SEPTAL VASOPRESSIN MODULATES ANXIETY-RELATED BEHAVIOR IN RATS

Arginine vasopressin (AVP) or its VI receptor antagonist d(CH2)(5)Tyr( Me)AVP was administered directly into the septal brain area of adult m ale rats by means of inverse microdialysis. Immediately after a 30-min dialysis period, during which either approximately 0.25 ng AVP or 5 n g of the V1 antagonist were delivered into the brain tissue, anxiety-r elated behaviour of the animals was measured on an elevated plus-maze apparatus. While synthetic AVP failed to alter plus-maze behaviour com pared to vehicle-treated controls, animals treated with the V1 recepto r antagonist made more entries into (P < 0.01) and spent more time on the open arms (P < 0.05), indicating reduced anxiety. Since administra tion of neither AVP nor the VI antagonist significantly influenced gen eral locomotor activity of the rats on the plus-maze and in an open he ld, these data point towards a critical involvement of intraseptally r eleased AVP in the emotional evaluation of novel situations.