Effect of Toxoplasma gondii infection upon the expressions of brain-derived neurotrophic factor and N-methyl-D-aspirate receptor in rat hippocampus / 中国人兽共患病学报

ABSTRACT

To investigate the effect of Toxoplasma gondii infection upon the expression of brain-derived neurotrophic factor (BDNF) mRNA and N-methyl-D-aspirate receptor (NMDA) subunits NR2A and NR2B,Wistar rats of 4 weeks old were randomly divided into 3 groups with 10 rats in each group in which 2 mL suspensions of T.gondii tachyzoits in the concentrations of 2×10~7/mL and 2×10~5/mL were injected intra-peritoneally to rats in group A and group B respectively, serving as the experimental groups, while 2 mL of sterile physiologic saline was injected intra-peritoneally in group C serving as the control group. Four weeks after injection, the expressions of BDNF mRNA and BDNF protein in the brain tissues were detected by in situ hybridization and immunohistochemical assay and the expressions of NR2A and NR2B immune activity in the hippocampal CA1,CA3 and DG were investigated by using computer-assisted image analysis system. Compared with the control group, the expression of BDNF protein in the hippocampus of the experimental groups was significantly enhanced [(64.27±23.18), (50.39±19.34) vs (44.68±22.74)/mm~2,P＜0.05]. In addition, the increased expressions of BDNF mRNA in the hippocampus of the experimental groups were also demonstrated [(0.13±0.02), (0.12±0.02) vs (0.09±0.01); P＜0.05]. In the expression of the NR2A protein, their expressions in group A and B of rats were significantly lower than that of group C in CA3 (P＜0.05),but there was no significant change in CA1 and DG. In the expression of NR2B protein, the expressions in group A and B were also lower than that of group C in CA1 and CA3, and had no significant change in DG. It is evident that the expressions of BDNF mRNA and BDNF protein in hippocampal tissues were significantly increased following chronic infection with T.gondii, supporting the hypothesis that BDNF may be involved in the intrinsic neuro-protective mechanism.