Protective actions of the 5-HT2A/2C receptor agonist, DOI, on 5-HT1A receptor-mediated inhibition of lordosis behavior.

Sexually receptive proestrous rats were infused bilaterally into the ventromedial nucleus of the hypothalamus (VMN) with 200 ng of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), 1000 or 2000 ng of 5-methoxy-3-(di-n-propylamino) chroman (5-MEO-DPAC), or 1000 or 2000 ng of serotonin (5-HT) plus or minus the 5-HT2A/2C agonist, (2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI). DOI protected against the lordosis-inhibiting effects of 5-HT and each of the 5-HT1A agonists. These results substantiate a prior report that 2000 ng DOI could protect against the lordosis-inhibiting action of 200 ng 8-OH-DPAT and demonstrate that such protection is not unique to a single 5-HT1A agonist. Consequently, these results strengthen evidence that functionally significant interactions occur among 5-HT receptors within the VMN.