Basic Neurobiology of Addiction
Vasopressin has an hormonal function as an antidiuretic hormone that helps control water balance in the body. It is derived from the posterior pituitary within the HPA axis but also has extrahypothalamic actions in the central nervous system. Vasopressin is distributed widely in the brain outside of the HPA axis, with the highest concentrations in the suprachiasmatic and supraoptic nuclei and substantial levels in the septum and locus coeruleus. Vasopressin neurons innervate the extended amygdala and are derived from cell bodies in the medial bed nucleus of the stria terminalis. The distribution of vasopressin receptors is prominent in the rat’s extended amygdala, with high concentrations in the lateral and supracapsular bed nucleus of the stria terminalis, central nucleus of the amygdala, and nucleus accumbens shell. Vasopressin produces autonomic arousal-promoting effects in brain structures relevant to memory, including the hippocampus. Vasopressin V1b receptor antagonists have been shown to produce anxiolytic-like and antidepressant-like effects in animal models, and such anxiolytic-like actions were shown to be localized to the amygdala (Figure 2.15).