Vasopressin and oxytocin in brain areas of rats with high or low behavioral performance.

Animals were selected from a population of 55 rats which differed significantly in their ability to perform a behavioral task, a foot-shock motivated brightness discrimination (BD). Using highly specific and sensitive radioimmunoassays, the contents of arginine vasopressin (AVP) and oxytocin (OXT) were measured in 5 brain areas and the plasma of these animals. AVP levels in the septum/striatum and posterior pituitary of rats with high performance significantly exceeded those of the low performance group. Compared to the low performance rats, the OXT content of the high performance rats was higher in the septum/striatum, but was lower in the hippocampus. No significant differences between the groups were found in the hypothalamus, motor cortex and the plasma. The results suggest that both AVP and OXT are signals in central pathways involved in information processing. In particular, high endogenous AVP and OXT levels in neurons of the septum/striatum and low OXT levels within hippocampal neurons might be prerequisites for high performance in the conditioned BD reaction.