Radioimmunoassay of plasma progesterone, testosterone, total estrogen and immunoreactive gonadotropin in the nesting and non-nesting green sea turtle, Chelonia mydas (L.).

Plasma progesterone, testosterone, total estrogens and immunoreactive gonadotropin were measured in nesting and non-nesting sea turtles, Chelonia mydas. Progesterone and gonadotropin concentrations were significantly higher in nesting than in non-nesting turtles, testosterone was not significantly different in either group and total estrogens appeared to be slightly in the nesting group.     

Capillary blood flow in the testes and testosterone secretion in the starved rat

Summary The average capillary blood flow in the testes was found to be 181 l/min/g testis tissue (n=19) in rats starved for 5 days and 273 l/min/g (n=18, p<0.01) in the control group. Plasma testosterone was significantly decreased in the starved animals (1.00±0.06 ng/ml vs 5.43±0.63 ng/ml). When starved and control rats were stimulated with human chorion gonadotropin, testosterone values in plasma were greatly increased in both groups. The capillary blood flow was not altered. The data indicate that human chorion gonadotropin can stimulate testosterone production in the starved rat without influencing the reduced capillary blood flow.     

Alzheimer’s disease: the impact of age-related changes in reproductive hormones

The relationship between hormones and Alzheimers disease (AD) has been intensely researched. While the majority of this work has focused on the sex steroids, estrogens, and more recently androgens, a serendipitous patient encounter led one of us (R.L.B.) to question whether other hormones of the hypothalamic-pituitary-gonadal axis might play a role in the pathogenesis of AD. The age-related decline in reproductive function results in a dramatic decrease in serum estrogen and testosterone concentrations and an equally dramatic compensatory increase in serum gonadotropin concentrations. Indeed, there is growing evidence that the gonadotropin luteinizing hormone, which regulates serum estrogen and testosterone concentrations, is an important causative factor in the development of AD. This review provides information supporting the gonadotropin hypothesis. We put forth a novel mechanism of how changes in serum luteinizing hormone concentrations could contribute to the pathogenesis of AD and discusses potential therapeutic anti-gonadotropin compounds.     

The relationship between high and low trait psychological stress,serum testosterone,and serum cortisol

Summary Psychological stress, as measured by the parameters of trait anxiety, hostility, and depression, was compared in the group of males age 30–55 with serum levels of testosterone. Those males who were classified as high psychological stress had significantly lower testosterone levels than did their low stress counterparts. However, comparison of their serum cortisol values revealed similar concentrations in both groups.     

Inhibition of post-hemicastration hypertrophy of the remaining testis by testosterone or aqueous testicular extract treatments in the young rat]

In the 10 day old hemicastrated Rat daily injections of testosterone (total doses of 0.04 to 4 mg/Rat) or of proteinaceous extract of Rat testis (4 mg/Rat) inhibit compensatory hypertrophy of the remaining testis. Both testosterone and testicular proteinaceous extract could be involved in the growing processes of the testis, locally or by means of modification of gonadotropin secretion. Results have been analysed by covariance analysis to eliminate the influence of body weight variations.     

Zinc,copper and selenium in reproduction

Of the nine biological trace elements, zinc, copper and selenium are important in reproduction in males and females. Zinc content is high in the adult testis, and the prostate has a higher concentration of zinc than any other organ of the body. Zinc deficiency first impairs angiotensin converting enzyme (ACE) activity, and this in turn leads to depletion of testosterone and inhibition of spermatogenesis. Defects in spermatozoa are frequently observed in the zinc-deficient rat. Zinc is thought to help to extend the functional life span of the ejaculated spermatozoa. Zinc deficiency in the female can lead to such problems as impaired synthesis/secretion-of (FSH) and (LH), abnormal ovarian development, disruption of the estrous cycle, frequent abortion, a prolonged gestation period, teratogenicity, still-births, difficulty in parturition, pre-eclampsia, toxemia and low birth weights of infants. The level of testosterone in the male has been suggested to play a role in the severity of copper deficiency. Copper-deficient female rats are protected against mortality due to copper deficiency, and the protection has been suggested to be provided by estrogens, since estrogens alter the subcellular distribution of copper in the liver and increase plasma copper levels by inducing ceruloplasmin synthesis. The selenium content of male gonads increases during pubertal maturation. Selenium is localized in the mitochondrial capsule protein (MCP) of the midpiece. Maximal incorporation in MCP occurs at steps 7 and 12 of spermatogenesis and uptake dereases by step 15. Selenium deficiency in females results in infertility, abortions and retention of the placenta. The newborns from a selenium-deficient mother suffer from muscular weakness, but the concentration of selenium during pregnancy does not have any effect on the weight of the baby or length of pregnancy. The selenium requirements of a pregnant and lactating mother are increased as a result of selenium transport to the fetus via the placenta and to the infant via breast milk.     

