Differential responses in immunoreactive arginine-vasopressin content of microdissected brain regions during passive avoidance behavior.

Immunoreactive arginine-vasopressin (IR-AVP) was measured in various hypothalamic and extrahypothalamic nuclei of male Wistar rats immediately after the 24 h retention test of a passive avoidance response. IR-AVP concentrations in paraventricular, suprachiasmatic and lateral septal nuclei were significantly decreased in comparison with the non-shocked rats, while IR-AVP was increased in the central amygdala nucleus, subfornical organ and locus coeruleus. No significant differences in IR-AVP levels were found in the habenular and periventricular hypothalamic nucleus, organum vasculosum of lamina terminalis and medial and dorsal raphe nucleus.