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Gel filtration on Sephadex columns has been used to study the influence of steroids in vitro on the cortisol-binding capacity of human plasma transcortin (De Moor, Heirwegh, Heremans & Declerck-Raskin, 1962; De Moor, Deckx & Steeno, 1963). Testosterone and progesterone, added in the same amounts as cortisol, displaced 25 and 23% respectively of bound cortisol.
In view of their similar structure, various anabolic steroids as well as progestagens were tested in the same manner. Plasma with a low concentration of corticosteroids taken at 12 p.m. from a normal sleeping individual, was overloaded either with cortisol or with cortisol and an equal amount of the steroid to be tested. The loading dose was always 500 ng./ml. After 15 min. of incubation at room temperature, the plasma samples were submitted to gel filtration (also at room temperature) and the protein-bound corticosteroid was determined fluorimetrically. The results are expressed as percentual decrease of
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Reports on diurnal variation in plasma corticosteroids in man, monkey, dog, rat, mouse and other species have been reviewed by Yates, Russell & Maran (1971) and by Yates & Urquhart (1962). We wish to report evidence of diurnal variation in the peripheral plasma cortisol levels of sheep, demonstrable after they had been allowed adequate time to adapt to the environment in which they were tested.
Three anoestrous New Zealand Romney ewes were placed indoors in crates with minimal restraints. They were placed immediately adjacent to each other and were free to sit or stand. They were given hay, lucerne pellets and water ad libitum. No attempt was made to regulate feeding and an excess of feed was ensured at all times. Each animal had an indwelling jugular cannula, inserted at least 3 h before the first sampling, which remained in situ throughout the experiment. On each occasion 10 ml blood
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Departments of *Physiology and †Zoology, Monash University, Clayton, Victoria 3168, Australia
(Received 19 December 1974)
In the shrew-like marsupial Antechinus stuartii from eastern Australia, there is an abrupt and total mortality of males after a 7 to 10-day mating period in August or September (Woolley, 1966; Wood, 1970). Males isolated in the laboratory before mating survive beyond the time of natural mortality (Wood, 1970).
Barnett (1973) observed increased peripheral corticosteroid concentrations in males taken from natural populations in the last weeks of life. To test whether this change could be a cause of the mortality, exogenous cortisol was injected into laboratory-held males.
Male A. stuartii were captured before the mating period in July 1973 and 1974 at Powelltown, Victoria, and caged singly under the natural Melbourne photoperiod. Their average initial body weight was 30·1 ± 3·6 g (n = 38). In each year they were divided into three groups: two
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It has been suggested by Selye (1951) and Gray & Ramsey (1957) that the adrenal cortex and centres regulating its function may be involved not only in the physiological control of gastric secretion but also in the aetiology of peptic ulceration. This possibility became of great interest after the introduction of corticosteroids into clinical practice; long-term treatment has been reported to have, as a side-effect, a high incidence of peptic ulcers which are similar to spontaneous ones (Garb, Soule, Bartholomew & Cain, 1965).
Determinations of plasma concentration and urinary excretion of corticosteroids in patients with peptic ulcer failed to detect differences from normal subjects. However, it is likely that the quantitative changes in cortical activity may be too subtle to be shown by this type of test: they may only be demonstrable by following the circadian fluctuations in adrenocortical secretion.
The circadian changes in the plasma cortisol levels were therefore
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Relatively small doses of glucocorticosteroids are known to cause improvement of menstrual disorders and to facilitate conception in patients with ovarian dysfunction (Jefferies & Levy, 1959; Jefferies, 1960; Perloff, 1959). They have also been shown to produce significant changes in the excretion of urinary 17-ketosteroids (17-KS).
The clinical improvement and the decrease in 17-ketosteroid excretion are usually explained by a suppressive action on adrenocortical function. On the other hand, there is evidence of an effect of corticosteroids on the functional relationship between ovary and adenohypophysis. Butt, Crooke, Cunningham & Palmer (1963) have demonstrated an increase in FSH and urinary oestriol in women with the Stein-Leventhal syndrome after administration of dexamethasone.
The effect of intravenous administration of cortisol on the concentration of androgens in the ovarian venous blood and the ovarian tissue has been studied in four women. Patient 1 suffered from ovarian hirsutism and oligomenorrhoea, interrupted by periods of
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Department of Animal Science and Production, University of Western Australia, Nedlands, Western Australia 6009, Australia
(Received 13 March 1978)
The activity of the adrenal gland is believed to be governed by the secretion of corticotrophin (ACTH) in a positive stimulus/negative feedback equilibrium. There is increasing evidence that in man, the secretion of corticosteroids never actually reaches a steady-state condition and that the circadian rhythm displayed by these hormones in the circulation is therefore the result of a number of secretory episodes over a 24 h period (Hellman, Nakada, Curti, Weitzman, Kream, Roffwarg, Ellman, Fukushima & Gallagher, 1970; Weitzman, Fukushima, Nogeire, Roffwarg, Gallagher & Hellman, 1971). Data presented by McNatty, Cashmore & Young (1972) also raise the possibility that a similar pattern of hormone release may exist in the sheep. However, McNatty et al. (1972) collected samples relatively infrequently and it is hard to define peaks in cortisol concentration. With more
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Wisconsin Regional Primate Research Center, University of Wisconsin, Madison, Wisconsin 53706, U.S.A.
