Plasma prostaglandin E2 (PGE2) and sex hormones (progesterone, androgens, and 17-beta-estradiol) were determined in the male crested newt, Triturus carnifex, during the annual sexual cycle. In vivo experiments were carried out to study the effects of PGE2 on plasma sex hormones during prereproduction, reproduction, and postreproduction; contemporaneously, in vitro experiments were performed to study the effects of PGE2 on the testicular release of sex hormones. The effects of one week's captivity on PGE2 and sex hormones was also evaluated. Plasma PGE2 increases in autumn, during the recovery of gonad and secondary sexual characteristics; it peaks in January, at the start of reproduction, and decreases during reproduction to peak again in April, at the end of reproduction. Plasma sex hormones show trends similar to those found in previous studies. In autumn, PGE2 and androgen patterns are positively correlated, whereas the April PGE2 peak coincides with a drop in plasma androgens. In vivo and in vitro experiments suggest the causal relation between PGE2 and androgens. When injected in prereproductive newts or added to cultured testis in this period, PGE2 increases androgen production. An opposite in vivo and in vitro effect is obtained during reproduction. These findings suggest that PGE2 is involved in inducing the autumnal recovery of gonad and secondary sexual characters (through the stimulation of androgen production), and in terminating the breeding processes (through the inhibition of androgen production and/or clearance). Finally, captivity causes a decrease of plasma PGE2, androgens, and estradiol, a phenomenon quite common in captive vertebrates.

PROSTAGLANDIN-E2 AND REPRODUCTION IN THE MALE CRESTED NEWT, TRITURUS-CARNIFEX (LAUR)

GOBBETTI, Anna;ZERANI, Massimo
1992-01-01

Abstract

Plasma prostaglandin E2 (PGE2) and sex hormones (progesterone, androgens, and 17-beta-estradiol) were determined in the male crested newt, Triturus carnifex, during the annual sexual cycle. In vivo experiments were carried out to study the effects of PGE2 on plasma sex hormones during prereproduction, reproduction, and postreproduction; contemporaneously, in vitro experiments were performed to study the effects of PGE2 on the testicular release of sex hormones. The effects of one week's captivity on PGE2 and sex hormones was also evaluated. Plasma PGE2 increases in autumn, during the recovery of gonad and secondary sexual characteristics; it peaks in January, at the start of reproduction, and decreases during reproduction to peak again in April, at the end of reproduction. Plasma sex hormones show trends similar to those found in previous studies. In autumn, PGE2 and androgen patterns are positively correlated, whereas the April PGE2 peak coincides with a drop in plasma androgens. In vivo and in vitro experiments suggest the causal relation between PGE2 and androgens. When injected in prereproductive newts or added to cultured testis in this period, PGE2 increases androgen production. An opposite in vivo and in vitro effect is obtained during reproduction. These findings suggest that PGE2 is involved in inducing the autumnal recovery of gonad and secondary sexual characters (through the stimulation of androgen production), and in terminating the breeding processes (through the inhibition of androgen production and/or clearance). Finally, captivity causes a decrease of plasma PGE2, androgens, and estradiol, a phenomenon quite common in captive vertebrates.
1992
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11581/218788
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