Influence of a dopamine agonist (lisuride) on sex-specific behavioural patterns in rats. II. Long-term effects

Intact female and neonatally castrated male rats were treated with the dopamine agonist/serotonin antagonist lisuride during the early postnatal differentiation period of the brain (Day 2-12) or during the peripuberal maturation period (Day 26-40). It was found that early postnatal as well as peripuberal activation of the dopaminergic system in females resulted in masculinized social play-fighting behaviour, and lisuride application as late as peripuberally resulted in permanent masculinization of sexual behaviour. Comparable trends were found after peripuberal androgen administration. On the other hand, the demasculinized social play fighting as well as the sexual behaviour of neonatally castrated males, which is usually bisexual or even predominantly heterotypical, could be normalized--at least in part-by early postnatal or peripuberal lisuride administration. These findings confirm once more our previous reports that neurotransmitters can act directly as organizers of the brain. This holds true not only for the differentiation period but also for the maturation period.