Catecholaminergic and neuropeptide Y-immunoreactive synaptic inputs onto median preoptic nucleus neurons projecting to the ventrolateral medullary catecholaminergic area in the rat

Median preoptic nucleus (POMe) neurons are innervated by catecholaminergic and neuropeptide Y (NPY)-immunoreactive nerve terminals originating from th e catecholamine area of the ventrolateral medulla (VLM). The possibility th at such POMe neurons project to the VLM catecholamine area was investigated in the rat. Immunoelectron microscopy revealed synaptic contacts of tyrosi ne hydroxylase- and NPY-immunoreactive axon terminals onto POMe neurons ret rogradely labeled from the VLM catecholamine area, suggesting the existence of bidirectional connections between these two regions. (C) 1999 Elsevier Science B.V. All rights reserved.