Ultrastructural demonstration of dopamine-beta-hydroxylase immunoreactive nerve terminals on vasopressin neurons in the paraventricular nucleus of the rat by double-labeling immunocytochemistry.

The noradrenergic innervation of vasopressin (VP) neurons in the paraventricular nucleus (PVN) of the rat was studied ultrastructurally by double-labeling immunocytochemistry combining the preembedding peroxidase-antiperoxidase method for dopamine-beta-hydroxylase (DBH) with the post-embedding immunogold staining method for neurophysin II, the carrier protein of VP. DBH-like immunoreactive nerve terminals were found to make synaptic contacts with neurophysin II-like immunoreactive neuronal perikarya and their processes. This provides morphological evidence for noradrenergic control of the release of VP, at the PVN of the rat.