Sorenson E M, Chiappinelli V A
Department of Pharmacology, St. Louis University School of Medicine, Missouri 63104.
Neuron. 1990 Sep;5(3):307-15. doi: 10.1016/0896-6273(90)90167-e.
We examined nicotinic acetylcholine receptors in the avian brain using a combination of autoradiographic and intracellular electrophysiological techniques. We found that the lateral spiriform nucleus (SPL) in the mesencephalon has a very high density of 3H-nicotine binding sites but no detectable 125I-K-bungarotoxin (125I-K-BuTx) or 125I-alpha-bungarotoxin (125I-alpha-BuTx) bindings sites. Intracellular recordings in brain slices revealed that SPL neurons depolarize in response to nicotine and carbachol (in the presence of atropine). These depolarizations were blocked by the classic nicotinic antagonists d-tubocurarine and dihydro-beta-erythroidine. As predicted for nicotinic receptors with a high affinity for nicotine, neither K-BuTx nor alpha-BuTx blocked these nicotinic responses. Thus, although the existence of high-affinity 3H-nicotine binding sites has been known for some time, we now report the in situ detection of a functional nicotinic receptor that has a high affinity for nicotine and is K-BuTx-insensitive.
我们运用放射自显影和细胞内电生理技术相结合的方法，对鸟类大脑中的烟碱型乙酰胆碱受体进行了研究。我们发现，中脑的外侧螺旋状核（SPL）具有非常高的³H-尼古丁结合位点密度，但未检测到¹²⁵I-κ-银环蛇毒素（¹²⁵I-K-BuTx）或¹²⁵I-α-银环蛇毒素（¹²⁵I-α-BuTx）结合位点。脑片的细胞内记录显示，SPL神经元在尼古丁和卡巴胆碱（存在阿托品的情况下）作用下会发生去极化。这些去极化反应被经典的烟碱拮抗剂d-筒箭毒碱和二氢-β-刺桐碱所阻断。正如对尼古丁具有高亲和力的烟碱型受体所预期的那样，K-BuTx和α-BuTx均未阻断这些烟碱反应。因此，尽管高亲和力的³H-尼古丁结合位点的存在已为人所知有一段时间了，但我们现在报告在原位检测到一种对尼古丁具有高亲和力且对K-BuTx不敏感的功能性烟碱型受体。
