[Effects of perinatal exposure to methylmercury on the structure of hippocampus and cerebellum in young rats].

Objective: To evaluate the effects of perinatal exposure to methylmercury on the structure of hippocampus and cerebellum in young pups.

Methods: Divided the 9 pregnant SD rats into three groups randomly: group I, II and III After exposing the rats of the three groups from day 7 in pregnancy through lactation with methylmercury (the dose were 0, 0.1 and 1mg/(kg x d) respectively), examined the early physiology development and the structure of hippocampus and cerebellum of day-21-offspring rats.

Results: Except for changes in body weight on 21 day, the offspring showed no apparent changes in appearance and physiology. Pyknosis in several neurons and disturbance arrangement of pyramidal cells in CA3 and CA4 region of the hippocampus were observed in hippocampus and cerebellum of the rats in group III under the microscope, while no pathological changes were observed in group II. Testing the positive expression of immunohistochemistry, we found out that the NF expression of hippocampus in II and III groups were lower than group I (F = 7.94, P < 0.01), while that of GFAP were increased significantly (F = 10.10, P < 0.01). NF expression of cerebellum in group III was lower than group II and group I (F = 6.85, P < 0.05). while that of GFAP was higher than the other two groups (F = 6.85, P < 0.05). The ultrastructure changes happened in both II and III groups examined through electron microscope, including irregular form in nucleus of neurons, pyknosis of soma, degeneration of mitochondria, lysis of dendrite and axon, et al.

Conclusion: Perinatal low-level methylmercury exposure affected the ultrastructure and expressions of the neural cells in cerebellum and hippocampus of the young rats.