Inhibitory effects of matrine on electrical signals and amino acid neurotransmitters in hippocampal brain slices

摘要

BACKGROUND:Studies on electrical signals of hippocampal brain slices in vivo have shown that matrine inhibits benzylpenicillin sodium-induced activation of neuronal signal transduction. OBJECTIVE:To verify the inhibition effect of matrine on activation of electrical signals in rat brain slices and the role matrine plays in hippocampal amino acid transmitter release. DESIGN,TIME AND SEFFING:The in vitro,neurophysiological,controlled experiment was performed in the Zhejiang Province Key Laboratory of Cardio-cerebrovascular Disease and Nerve System Drugs Appraisement and Chinese Traditional Medicine Screening and Research between July 2003 and May 2004.The in vivo,neuronal,biochemical experiment was performed in the Zhejiang Province Key Laboratory of Chinese Traditional Medicine Quality Standardization from July 2005 to December 2006. MATERIALS:Forty healthy,Sprague Dawley rats,7-8 weeks old,and 120 healthy,ICR mice,5-6 weeks old,were included in this study,irrespective of gender.Matrine powder was provided by the National Institute for the Control of Pharmaceutical and Biological Products,China.Matrine injection was purchased from Zhuhai Biochemical Pharmaceutical Factory,China.Penicillin was bought from Shijiazhuang Pharmaceutical Group Co.,Ltd.,China. METHODS:(1) Rats were randomly assigned to four groups:control,penicillin model,and matrine high-dose and low-dose,with 10 rats in each group.The control group was perfused with artificial cerebrospinal fluid.In the remaining three groups,hippocampal brain slices were perfused with normal artificial cerebrospinal fluid containing 1×10~6 U/L penicillin for the first 10 minutes.The penicillin model group received artificial cerebrospinal fluid for an additional 30 minutes,while the matrine high-dose and low-dose groups received 0.1 g/L and 0.05 g/L matrine,respectively,for an additional 30 minutes.(2) Mice were randomly assigned to four groups(n=30).The matrine high-, medium-,and low-dose groups were separately injected with 58.5,39.0,and 19.5 mg/kg matrine via caudal vein,respectively.No intervention was administered to the normal group. MAIN OUTCOME MEASURES:The field potential value in the CA1 region of penicillin-induced rat hippocampal brain slices was analyzed using the evoked field potential technique;chromatography was utilized to determine y-aminobutyric acid and glutamic acid content in the mouse hippocampus. RESULTS:(1) Both 0.1 g/L and 0.05 g/L matrine reduced the number of evoked field potentials in the penicillin-induced rat hippocampal brain slices(P<0.05 or P<0.01).In addition,0.1 g/L matrine led to a reduction of evoked field potential amplitude(P<0.05).(2) Compared with normal mice, y-aminobutyric levels were dramatically increased at 20 minutes after high-dose matrine treatment (P<0.05).In addition,significantly increased y-aminobutyric acid levels were observed at 40 minutes after medium-and low-dose matrine treatments(P<0.05 or P<0.01).The glutamic acid/y-aminobutyric acid ratio was significantly less at 20 minutes after high-dose matrine treatment compared with the normal mice group(P<0.05). CONCLUSION:Matrine exerts a central inhibitory effect via increased inhibitory neurotransmitter y-aminobutyric acid levels in the hippocampus.