Kisspeptin has an indispensable role in gonadotropin-releasing hormone/gonadotropin secretion in mammals. In rodents
kisspeptin neurons are located in distinct brain regions
namely the anteroventral periventricular nucleus-periventricular nucleus continuum (AVPV/PeN)
arcuate nucleus (ARC)
and medial amygdala (MeA). Among them
the physiological role of AVPV/PeN kisspeptin neurons in males has not been clarified yet. The present study aims to investigate the acute effects of the olfactory and/or mating stimulus with a female rat on hypothalamic and MeA Kiss1 mRNA expression
plasma luteinizing hormone (LH) and testosterone levels in male rats. Intact male rats were exposed to the following stimuli: exposure to clean bedding; exposure to female-soiled bedding as a female-olfactory stimulus; exposure to female-soiled bedding and mating stimulus with a female rat. The mating stimulus significantly increased the number of the AVPV/PeN Kiss1 mRNA-expressing cells in males within 5 minutes after the exposure
and significantly increased LH and testosterone levels
followed by an increase in male sexual behavior. Whereas
the males exposed to female-soiled bedding showed a moderate increase in LH levels and no significant change in testosterone levels and the number of the AVPV/PeN Kiss1 mRNA-expressing cells. Importantly
none of the stimuli affected the number of Kiss1 mRNA-expressing cells in the ARC and MeA. These results suggest that the mating-induced increase in AVPV/PeN Kiss1 mRNA expression may be
at least partly
involved in stimulating LH and testosterone release
and might consequently ensure male mating behavior. This study would be the first report suggesting that the AVPV/PeN kisspeptin neurons in males may play a physiological role in ensuring male reproductive performance.
