EFFECTS OF NEONATAL EXPOSURE TO NICOTINE ON ELECTROPHYSIOLOGICAL PARAMETERS IN ADULT RATS

In clinical studies and animal models, there is evidence that nicotine exposure during gestation can result in deficits in cognitive perform ance. The present study examined the effects of two doses of neonatal nicotine exposure on adult brain activity as assessed by the N1 and P3 components of the event-related potential (ERP) and background electr oencephalography (EEG). Nicotine (0 mg, 1 mg/kg/day, 4 mg/kg/day) was administered to neonatal rat pups from postnatal day 4 (PN4) through P N12 with an artificial rearing paradigm; suckled rats served as additi onal control subjects. Nicotine exposure was specifically found to alt er responses of the P3 component of the ERP, recorded in dorsal hippoc ampus, to changes in stimulus parameters. A significant reduction in t he response of the P3A component to the noise tone as compared with th e level of the frequently presented tone was found. A significant redu ction in the response to the noise rone as compared with the level of the infrequently presented tone also was seen in the P3B component. No effects of drug exposure were found on the N1 component in any lead, although artificial rearing produced specific effects on the latency o f the N1 component in cortex. No significant differences among treatme nt groups were found on any of the EEG-dependent variables. Female rat s overall were found to have significantly higher EEG amplitudes than the males, a finding previously reported in our laboratory. However, n o overall effects of gender were found on any ERP component. These stu dies suggest that neonatal nicotine exposure specifically reduces the electrophysiological response of the hippocampus to changes in auditor y stimuli. Additional studies will be necessary to link these P3 ampli tude changes to the effects of nicotine on the developing brain in hum an and animal subjects. (C) 1997 Elsevier Science Inc.