Potentiation of D- and L-amphetamine effects on copulatory behavior in female rats by treatment with alpha-adrenoreceptor blocking drugs.

The influence of noradrenergic mechanisms on the effects of D- and L-amphetamine on lordosis behavior and stereotype activity was studied in ovariectomized estrogen + progesterone treated rats. Phenoxybenzamine, phentolamine and prazosin, which all block alpha-adrenergic receptors potentiated the inhibitory effect of D-amphetamine on lordosis behavior. Phenoxybenzamine and prazosin also potentiated the effect of L-amphetamine, while phentolamine did not increase the effect. No augmented effect of D- or L-amphetamine was obtained on stereotype activity after pretreatment with phenoxybenzamine or phentolamine. L-propranolol, which blocks beta-adrenergic receptors and pimozide, a dopamine receptor blocker did not influence the effect of D- or L-amphetamine on lordosis behavior. Clonidine an alpha-receptor stimulant drug inhibited lordosis response in estrogen treated rats. This is probably due to a presynaptic effect, decreasing the release of NA from nerve terminals. The possibility that D- and L-amphetamine activates a NA system which influences lordosis behavior either by a direct facilitation or by decreasing the activity of an inhibitory serotonergic system is discussed.