Central control of penile erection

Recent work on the central nervous system control of penile erection is reviewed. Penile erection is completely dependent on commands from the central nervous system. Clinical experience and experimental studies clearly demonstrate that systems within the spinal cord are fully capable of generating penile erection. Spinal erectile centers may he activated by genital afferents or by descending commands from higher CNS sites. An important inhibitory pathway from the nucleus paragigantocellularis has been demon-strated. The inhibition of spinal sexual responses is mediated by the neurotransmitter serotonin. The medial preoptic region has been demonstrated to be crucially involved in sexual behavior. It is likely that it participates in the integration of hormonal and sensory cues necessary for sexual behavior. The medial amygdala and paraventricular nucleus of the hypothalamus have also been shown to play key roles. Future CNS research may lead to new therapeutic approaches as well as the avoidance of untoward sexual side effects from centrally acting drugs.