Differential effects of quinelorane and pergolide on behaviour, blood pressure, and body temperature of spontaneously hypertensive rats and Wistar-Kyoto rats.

The systemic administration of the dopamine agonists quinelorane or pergolide to Wistar-Kyoto rats (WKY) induced a significant increase of locomotor 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 dopamine system, quinelorane and pergolide induced similar dose-dependent contralateral turning that, in the case of pergolide, was significantly greater in SHR than in WKY. Both quinelorane and pergolide induced yawning similarly in WKY and SHR, and quinelorane was more potent than pergolide. The intravenous administration of quinelorane induced an immediate and dose-dependent increase in blood pressure in WKY and SHR, which could be completely prevented by pretreating the rats with the dopamine antagonist haloperidol. Pergolide similarly caused a rise in blood pressure in WKY and SHR, but its effect could only partially be blocked by haloperidol. The subcutaneous injection of quinelorane or pergolide induced similar dose-dependent hypothermia in WKY. Pergolide also caused a decrease of body temperature in SHR, but quinelorane had little effect in this strain. These results show differences in the effects of quinelorane and pergolide between various experimental test situations and between WKY and SHR. These differences may be related to the involvement of dopamine receptor subtypes and to the previously described changes in central dopaminergic activity in SHR.