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.     

Combined effects of testosterone and estradiol on the ventral lobe of the rat postate in organ culture]

After organ culture without hormone, the epithelial gland cells of Rat veantral prostate undergo atrophic changes, whereas the interstitial stroma components tend to increase. Estradiol (1-1,000 nM),added to the culture medium, is ineffective. On the contrary, testosterone (1-100 nM) maintains epithelial cells and prevents the increase of interstitial stroma. When estradiol (1-1,000 nM) is combined with a physiological concentration of testosterone (1-4 nM), the epithelial cells are well maintained, but the inhibitory action of testosterone on the stroma is counteracted so that the glandular epithelium and the interstitial stroma are both stimulated. However, when testosterone is used at supraphysiological (10-100 nM) concentrations, estradiol is completely ineffective and the structure of the prostate is identical to the one given by the androgen alone.     

Plasma, testicular, and adrenal cortex levels of androgens in the perinatal period and determination of neonatal hypertestosteronemia in guinea pigs]

The perinatal period is characterized in the male faetus and new-born Guinea-Pig by a prenatal increase in testis testosterone and by a neonatal peak in plasma testosterone. This transient rise in plasma testosterone is testis dependent and light dependent at birth.     

The effect of gonadotropic hormones and the fetal hypophysis on testosterone production by the testis of 18 day mouse fetuses in organ culture]

The production of testosterone (measured by radioimmuno-assay) by the 18-day-old mouse fetal testis may be stimulated specifically by ovine LH (1 ng, p less than 0.005) and HCG in organ culture. A stimulation by FSH is observed only with high doses (10 mug, p less than 0.0005). Prolactin and ACTH have no effect. Age-matched fetal pituitaries increase significantly the testosterone production in the culture medium (p less than 0.0005).     

Demonstration of "hydroxylase" and "epoxide hydrase" activities in preparations of nucleoli isolated from rat liver]

Aryl hydrocarbon hydroxylase (AHH) activity and epoxyde hydrase (EH) activity have been found in Rat liver nucleoli obtained from untreated (C) and methylcholanthrene (MC) pretreated Rats. Electron microscopic observations of nucleolar preparations did not reveal significant contamination either by intact nuclei or by nuclear membranes. Very low but detectable activity of NADPH cytochrome C reductase was found in the nucleoli. Nucleolar preparations revealed little AHH activity (12-18 pmoles/min/mg). AHH was inducible by MC in nuclei but not in nucleoli. The presence of EH in nucleoli was demonstrated with phenanthrene 9,10-oxide (550-620 pmoles/min/mg) and benzopyrene 4,5-oxide (92-116 pmoles/min/mg). These values were lower than those obtained using intact nuclei. The addition of TCPO (10(-4) M) inhibited EH activity.     

Pituitary-testicular relationships in the rat embryo]

LH given to the Rat embryo at the time of hypophysectomy by decapitation (18 days of intrauterine life) will prevent the drop in androgen synthesis which normally ensues. This is regarded as definite proof that androgen synthesis is under pituitary control in the rat embryo at late gestational stages. On the other hand, the decrease in androgen synthesis following testosterone injection to the pregnant female points to the fact that there is a negative feedback of testosterone on pituitary LH secretion.     

Effect of progesterone on male and female sex behavior induced by steroid hormones in adult ovariectomized ewes]

Ovariectomized adult Ewes daily treated with I/M injections of testosterone propionate (10 mg/day) or oestradiol benzoate (200 microgram/day) show male-like sexual behaviour and simultaneously a permanent female receptivity. Additional daily treatment with 100 mg of progresterone results in a rapid decrease in male sexual responses both when Ewes are treated with testosterone and with oestradiol. No effect is observed on the female receptivity. Cyproterone acetate (100 mg/day) given to Ewes in addition to daily injection of testosterone propionate (10 mg/day) has effects similar to those of progesterone. These results show that progesterone has antiandrogen and antioestrogen properties and that this hormone administered at high doses is able to inhibit male activity.     

Increase in serum testosterone in newborn rats]

The changes in serum testosterone and dihydrotestosterone concentrations have been measured in the newborn Rat, before, during and up to 6 hrs after birth. A sudden and transient increase of serum testosterone has been found between 0 and 2 hrs. At 4 hrs, the value returns to that found in the foetus at the end of gestation.     