(Received 22 May 1978)
In a wide variety of species corticotrophin (ACTH) is known to stimulate the synthesis and secretion of adrenocortical steroids. Studies with rhesus monkeys have shown that these responses can be affected by a number of factors including the method of handling and the type of physical restraint (Mason, 1959). In addition, androgens may depress plasma levels of glucocorticoids in primates (Brown & Migeon, 1956; Huis in't Veld, Louwerens & van den Spek, 1960). It was therefore decided to study the response of plasma cortisol to ACTH without these neural or hormonal influences. This report describes the effects of ACTH on castrated rhesus monkeys adapted to chronic restraint.
Four chair-restrained, orchidectomized rhesus monkeys (Macaca mulatta) bearing chronic indwelling venous catheters were used as experimental subjects and were housed, maintained and subjected to blood sampling as
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SUMMARY
The metabolism and the rate of transfer of cortisol across the placenta in pregnant guinea-pigs and foetuses were studied by constant intravenous infusions of tritium-labelled cortisol. Estimates of endogenous and radioactive plasma cortisol levels were used to calculate the following parameters at four stages before parturition (days 62, 64, 66 and 67; parturition occurring at day 68): metabolic clearance rate; production rate; adrenal secretory rate; transfer rate from mother to foetus and from foetus to mother; irreversible removal rate; the fraction of cortisol derived from the other in the foetal and maternal vascular compartments; the fraction of secreted and recycled cortisol involved in the transfer. The metabolic clearance rate and the rates of production and secretion of cortisol were higher in the mother than in the foetus between days 62 and 67 of gestation. About 90% of the foetal cortisol was of maternal origin. The fraction of maternal cortisol of foetal origin increased in the last days of gestation.
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Abstract
Fetal maturation and the timing of parturition in both sheep and primates are thought to be controlled by the hypothalamic-pituitary-adrenal axis but little is known about the endocrinology of the equine fetus. We investigated the ontogeny of plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol and corticosteroid binding capacity in the late-gestation fetal horse. We also wished to determine whether there is ultradian rhythmic release of ACTH and cortisol in fetal horses and we compared fetuses to maternal and non-pregnant adult horses. Six fetuses, 278–304 days gestation (term ≈335), were catheterized and sampled daily until delivery. Mean (± s.e.m.) ACTH concentrations increased significantly from 159 ±21 to 246 ±42 pg/ml over the last 2 days before parturition. Fetal cortisol increased significantly from 3·1±1·0 to 13·4±3·7 ng/ml (mean±s.e.m.) over the last 9 days before delivery. The slope of regressions for ACTH and cortisol concentrations with respect to time were positive in all subjects and statistically significant in 3 of 6 for ACTH and 5 of 6 for cortisol. Fetal corticosteroid binding capacity declined from 49·5 ±20·5 to 16·1 ± 2·2 ng/ml (mean ± s.e.m.) over the last 10 days before parturition. However, the greatest changes in ACTH, cortisol and corticosteroid binding capacity occurred very late in gestation, during the last 48 to 72 h before parturition. Significant peaks and nadirs in plasma ACTH concentration were detected in all 20 experiments and in plasma cortisol concentration in 17 of 20 experiments using Cluster analysis. We found statistically significant periods of oscillation between 11 and 64 min in plasma ACTH (19 of 20 experiments) and cortisol (15 of 20 experiments) using power spectral density analysis. Statistically significant periods between 11 and 17 min were detected in 11 of 20 experiments for ACTH and in 8 of 20 for cortisol. We conclude that: 1) at the end of gestation, equine fetal plasma ACTH and cortisol concentrations increase while corticosteroid binding capacity decreases suggesting that there is a disproportionately large increase in unbound cortisol at this time; 2) the secretion of ACTH and cortisol is rhythmic in both fetal and adult horses; 3) most animals exhibit a period of oscillation between 11 and 17 min; and 4) there is no apparent developmental change from late gestation to adulthood in the ultradian oscillator influencing ACTH and cortisol secretion in this species.
Journal of Endocrinology (1995) 144, 271–283
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SUMMARY
The effects of clomiphene citrate were studied in nine normal men, in three patients with partial panhypopituitarism, and in four patients with isolated gonadotrophin deficiency. The administration of this drug to the normal subjects in a dosage of 3 mg/kg/day for 10 days resulted in a mean rise in serum luteinizing hormone (LH) of 107%, in plasma 17β-hydroxyandrogens (17-OHA) of 114%, and in plasma total cortisol of 86%. The rise of testosterone concentration in normal subjects was associated with a doubling of the non-protein bound fraction, and also with increased binding of testosterone to sex hormone-binding globulin (SHBG). In contrast, plasma non-protein bound and urinary unconjugated cortisol remained unchanged. The percentage of plasma cortisol not bound to protein fell, indicating that the rise in total plasma cortisol was secondary to increased protein binding. This was confirmed by finding increased binding of both cortisol and testosterone to their specific binding globulins at 1 °C, due apparently to increased concentrations of SHBG and corticosteroid-binding globulin after clomiphene administration. All the responses to clomiphene were prevented by simultaneous administration of fluoxymesterone in two normal subjects.
All the hypopituitary patients showed no rise of LH, 17-OHA or cortisol. The hypogonadotrophic patients, however, showed a normal total cortisol rise.
It is suggested that clomiphene has two actions. First, it interferes with the hypothalamic feed-back mechanisms for testosterone, resulting in increased LH secretion, and secondly it has an oestrogen-like effect in stimulating production of steroid-binding globulins.
