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SUMMARY
The human pronephros showed no hydroxysteroid dehydrogenase activity. The human mesonephros, like piscine and amphibian mesonephroi had 16β- and 17β-hydroxysteroid dehydrogenase activity and a possible function of the human mesonephros is suggested. Metanephric kidneys had 3α-, Δ5-3β-, 3β-, 6β-, 16α-, 16β-, and 17β-hydroxysteroid dehydrogenases; 11β-hydroxysteroid dehydrogenase was present in all adult mammalian metanephric kidneys surveyed. 3α-Hydroxysteroid dehydrogenase was selectively present and very active in the proximal and distal convoluted tubules, particularly of the juxta-medullary glomeruli. This function is thought to be related to the excretion of 3α-ketosteroids. 11β-Hydroxysteroid dehydrogenase was confined to the collecting tubules and its possible involvement in the metabolism of cortisol, aldosterone or androgens in the kidney is noted. 17β-Hydroxysteroid dehydrogenase may be concerned in the excretion of the sex steroids; it occurs throughout the nephron. Δ5-3β-, 16α-, and 16β-hydroxysteroid dehydrogenases were not as active histochemically in the kidney as the 3α-, 3β-, 11β- and 17β-hydroxysteroid dehydrogenases.
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ABSTRACT
Three experiments were conducted to compare the ability of different preparations of growth hormone-releasing factor (GRF) to stimulate GH secretion in sheep maintained in positive and negative energy balance.
In experiment 1 five sheep were injected (i.v.) with three preparations of human pancreatic GRF (hpGRF-44, hpGRF-40, hpGRF-29-NH2) and one preparation of rat hypothalamic GRF (rhGRF-29-NH2) all at 98·0 pmol/kg, or control vehicle, in a Latin square design when the animals either had free access to food or were fed half their maintenance requirements. Analysis of plasma samples, obtained before and for 150 min after injection, revealed that the reduced food intake resulted in the expected changes in body weight and circulating GH, insulin, glucose, urea and non-esterified fatty acids. The maximum post-injection concentrations of GH did not differ between either the two levels of feeding or the four GRF preparations but the mean post-injection concentration of GH was significantly higher for all GRF treatments on the restricted ration (P < 0·001). The mean post-injection response to rhGRF-29-NH2 was less than that obtained with hpGRF-44 for sheep with food available ad libitum (P < 0·05) and was clearly more persistent for all GRF treatments in animals fed the reduced diet (P < 0·001).
In experiment 2 the same five sheep were injected i.v. with rhGRF-29-NH2 (98·0 pmol/kg) when they had free access to food and after food had been withdrawn for 3 days. The peak concentrations of plasma GH and the speed of the response did not differ between feeding and food deprivation but the average post-injection concentration of GH was higher (P < 0·05) when the animals were deprived because the response was more persistent.
In experiment 3 the effects of i.v. injection of hpGRF-10-NH2, hpGRF-10-OH and hpGRF-10-OCH3 were examined at three different doses (8, 80 and 800 nmol/kg) each in three sheep. None of these treatments stimulated a significant increase in circulating GH.
J. Endocr. (1985) 105, 113–119
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Search for other papers by K. C. CALMAN in
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SUMMARY
11β-Hydroxysteroid dehydrogenase can be demonstrated histochemically by incubating tissues with nitro blue tetrazolium (2,2′-di-p-nitrophenyl-5,5′-diphenyl-3,3′-(3,3′-dimethoxy-4,4′-diphenylene) ditetrazolium chloride), NAD or NADP and an appropriate steroid. Suitable steroid substrates are: (1) 11β-hydroxyandrost-4-ene-3,17-dione (11β-hydroxyandrostenedione), (2) 3,11β-dihydroxyoestra-1,3,5(10)-trien-17-one (11β-hydroxyoestrone), (3) 3α,11β-dihydroxy-5α-androstan-17-one, (4) 3α,11β-dihydroxy-5β-androstan-17-one and (5) 11β-hydroxypregn-4-ene-3,20-dione(11β-hydroxyprogesterone).
11β-Hydroxysteroid dehydrogenase activity was found in the Leydig cells of six human testes from subjects ranging in age from 12 to 57 yr. with all five substrates.
The Leydig cells of the mouse testis contain demonstrable 11β-hydroxysteroid dehydrogenase activity and the volume of reactive tissue increases regularly between birth and the end of the 10th week of postnatal life; this growth curve is sigmoid in form. An extremely weak histochemical reaction with human placenta obtained at term was observed, 11β-hydroxyandrostenedione being the only substrate utilized to any extent. A specimen of hydatid mole, however, showed intense 11β-hydroxysteroid dehydrogenase activity with all substrates surveyed. 11β-Hydroxysteroid dehydrogenase was also found in the ova, granulosa, theca interna, interstitial tissue and corpora lutea of the mouse ovary.
