Nucleus accumbens dopamine increases sexual motivation in sexually satiated male rats.

ABSTRACT

RATIONALE The influence of the main dopaminergic brain regions controlling copulation, the medial preoptic area (mPOA) and the nucleus accumbens (NAcc), on male rat sexual behavior expression has not been fully established. OBJECTIVE: This work analyzes the sexual effects of dopamine (DA) receptor activation in the mPOA or the NAcc of sexually active male rats, with an intact (sexually experienced) or a reduced (sexually exhausted) sexual motivation. METHODS: The non-specific DA receptor agonist apomorphine and the D2-like receptor agonist quinpirole were infused into the mPOA or the NAcc of sexually experienced or sexually exhausted male rats and their sexual behavior recorded. RESULTS: DA receptor activation neither in the mPOA nor in the NAcc modified the copulatory behavior of sexually experienced male rats. DA receptor stimulation in the NAcc, but not in the mPOA, reversed the characteristic sexual inhibition of sexually satiated rats, and D2-like receptors were found to participate in this effect. CONCLUSION: The optimal sexual performance of sexually experienced male rats cannot be further improved by DA receptor activation at either brain region. In sexually satiated rats, which are sexually inhibited and have a diminished sexual motivation, NAcc DA receptor stimulation appears to play a key role in their capacity to respond to a motivational significant stimulus, the receptive female, with the participation of D2-like receptors. Activation of DA receptors with the same drug, at the same dose and in the same brain region, produces different effects on copulatory behavior that depend on the animal's sexual motivational state.