Intermittent hypoxia can evoke persistent increases in ventilation (over(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 (over(V, ̇)E) in neonatal rats. An osmotic minipump delivered nicotine 6 mg/kg per day or saline to pregnant dams. over(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% O2), hypoxia (10 × 5 min, 5% O2) and 30 min post-hypoxia. PN pups had reduced BL over(V, ̇)E (p < 0.05) but greater increases in over(V, ̇)E during hypoxia (p < 0.05). Post-hypoxia over(V, ̇)E (i.e. LTF) showed an age × 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.
Bibliographical noteFunding Information:
Support for this work was provided by a grant from the James & Esther King Biomedical Research Program. Support was also provided by NIH grant T32HD043730T32 (B.J.D.). The authors thank Dr. Ralph F. Fregosi (University of Arizona) for help with the osmotic pumps and advice regarding the data. We also thank Ms. Heather Carr for help with data collection and analyses.
- Developmental plasticity