Central vasopressin administration failed to influence anxiety behavior after pinealectomy in rats.

Experiments were performed to measure the influence of centrally applied arginine vasopressin (AVP) on anxiety-related behavior in pinealectomized (PE) rats and sham-operated (SO) controls. In the PE animals, microdialysis application of 200 pg AVP into the mediolateral septum, as well as intracerebroventricular administration of 10 ng AVP, failed to influence anxiety-related behavior measured in the elevated plus-maze test. However, in SO animals, the percentage of time spent on the open arms of the elevated plus-maze was found to be higher in both experiments. Pinealectomy alone was without effect in this respect. The results suggest that central AVP may be involved in the modulation of anxiety-related behavior in rats, even though this modulation is dependent on an intact pineal function.