Inhibition of testicular androgenesis by urinary gonadotropin-inhibiting substances in rats

The effect of urinary gonadotropin-inhibiting substances (GIS) on the androgen synthesis in rat testes was studied in vitro and in vivo. GIS, which was added to the incubation medium containing tesased testicular tissues and injected into rats for 2 days, showed a suppressive effect on the formation of androstenedione from pregnenolone in the testis.     

Inhibition of testicular androgenesis by urinary gonadotropin-inhibiting substances in rats

Summary The effect of urinary gonadotropin-inhibiting substances (GIS) on the androgen synthesis in rat testes was studied in vitro and in vivo. GIS, which was added to the incubation medium containing teased testicular tissues and injected into rats for 2 days, showed a suppressive effect on the formation of androstenedione from pregnenolone in the testis.Supported by a Scientific Research Grant from the Ministry of Education of Japan.     

Conversion of testosterone to androstenedione by liver homogenates of testicular feminized mice

Summary Liver homogenates of testicular feminized (Tfm) mice carrying the protective (o^hv) gene were found to be less capable of converting testosterone to androstenedione than Tfm without the protective gene.This work was supported by the Medical Research Council of Canada, No. MT 4192 and Ortho Pharmaceutical Company.     

Sertoli cells of adult rats in vitro. II. Effect of different steroid precursors on estradiol 17 beta-synthesis.

The estradiol 17 beta-synthesis by delta 4 pathway has been studied in homogenous cultures of Sertoli cells isolated from adult rat testes. The data reported clearly demonstrate that progesterone, androstenedione, testosterone and estrone induce an increase of the estradiol 17 beta-production.     

Identification of steroid hormones fromLacerta sicula testes

Riassunto Gli autori hanno analizzato gli steroidi presenti nel tessuto testicolare diLacerta sicula. Sono stati identificati i seguenti steroidi: progesterone, androstenedione, testosterone, androsterone, deidroepiandrosterone, pregnenolone, 20-idrossipregn-4-ene-3-one, estradiolo-17, estrone. Viene discusso il rapporto progesterone androstenedione testosterone, paragonandolo a quello trovato in altri vertebrati inferiori.     

Pituitary control of androgen synthesis in the rat embryo]

Removal of the hypophysis by decapitation of the 19--or 20 days--old Rat embryo is followed by a significant decrease in the ability of the embryonic testis to synthesize testosterone and androstenedione from acetate in vitro. It is concluded that pituitary-testis relationships first appear at 19 days of intrauterine life.     

Evolution of testosterone metabolism during neonatal life in the guinea pig]

The neonatal period is characterized in the male Guinea-Pig by a steady increase in the metabolic clearance rate of testosterone and by a decrease in the conversion rate of testosterone to androstenedione. The transient rise in testosterone production rate on day 3 is concomitant with the neonatal peak in plasma testosterone.     

In vitro conversion of steroid hormones in bovine ovarian follicles

Summary In bovine ovarian follicles an in vitro conversion of androstenedione and oestrone into oestradiol-17, and of oestradiol-17 into oestrone was observed. There was no in vitro conversion of pregnenolone, progesterone, dehydroepiandrosterone and testosterone.     

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.     

Estradiol treatment reduces a cytosol androgen binding protein in male rat liver

Summary The in vivo treatment of male rats with estradiol-17 resulted in a significant decrease in liver cytosol of the protein which binds specifically androstenedione and testosterone.Acknowledgment. This investigation was supported by a grant to N. S. from the Iwate-Keiryokai Medical University Research Foundation.     

Androstenedione or corticosterone treatment during pregnancy alters estrous cycle of adult female offspring in mice

Female offspring from mice injected with androstenedione during late pregnancy showed lengthened vaginal cycles, persistent estrus and decreased incidence of pro-estrus and diestrus, whilst offspring from mice injected with corticosterone showed increased incidence of diestrus. These observations give qualified support to the hypothesis that stress during pregnancy alters the female offspring reproductive system through the action of adrenal steroids.     

