目的:探讨热灸法的作用机制及最佳的热灸刺激参数。方法:选用SD大鼠15只,微电极胞外记录延髓背侧网状亚核(SRD)神经元活动,观察7种不同温度(40、42、44、46、48、50、52℃)和7种不同圆形面积(直径分别为1.0、1.5、2.0、2.5、3.0、3.5、4.0 cm)组成的不同组合的热刺激对SRD神经元放电活动的影响。刺激部位以"中脘"穴为中心,刺激持续时间为30 s。结果:40℃和42℃的热刺激在任何面积下对SRD神经元均无激活作用;44℃-Φ3.5 cm和44℃-Φ4.0 cm的刺激组合对SRD神经元有明显激活作用;温度达46℃以上后,热刺激面积与SRD神经元的放电活动呈线性相关;48℃-Φ3.0 cm、50℃-Φ3.5 cm、52℃-Φ3.5 cm刺激组合达到SRD神经元放电活动的平台期,在温度不变的条件下,SRD神经元放电不再随刺激面积的增大而增加。结论:伤害性范围内的热刺激可以激活SRD神经元,当热刺激达到一定参数后,SRD神经元的激活反应会出现平台期。
Objective To observe the effect of regional thermal(moxibustion-like) stimulation on discharges of neurons in the medullary subnucleus reticularis dorsalis(SRD) and to study the best thermal stimulation parameters in the rat.Methods Experiments were performed on 15 male Sprague-Dawley rats under anesthesia(10% urethane,1.0-1.5 g/kg).Unit discharges of single neurons in the medullary SRD were recorded extracellularly with glass micropipettes.Thermal stimulation(warm water filled in a glass bottle) with different temperature(40 ℃,42 ℃,44 ℃,46 ℃,48 ℃,50 ℃,52 ℃) and covering different area(diameter: 1.0 cm,1.5 cm,2.0 cm,2.5 cm,3.0 cm,3.5 cm,4.0 cm) was applied to "Zhongwan"(CV 12) region for 30 s.Firing rates of SRD neurons were analyzed by using Power-Lab Chart 5.0.Results When thermal stimulation with temperature of 40 ℃ and 42 ℃ and the stimulated area of 1.0-4.0 cm in diameter was applied to CV 12 region,discharges of the medullary SRD neurons had no obvious changes.When the temperature was increased to 44 ℃and 46 ℃,the electrical activities of SRD neurons were increased linearly along with the increase of the stimulated area of 1.0-4.0 cm in diameter.When the temperature was increased further from 48 ℃ to 52 ℃,the increased electrical activities of SRD neurons peaked at the stimulated area of 3.5 cm in diameter.In addition,thermal stimulation at a temperature of 50 ℃ and an area of 4.0 cm in diameter induced a larger increase of discharges of SRD neurons in comparison with that of 46 ℃ plus an area of 3.5 cm/4.0 cm in diameter(P0.05).No significant differences were found between 50 ℃ and 52 ℃ at any stimulated areas mentioned above(P0.05).Conclusion Noxious thermal(44-52 ℃) stimulation of CV 12 region can activate SRD neuron,which reaches a plateau when the stimulated area is increased to a certain range.