Model of emotional stress in rats

A new experimental rat model for suppression of release of arginine vasopressin (AVP) was evaluated. Release of AVP is potentiated by physiologic stimuli, but is suppressed by emotional stress. Rats were exposed to the aggressive behavior of other rats injected with 6-hydroxydopamine hydrochloride (6-OHDA) in both lateral ventricles and subjected to a pain stimulus applied to the tail. To ascertain whether emotional stress is induced by use of this method, plasma corticosterone, glucose, and AVP concentrations were measured in the stressed group of rats (n = 8) placed near a group of aggressive (fighting) rats. Characteristic changes in behavior, significant increases in plasma corticosterone and glucose values, and lack of increase in plasma AVP concentration in stressed rats confirmed that they experienced emotional stress. This new model meets the experimental requirements for suppression of AVP release in rats.