科研之友
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摘要
The current study investigated the -aminobutyric acid (GABA) levels and GABA metabolic enzymes (GABA transaminase (GABA(T)) and glutamate decarboxylase (GAD)) activities at 2 and 4 h after treatment, using a high-performance liquid chromatography with ultraviolet detectors and colorimetric assay, in the cerebral cortex of mice treated with 20, 40 or 80 mg/kg -cypermethrin by a single oral gavage, with corn oil as vehicle control. In addition, GABA protein (4 h after treatment), GABA(T) protein (2 h after treatment) and GABA receptors messenger RNA (mRNA) expression were detected by immunohistochemistry, Western blot and real-time quantitative reverse transcriptase polymerase chain reaction, respectively. -Cypermethrin (80 mg/kg) significantly increased GABA levels in the cerebral cortex of mice, at both 2 and 4 h after treatment, compared with the control. Also, GABA immunohistochemistry results suggested that the number of positive granules was increased in the cerebral cortex of mice 4 h after exposure to 80 mg/kg -cypermethrin when compared with the control. Furthermore, the results also showed that GABA(T) activity detected was significantly decreased in the cerebral cortex of mice 2 h after -cypermethrin administration (40 or 80 mg/kg). No significant changes were found in GAD activity, or the expression of GABA(T) protein and GABA(B) receptors mRNA, in the cerebral cortex of mice, except that 80 mg/kg -cypermethrin caused a significant decrease, compared with the vehicle control, in GABA(A) receptors mRNA expression 4 h after administration. These results suggested that attenuated GABA(T) activity induced by -cypermethrin contributed to increased GABA levels in the mouse brain. The downregulated GABA(A) receptors mRNA expression is most likely a downstream event.
