Facilitation of lordosis behavior by clonidine in female guinea pigs.

Lordosis behavior was induced in previously unreceptive, ovariectomized estrogen-primed female guinea pigs by administration of the noradrenergic agonist clonidine. Clonidine also enhanced lordosis responding in females that were weakly receptive after estrogen priming. Unlike progesterone, the lordosis-facilitating effect of clonidine was not accompanied by a subsequent refractory period. Clonidine had a weak lordosis facilitatory effect when administered during the decline in receptivity to estrogen plus progesterone-primed animals and failed to induce lordosis when administered during the refractory period.