Effect of Fluoride and Arsenic Exposure on Protein Expression of GroupⅠMetabotropic Glutamate Receptors in Hippocampus Tissue in Male Offspring Rat

Objective To measure the protein expressions of group I metabotropic glutamate receptors(mGluRs), including mGluR1α and mGluR5 in hippocampus after exposure to fluoride, arsenic, and combination in male offspring rats.

Methods Specific pathogen free SD rats(n=80) were mated with a 1 : 1 male-to-female ratio. The pregnant rats were randomly assigned to four groups:control, arsenic, fluoride, and combination groups, with 10 rats each. The control rats drank tap water. Rats in the three exposure groups drank water with sodium fluoride(100 mg/L), sodium arsenite(75 mg/L), and sodium fluoride(100 mg/L) plus sodium arsenite(75mg/L) combination from day 0 of pregnancy to postnatal day 21(PND21) of pups. The weaned pups drank the same water as mother rats till postnatal day 42(PND42). The contents of glutamate(Glu) and gamma aminobutyric acid(GABA) in hippocampus of pups were detected by high performance liquid chromatography. The protein expressions of mGluR1α and mGluR5 were detected by Western blot.

Results Compared with the control group, the levels of Glu in hippocampus in the PND21 and PND42 pups and the level of GABA in the PND42 pups of the arsenic group and the combination group were decreased(P < 0.05). Compared with the fluoride group, the level of Glu in hippocampus in the PND42 pups was decreased(P < 0.05). The protein expression of mGluR1α decreased in hippocampus in the PND21 pups in the arsenic group and the combination group as well as in the PND42 pups in the fluoride, arsenic and combination groups(P < 0.05). The protein expression of mGluR5 decreased in hippocampus in the PND21 pups in the fluoride, arsenic, and combination groups and in the PND42 pups in the arsenic and combination groups(P < 0.05). The protein expression of mGluR1α in the PND21 and PND42 pups in the combination group was lower than that in the fluoride group(P < 0.05).

Conclusion Fluoride and arsenic exposure, either single or combined, may down-regulate the protein expression of mGluR1α and mGluR5 in hippocampus of male offspring rat, especially combined exposure.