Evidence for regulation of body temperature in rats by dopamine D2 receptor and possible influence of D1 but not D3 and D4 receptors.

The dopamine D(3) receptor agonist PD 128907 decreased body temperature in the rat. The selective dopamine D(3) and D(4) receptor antagonists, A-437203 and L-745,870, respectively, did not prevent this effect. In contrast, PD 128907-induced hypothermia was antagonized by SCH 23390, a selective D(1) receptor antagonist, and by L-741,626, a selective D(2) receptor antagonist. Moreover, the selective D(2) receptor agonist trihydroxy-N-n-propylnoraporphine (TNPA) elicited a robust hypothermia which was prevented by pretreatment with L-741,626 but not by A-437203. In agreement with previous data obtained in D(3) knock-out mice, present results suggest that D(2) rather than D(3) receptors mediate dopamine receptor agonist-induced hypothermia in rats. In addition, it appears that both D(1) and D(2) receptors may be involved in a cooperative manner.