Maternal nicotine exposure enhances cutaneous axon reflexes in the neonatal rat.

Chronic nicotine exposure enhances axon reflexes in adult rats. Since smoking mothers expose their infants to nicotine, this study investigated whether late gestational and or lactational maternal nicotine exposure affects neonatal axon reflexes. Osmotic pumps, implanted subcutaneously in adult female rats, delivered either nicotine (5 mg kg-1 day-1) or saline. Axon reflex responses of infant progeny, evoked by iontophoresis of 2 mC acetylcholine, were measured by laser Doppler flowmetry. Nicotine-exposed infants showed significantly enhanced axon reflexes during both gestational and lactational nicotine exposure, which recovered after exposure ceased. Controls did not exhibit these changes. Maternal nicotine exposure reversibly sensitized nicotinic cholinoceptors on infant cutaneous sensory nerves, but not muscarinic cholinoceptors on vascular endothelium. This may result from upregulation of cutaneous nicotinic cholinoceptors.