Objective The present study aimed to test whether exposure to benzo(a)pyrene [B(a)P] affects spatial learning and short-term memory by modulating the expression of the Gria1 and Grin2a glutamate receptor subunit genes in the hippocampus.Methods Thirty-six 21-24-day-old,male rats were randomly assigned into high-,medium-,and low-dose toxin exposure groups (6.25,2.5,and 1 mg/kg,respectively) and a control group,each containing nine rats.The behavioral performance of adult rats exposed to sub-chronic administration of B(a)P was monitored by learning and memory tests (Morris water maze).Real-time PCR assays were used to quantify Gria1 and Grin2a gene expression in the hippocampus.ResultsAt medium and high doses,B(a)P impaired spatial learning performance.The crossing-platform-location frequency and the time spent swimming in the platform area,which both relate to short-term memory,were significantly decreased in B(a)P-treated rats compared with controls.The level of Gria1 mRNA increased 2.6-5.9-fold,and the level of Grin2a mRNA increased 10-14.5-fold,with a greater fold increase associated with higher doses of B(a)P.Conclusion We demonstrated that sub-chronic administration of B(a)P inhibits spatial learning and short-term memory,and increases Gria1 and Grin2a expression in the hippocampus.This suggests a relationship of B(a)P exposure levels with Gria1 and Grin2a expression and impairment of short-term and spatial memory.