新霉素抑制PC12细胞烟碱受体介导的反应

Neomycin inhibits nicotinic receptor-mediated response in pheochromocytoma (PC12)cells

新霉素是一种氨基甙类抗生素 ,在细胞水平可以抑制磷脂酶C介导的信号转导系统。本研究采用全细胞膜片钳技术 ,以大鼠肾上腺嗜铬细胞瘤细胞 (PC12 )为标本 ,观察了新霉素对乙酰胆碱诱发电流 (IACh)的影响。药理学鉴定表明 ,PC12细胞上的IACh是通过ACh激动烟碱受体引起的。钳制电压为 - 80mV时 ,ACh (30μmol/L)诱发一内向电流 ;细胞外同时给予新霉素 (0 0 1～ 1mmol/L)和ACh (30 μmol/L) ,可显著抑制IACh峰值。此抑制作用迅速、可逆 ,呈浓度依赖性。用新霉素预处理细胞 3～ 8min不影响其对IACh的抑制作用。用外源性蛋白激酶C (PKC)激动剂激活PKC ,同样可抑制IACh,而细胞内透析PKC抑制剂 (PKCI 19 31,0 1～ 5 μmol/L)不影响新霉素对IACh的抑制作用。以上结果提示 ,新霉素对PC12细胞的IACh有抑制作用 。

Neomycin is one of the aminoglycoside antibiotics, and on the cellular level it inhibits phospholipase C. The effects of neomycin on the acetylcholine (ACh) induced current ( I ACh ) were studied in pheochromocytoma (PC12) cells by using the whole cell clamp technique. The I ACh on PC12 cells proved to be generated through activation of the neuronal nicotinic receptor. ACh (30 μmol/L) induced an inward current at a holding potential of -80 mV. When the cells were applied with neomycin (0 01～1 mmol/L) and ACh (30 μmol/L) simultaneously, an inhibitory effect of neomycin on the peak of I ACh was observed. This effect was fast, reversible and concentration dependent. Pretreatment with neomycin for 3～8 min had no influence on its inhibitory effect. Activation of protein kinase C by using an exogenous activator exerted an inhibitory action on I ACh . However, intracellular dialysis with a PKC inhibitor (PKCI 19 31, 0 1～5 μmol/L) did not affect the inhibitory effect of neomycin. The results obtained suggest that neomycin exerts an inhibitory effect on I ACh without involvement of the blockage of phospholipase C.