ACh受体在皮质酮引起的大鼠延髓腹外侧区前交感神经元反应中的作用

ROLES OF ACh RECEPTORS IN THE EFFECTS OF CORTICOSTERONE ON PRESYMPATHETIC NEURONS IN THE VENTROLATERAL MEDULLA OF RATS

目的 :研究乙酰胆碱 (ACh)受体在皮质酮 (CORT)对大鼠头端延髓腹外侧区 (RVLM)前交感神经元快速效应中的作用 ,探讨糖皮质激素在交感心血管活动调节中的非基因组机制。方法 :本研究采用细胞外记录和微电泳等方法观察CORT对氨基甲酸乙酯麻醉大鼠RVLM前交感神经元的作用 ,观察分别给予ACh受体拮抗剂阿托品 (ATR)、筒箭毒 (d TC)或六烃季铵 (C6)后CORT对RVLM前交感神经元的影响。结果 :在RVLM共记录到 33个前交感神经元 ,CORT能导致 2 5 (76 % )个前交感神经元快速兴奋 ,且具有剂量依赖性 ,余 8个前交感神经元没有反应 ;其中被CORT兴奋的 10个单位微电泳ATR后神经元的放电明显下降 ,但对CORT导致的兴奋作用没有明显的影响。分别向 7和 6个被CORT兴奋的前交感神经元微电泳d TC和C6后 ,单位放电没有变化 ,同时对CORT导致的兴奋作用无影响。结论 :CORT对RVLM前交感神经元具有快速的兴奋作用 。

Aim: To investigate the roles of acetylcholine (ACh) receptors in the rapid effects of corticosterone(CORT) on the presympathetic neurons in the rostral ventrolateral medulla (RVLM) of rats,and study the non-genomic mechanism of glucocorticoid(GC)in the integration of sympathetic cardiovascular activity. Methods: The effects of microelectrophoresis of CORT on the discharge of the presympathetic neurons in the RVLM were observed by extracellular recording in urethane-anaesthetized rats. The responses of atropine (a blocker for M type of ACh receptor,ATR),d-tubocurarine (a blocker for N 1 type of ACh receptor,d-TC) and hexamethonium (a blocker for N 2 type of ACh receptor,C 6) to the effects of CORT on the presympathetic neurons were investigated respectively. Results: Totally 33 presympathetic neurons in the RVLM were recorded. Among them the firing rate of 25 (76%) presympathetic neurons was increased by microelectrophoresis of CORT. The effects of CORT were also positively correlated with the currents. In the other 8 presympathetic neurons,had was shown no effect after microelectrophoresis of CORT. In 10 presympathetic neurons,which discharge was increased by CORT,microelectrophoresis of ATR decreased the firing rate of these presympathetic neurons (P<0.05),and did not fully block the excitatory effect induced by CORT. In both 7 and 6 presympathetic neurons,application of d-TC and C 6 had no effect on these neurons respectively,and did not fully block the excitatory effect induced by CORT. Conclusion: CORT had rapid excitatory effects on the presympathetic neurons in the RVLM,which effect might be independent on ACh receptors.