INITIAL CHARACTERIZATION OF THE NICOTINIC ACETYLCHOLINE-RECEPTORS IN RAT HIPPOCAMPAL-NEURONS
INITIAL CHARACTERIZATION OF THE NICOTINIC ACETYLCHOLINE-RECEPTORS IN RAT HIPPOCAMPAL-NEURONS
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DOI：
10.3109/10799899109064693
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发表时间：
1991-01-01
期刊：
影响因子：
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通讯作者：
ALBUQUERQUE, EX
中科院分区：
文献类型：
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作者：
ALKONDON, M;ALBUQUERQUE, EX
使用全细胞膜片钳技术，在 Na+-外部、Cs+-内部和名义上不含 Mg2+ 的溶液中，研究了胎鼠（妊娠 17-18 天）海马细胞原代培养物中神经元烟碱乙酰胆碱受体的特性。烟碱激动剂乙酰胆碱、(+)anatoxin-a、(-)和(+)尼古丁都会在海马神经元中诱发内向全细胞电流，这些电流的电压被钳制在接近其静息电位的水平。在第 6 天左右首次检测到对 (+)anatoxin-a 的敏感性，此后反应的强度随着培养天数的增加而增加，直至约 40 天。全细胞电流波形由多个峰值组成，其相对幅度取决于激动剂浓度。这些电流被微摩尔浓度的 d-筒箭毒碱、美加明和二氢-β-赤霉素可逆地阻断。在纳摩尔浓度下，神经元银环蛇毒素、α-银环蛇毒素和 α-眼镜蛇毒素会引起不可逆的电流阻断，但它们不受河豚毒素、阿托品、DL-2-氨基-5-磷酸戊酸、Mg2+ 和 6,7-二硝基喹喔啉-2, 3-二酮的影响。此外，皮摩尔浓度的甲基乌头碱也以可逆的方式阻断电流。 (+)anatoxin-a 和乙酰胆碱引起的电流-电压图显示较大的内向电流和较小的外向电流或没有外向电流。目前的结果表明，大鼠海马神经元中存在内向整流、蛇神经毒素敏感的功能性烟碱乙酰胆碱受体离子通道。
The properties of the neuronal nicotinic acetylcholine receptor in primary cultures of hippocampal cells from fetal rats (17-18 days gestation) were studied using the whole-cell patch-clamp technique in Na+-external, Cs+-internal and nominally Mg2+-free solutions. The nicotinic agonists acetylcholine, (+)anatoxin-a, and (-) and (+)nicotine all evoked inward whole-cell currents in hippocampal neurons that were voltage clamped near their resting potentials. Sensitivity to (+)anatoxin-a was first detected at around day 6, and thereafter the magnitude of the response increased as a function of number of days in culture up to about 40 days. The whole-cell current waveforms consisted of more than one peak whose relative amplitude depended on the agonist concentration. These currents were reversibly blocked by micromolar concentrations of d-tubocurarine, mecamylamine, and dihydro-beta-erythroidine. At nanomolar concentrations, neuronal bungarotoxin, alpha-bungarotoxin and alpha-cobratoxin caused an irreversible blockade of the currents but they were unaffected by tetrodotoxin, atropine, DL-2-amino-5-phosphonovaleric acid, Mg2+, and 6,7-dinitroquinoxaline-2, 3-dione. In addition, the currents were also blocked in a reversible manner by methyllycaconitine at picomolar concentration. The current-voltage plots elicited by both (+)anatoxin-a and acetylcholine revealed larger inward currents and smaller or no outward currents. The present results demonstrate the existence of an inwardly rectifying, snake neurotoxin-sensitive functional nicotinic acetylcholine receptor ion channel in rat hippocampal neurons.