Improved behavioral performance of rats after pre- and postnatal administration of vasopressin

In two separate and independent experimental series it was studied, whether 8-arginine-vasopressin (AVP) or 8-lysine-vasopressin (LVP) administered daily in microgram amounts to pregnant rats, and/or to their offspring postnatally for 30 days, induce alterations that can be registered by a behavioral test. The realization of the test used, a foot-shock motivated brightness discrimination (BD) reaction, includes learning and memory processes. There is one general result of the two experimental series, which include 263 rats divided up in different combinations of pretreatment. Vasopressin (VP), AVP or LVP, pre- and postnatally administered, induces a significantly improved BD performance of approximately 40%, compared to the control groups. The improvement is detectable in different ages of the offspring, in females as well as in males. A smaller though also significant improvement was observed when AVP or LVP was injected only postnatally. The critical period in which the peptides are able to induce the alterations measured probably includes prenatal and postnatal periods in the lives of the rats. What molecular interactions actually underly the improved behavioral performance remain to be clarified.