It is well established that vasopressin contributes to the control of the circulation both centrally and peripherally. However, the exact mechanism is still vague. To investigate whether central vasopressin V2 receptors are implicated, nonpeptide and selective V2 antagonist was injected intracerebroventricularly to conscious rats both under baseline physiological conditions and during exposure to acute emotional stress. Cardiovascular variability was also analyzed in rats over-expressing V2 receptors in the paraventricular nucleus of the hypothalamus. Our results show that vasopressin by the...