艾灸对D-半乳糖衰老小鼠学习记忆、大脑组织NOS/NO-cGMP信号系统及c-fosmRNA的影响

目的探讨艾灸疗法改善学习记忆的作用机制。方法将72只雄性小鼠随机分为生理组、模型组、艾灸1组、艾灸2组、电针组和尼莫地平组,每组12只。模型组及艾灸组连续42 d于小鼠颈背部皮下注射D-半乳糖,生理组注射等量生理盐水。造模第13天开始干预治疗,艾灸1组灸足三里、悬钟穴,艾灸2组灸关元、百会穴,隔天治疗1次,共治疗15次。采用水迷宫检测学习记忆,检测脑组织匀浆一氧化氮(NO)、一氧化氮合酶(NOS)、环磷酸鸟苷(cGMP)含量,原位杂交检测各组小鼠大脑皮层、海马CA3区c-fosmRNA的表达。结果模型组"潜伏期"较生理组、艾灸1组、艾灸2组、尼莫地平组延长(P<0.01,P<0.05),模型组"原象比"和"垮台次数"较其他各组缩短、降低(P<0.01,P<0.05)。模型组脑组织NO含量、总一氧化氮合酶(TNOS)、诱导型一氧化氮合酶(iNOS)活力较其他5组均显著升高(均P<0.01),模型组脑组织cGMP含量较其他5组均显著降低(均P<0.01)。模型组小鼠大脑皮质、海马CA3区c-fosmRNA表达的神经元密度较其他5组均降低(P<0.01,P<0.05)。结论艾灸疗法可能通过提高cNOS的活力,生成生理活性的NO,增加第二信使cGMP的含量,即通过NO-cGMP信号转导系统,促进大脑皮质、海马CA3区神经元细胞c-fosmRNA表达,维持长时程增强(LTP),改善学习记忆能力。

Effect of Moxibustion on Learning and Memory, and Cerebral NOS/NO-cGMP Signal Transduction System and Expression of C-fos mRNA in D-galactose-Induced Senile Mice

Objective To explore the mechanism of improving action of moxibustion on learning and memory. Methods Seventy-two male mice were randomly allocated to normal, model, moxibustion 1, moxibustion 2, electroacupunctue and Nimodipine groups, 12 mice each. The model and moxibustion groups of mice received nuchal subcutaneous injections of D-galactose for 42 consecutive days. The normal group was injected with an equal volume of normal saline. Treatment was given at 13 days after model making. In moxibustion 1 group, moxibustion was performed on points Zusanli and Xuanzhong and in moxibustion 2 group, on points Guangyuan and Baihui. Treatment was provided once every other day, for a total of 15 times. Leaming and memory were assessed using a water maze. The nitric oxide （NO）, nitric oxide synthase （NOS） and cyclic guanosine monophosphate （cGMP） contents of brain homogenates were measured. The expression of c-fos mRNA in the cerebral cortex and hippocampal CA3 region was examined by in situ hybridization in each group of mice. Results The ＂latency＂ lengthened significantly in the model group compared with the normal, moxibustion l, moxibustion 2 and Nimodipine groups （P〈 0.01,P（0.05）. The targeted quadrant time and the spanning （original） platform frequency decreased in the model group compared with the other groups （P（0.01,P〈 0.05）. Cerebral NO content, total nitric oxide synthase （TNOS） and induced nitric oxide synthase （iNOS） activities increased significantly in the model group compared with the other five groups （P（0.01）. Cerebral GMP content decreased significantly in the model group compared with the other five groups （P（0.01）. The density of c-fos mRNA-expressing neurons in the cerebral cortex and hippocampal CA3 region decreased significantly in the model group of mice compared with the other five groups （P（0.01,P~0.05）. Conclusion Moxibustion can maintain long-term potentiation （LTP） and improve learning ability and memory through increasing cNOS activity to produce bioactive NO and raising second messenger cGMP content, that is, promoting the expression of neuronal c-fos mRNA in the cerebral cortex and hippocampal CA3 region by means of a NO-eGMP signal transduction system.