THE EFFECT OF THE DOPAMINE AGONIST, APOMORPHINE, ON REGIONAL CEREBRALBLOOD-FLOW IN NORMAL VOLUNTEERS

Apomorphine, a non-selective dopamine agonist, has been used as a phar macological probe for investigating central dopaminergic neurotransmis sion in psychiatric illness. In this study repeated measurements of re gional cerebral blood flow (rCBF) were made in normal volunteers befor e, and after, the administration of apomorphine (5 or 10 mug/kg), or p lacebo. The difference in rCBF, before and after drug (apomorphine ver sus placebo), was used to identify brain areas affected by apomorphine . Compared to placebo, both doses of apomorphine increased blood flow in the anterior cingulate cortex. Apomorphine 10 mug/kg also increased prefrontal rCBF (right > left). No decreases in rCBF were noted follo wing either dose of apomorphine. Apomorphine-induced increases of ante rior cingulate blood flow might serve as an in vivo index of central d opamine function. Such an approach would complement established neuroe ndocrine challenge paradigms for investigating central dopamine neurot ransmission in psychiatric illness.