鞘内注射强啡肽A(1-17)对不同功能运动神经元群树突的影响

目的:探讨强啡肽A对大鼠趾长伸肌(EDL,快肌)、比目鱼肌(SOL,慢肌)两种不同功能运动神经元(Mn)群树突的影响。方法:采用脊髓蛛网膜下隙给予强啡肽A,以霍乱毒素B亚单位结合辣根过氧化酶(CB-HRP)逆行标记EDL-Mn、SOL-Mn群,Mesulam-TMB法显示两运动神经元群被标记的树突。结果:与相应对照组比,强啡肽A致一过性后肢瘫大鼠用药后1h,位于腰4~5脊髓节段腹角的EDL-Mn、SOL-Mn群树突的分布范围减小,尤以EDL-Mn群为甚;EDL-Mn平均树突长度比对照缩短59.5%,而SOL-Mn平均树突长度比对照缩短35.6%。永久性后肢瘫大鼠用药后3h,EDL-Mn群仅见胞体和近端树突;与之相比,SOL-Mn群仍保留有较长的树突和较广的分布范围。结论:强啡肽A致一过性后肢瘫大鼠两群运动神经元树突明显受累,且以EDL-Mn群为甚,其差别可能与两群运动神经元所接受强啡肽A信息传入不同有关。

Effect of intrathecal administration of dynorphin A(1-17) on the dendrites of two kinds of motoneurons in rat

Objective:To study the effect of dynorphin A(Dyn) on the dendrites of two kinds of motoneuron(Mn) pools in rat extensor digitorum longus(EDL,fast-twitch) and soleus(SOL,slow-twitch).Methods: Intrathecal administration of Dyn and cholera toxin B subunit conjugated with horseradish peroxidase(CB-HRP) retrograde labeling were mainly used.The dendrites of EDL-Mn or SOL-Mn pools were revealed by Mesulam-TMB and identified by CB-HRP.Results: Compared with the corresponding control,the scopes of dendrites of EDL-Mn and SOL-Mn pools at the level of the fourth and fifth lumbar segments decreased in Dyn-induced transient paralysis rats,especially in EDL-Mn pool.1h after Dyn-treatment,the average dendritic length of Mn in Dyn-induced transient paralysis rats was significantly shorten 59.5% and 35.6% of the corresponding control in EDL-Mn and SOL-Mn respectively.In Dyn-induced irreversible paralysis rats,3h after Dyn-treatment,only the perikarya and proximal dendrites left in EDL-Mn pool.In contrast,the more extensive and longer dendrites were still observed in SOL-Mn pool.Conclusion: The results above indicate that the dendrites of EDL-Mn and SOL-Mn are affected in Dyn-induced transient paralysis rats,especially in EDL-Mn,which may reflect the difference of Dyn inputs to both motoneuron pools.