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  • Author: K. D. R. Setchell x
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K. D. R. SETCHELL, K. S. CHUA and R. L. HIMSWORTH

SUMMARY

Urinary steroids and steroid conjugates were measured in the squirrel monkey (Saimuri sciureus). The principal steroids excreted were cortisol, 11β,17α,20β,21-tetrahydroxy-4pregnen-3-one (20β-dihydrocortisol), 11β,17α,20α,21-tetrahydroxy-4-pregnen-3-one (20α-dihydrocortisol), α- and β-cortol and α- and β-cortolone. The majority of the steroids were excreted unconjugated and a conspicuous feature of the pattern was the large amount of urinary free cortisol. Unlike man there was an insignificant excretion of 3α,17α,21-trihydroxy-5β-pregnane-11,20-dione (tetrahydrocortisone) and 3α,11β,17α,21-tetrahydroxy-5β-pregnan-20-one (tetrahydrocortisol). A steroid not previously identified in urine from any species was one of the major glucuronide conjugates; it was characterized as having the structure 3β,17α,20ξ,21-tetrahydroxy-5β-pregnan-11-one. Administration of dexamethasone resulted in complete suppression of steroid output, whilst the response to adrenocorticotrophic hormone was inconstant.

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R. P. MICHAEL, K. D. R. SETCHELL and T. M. PLANT

SUMMARY

The assays of testosterone and corticosteroids in plasma from adult male rhesus monkeys using competitive protein-binding and radioimmunoassay techniques are described. The radioimmunoassay for testosterone was conducted without chromatography and, therefore, additionally estimated 17β-hydroxy-5α-androstan-3-one (dihydrotestosterone). Levels of testosterone in the peripheral plasma of 14 intact male rhesus monkeys showed marked fluctuations over a period of 24 h. Concentrations of testosterone at 22.00 h (1776 ± 814 ( ± s.d.) ng/100 ml) were approximately double those at 08.00 h (858 ± 407 ng/100 ml), 12.00 h (898 ± 316 ng/100 ml) and 16.00 h (784 ± 530 ng/100 ml). Castration resulted in low plasma testosterone levels (85 ± 29 ng/100 ml), and the increases at 22.00 h were no longer observed. In intact males, the 'basal' plasma corticosteroidlevel(08.00 h) was 22·4 ± 6·0 μg/100 ml. Administration of synthetic corticotrophin raised plasma corticosteroid levels without changing plasma testosterone concentration. Because plasma testosterone levels were not related to changes in adrenocortical activity, the noctural rises appear to be due to changes in testicular secretion.

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K. D. R. SETCHELL, LESLEY H REES and R. L. HIMSWORTH

SUMMARY

The half-life of plasma cortisol in the rhesus monkey (M. mulatta), determined by two methods, was about 130 min and longer than that in man; it was unaffected by administration of dexamethasone. Dexamethasone (5 mg, i.v.) immediately inhibited the secretion of ACTH from the monkey pituitary. The plasma half-life of NH2-terminal immunoreactive ACTH was found to be about 55 min which was much longer than the biological half-life. The adrenal synthesis of cortisol was inhibited by metyrapone which caused a prompt increase in the plasma concentration of ACTH and 11-deoxycortisol. The hypothalamicpituitary-adrenal system of the rhesus monkey sedated with phencyclidine hydrochloride responded rapidly to alteration in the level of steroids in the circulation.

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K. D. R. SETCHELL, C. H. L. SHACKLETON and R. L. HIMSWORTH

SUMMARY

The physiological regulation of the plasma corticosteroid concentration, measured by competitive protein-binding, was studied in female rhesus monkeys (M. mulatta) sedated with phencyclidine hydrochloride. Morning basal levels of plasma corticosteroids were found to be in the range 8·0–25·2 μg/100 ml, which is lower than that previously reported in this species. A circadian rhythm in plasma cortisol concentration was demonstrated. Prolonged sedation with phencyclidine was associated with a gradual increase in the plasma cortisol concentration. Synthetic α1–24 adrenocorticotrophic hormone given intravenously caused a rapid rise in plasma cortisol, the minimum effective dose was between 1 and 10 ng/kg body weight and the response was maximal after 1000 ng/kg. The administration of lysinevasopressin and the induction of hypoglycaemia by insulin were both followed by an increase in the plasma corticosteroid concentration. Metyrapone caused a decline in plasma 11-hydroxycorticosteroids and a concomitant increase in total corticosteroids measured by competitive protein-binding. It is concluded that the hypothalamic-pituitary-adrenal system in the rhesus monkey functions in a manner which is qualitatively and quantitatively similar to that of man.

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M. Axelson, J. Sjövall, B. E. Gustafsson and K. D. R. Setchell

ABSTRACT

The dietary origin of the weak oestrogen equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman) present in human urine has been investigated using gas chromatography–mass spectrometry. Feeding experiments with different food constituents and monitoring the urinary excretion of equol revealed that soya food yields more than 0·1 mg urinary equol/g flour ingested. From this source the glucoside of daidzein (4′,7-dihydroxyisoflavone) has been isolated and identified as a precursor of equol. Both equol and daidzein were characterized as monoglucuronide conjugates in human urine and the concentration of urinary equol exceeded the concentrations of the classical oestrogens by 100- to 1000-fold after ingestion of a single meal containing soya protein. The potential biological significance of this result is discussed.

J. Endocr. (1984) 102, 49–56