Objectives: To investigate the effects of Nonylphenol (NP) in pups from dams exposed during gestational and lactational periods on immediate early genes (c-jun, c-fos) in hippocampus and the learning and memory of F1 rats.
Materials and methods: Twenty eight pregnant dams, stratified by pregnancy date, were randomly assigned into 4 groups, which were gavaged with NP at the doses of 50 mg/kg/day, 100 mg/kg/day, 200 mg/kg/day and groundnut oil, respectively. Step-down avoidance test, and learning and memory effects of NP were evaluated on 8-weeks-old pups. The expressions of c-jun and c-fos and the activities of choline acetyltransferase (ChAT) and acetylcholinesterase (AchE) were evaluated in hippocampus of pups.
Results: Compared to the control, reaction time (RT) that pups spent to jump to the platform was longer (P=0.02), the number of errors were higher (P=0.01), and the step-down latency was shorter in the 200 mg/kg/day NP-treated group (P=0.04). Exposure to NP induced a significant reduction in ChAT activity in hippocampus in the 100 (P=0.005) and 200 mg/kg/day NP-treated groups (P=0.002), whereas exposure to 200 mg/kg/day caused a significant increase in AchE activity (P=0.004); a dose-response relationship was revealed between ChAT and AchE activities and NP exposure in the hippocampus of pups (r=-0.821, P=0.01; r=0.757, P=0.04). Exposure to NP in the 100 and 200 mg/kg/day NP-treated groups exhibited an increase in number of c-fos and c-jun positive cells.
Conclusion: Exposure to NP might negatively affect learning and memory ability in F1 rats, possibly due to the alterations in the expression of c-jun and c-fos, and ChAT, AchE activities in hippocampus of pups.
Keywords: Learning and memory; Neurotransmitters; Nonylphenol; Pups.