Androgen levels in the rete testis fluid during sexual development

Summary The concentrations of testosterone (T) and 5-dihydrotestosterone were measured in fluid collected from the rete testis of immature and adult rats. The results indicate that adult levels of T are attained in the seminiferous tubules much earlier than in the peripheral circulation.This work was performed at the Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts, USA and supported by the National Institutes of Health through grants HD12641 and HD12642. We thank Dr B.V. Caldwell for antiserum to testosterone.     

Seasonal plasma testosterone variations in the stone marten]

Plasma testosterone levels change with annual sexual cycle of the stone marten. Very low during the decrease and the quiescence of the testis, it rises during the testis onset and reaches a maximal peak during the co?t period (May to July).     

Demonstration of a specific androgen binding protein (ABP) in the seminal plasma of the ram]

A specific androgen binding protein has been demonstrated in the seminal plasma of adult Ram. This protein binds especially to 5 alpha-DHT and testosterone and much lower to oestradiol-17 beta. Its characteristics such as Ka (in order 10(9) M(-1) at 4 degrees C), relative mobility (Rf) and its specificity are similar to those of the androgen binding protein (ABP) of the Rete Testis Fluid and the epididymal plasma of the Ram. It is probable that this protein secreted from the testis, crosses the epididymis before being secreted in the seminal plasma at the moment of the ejaculation.     

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.     

Inhibition of biological methylations by t,t-farnesylacetone, a constituant of the androgenic gland of the male crab, Carcinus maenas]

t, t-farnesylacetone 1 and hexahydrofarnesylacetone 2 have been previously identified in extracts from the androgenic gland of the male Crab Carcinus maenas. These compounds inhibit in vitro the methylation of E. coli B tRNA and of Calf thymus histones with S-adenosylmethionine methyl-14C as methyl donor and methylases from Crab testis. Rat liver or a 1-adenine methylase from a Mouse plasmocytoma (1 is approximately 200 times more active than 2).     

Effects of S-adenosylmethionine and S-adenosylhomocysteine on in vivo synthesis of noradrenaline and serotonin in different parts of the rat brain]

S-adenosylmethionine (0,1 mg/kg/ip) decreases in vivo, norepinephrine (NE) synthesis and does not affect 5-hydroxytryptamine (5 HT) synthesis in the Rat brain. S-adenosylhomocysteine (7 mg/kg/ip) increases NE synthesis and decreases 5 HT synthesis. Neither nucleoside affects dopamine synthesis.     

Seasonal variations in the nyctohemeral rhythm of plasma testosterone in the European badger Meles meles L

In the badger a seasonal sexual rhythm of the plasma testosterone is observed. There is also a nycthemeral rhythm of the testosterone secretion; during the regressed period of the testis this rhythm is bimodal with testosterone peaks during the light phase of the day; during the active period and "activity rhythm" with many transitorys peaks during the dark phase is added.     

Evolution of testosterone and dihydrotestosterone in plasma, testicle and ovary of the guinea pig throughout fetal life]

High testosterone concentrations were found in the plasma of male fetus at the stage of sexual differentiation. Then the fetal testis is the principal source of circulating testosterone; its action on the Wolffian duct would occur by the systemic pathway. In female fetus, androgens were synthesized by the gonad and the relatively high levels found in the plasma have probably another source.     

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.     

Comparison of estradiol benzoate and dihydrotestosterone propionate with testosterone propionate on the induction of male-like sexual behavior in female sheep ovariectomized as adults]

Daily I/M injections of 200 microgram of oestradiol benzoate induce in female Sheep, ovariectomized as adults, male-like sexual reactions similar to what is obtained with 10 mg testosterone propionate per day. Simultaneously, a permanent female sexual receptivity is observed. Oestradiol benzoate at the dose of 20 microgram/day, and dihydrotestosterone propionate (10 mg/day) are both totally ineffective. The result support the hypothesis of the necessity of the aromatization of testosterone for the action on sexual behaviour.     

Tissue specificity of testosterone fixation: demonstrated by ultrastructural immunocytochemistry after cryoultramicrotomy]

Testosterone can be detected by immunocytochemistry on ultrathin slices obtained by cryoultramicrotomy. Testosterone detected by this method is likely bound on a binding site having a high affinity. In order to study the tissue specificity of this binding, testosterone was tested in Rat pituitary gland, liver and adrenal glands. Immunoreactive testosterone was detected in the gonadotropic cells of the pituitary gland, in the hepatocytes. Testosterone was not detected by immunocytochemistry in the pituitary cells other than the gonadotropic cells and in the cells of the medulla of adrenal glands. These data testify in favour of tissue specificity of the testosterone binding.     

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.