DIFFERENTIAL-EFFECTS OF QUINELORANE AND PERGOLIDE ON BEHAVIOR, BLOOD-PRESSURE, AND BODY-TEMPERATURE OF SPONTANEOUSLY HYPERTENSIVE RATS AND WISTAR-KYOTO RATS

The systemic administration of the dopamine agonists quinelorane or pe rgolide to Wistar-Kyoto rats (WKY) induced a significant increase of l ocomotor activity at higher doses. In spontaneously hypertensive rats, these compounds induced a significant hypoactivity at low doses, but only a modest,and late, increase in locomotor activity at higher doses . Quinelorane was more potent than pergolide on locomotor activity. In WKY and SHR, which had unilateral lesions of the nigrostriatal dopami ne system, quinelorane and pergolide induced similar dose-dependent co ntralateral turning that, in the case of pergolide, was significantly greater in SHR than in WKY. Both quinelorane and pergolide induced yaw ning similarly in WKY and SHR, and quinelorane was more potent than pe rgolide. The intravenous administration of quinelorane induced an imme diate and dose-dependent increase in blood pressure in WKY and SHR, wh ich could be completely prevented by pretreating the rats with the dop amine antagonist haloperidol. Pergolide similarly caused a rise in blo od pressure in WKY and SHR, but its effect could only partially be blo cked by haloperidol. The subcutaneous injection of quinelorane or perg olide induced similar dose-dependent hypothermia in WKY. Pergolide als o caused a decrease of body temperature in SHR, but quinelorane had li ttle effect in this strain. These results show differences in the effe cts of quinelorane and pergolide between various experimental test sit uations and between WKY and SHR. These differences may be related to t he involvement of dopamine receptor subtypes and to the previously des cribed changes in central dopaminergic activity in SHR.