Catecholamine-CRF synaptic interaction in a septal bed nucleus: afferents of neurons in the bed nucleus of the stria terminalis

Abstract

Projections of catecholamine neurons to the bed nucleus of the stria terminalis (BST), especially its corticotropin releasing factor (CRF)-producing neurons, are implicated as being major contributors to the neurochemically mediated central regulation of the stress response. The purpose of the present study was to examine in the BST of the rat brain the morphological characteristics of interactions between two neuron populations of the brain, catecholaminergic and CRF neurons. A double-label immunocytochemical, light and electron microscopic technique allowed the demonstration of the synaptic interaction between dopamine (DA, i.e., tyrosine hydroxylase-containing) and norepinephrine (NE, i.e., dopamine-beta-hydroxylase-containing) axons and CRF neurons in the BST. DA terminals formed synapses with dendrites and soma of CRF neurons in the dorsolateral BST. NE terminals formed synapses with dendrites of CRF neurons in the ventrolateral BST. In conclusion, catecholamine afferents can directly affect the contribution of CRF neurons of the BST to an animals response to stress.