Granulosa cells from preovulatory follicles show increased expression of 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) at the time of ovulation. As ovulation may be an inflammatory process, this may be a mechanism of local enhancement of the activity of anti-inflammatory glucocorticoids. In this study, we examined direct effects of LH, the proinflammatory cytokine, interleukin-1beta (IL-1beta), and pharmacological activators of protein kinase A (PKA) (forskolin and dibutyryl (db) cAMP) and PKC (LH-releasing hormone and phorbol 12-myristate 13-acetate (PMA)) signalling on the expression of 11betaHSD1 mRNA in vitro. Granulosa cells from immature female rat ovaries were cultured (pretreatment) in serum-free medium 199 containing recombinant human (rh) FSH (1 ng/ml) for 48 h to induce responsiveness to LH. Cell monolayers were then washed and cultured (test treatment) for a further 12 h in the presence of rhLH (0-100 ng/ml), IL-1beta (0-50 ng/ml), or both. Total RNA was extracted from granulosa cell monolayers and taken for quantitative ribonuclease protection analysis of 11betaHSD1 mRNA. The low level of 11betaHSD1 mRNA detectable in unstimulated (control) cultures was increased approximately twofold by the 48-h pretreatment with rhFSH. Subsequent exposure to rhLH (1-100 ng/ml) for a further 12 h dose-dependently increased 11betaHSD1 mRNA expression by an additional two- to threefold. Forskolin (10 microM), db-cAMP (2 mM), LH-releasing hormone (LHRH; 1 microM) and PMA (200 nM) were also stimulatory. IL-1beta (0.05-50 ng/ml) stimulated 11betaHSD1 mRNA expression in a dose-related manner, both in the absence and in the presence of rhLH (3 ng/ml). The interaction between IL-1beta (5 ng/ml) and rhLH (3 ng/ml) was additive. Co-treatment with a 50-fold excess of IL-1 receptor antagonist fully reversed the action of IL-1beta. We conclude that 11betaHSD1 mRNA expression in functionally mature granulosa cells is directly stimulated by gonadotrophins and IL-1beta in vitro, potentially involving post-receptor signalling via PKA- and PKC-mediated pathways. Thus both LH and IL-1beta may serve physiological roles in the upregulation of 11betaHSD1 gene expression by granulosa cells in ovulatory follicles.

ABSTRACT

Plasma samples were obtained throughout pregnancy and pseudopregnancy from Sprague–Dawley (SD) rats and during pregnancy from rats of the Munich Wistar (MW) strain. The concentrations of progesterone, oestradiol, prolactin, plasma renin activity (PRA), aldosterone and corticosterone were measured by radioimmunoassay to establish hormonal profiles in the two strains of rat.

Circulating progesterone concentrations in both strains of rat were significantly higher during pregnancy than in virgin controls, except at term in the SD group. The hormonal pattern for pseudopregnancy was similar to that of the first half of pregnancy. Oestradiol concentrations were similar to, or lower than, those in virgin controls throughout pseudopregnancy and for the first 2 weeks of pregnancy in both strains of rat. Increased concentrations of steroid were seen only in the pregnant groups towards term. In SD rats, highest prolactin concentrations were apparent during the first half of pregnancy and pseudopregnancy, and at term in the pregnant group. Pregnant MW rats showed a different profile for this hormone, with low levels throughout pregnancy except at term. In all groups PRA rose to a peak at day 9 and decreased to day 16. Pregnant SD rats also showed a significant increase at term. Aldosterone concentrations were significantly increased at several stages of pregnancy in both strains of rat, particularly during the second half of gestation. Pseudopregnant animals showed a different hormone profile, with no significant changes until day 16 when lower concentrations were recorded. There was little variation in the circulating corticosterone concentration except in pregnant rats at term when levels fell.

These findings are discussed in relation to the known renal changes of pregnancy and pseudopregnancy.

J. Endocr. (1987) 113, 435–444

Abstract

Synthetic glucocorticoids stimulate the production of corticosteroid-binding globulin (CBG) by the liver of the sheep fetus near term (day 145). We have examined whether physiological changes in plasma cortisol alter plasma CBG concentrations, patterns of glycosylation and the amount of hepatic CBG mRNA at earlier times during pregnancy (day 100), prior to the activation of fetal hypothalamic-pituitary-adrenal function. Cortisol was infused into chronically catheterized sheep fetuses in amounts that raised the plasma cortisol concentration by about 15 nmol/l. This treatment resulted in a significant increase in the plasma corticosteroid-binding capacity and in the amount of CBG mRNA in the fetal liver, but did not alter the proportion of CBG retained using Concanavalin A chromatography. We conclude that the CBG gene in the liver of fetal sheep responds to physiological changes in plasma concentration of cortisol and we speculate that the rise in plasma CBG concentration is important in diminishing the negative feedback effect of circulating cortisol on the fetal pituitary and hypothalamus.

