Prenatal nicotine exposure alters respiratory long-term facilitation in neonatal rats.

Intermittent hypoxia can evoke persistent increases in ventilation (V (E)) in neonates (i.e. long-term facilitation, LTF) (Julien et al., 2008). Since prenatal nicotine (PN) exposure alters neonatal respiratory control (Fregosi and Pilarski, 2008), we hypothesized that PN would influence LTF of ventilation (V (E)) in neonatal rats. An osmotic minipump delivered nicotine 6 mg/kg per day or saline to pregnant dams. V (E) was assessed in unanesthetized pups via whole body plethysmography at post-natal (P) days 9-11 or 15-17 during baseline (BL, 21% O(2)), hypoxia (10 x 5 min, 5% O(2)) and 30 min post-hypoxia. PN pups had reduced BL V (E) (p<0.05) but greater increases in V (E) during hypoxia (p<0.05). Post-hypoxia V (E) (i.e. LTF) showed an agex treatment interaction (p<0.01) with similar values at P9-11 but enhanced LTF in saline (30+/-8%BL) vs. PN pups (6+/-5%BL; p=0.01) at P15-17. We conclude that the post-natal developmental time course of hypoxia-induced LTF is influenced by PN.