Effect of subchronic benzo [a]pyrene exposure on the synaptic plasticity of hippocampus in SD rats

Objective To explore the effects of subchronic benzo[a]pyrene( B[a]P) exposure on learning and memory ability,the expression of protein kinase C( PKC),N-methyl-D-aspartate receptor( NMDAR),and Calmodulin-dependent protein kinase Ⅱ( Ca MKⅡ) in rats. Methods Fifty specific pathogen free healthy male SD rats were randomly divided into 5 groups: a blank control group,a solvent control group,a low-,a medium- and a high-dose groups,with 10 rats in each group. Blank control group was not treated; the other 4 groups were treated with 0. 00,1. 00,2. 50 and 6. 25 mg / kg body weight of B[a]P in olive oil respectively by intraperitoneal injection every other day for 60 days. Morris water maze test was used to evaluate the learning and memory ability of rats,the relative expression levels of PKC,NMDAR and Ca MKⅡwere detected by Western-blot. Results Morris water maze test showed that there were interactive effects between B[a]P exposure doses and exposure time on escape latency( P 0. 01). The first time to go through the platform in medium-dose group was longer than those of the blank control group,solvent control group and low-dose group( P 0. 05),while the time spent in the target quadrant was shorter than that of the blank control group( P 0. 05); the first time to go through the platform was longer in the high-dose group compared with those of the rest 4 groups( P 0. 05),while the time spent in the target quadrant was shorter than those of the blank control group,solvent control group and low-dose group( P 0. 05).The relative expression levels of NMDAR and Ca MKⅡin low- and medium-dose groups were significantly lower than those in blank control group( P 0. 05); the relative expression levels of PKC and Ca MKⅡin high-dose group were lower than those of the other 4 groups( P 0. 05),the relative expression level of NMDAR of high-dose group was lower than those of the blank control group,solvent control group and low-dose group( P 0. 05). Conclusion The damage of learning and memory ability in rats induced by subchronic B[a]P exposure may be related to the decreased expression of PKC,NMDAR and Ca MKⅡ,which could further influence the synaptic plasticity.