Effects of oxytocin, des-glycinamide-oxytocin and anti-oxytocin serum on the alpha-MPT-induced disappearance of catecholamines in the rat brain.

Oxytocin (OXT) attenuates memory processes and endogenous OXT might be regarded as an amnesic neuropeptide. In this study, the mode of action of OXT on brain catecholaminergic neurotransmission has been analyzed. Peripheral injection of OXT facilitated the alpha-MPT-induced disappearance of noradrenaline (NA) in the mesencephalon. Dopamine (DA) disappearance was inhibited in the mesencephalon and facilitated in the striatum. The accelerated striatal DA disappearance was not observed if the peptide was given together with alpha-MPT, but only if OXT was injected after alpha-MPT treatment. Intraventricular injection of OXT or des-glycinamide-oxytocin (DG-OXT) caused a decrease in the DA disappearance in the mesencephalon, whereas central administration of anti-oxytocin serum (anti-OXT) accelerated the DA disappearance in the same region. The data raise the possibility that DA utilization in the mesencephalon may be correlated with the influence of OXT on CNS processes.