Vasopressin, maternal behavior, and pup well-being

The brain peptide, vasopressin (VP), was studied with respect to its effects on maternal care in rearing natural and cross-fostered pups. Long-Evans (LE) rats synthesize hypothalamic VP; whereas, Brattleboro (DI) rats do not produce this peptide. Long-Evans dams exhibited superior maternal care when compared with DI dams when rearing their own as well as foster pups. This enhanced behavior was evidenced by the higher survival rate of pups reared by LE mothers compared to those reared by DI mothers. Later, when the offspring were subjected to the stress of 23 hours of food restriction each day, LE animals reared by their natural mothers survived for a significantly longer period of time and developed significantly less stomach pathology than DI animals reared by their natural mothers or LE foster mothers. The results demonstrated that the secondary factor of maternal care in the absence of VP was of little consequence in the characteristic difficulties observed in DI offspring.