Effects of sex and chronic neonatal nicotine treatment on Na2+/K+/Cl− co-transporter 1, K+/Cl− co-transporter 2, brain-derived neurotrophic factor, NMDA receptor subunit 2A and NMDA receptor subunit 2B mRNA expression in the postnatal rat hippocampus

► mRNA expression patterns were examined in male and female rat hippocampi at postnatal days 5 and 8. ► The effects of chronic neonatal nicotine exposure on mRNA expression were compared in males and females. ► Males have higher expression of NKCC1, BDNF and NR2A and lower expression of NR2B at postnatal day 5. ► Postnatal nicotine exposure increases KCC2 and BDNF expression in male but not female hippocampus. ► No sex or treatment effect on mRNA expression was observed at postnatal day 8.