Sexual bipotentiality of the olfactory pathway for sexual behavior in goldfish

Abstract

The goldfish Carassius auratus is a gonochoristic fish, but heterotypic sexual behavior can be induced by hormonal treatment in both males and females. Olfaction is essential for gender-typical sexual behavior in both male and female goldfish. Males have a stimulatory olfactory pathway for their sexual behavior. Female sex pheromones elicit male-typical sexual behavior in males. Olfactory blockage by nasal occlusion or olfactory tract section (OTX) stops elicitation of this behavior in males. Females have an inhibitory pathway for their sexual behavior. Female-typical sexual behavior is triggered by prostaglandin (PG). Olfactory blockage by nasal occlusion inhibits the sexual behavior of females. However, OTX stops this inhibition, and PG-injected OTX females resume their typical sexual behavior. In the present study, we examined whether these gender-typical olfactory pathways are heterotypic in goldfish to elucidate their brain bisexuality. Male-typical behavior was induced in females by androgen treatment and exposure to a pheromone; however, as in males, this behavior was not elicited when the females underwent nasal occlusion or OTX. Female-typical behavior was induced in males by PG treatment; nasal occlusion suppressed this behavior in males as it did in females. Following OTX, PG-injected males resumed female-typical behavior, as did PG-injected females. These results indicate that both male and female goldfish possess bisexual olfactory pathways for sexual behavior.