Hormonal Induction of Male Courtship Behavior in the Japanese Newt, Cynops pyrrhogaster

Prolactin opens the sensitive period for androgen regulation of a larynx-specific myosin heavy chain gene

“…The synergy between androgen and prolactin has been demonstrated in several species affecting both development of secondary sexual characteristics and induction of sexual behavior (Toyoda et al, 1993). During the breeding season of the red-spotted newt, the tail fin of the male grows and the nuptial pads form.…”

Localization of prolactin receptor in the newt brain

“…In Triturus cristatus, the courtship-controlling center has been assumed to be located in the preoptic area (Malacarne and Giacoma 1980). In this study, large numbers of PRLR-like immunoreactivity have been observed in the preoptic area; therefore, this region might be important for exhibiting courtship behavior induced by PRL in combination with androgen (Toyoda et al 1993). …”

“…The localization and function of newt brain PRL are still unclear, but plasma PRL secreted from the anterior pituitary would presumably be more important than brain PRL in the expression of courtship behavior, because plasma PRL levels increase in breeding newts (Mosconi et al 1994) and hypophysectomy suppresses the expression of courtship behavior (Toyoda et al 1993). Thus, PRL transported from the blood into the cerebrospinal fluid via the choroid plexus receptor is considered to play an important role in the expression of courtship behavior, although a possible contribution of PRL transported to the brain through retrograde blood flow by the portal system as reported in mammals (Oliver et al 1977;Porter et al 1978) cannot be excluded.…”

“…In the newt, PRL induces development of sex characters (Dent 1975;Kikuyama et al 1986); migration to water, in which sperm transfer and oviposition take place (Chadwick 1941); spermatogonial cell death (Mazzi et al 1967;Yazawa et al 1999); development of the abdominal gland of the cloaca (Kikuyama et al 1975;Yamamoto et al 1996), which secretes femaleattracting pheromone Yamamoto et al 2000); enhancement of oviducal egg-jelly secretion (Kikuyama et al 1986); enlargement of Mauthner neurons, which facilitate the rapid tail-vibration performed by male newts during courtship (Matsumoto et al 1995(Matsumoto et al , 1997; expression of courtship behavior (Kikuyama et al 1980;Malacarne et al 1982;Toyoda et al 1993). We have previously purified PRL from the newt Cynops pyrrhogaster (Matsuda et al 1990a) and developed a homologous radioimmunoassay (RIA) for newt PRL (Matsuda et al 1990b).…”

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

“…The male then discharges spermatophores, which are captured by the female's cloacal orifice and transported into the cloacal cavity . Long-term research conducted by our group has demonstrated that multiple hormones, including androgen (Toyoda et al, 1993), prolactin (PRL) (Toyoda et al, 1993(Toyoda et al, , 1996(Toyoda et al, , 2005, gonadotropin (GTH) (Toyoda et al, 1993), and arginine vasotocin (AVT) (Toyoda et al, 2003), are involved either directly or indirectly in the expression of this behavior by the breeding red-bellied male newts. This is exemplified by the large increase in plasma concentrations of PRL (Matsuda et al, 1990), GTH (Tanaka et al, 1980), and androgen (Tanaka and Takikawa, 1983) in male newts during the breeding season in comparison to the non-breeding season.…”