THE INTERACTION BETWEEN PRENATAL STRESS AND NEONATAL HANDLING ON NOCICEPTIVE RESPONSE LATENCIES IN MALE AND FEMALE RATS

Neonatal handling produces physiological and behavioral changes that p ersist into adulthood. These effects are opposite to those resulting f rom prenatal stress (PS). We examined the interaction between PS and h andling on nociception in adult male and female rats. Randomly selecte d pregnant rats were subjected to restraint stress on days 13-17 of ge station for 25 min each day, or left undisturbed. At birth, selected s tressed/nonstressed litters were assigned to be handled. Handling cons isted of 15 min of separation from the dam, once per day, from postnat al days 1-14. At 4 months of age, rats were placed on a 50 degrees C h ot plate, and their latencies to paw lick were recorded. Prenatal stre ss and handling interacted to affect latencies in male rats. Handled ( H)/PS rats had significantly lower paw lick latencies than nonhandled (NH)/PS rats (p < 0.05). However, handling had no effect on the male o ffspring of control dams. Handling elevated paw lick latencies in the female offspring of control dams, an effect that was most pronounced i n diestrous vs. estrous rats. The NH/PS rats showed significantly elev ated latencies compared to NH/NS rats (p < 0.05). These results sugges t that handling effects on nociception are most apparent in rats subje cted to PS; in males at least, these effects would otherwise not be pr esent.