Journal of Endocrinology (1994) 140, 425–430

Slices of human fetal adrenal glands (obtained after abortion at 10–18 weeks of gestation) were superfused sequentially with buffer or with buffer incorporating human ACTH, synthetic ACTH(1–24), human GH, human chorionic gonadotrophin, α-melanocyte stimulating hormone, metenkephalin, ovine prolactin, β-lipotrophic hormone or corticotrophin-like intermediate lobe peptide in concentrations from 10⁻⁶ to 10⁻⁹ mol/l. Changes in the concentration of dehydroepiandrosterone sulphate (DHAS) in the effluent in response to addition or removal of the polypeptides were measured by radioimmunoassay. Comparison of the quantity of DHAS in the effluent collected during superfusion (5 h) with that present in the tissue initially indicated that synthesis of this conjugated steroid occurred during superfusion.

Increases in the concentration of DHAS in the effluent were provoked by exposure of the tissue to all the polypeptides except corticotrophin-like intermediate lobe peptide.

These effects were unlikely to be non-specific since incorporation of gonadotrophins, albumin or dextran into the superfusate did not stimulate corticosteroid synthesis from viable bovine adrenal tissue.

It was concluded that a number of pituitary polypeptides have the potential to provoke androgen sulphate synthesis by the human fetal gland in early gestation. Consequently there may be no single fetal corticotrophin at this stage and androgen production may be regulated by a number of trophic factors.

ABSTRACT

Three experiments were conducted in the period between July and November with non-lactating red deer hinds to describe the effects of treatment with melatonin during this period on voluntary food intake (VFI), the onset of the breeding season, coat changes and plasma concentrations of prolactin and tri-iodothyronine (T₃), and to examine whether prolactin mediated the observed effects.

In experiment 1, eight animals were treated orally each day with either 10 mg melatonin at 16.00 h or 10 mg melatonin at 16.00 h plus 10 mg domperidone (a dopamine antagonist) given twice daily for 120 days from July; eight animals were maintained as controls. In experiment 2, the same numbers of animals per treatment were used to compare treatments in which 10 mg melatonin or 20 mg bromocriptine (a dopamine agonist) were given orally each day at 16.00 h for 119 days from late June and compared with an untreated control group. In experiment 3, six animals were treated daily for 105 days from mid August with 5 mg domperidone given i.m. and compared with six control animals.

In experiments 1 and 2, the VFI of control animals reached a peak in late August and thereafter declined. Melatonin-treated animals showed a similar pattern but the peak in VFI was significantly (P<0·05) advanced by 2 weeks compared with controls, although the VFIs of both groups were similar in November. The mean date of onset of the breeding season of the melatonin-treated animals was advanced significantly (P < 0·05) by 23 days in both experiments and the coats of these animals had less undercoat and were pale coloured and patchy compared with the controls. The changes in VFI, coat and the onset of the breeding season were associated with the rapid decline in plasma prolactin concentration after the start of the melatonin treatment and significantly (P<0·01) lower plasma T₃ concentrations than those of control animals.

In experiments 1 and 3, plasma prolactin concentrations in animals treated with domperidone were higher than those of controls for periods of 2–3 weeks. These short-term increases in plasma prolactin concentration were not associated with changes in VFI, coat or onset of the breeding season compared with controls.

In experiment 2, the pattern of decline in plasma prolactin concentrations was the same in bromocriptine-treated animals as in the melatonin-treated animals; plasma T₃ concentrations were also similar in the two groups. The pattern of change in VFI over time in bromocriptine-treated animals was significantly (P<0·05) different from that of melatonin-treated animals and there was also a reduced amount and length of winter coat in the bromocriptine-treated animals. The mean date of onset of the breeding season in bromocriptine-treated animals was not significantly different from that of controls. It was concluded that a reduction in plasma prolactin concentration induced by bromocriptine produced different effects from that induced by melatonin treatment and that the effects of melatonin are unlikely to be induced through changes in contemporary plasma prolactin concentrations.

Journal of Endocrinology (1990) 125, 241–249

SUMMARY

The competitive protein-binding radioassay (CPB method) of Murphy (1967) has been adapted to determine total cortisol levels in the plasma of the eel, Anguilla anguilla L. Validation of the method for this species depended in part on the development of a chromatographic—fluorimetric technique for eel cortisol, following classical procedures and using radioactive tracers; by this means, the specificity of the CPB method for cortisol in eel plasma was established. Accuracy, precision and sensitivity of the CPB method were also investigated and were shown to be satisfactory.

Plasma total cortisol levels were determined in eels during osmotic adjustments after transfers from fresh water (FW) to sea-water (SW) and vice versa, and from FW to distilled water. Plasma osmotic pressure and/or sodium levels were monitored simultaneously, to follow the progress of osmotic regulation. In only one of the transfer situations did the plasma cortisol level change significantly, showing a marked transitory increase during the first few days after transfer from FW to SW, corresponding to the development and correction of an 'osmotic crisis'. Plasma cortisol levels were the same in eels adapted for long periods to FW and to SW. Plasma cortisol fell to extremely low levels after hypophysectomy.

These results are discussed in the light of the literature on hormonal control of osmoregulatory mechanisms in the eel, with particular emphasis on the role of adrenocorticosteroids in ionic regulation of animals in SW.