Plasma steroid and protein hormone concentrations in patients with benign prostatic hypertrophy and in normal men

Summary Serum levels of testosterone, FSH, LH and prolactin were measured by RIA in patients with BPH (benign prostatic hypertrophy) and in control men. The testosterone concentrations in the BPH group were significantly lower than that of the control group. Serum concentrations of FSH, LH, prolactin and estradiol, did not differ significantly in the 2 groups.     

Plasma steroid and protein hormone concentrations in patients with benign prostatic hypertrophy and in normal men.

Serum levels of testosterone, FSH, LH and prolactin were measured by RIA in patients with BPH (benign prostatic hypertrophy) and in control men. The testosterone concentrations in the BPH group were significantly lower than that of the control group. Serum concentrations of FSH, LH, prolactin and estradiol, did not differ significantly in the 2 groups.     

Effect of testosterone on the hypothalamic-pituitary-gonadal axis of pinealectomized and pineal-intact male rats.

Previous studies indicate that steroid hormones alter pineal biochemistry, and it has been suggested that at least part of the negative feedback effect of steroid hormones on pituitary gonadotropin release may be mediated by the pineal gland. In this study, pinealectomy did not alter the inhibitory effect of testosterone on neuroendocine-gonadal activity in the male rat, suggesting that the pineal gland does not mediate the response of the rat hypothalamic-pituitary axis to testosterone.     

Demonstration of testosterone secretion by testicular tissue of hypophysectomized boar as affected by HCG in organ culture]

Boar Leydig cells undergo a strong atrophy from 1 to 3 months after hypophysectomy but can be reactivated by the gonadotropin HCG in organ culture conditions. This reactivation which appeared at histological and ultrastructural level was evidenced by the capacity of testicular tissue to synthesize testosterone as judged by radioimmunoassay. Both synthesis in the tissue and release into the medium increased according the incubation time with HCG; the adjonction of 17 alpha-OH-pregneolone to culture medium led to increase the intra and extra-tissular concentration of testosterone.     

Effects of photoperiod,temperature and testosterone-treatment on plasma T3 and T4 levels in the Djungarian hamster,Phodopus sungorus

Summary The effects of photoperiod, temperature and testosterone treatment on plasma T₃ and T₄ levels were investigated in the Djungarian hamster. Plasma T₃ level was affected by temperature (25°C<7°C) but not by photoperiod. Plasma T₄ level was affected by photoperiod (short day < long day) at 25°C. Administration of testosterone increased plasma T₄ level under short photoperiod at 25°C. Thus, higher plasma T₄ level under long photoperiod at 25°C might be induced by testosterone.     

The effect of guanethidine treatment of testicular blood flow and testosterone production in rats

Testicular blood flow was measured by means of Xenon-133 clearance in control rats and rats treated with guanethidine for 3 weeks. Plasma and testis testosterone concentrations were also measured, and the effect of hCG-treatment was examined. No difference in testicular blood flow between the control group and the guanethidine-treated group was found. However, in guanethidine-treated rats, plasma and testis testosterone concentrations after hCG-treatment were significantly decreased. The results may indicate that adrenergic nerves are involved in the regulation of Leydig cell function.     