Androstenedione or corticosterone treatment during pregnancy alters estrous cycle of adult female offspring in mice

Summary Female offspring from mice injected with androstenedione during late pregnancy showed lengthened vaginal cycles, persistent estrus and decreased incidence of pro-estrus and dïestrus, whilst offspring from mice injected with corticosterone showed increased incidence of dïestrus. These observations give qualified support to the hypothesis that stress during pregnancy alters the female offspring reproductive system through the action of adrenal steroids.     

A multivariate approach to socio-ecological development and endocrine variance in the spotted hyaena, Crocuta crocuta Erxleben.

This investigation of the socio-ecological development and endocrine variance in the spotted hyaena, Crocuta crocuta, illustrates that the complexity of a multivariate endocrine system cannot fully be understood using the concept of a class mean (mu). Any comprehensive investigation of a multivariate endocrine system should also include an analysis of variance (sigma), as it may provide additional insights into the dynamics of an endocrine hypervolume. Mean cortisol concentrations could not differentiate between various social and reproductive categories (MANOVA); however, in males an analysis of variance (principal component analysis) indicated that the contrast between cortisol and androstenedione was the principle axis of variance once the androgen secreting ability had been accounted for. On the other hand, the same contrast was found to be the principal axis of variance in the female sub-sample, suggesting that cortisol may play a significant role in regulating the endocrine dynamics of this species, despite showing little variance in mean values among various social and reproductive categories.     

Age variation in the increase of hypothalamic and brain stem contents of phenylethanolamine m-octopamine and p-octopamine in spontaneously hypertensive rats (SH Kyoto).

Phenylethanolamine, m-octopamine and p-octopamine contents were determined as a function of age in the hypothalamus and brain stem of spontaneously hypertensive rats and controls Wistar Kyoto. In hypothalamus, the content of the 3 amines was 2--4-fold greater for the SH rats. In the brain stem, the phenylethanolamine and p-octopamine contents were 2--3-fold greater in SH rats but 5--6-fold higher in the case of m-octopamine. The difference appears at 3 weeks and correlates the blood pressure with the increase of age. The significance of these findings is discussed.     

Effects of female sex hormones on polyamine-oxidizing enzyme activities and polyamine concentrations in immature rat uterus and liver

17-estradiol (E₂) and progesterone (P) treatment of immature female rats (10 g/100 g body weight) respectively resulted in 1.38-fold (p<0.02) and 1.42-fold (p<0.02) increase in the uterine polyamine oxidase activity, and 2.45-fold (p<0.001) and 1.43-fold (p<0.02) increase in the uterine diamine oxidase activity, as compared to the controls. E₂ caused a 5-fold (p<0.05) and a 1.36-fold (p<0.05) increase in putrescine and spermidine concentration respectively in rat uterus. Increases of 1.7-fold (p<0.02) and 1.6-fold (p<0.05) in putrescine and spermine concentration were determined in the P-treated uterus, as compared to the controls. The spermidine/spermine ratio, which is regarded as an index of growth rate, was higher in the E₂-treated uterus and lower in the P-treated uterus than in the control uterus. No statistically significant hormonal effects were estimated in the immature liver. The data reported suggest the possibility of an involvement of polyamine-oxidizing enzymes in the modulation of polyamine concentrations in rat uterus by the female sex hormones.     

Sertoli cells of adult rats in vitro. II. Effect of different steroid precursors on estradiol 17β-synthesis

Summary The estradiol 17-synthesis by ⁴ pathway has been studied in homogenous cultures of Sertoli cells isolated from adult rat testes. The data reported clearly demonstrate that progesterone, androstenedione, testosterone and estrone induce an increase of the estradiol 17-production.This work was partially supported by grants No. 77.01322.04 and No. 77.01958.04 from the Consiglio Nazionale delle Ricerche.The excellent technical assistance of Antonio Muller and Massimo Rosati is deeply appreciated.     

