Neonatal paw pricking alters adolescent behavior in a sex-dependent manner and sucrose partially remediates the effects

Abstract

Neonatal exposure to noxious stimuli such as repeated heel lances can cause behavior changes. In the NICU sucrose given prior to procedures attenuates the immediate behavioral response to noxious stimuli but may not ameliorate the long-term consequences, and treatment with 24 % sucrose can brain structure and behavior in adult rodents. We used a rat model to determine whether paw pricks during the neonatal period alter social interaction and/or paw withdrawal thresholds (PWT) in adolescence, and if 7 % sucrose mitigates these effects. One male and one female pup per litter was assigned to each of six experimental groups (no paw prick (control), 1 paw prick (1PP), or 2PP, ± sucrose). Hind paws were pricked once or twice each day between postnatal day (P)3 and P10. Social behavior and PWT were tested in adolescence using the modified social interaction test and von Frey filaments, respectively. Social behavior was altered in the 2PP group; total time interacting was lower in 2PP rats, primarily due to less time sniffing a play partner. Sucrose did not mitigate effects of paw prick but trended to alter social behaviors in males; it decreased time in contact but increased social motivation (movement toward a play partner). PWTs were higher in 2PP animals, this was not altered by sucrose. Thus, rat pups exposed to paw pricks in the neonatal period have some altered behaviors in adolescence. The nature of the behavioral changes is sex-dependent, but sucrose did not mitigate these changes.