The effect of guanethidine treatment of testicular blood flow and testosterone production in rats

Summary Testicular blood flow was measured bymeans of Xenon-133 clearance in control rats and rats treated with guanethidine for 3 weeks. Plasma and testis testosterone concentrations were also measured, and the effect of hCG-treatment was examined. No difference in testicular blood flow between the control group and the guanethidinetreated group was found. However, in guanethidine-treated rats, plasma and testis testosterone concentrations after hCG-treatment were significantly decreased. The results may indicate that adrenergic nerves are involved in the regulation of Leydig cell function.     

Metabolism of C19-steroids in testicular tissue of the newtTriturus vulgaris,during and after breeding

Summary Incubation studies with testicular homogenates ofTriturus vulgaris showed that testosterone was quantitatively the most important metabolite of dehydroepiandrosterone and androstenedione during breeding. After breeding the recovery of testosterone declined. This suggests that 17-hydroxysteroid dehydrogenase may be regulated for the needs of testicular androgen production.     

Effects of photoperiod, temperature and testosterone-treatment on plasma T3 and T4 levels in the Djungarian hamster, Phodopus sungorus

The effects of photoperiod, temperature and testosterone treatment on plasma T3 and T4 levels were investigated in the Djungarian hamster. Plasma T3 level was affected by temperature (25 degrees C less than 7 degrees C) but not by photoperiod. Plasma T4 level was affected by photoperiod (short day less than long day) at 25 degrees C. Administration of testosterone increased plasma T4 level under short photoperiod at 25 degrees C. Thus, higher plasma T4 level under long photoperiod at 25 degrees C might be induced by testosterone.     

Klangspektrographische Untersuchung der Lautäusserung beim Krallenfrosch,Xenopus laevis

Summary Three different calls of the clawed toadXenopus laevis are described and their sound spectrograms are presented. The male and female have one characteristic call each, which is heard during clasping after stimulating the mating behaviour with chorionic gonadotropin. A second call of the male is heard without hormone treatment, often after feeding or change of water.     

Effect of testosterone on the hypothalamic-pituitary-gonadal axis of pinealectomized and pineal-intact male rats

Summary Previous studies indicate that steroid hormones alter pineal biochemistry, and it has been suggested that at least part of the negative feedback effect of steroid hormones on pituitary gonadotropin release may be mediated by the pineal gland. In this study, pinealectomy did not alter the inhibitory effect of testosterone on neuroendocrine-gonadal activity in the male rat, suggesting that the pineal gland does not mediate the response of the rat hypothalamic-pituitary axis to testosterone.We wish to thank Susan H. Losee, Brigitte G. Mann and John Georgeson for excellent technical assistance. This investigation was supported by NSF grant SER 77-03836 and a grant from the University of Wisconsin-Parkside Committee on Research to E.P.W. and by NIH grant HD-09885 and NSF grant PCM 76-09955 to F.W.T.     

Effects of gonadal hormones on the lipid contents of the frogRana esculenta

Summary The effects of exogenous gonadal hormones on the lipid contents of the liver and ovary and also on water content in the frog,Rana esculenta, were studied. Estrogen treatment significantly enhanced, whereas testosterone treatment reduced, the lipid and cholesterol contents. Water content of the frogs increased significantly after treatment by either hormone.Acknowledgment. I wish to thank Dr Hussain Al-Adhub, College of Science for providing all necessary laboratory facillities. Present address: Physiology Laboratory, Department of Zoology, Patna University, Patna-80005, Bihar (India).     

La question des hétérochromosomes chez les Sauropsidés. I. Reptiles

Summary In contradiction to some Japanese authors (Oguma, Makino, Nakamura), we are unable to find any difference in the chromosome sets of the male and female ofLacerta vivipara (2N = 36). In a saurian, where the analysis is very easy (Chamaeleon bitaeniatus), there are, without the smallest doubt, 24 chromosomes in both sexes (20M + 4m). The evidence of a female heterogamety in turtles is by no means satisfying.