Key role of glutamic acid for the cytotoxic activity of the cyclotide cycloviolacin O2

Cyclotides are cyclic plant proteins with potent cytotoxic effects. Here we systematically probed the importance of surface-exposed charged amino acid residues of the cyclotide cycloviolacin O2, using a strategy involving chemical modifications. We show that the single glutamic acid plays a key role for the cytotoxicity: methylation of this residue produced a 48-fold decrease in potency. Virtually no change in potency was observed when masking the single arginine residue using 1,2-cyclohexanedione, while acetylation of the two lysine residues reduced the potency 3-fold. The derivative with modifications at both arginine and lysine residues showed a 7-fold loss of potency. In addition, we show that the activity is dependent on an intact disulfide network and that the short sequences between the six cysteine residues, that is, the backbone loops, are devoid of cytotoxic activity. Received 11 October 2005; received after revision 3 November 2005; accepted 15 November 2005     

Age variation in the increase of hypothalamic and brain stem contents of phenylethanolamine m-octopamine and p-octopamine in spontaneously hypertensive rats (SH kyoto)

Summary Phenylethanolamine, m=octopamine and p-octopamine contents were determined as a function of age in the hypothalamus and brain stem of spontaneously hypertensive rats and controls Wistar Kyoto. In hypothalamus, the content of the 3 amines was 2–4-fold greater for the SH rats. In the brain stem, the phenylethanolamine and p-octopamine contents were 2–3-fold greater in SH rats but 5–6-fold higher in the case of m-octopamine. The difference appears at 3 weeks and correlates the blood pressure with the increase of age. The significance of these findings is discussed.This work has been completed at the Tokyo University. The author is grateful to Professor Z. Tamura, Dr K. Imai and A. Ooshima as well as to the French Foreign Office and the Japanese Society for the Promotion of Sciences.     

Metallothionein induction by cadmium and zinc in rat secretory organs

Metallothionein (MT) levels were determined in four secretory organs of the rat following administration of zinc (Zn) and cadmium (Cd). The concentrations of MT in the lacrimal, parotid and adrenal glands of untreated rats were in the range of 2.2-4.9 micrograms/g wet weight tissue while in the pancreas it was shown to be 15.2 micrograms/g. Injection of zinc at total doses of 16, 32 and 80 mg/kg resulted in a 1.8-, 3.2- and 5.9-fold increase in lacrimal MT content, respectively, while a 10.2- and 13.1-fold elevation was observed following treatment with 4 and 8 mg/kg of Cd, respectively. Similar findings were found in the adrenal gland. The parotid MT was elevated 5.9 and 17 times following Zn treatment at doses of 16 and 80 mg/kg respectively, whereas 4 mg/kg of Cd increased MT 14.4 times in this gland. Pancreatic MT was elevated by 39- and 40-fold after injection of Zn at doses of 16 and 32 mg/kg respectively, whereas 4 and 8 mg/kg of Cd caused a 9.8- and 17.9-fold induction, respectively. These results may indicate that secretory organs participate in metabolism of heavy metals in the mammalian body.     

A multivariate approach to socio-ecological development and endocrine variance in the spotted hyaena,Crocuta crocuta Erxleben

This investigation of the socio-ecological development and endocrine variance in the spotted hyaena,Crocuta crocuta, illustrates that the complexity of a multivariate endocrine system cannot fully be understood using the concept of a class mean (). Any comprehensive investigation of a multivariate endocrine system should also include an analysis of variance (), as it may provide additional insights into the dynamics of an endocrine hypervolume. Mean cortisol concentrations could not differentiate between various social and reproductive categories (MANOVA); however, in males an analysis of variance (principal component analysis) indicated that the contrast between cortisol and androstenedione was the principle axis of variance once the androgen secreting ability had been accounted for. On the other hand, the same contrast was found to be the principal axis of variance in the female sub-sample, suggesting that cortisol may play a significant role in regulating the endocrine dynamics of this species, despite showing little variance in mean values among various social and reproductive categories.