Catecholamines stimulate testicular steroidogenesis in vitro in the Siberian hamster, Phodopus sungorus.

We have examined direct effects of catecholamines on testicular testosterone production in a seasonally breeding species, the Siberian hamster, Phodopus sungorus. Testicular parenchyma from gonadally active long photoperiod (LD)-exposed and gonadally regressed short photoperiod (SD)-exposed animals was incubated for 6 h with norepinephrine, epinephrine, beta-adrenoceptor agonist isoproterenol, or alpha-adrenoreceptor agonist phenylephrine (all at 10 microM), as well as with various concentrations of norepinephrine (10 nM-10 microM), and 10 microM norepinephrine with or without hCG (0.7, 3.1, and 12.5 mIU/ml). In addition, effects of alpha-adrenoreceptor antagonist prazosin and beta-adrenoreceptor antagonist propranolol (50 microM) were tested in the incubations containing 10 microM norepinephrine. In the incubations of testes from both LD and SD Siberian hamsters, norepinephrine was most effective in stimulating testosterone production, followed by epinephrine and phenylephrine, while isoproterenol failed to increase testosterone accumulation. The stimulatory effects of norepinephrine were dose-dependent and were prevented by coincubation with prazosin, but not affected by coincubation with propranolol. In combination with various doses of hCG, norepinephrine failed to stimulate testosterone production above the levels obtained with hCG alone. These data indicate that the testicular receptors mediating the action of catecholamines on testicular steroidogenesis in Phodopus sungorus are of the alpha 1-subtype, a result in accordance with a previous study in the golden hamster. However, the results of the present study are strikingly different from the findings obtained in the golden hamster in terms of the effects of photoperiod on the responsiveness of testicular steroidogenesis to catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated corticosterone levels in transgenic mice expressing human or bovine growth hormone genes.

Ectopic expression of human or bovine growth hormone (GH) genes in 6 lines of transgenic mice was associated with a significant increase in plasma corticosterone levels. Elevated corticosterone levels were detected in both sexes under basal conditions and after ether stress. The adrenal activity of 3 beta-hydroxysteroid dehydrogenase was measured in two of these lines and was found to be significantly increased in transgenic animals. Plasma corticosterone levels in transgenic mice did not correlate with known differences between the various lines in male and female fertility or in the life span.

Histamine affects testicular steroid production in the golden hamster.

Localization of mast cells in the testis and ability of histamine (HA) to stimulate testicular testosterone (T) production in vitro were examined in gonadally active adult golden hamsters, kept under a long daily photoperiod (LD) and in gonadally regressed adult golden hamsters exposed to an inhibitory short photoperiod (SD). In both groups mast cells were present in the capsule of the testes and occasionally in vicinity of intratesticular blood vessels. Histamine stimulated T production in a dose dependent manner in incubations of regressed testes of SD animals, but had no stimulatory effect in the active testes of LD animals. In the incubations of SD testes, the effects of HA were abolished by the H-1 antagonist pyrilamine, but unaffected by the H-2 antagonist cimetidine. In both groups, HA enhanced the stimulatory effects of hCG. These results indicate that HA has steroidogenic activity in the testis and may be a factor involved in the regulation of Leydig cell function.

Histamine affects testicular steroid production in the golden hamster.

Localization of mast cells in the testis and ability of histamine (HA) to stimulate testicular testosterone (T) production in vitro were examined in gonadally active adult golden hamsters, kept under a long daily photoperiod (LD) and in gonadally regressed adult golden hamsters exposed to an inhibitory short photoperiod (SD). In both groups mast cells were present in the capsule of the testes and occasionally in vicinity of intratesticular blood vessels. Histamine stimulated T production in a dose dependent manner in incubations of regressed testes of SD animals, but had no stimulatory effect in the active testes of LD animals. In the incubations of SD testes, the effects of HA were abolished by the H-1 antagonist pyrilamine, but unaffected by the H-2 antagonist cimetidine. In both groups, HA enhanced the stimulatory effects of hCG. These results indicate that HA has steroidogenic activity in the testis and may be a factor involved in the regulation of Leydig cell function.