[Effects of benzo(a)pyrene exposure on the ATPase activity and content of Ca²⁺ in the hippocampus of neonatal SD rats].

OBJECTIVE: To investigate the effect of benzo(α)pyrene on the ATPase activity and content of Ca²⁺ in the hippocampus of neonatal SD rats. METHODS: Sixty male and 60 female 4-days-old neonatal SD rats were randomly divided into 5 groups (n=24): a blank control group, a vehicle control group (peanut oil), 3 benzo(α)pyrene groups (0.02, 0.2 and 2 mg/kg, respectively). SD rats were given benzo(α)pyrene (dissolved in peanut oil) by gavage daily from postnatal day 4 (PND4) to PND20. The nerve reflex, the condition of neuro-muscle development and motion function were examined in the period of treatment. The colorimetric technique was used to detect the activity of Ca²⁺-ATPase and Ca²⁺-Mg²⁺-ATPase in hippocampus after the treatment. The concentration of Ca²⁺ of synapse in the hippocampus of rats was detected by fluorescent labeling. RESULTS: The results from the behavior tests showed that duration of surface reflex latency in rats with medium dose of benzo(α)pyrene was longer compared with that in the control group in PND12. The duration of surface reflex latency in rats with high dose of benzo(α) pyrene is longer in PND 14 and PND 16 compared with that in the control group (P<0.05). Compared with the rats in the control group, the activities of Ca²⁺-Mg²⁺-ATPase and Ca²⁺-ATPase in hippocampus in rats with high dose benzo(α) pyrene were significantly decreased, and the degree in the decrease of Ca²⁺-ATPase activity was dose-dependent (P<0.05). The contents of Ca²⁺ in the hippocampus in rats with medium or high dose of benzo(α) pyrene were significantly increased compared with that in the control group (P<0.05), which showed a dose-dependent manner (P<0.05). CONCLUSION: Benzo(α)pyrene exposure led to the decrease in ATPase activity as well as Ca²⁺ overload of the synapse in the hippocampal tissue, which in turn results in the nerve damage of newborn SD rats.