Involvement of the neurosteroid 7α-hydroxypregnenolone in the courtship behavior of the male newt Cynops pyrrhogaster

Possible hormonal interaction for eliciting courtship behavior in the male newt, Cynops pyrrhogaster

“…This compound has been reported to be an androgen receptor antagonist as well (Eil, 1992). Previously, Toyoda et al (2012) reported that the ketoconazole-induced tail vibration behavior is resumed completely following an injection of 7a-OH PREG. Accordingly, we ascribed the suppression of the behavior observed in the present experiment to a decline in the synthesis of a neurosteroid, 7a-OH PREG rather than the suppression of androgen for its receptor binding.…”

“…These results indicate that androgen as well as flutamide acts centrally to influence the expression of the tail vibration behavior. On the other hand, the remaining three hormones such as PRL, AVT and 7a-OH PREG have already been demonstrated to act centrally to induce the tail vibration behavior (Toyoda et al, 2003(Toyoda et al, , 2012. Accordingly, the substances such as antibody against newt PRL receptor, V1 receptor antagonist, flutamide, an androgen receptor antagonist and ketoconazole, an inhibitor of cytochrome P450 steroidogenic enzymes (Kan et al, 1985) were administered intracerebroventricularly to reduce the action of endogenous hormones such as PRL, AVT and androgen or the amount of hormone such as 7a-OH PREG.…”

“…The effective amount of each substance in solution, with the exception of flutamide, had been determined in earlier studies (Toyoda et al, 1993(Toyoda et al, , 2003(Toyoda et al, , 2012.…”

“…In the case of 7a-OH PREG to be supplemented, which was administered intracerebroventricularly, its injection was performed 1 h after the injection of a substance that is to suppress the behavior. When ketoconazole was used for suppressing the behavior, the hormone supplementation was performed 4 h after ketoconazole injection since it's effect becomes conspicuous 6 h after the ICV injection (Toyoda et al, 2012) The final experiment was conducted to compare the activity of enhancing the frequency of the tail vibration behavior between AVT and 7a-OH PREG. To this end, sexually inactive male newts (winter newts) were injected intraperitoneally with 1 IU PRL and 5 lg TP daily for 7 days.…”

“…Endogenous PRL was found to act centrally to bring about the tail-vibrating behavior (Toyoda et al, 1996. Subsequent studies revealed that arginine vasotocin (AVT) enhances the expression of the courtship behavior (Toyoda et al, 2003), and more recently a neurosteroid, 7a-hydroxypregnenolone (7a-OH PREG) has been added to the list of hormones involved in eliciting the courtship behavior (Toyoda et al, 2012).…”