ATTENUATION OF THE LORDOSIS-INHIBITING EFFECTS OF 8-OH-DPAT BY TFMPP AND QUIPAZINE

Regularly cycling, proestrous female rats received infusions of 200 ng of the serotonin (5-HT) 1A receptor agonist, (+/-) 8-hydroxy 2-(di-n- propylamino) tetralin-HBr (8-OH-DPAT), or 200 ng 8-OH-DPAT and 1000 or 2000 ng of N-(3-trifluoro-methylphenyl) piperazine hydrochloride (TFM PP) or 2-(1-piperazinyl) quinoline dimaleate (quipazine). Infusions we re made bilaterally into the ventromedial nucleus of the hypothalamus (VMN). Animals receiving 200 ng 8-OH-DPAT exhibited a decline in lordo sis behavior following infusion. Rats receiving 8-OH-DPAT and 1000 or 2000 ng quipazine or TFMPP were protected from the lordosis-inhibiting effects of 8-OH-DPAT, alone. Although both quipazine and TFMPP act on multiple 5-HT receptors, they overlap in their agonist action at 5-HT 2 receptors. Consequently, these results provide further evidence supp orting the contention that within the VMN, both 5-HT2, and 5-HT2 recep tor subtypes contribute to the modulation of lordosis behavior in the female rat. The data are discussed in terms of the relative potency of 5-HT at 5-HT receptors mediating inhibition and facilitation of lordo sis behavior. (C) 1998 Published by Elsevier Science B.V. All rights r eserved.