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SUMMARY
The histochemical utilization of 3α-, 6β-, 11α-, 12α-, 16α-, 16β-, 17α-, 21- and 24-hydroxysteroids in human and mouse testis, human placenta, mouse ovary and rat adrenal has been investigated using a coupling method and the tetrazolium salt, Nitro-BT. 3α-Hydroxysteroid dehydrogenase was present in the human Leydig cells and placental syntrophoblast, but there was little in rat adrenal zona fasciculata and in mouse ovary; the enzyme is NAD or NADP dependent. 6β-Hydroxysteroid dehydrogenase was present in human Leydig cells, mouse Leydig cells, placental syntrophoblast, ova, granulosa, theca interna, corpora lutea and interstitial tissue; it is NAD dependent. 11α-Hydroxysteroid dehydrogenase activity was very poorly developed, being NAD dependent and demonstrable only in human Leydig cells. 12α-Hydroxysteroid dehydrogenase could be demonstrated in some human Leydig cells; it was both NAD and NADP dependent. 16α-Hydroxysteroids were very poorly used by all the tissues surveyed. 16β-Hydroxysteroids gave an intense histochemical reaction with NAD in human Leydig and Sertoli cells, in placental trophoblast, in adrenal zonae glomerulosa, fasciculata and reticularis and in all ovarian tissues. 17α-, 21- and 24-hydroxysteroids were poorly utilized by human Leydig cells, but not by the other tissues. The first two were NAD dependent; 24-hydroxysteroid utilization was both NAD and NADP dependent.
The techniques used are believed to demonstrate specific hydroxysteroid dehydrogenases because of variations in pyridine nucleotide requirement and in the location in the tissues of different hydroxysteroid dehydrogenases. Moreover, stereoisomers of the same hydroxysteroid behave differently in this system. The role of steroid 5α- and 5β-dehydrogenases is discussed in connexion with the histochemical results.
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SUMMARY
The histochemical utilization of 3α-, 3β-, 6β-, 11α-, 11β-, 12α-, 16α-, 16β-, 17α-, 17β-, 20α-, 21- and 24-hydroxysteroids by three normal adult human adrenal glands, two human foetal adrenal glands, three adrenals from patients with Cushing's syndrome and one adrenal adenoma are described.
The normal adult human adrenal showed high 16β-hydroxysteroid dehydrogenase activity in the zona glomerulosa. Activity restricted to the outer part of the zona fasciculata was recorded with 3α-, 3β-, 6β-, 11β-, 16α-, 16β-, and 17β-hydroxysteroids. The zona reticularis utilized 3α-, 3β-, 11β-, 16β- and 17β-hydroxysteroids less well than the zona fasciculata.
The adrenals of Cushing's syndrome showed activity only for 3β- and 16β-hydroxysteroid dehydrogenases; this activity was noted in all three zones. The activity pattern of the adrenal adenoma resembled that of the normal adult human adrenal except that greater activity for 16α-hydroxysteroid dehydrogenase was noted.
The foetal part of the human foetal cortex was extremely active, showing 3α-, 3β-, 6β-, 11β-, 12α-, 16α-, 16β-, 17β-, 20β- and 21-hydroxysteroid dehydrogenase activity. The definitive cortex behaved similarly to the adult gland and possessed 3α-, 3β-, 11β-, 16β- and 17β-hydroxysteroid dehydrogenases; some evidence of zoning of the definitive cortex was seen with the 16β-hydroxysteroid.
The relevance of these findings in the light of current knowledge of adrenal zonation is discussed.
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SUMMARY
Plasma human growth hormone (HGH) and serum phosphorus concentrations were measured during the fasting ambulatory state in middleaged men, pre- and postmenopausal women and postmenopausal women who had been taking 20–40 μg mestranol daily for 1–3 years.
The mean plasma HGH concentrations were consistently higher in the women than they were in the men, there was little difference between the mean values for pre- and postmenopausal women, and the mestranoltreated women had significantly higher mean values than the untreated postmenopausal women.
The mean serum phosphorus concentration was significantly higher after menopause and was significantly lower in those women on long-term lowdose mestranol therapy. A significant direct correlation was found between serum phosphorus and plasma HGH concentrations in untreated postmenopausal women.
It is suggested that the postmenopausal relative hyperphosphataemia is consistent with increased HGH activity.
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ABSTRACT
Although it is well known that exogenous bovine GH (bGH) increases milk yield in ruminants it has not been possible to determine whether an increase in endogenous GH secretion has the same effect. The recent isolation of human pancreatic GH-releasing factor (hpGRF-44) has enabled this comparison of the effects of bGH and hpGRF-44 on milk production in sheep.
