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S Dalterio

Publications and source records attributed to S Dalterio.

42 records · Page 3Linked to original sources
PubMed1976

Prostaglandins inhibit testosterone secretion by mouse testes in vitro.

Production of testosterone (T) by decapsulated mouse tests in vitro was significantly inhibited by adding prostaglandin (PG) A1, PGA2 or PGE1 to the incubation medium. Prostaglandin A1 at a concentration of 10(-6)M inhibited T production in this system both in the presence of moderate amounts of hCG (12.5 or 25.0 mIU/ml), and in the absence of gonadotropins. However, in the presence of very high levels of hCG (125.0 mIU/ml), all PGs tested appeared to have had a slight potentiating effect on T production when added in concentrations ranging from 10(-7) to 10(-5)M, and the inhibition of T accumulation in the medium was consistently observed only when the concentration of PGs was increased to 10(-3)M. These results suggest that a direct effect of PGs on testicular steroidogenesis may account for, or contributes to, the decrease in peripheral T levels observed after administration of PGs in vivo.

Animals↗
PubMed1975

Strange females increase plasma testosterone levels in male mice.

Male house mice paired with a normal female for 1 week do not have higher plasma testosterone levels than do males that remain in all-male groups, but paired males have markedly elevated testosterone levels 30 to 60 minutes after the resident female is replaced by another female. Elevation of testosterone levels in these males is similar to that in isolated males paired with a female, does not depend on copulation with the strange female, occurs under housing conditions that permit continuous exposure to the odors of other females and males, and does not occur when the resident female is replaced by another male for 30 to 60 minutes. The elevation thus appears to be a specific endocrine response to an encounter with a strange female. These results, along with previous findings suggesting that strange males affect endocrine function in females, indicate that bisexual encounters are likely to produce endocrine changes in members of both sexes.

Animals↗
PubMed1975

Evidence for episodic secretion of testosterone in laboratory mice.

The concentration of testosterone (T) in the peripheral plasma of laboratory mice is extremely variable. This variability is already evident at 20--25 days of age and is not eliminated by brief or chronic exposure to male or female mice, or by isolation. The variation in T levels in plasma samples collected from the same animals on different occasions is comparable to the variation between individuals bled on a single occasion. The concentration of T in the testis is as variable as that in the peripheral plasma. It is suggested that in the laboratory mouse T is produced and released in an episodic fashion, that elevations in T levels in peripheral plasma of mice are greater than those observed in other species, and that testicular secretory episodes are interspersed with periods of minimal steroidogenic activity.

Aging↗
PubMed1975

Prolactin restores plasma testosterone levels and stimulates testicular growth in hamsters exposed to short day-length.

In male hamsters, light deprivation was reported to reduce both testis weight and prolactin (PRL) levels. Therefore, we decided to examine the effects of PRL on testicular function in hamsters exposed to short day-length. Adult hamsters were exposed to 5 h of light per day to induce gonadal atrophy, and, starting two months later, were injected daily with 300 mug PRL, 20 mug LH or 150 mug FSH daily for 2 1/2 weeks. In animals treated with PRL the concentration of testosterone in peripheral plasma, as well as the weights of the testes and the accessory reproductive glands, were significantly greater than in the controls. Treatment with LH or FSH had no effect on any of the parameters examined. It is suggested that changes in the rate of PRL release may mediate the effects of light on testicular function in the hamster and possibly, in other species.

Animals↗