Influence of reserpine administration on neuropeptide Y immunoreactivity in the locus coeruleus and caudate-putamen nucleus of the rat brain.

The effects of treatment with reserpine (10 mg/kg, i.p.) a monoamine depleting agent, on neuropeptide Y immunoreactivity were studied immunohistochemically in neurons of two rat brain structures: locus coeruleus and caudate-putamen nucleus. It was found that reserpine after 24 h increased neuropeptide Y immunoreactivity level but no significant changes were observed 4 and 72 h or 5 days after the injection. The results indicate that despite the known co-existence of neuropeptide Y and noradrenaline in some neurons of the locus coeruleus no concomitant decrease in neuropeptide Y immunoreactivity level was found after reserpine when noradrenaline was depleted from nerve cell bodies and terminals. The increase in neuropeptide Y immunoreactivity observed 24 h after reserpine injection may suggest that the neuropeptide Y-containing neuronal systems of the locus coeruleus and caudate-putamen nucleus are controlled by monoaminergic afferents.