Early paracetamol exposure decreases brain-derived neurotrophic factor (BDNF) in striatum and affects social behaviour and exploration in rats.

The biochemical and behavioral responses to prenatal and early postnatal exposure to paracetamol in rats are not well understood. The effect of daily maternal and early life administration of 5 mg/kg (group P5) or 15 mg/kg paracetamol (group P15) was evaluated in two-month old male rats, relative to control animals receiving tap water (Con). Social behavior and episodic memory were investigated with Social Interaction and Novel Object Recognition (NOR) tests. Quantification of brain-derived neurotrophic factor (BDNF) was determined in prefrontal cortex, hippocampus and striatum using enzyme-linked immunosorbent assay (ELISA). Control animals exhibited a higher total frequency of social interactions and greater frequency of sniffing compared to rats exposed to paracetamol, and we found a statistically significant increase in the occurrence of pinning in paracetamol-treated animals. Rats from the 15 mg/kg group exhibited a greater interest in objects in the NOR test and spent more time exploring objects during the familiarization and choice phases. Biochemical analysis showed significant differences in striatal BDNF between the groups, specifically, a nearly two-fold decrease in striatal BDNF in the paracetamol groups (P5: 6.78 ± 0.60 pg/mg; P15: 6.06 ± 0.46 pg/mg) relative to the control group (Con: 11.33 ± 2.00 pg/mg). These results indicate that paracetamol exposure induces changes in social behaviour and exploration in rats and results in a significant decrease of striatal BDNF.