α-MSH对下丘脑葡萄糖敏感神经元活动的调制作用

α-MSH INFLUENCES THE EXCITABILITY OF GLUCOSENSING NEURONS IN RAT HYPOTHALAMUS

目的观察α-黑色素细胞刺激素(α-MSH)对下丘脑葡萄糖敏感神经元放电活动的影响。方法在麻醉状态下,观察α-MSH对大鼠下丘脑不同核团葡萄糖敏感神经元放电活动的调制作用。结果在下丘脑外侧区共记录到78个神经元,其中有46.15%(36/78)的神经元被鉴定为葡萄糖抑制型(GI)神经元,36个GI神经元中有27个被α-MSH抑制。对12个被α-MSH抑制的GI神经元预先给予MC4R的拮抗剂SHU9119,α-MSH的抑制效应部分被阻断。在腹内侧核共记录到56个神经元,39.28%(22/56)的神经元被鉴定为葡萄糖兴奋型(GE)神经元,22个GE神经元中20个被α-MSH兴奋。对10个被α-MSH兴奋的GE神经元预先给予SHU9119处理后,α-MSH的兴奋效应部分被阻断。在下丘脑室旁核共记录到68个神经元,29.41%(20/68)被鉴定为GI神经元,39.71%(27/68)被鉴定为GE神经元。20个GI神经元中14个被α-MSH抑制,27个GE神经元中24个被α-MSH兴奋。对7个被α-MSH抑制的GI神经元和18个被α-MSH兴奋的GE神经元均预先给予SHU9119,α-MSH效应亦部分被阻断。结论下丘脑的葡萄糖敏感神经元可能是α-MSH参与中枢摄食调控的作用靶点之一。

Objective To observe the effects of α-MSH on glucosensing neurons in rat hypothalamus. Methods Under anesthesia,the regulatory effects of α-MSH on glucosensing neuron activities of rat hypothalamic nuclei were recorded. Results The neuronal activity of 78 neurons in LHA was recorded,of which,46.15%（36/78） were identified as glucose-inhibited（GI） neurons.Of the 36 GI neurons,27 neurons were inhibited by-MSH.Pre-administration of MC4R antagonist SHU9119 to12-MSH-inhibited neurons partly abolished the inhibitory effect of-MSH.The neuronal activity of 56 neurons in VMH was recorded,39.28%（22/56） were identified as glucose-excited（GE） neurons.Of the 22 GE neurons,20 were activated by-MSH.Pre-administration of SHU9119 to 10 GE neurons partly abolished the excitatory effect of-MSH.The neuronal activity of 68 neurons was recorded in the PVN,29.41%（20/68） were identified as GI neurons,and 39.71%（27/68） were identified as GE neurons.Fourteen out of 20 GI neurons were inhibited by-MSH.Twenty-four out of 27 GE neurons were activated by-MSH.Pre-administration of SHU9119 to 7 GI neurons and 18 GE neurons partly abolish the effects exerted on them by-MSH. Conclusion The hypothalamic glucosensing neurons might be the potential targets on which-MSH acts to regulate central control of food intake.