l-3,4-dihydroxyphenylalanine (l-DOPA) increased dopamine content in the ectopic pituitary gland without altering the noradrenaline content, and produced similar effects in the hypothalamus and in-situ pituitary of grafted and control rats. Plasma prolactin concentrations were decreased by l-DOPA in both pituitary grafted and control rats. Administration of dl-treo-dihydroxyphenylserine (DOPS) increased noradrenaline content in the ectopic pituitary and reduced plasma prolactin concentrations in pituitary grafted rats. In contrast, injection of DOPS to control rats increased both hypothalamic noradrenaline content and plasma prolactin concentrations. These results suggest that dopamine and noradrenaline present in the ectopic pituitary tissue have a role in mediating prolactin release from pituitary transplants.

J. Endocr. (1987) 113, 45–49
Comparison of the feedback effect of magnesium and calcium on parathyroid hormone secretion in man
Authors: Ferment O. , Garnier P. E. , Touitou Y.
Published: December 2008

Administration of high doses of magnesium is known to produce a decrease in parathyroid hormone (PTH) secretion in human patients but the effect of magnesium on the secretion of PTH in healthy man is not known. We have looked at the effect of a relatively moderate i.v. dose of magnesium (7·08 mmol) in seven healthy men. In addition and for comparison the effect of calcium (4·25 mmol) was studied. Two magnesium salts were considered, magnesium sulphate (MgSO4) and magnesium pyrrolidone carboxylate (MgPC). Four i.v. injections were given at 08.00 h (MgPC, NaCl (control), MgSO4 and Ca gluconate), with an interval of 1 week between each injection.

Whatever the magnesium salt the variations in plasma concentrations of magnesium were the same whereas no change in erythrocyte magnesium was observed. Plasma concentration of C-terminal PTH did not show significant variations after MgPC or saline injection. Both MgSO4 and Ca gluconate produced a statistically significant 30% decrease in plasma PTH levels 45 min after the injection. The effect was more sustained with calcium (2 h) than with magnesium (45 min). The urinary excretion of magnesium was significantly higher after injection of MgSO4 than after MgPC. These results suggest (1) that magnesium was, on a molar basis, less potent than calcium in regulating PTH secretion in vivo, (2) that the nature of the magnesium salt used must be kept in mind for the interpretation of the effect of magnesium on PTH secretion in vivo and (3) that the decrease in plasma PTH can partly explain the larger urinary excretion of magnesium after MgSO4 than after MgPC.

J. Endocr. (1987) 113, 117–122
Measurement of circulating corticotrophin-releasing factor in man
Authors: Cunnah D. , Jessop D. S. , Besser G. M. , Rees L. H.
Published: December 2008

A radioimmunoassay was developed to measure corticotrophin-releasing factor (CRF-41) extracted from human plasma using Vycor glass. Assay sensitivity was 20 ng/l and intra- and interassay coefficients of variation were 10·2 and 11·4% respectively. The normal range of plasma CRF-41 was <20–110ng/l (n = 46). Plasma concentrations of CRF-41 in patients with Cushing's disease, Nelson's syndrome and Addison's disease were within the normal range. No correlation was found between CRF-41 and ACTH in these syndromes. Two patients with the ectopic ACTH syndrome had increased plasma concentrations of CRF-41. In normal subjects no changes in plasma CRF-41 occurred after insulin-induced hypoglycaemia, treatment with dexamethasone or feeding, and changes in the concentrations of CRF-41 did not reflect circadian changes in plasma concentrations of cortisol. Concentrations of immunoreactive CRF in plasma of women in the third trimester of pregnancy were increased (550–9300 ng/l) and gel filtration chromatography showed that this comprised CRF-41 and a higher molecular weight form. Reversed-phase high-performance liquid chromatography also revealed multiple peaks of immunoreactive CRF in extracts of plasma and placenta.

J. Endocr. (1987) 113, 123–131
A phaeochromocytoma presenting with Cushing's syndrome associated with increased concentrations of circulating corticotrophin-releasing factor
Authors: Jessop D. S. , Cunnah D. , Millar J. G. B. , Neville E. , Coates P. , Doniach I. , Besser G. M. , Rees L. H.
Published: December 2008

The case is described of a 61-year-old male who presented with hypertension and Cushing's syndrome which resolved on excision of a unilateral adrenal mass. Histology of the tumour revealed a benign phaeochromocytoma which immunostained for corticotrophin-releasing factor (CRF-41) but not for ACTH. Preoperative plasma concentrations of immunoreactive CRF-41 were increased, and gradients for both CRF-41 and ACTH were demonstrated across the tumour.

Post-operatively, CRF-41 was undetectable in plasma. The tumour contained high concentrations of immunoreactive CRF-41 which co-eluted with synthetic human CRF-41 on reversed-phase high-performance liquid chromatography. Tumour CRF-41 stimulated the release of ACTH in a dose-dependent manner from isolated rat anterior pituitary cells. We conclude that this tumour secreted CRF-41 and ACTH and had the capacity to produce ACTH-dependent Cushing's syndrome directly by secreting ACTH and indirectly by secreting CRF-41 to stimulate ACTH secretion from the anterior pituitary.

J. Endocr. (1987) 113, 133–138