Differential excitatory responses to oxytocin in sub-divisions of the bed nuclei of the stria terminalis.

The lateral dorsal nucleus of the bed nuclei of the stria terminalis (BST-LD) expresses dense oxytocin binding while lower binding is detected in the medial anterior BST (BST-MA) and adjacent ventrolateral septum (VLS). However, in vitro examination of neuronal responses to oxytocin showed that the BST-LD exhibited small, transient responses which desensitized upon repeated challenge. In contrast, the BST-MA and VLS exhibited significantly larger responses with no significant desensitization. This inverse relationship between oxytocin binding density and electrophysiological responsiveness is also seen in the central and medial amygdaloid nuclei, which have respective associations with the lateral and medial divisions of the BST. Thus, excitatory responses to oxytocin vary markedly between BST sub-divisions and may reflect associations within the extended amygdala.