Three pairs of Dorset ewes underwent three 4-day treatments according to a Latin square design. Treatment 1 involved: 2-hourly i.v. injections (∼ 3·0 ml) of bGH (15 μg/kg; 1·8 units/mg); treatment 2: 2-hourly i.v. injections (∼3·0 ml) of hpGRF-44 (0·6 μg/kg); treatment 3: 2-hourly i.v. injections (3·0 ml) of the vehicle. Treatment periods were separated by 10 days. Sheep were milked twice daily and the milk was analysed for fat, protein and lactose. Blood samples (5·0 ml) were taken before and at 15, 45, 75 and 100 min after every third injection throughout the 4 days. Plasma was analysed for insulin, glucose, urea and non-esterified fatty acids (NEFA).
The changes in plasma GH stimulated by hpGRF-44 were consistent and repeatable throughout the 4 days of treatment. In comparison to the controls, treatment with hpGRF-44 and bGH significantly increased average plasma GH (μg/l) for the 4 days (control, 5·7±0·2 (s.e.m.); hpGRF-44, 12·3±0·4, P<0·001; bGH, 14·5±0·5, P<0·001), and this was accompanied by similar increases in milk yield (hpGRF-44, 26·7±2·6%, P<0·001; bGH, 30·7±2·9%, P<0·001) and the concentration of milk fat (g/kg) (control, 28·6±0·5; hpGRF-44, 33·2±0·5; bGH 34·8±1·5, P<0·01 for both treatments). The post-treatment decline in milk yield was much slower after hpGRF-44 than after bGH injections. Both treatments stimulated significant increases in the average concentrations of plasma insulin, glucose and NEFA, and plasma urea was significantly reduced by treatment with bGH only.
It is concluded that raising endogenous GH secretion is equally as effective as exogenous bGH in stimulating milk production in sheep.
J. Endocr. (1985) 105, 189–196
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Neurophysin and the octapeptide hormones oxytocin and vasopressin are synthesized in the hypothalamus and stored in the posterior lobe of the pituitary gland. It has recently been shown that the release of both oxytocin and vasopressin or of vasopressin alone, in response to potent stimuli, is accompanied by a simultaneous release of neurophysin into the circulation (Burton, Forsling & Martin, 1971; McNeilly, Legros & Forsling, 1972). However, it has yet to be shown that neurophysin can be released at the same time as a specific release of oxytocin. This situation occurs in animals during both parturition (Folley & Knaggs, 1965) and lactation (Folley & Knaggs, 1966; McNeilly, 1972). The present report describes the simultaneous release of oxytocin and neurophysin during parturition in the goat.
Serial blood samples (approx. 10 ml each) were taken from an indwelling jugular cannula during the whole of labour in two pedigree British Saanen goats. Samples
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Somatomedin-like activity (SLA) was measured in plasma samples from cattle using the porcine costal cartilage disk bioassay. In 40-day-old pre-ruminant bull calves, SLA was highest in the plasma of eight Friesians (mean potency 0·97±0·06 (s.e.m.) units/ml), lowest in five Aberdeen Angus × Friesians (0·78±0·03, P<0·05) and intermediate in six Hereford × Friesians (0·89±0·09). Plasma levels of SLA were significantly (P<0·01) lower in eight lactating Friesian (high-yielding) cows (0·53 ± 0·04) than in five dry cows (0·76±0·06). Levels of SLA in the plasma of a further eight lactating Hereford × Friesian (low-yielding) cows (0·76±0·07) were similar to the levels in the plasma of the five dry dairy cows.
Large diurnal changes in plasma SLA occurred in lactating Hereford × Friesian and Friesian heifers. In three Hereford × Friesian heifers plasma levels of SLA were lowest at 19.00 h (0·39±0·07) and highest at 03.00 h (0·77±0·08). A similar pattern was present in plasma samples from three Friesian heifers; the lowest levels of SLA being at 21.00 h (0·37±0·07) and the highest at 05.00 h (0·61±0·13). Throughout the period of 24 h the overall mean levels of SLA were significantly (P<0·01) higher in the plasma samples from the three Hereford × Friesian heifers (0·6 ±0·01) than in the samples from the three Friesian heifers (0·49 ± 0·02 units/ml).
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ABSTRACT
Monoclonal antibody CAll was raised against ovine GH; its effects on GH activity were examined in a target species relevant for animal production in vivo. The monoclonal antibody was found to enhance the galactopoietic response to exogenous GH in adult lactating ewes and also to potentiate the diabetogenic activity of both exogenous and endogenous GH in ewe lambs. Thus it was shown that GH activity may be manipulated above its usual dose-response range in normal, intact animals of commercial importance via immunological means.
