Neuronal interaction between VIP and vasopressin neurones in the rat suprachiasmatic nucleus.

Synaptic interaction between VIP-like immunoreactive (VIP-LI) and vasopressin-like immunoreactive (VASO-LI) neurones both of which are main neuronal components in the SCN was investigated using double labelling immunoelectron microscopy. VIP-LI axons were identified as having synaptic contacts with VASO-LI neuronal perikarya and dendrites. VIP-LI axons also formed synapses on non-immunoreactive dendrites or dendritic spines. In addition to the above findings, VIP-LI neuronal elements also formed synaptic contacts with other VIP immunoreactive structures.