Sun Yunguang, Zhou Zhijun, Hu Yunping, Chen Jia, Jin Taiyi
School of Public Health, Fudan University, Shanghai 200032, China.
Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi. 2002 Aug;20(4):293-5.
To study the acute effects of dimethoate on the muscarinic-receptors(M1, M2) in the brain of rats.
24 Sprague-Dawley rats were divided into 4 groups randomly. They were administered subcutaneously with 0, 25, 50, 100 mg/kg dimethoate, respectively. Brains were removed after 48 hours of administration. Radioligand binding assay was used to determine the density and affinity of M1 and M2 receptors.
Rats in the treated group showed low density of M1 and M2 receptors compared with the control rats. The brain M1 receptor density of the rats in the highest dosage group was significantly lower than that in the control group while brain M2 receptors density had a decrease trend with increasing dosage, but the difference showed no significance. However, there were no differences of the affinity of both M1 and M2 among different treated groups. Correlation analysis showed there is positive relationship between cholinesterase activity and density of M1 receptors(r = 0.583, P < 0.01).
M1 and M2 receptors density decreased with the increasing dosage of dimethoate. It is suggested that the alleviating of cholinergic symptoms may be due to the decrease of M1 and M2 receptors in rat brain.
研究乐果对大鼠脑内毒蕈碱受体（M1、M2）的急性影响。
将24只Sprague-Dawley大鼠随机分为4组。分别皮下注射0、25、50、100mg/kg乐果。给药48小时后取出大脑。采用放射性配体结合法测定M1和M2受体的密度及亲和力。
与对照组大鼠相比，给药组大鼠的M1和M2受体密度降低。最高剂量组大鼠脑M1受体密度显著低于对照组，而脑M2受体密度随剂量增加呈下降趋势，但差异无统计学意义。然而，不同给药组间M1和M2的亲和力均无差异。相关性分析显示胆碱酯酶活性与M1受体密度呈正相关（r = 0.583，P < 0.01）。
M1和M2受体密度随乐果剂量增加而降低。提示大鼠脑内M1和M2受体减少可能是胆碱能症状减轻的原因。
