Apomorphine induces ejaculation in chronic decerebrate rats.

Chronically maintained supracollicular decerebrate (CD) rats, but not rats with midthoracic (T10) spinal transections (SPI) or neurologically intact controls, displayed erection and ejaculation following systemic administration of the dopamine (DA) agonist, apomorphine (APO). The response was blocked by pretreatment with the DA receptor antagonist, cis-flupentixol. CD rats, like intact controls, failed to display erections or penile cupping in response to the same mechanical stimulation that elicited short-latency responses in SPI rats. The present results demonstrate excitatory and inhibitory mechanisms of relevance to the copulatory behavior of the male rat that are endemic to the caudal brainstem neurally isolated from forebrain influence.