Dopamine and sexual function.

The use of the D1/D2 dopamine receptor agonist apomorphine SL for the treatment of erectile dysfunction provides a strong support in favour of a participation of the dopaminergic system in the control of sexual function. However, the exact involvement of dopamine in sexual motivation and in the control of genital arousal in humans is unknown. In contrast, experimental data suggest an implication of dopamine at all these stages of the copulatory behaviour in rodents. The release of dopamine at the level of the nucleus accumbens, which is innervated by the mesolimbic dopaminergic pathway originating in the ventral tegmental area, is positively implicated in the pre-copulatory or appetitive phase in male rats. There is also a permissive role in the copulatory or consumatory phase for dopamine released at the level of the median pre-optic area, which receives projection from the dopaminergic incertohypothalamic pathway within the hypothalamus. It is noteworthy that these participations of the dopaminergic system are not specific to sexual behaviour but rather reflect the more general involvement of dopamine in the regulation of cognitive, integrative and reward processes. Due to its role in the control of locomotor activity, the integrity of the nigrostriatal dopaminergic pathway is also essential for the display of copulatory behaviour. Somehow more specific to sexual function, it is likely that dopamine can trigger penile erection by acting on oxytocinergic neurons located in the paraventricular nucleus of the hypothalamus, and perhaps on the pro-erectile sacral parasympathetic nucleus within the spinal cord. The counterpart of such regulation of the genital arousal by dopamine has not yet been established in females. In conclusion, the central dopaminergic system is a key element of the control of sexual function.