Tizabi Yousef, Manaye Kebreten F, Smoot Duane T, Taylor Robert E
Department of Pharmacology, College of Medicine, Howard University, Division of Internal Medicine, Howard University Hospital, 520 W Street NW, Washington, DC 20059, USA.
Neurotox Res. 2004;6(4):311-6. doi: 10.1007/BF03033441.
The high incidence of smoking among alcoholics may be partially due to nicotine's ability to counteract some of the adverse effects of ethanol on motor coordination and/or cognitive functions. Neuroprotective effects of nicotine on ethanol-induced toxicity in cerebellar granular cells have been observed. In this study, we sought to determine whether similar protection is observed in neocortical cells and if so, what specific nicotinic receptor subtypes may be mediating the actions of nicotine. Primary cultures of neocortical cells were prepared from 20-day embryos obtained from time-pregnant Sprague-Dawley rats. Cells were cultured for 10 days and were then exposed for 3 days to various concentrations of ethanol with and without pretreatment with nicotine and nicotinic antagonists. Cellular toxicity was evaluated by measuring the lactate dehydrogenase level. Administration of ethanol (10-100 mM) resulted in a dose-dependent toxicity. Pretreatment with nicotine 5-20 microM resulted in a dose-dependent protection against ethanol-induced toxicity. The effects of nicotine were blocked by pretreatment with nicotinic antagonists such as mecamylamine (1-20 microM), dihydro-beta-erythroidine (DHBE) 50 nM-1.0 microM and methyllycaconitine (MLA) 5 nM-1 microM in a dose-dependent manner. Compared to previous studies, higher ethanol concentrations were required to induce toxicity in neocortical vs cerebellar granule cells. Moreover, the effects of nicotine in the neocortical cells were blocked by lower concentrations of MLA, but higher concentrations of DHBE compared to cerebellar cells. Collectively, the results suggest differential sensitivity of various neuronal populations to the toxic effect of ethanol. Furthermore, protective effects of nicotine against alcohol in various regions appear to be mediated by different nicotinic receptor subtypes. The neuroprotective effect of nicotine against ethanol-induced toxicity may be a contributing factor to the high incidence of smoking among alcoholics.
酗酒者中吸烟率高可能部分归因于尼古丁能够抵消乙醇对运动协调和/或认知功能的一些不良影响。已观察到尼古丁对小脑颗粒细胞中乙醇诱导的毒性具有神经保护作用。在本研究中，我们试图确定在新皮质细胞中是否也观察到类似的保护作用，如果是，哪些特定的烟碱受体亚型可能介导尼古丁的作用。从妊娠中期的斯普拉格-道利大鼠获得的20天胚胎中制备新皮质细胞的原代培养物。细胞培养10天，然后在有或没有尼古丁和烟碱拮抗剂预处理的情况下，暴露于各种浓度的乙醇中3天。通过测量乳酸脱氢酶水平评估细胞毒性。给予乙醇（10-100 mM）导致剂量依赖性毒性。用5-20 microM尼古丁预处理导致对乙醇诱导的毒性的剂量依赖性保护。烟碱拮抗剂如美加明（1-20 microM）、二氢β-刺桐碱（DHBE）50 nM-1.0 microM和甲基-lycaconitine（MLA）5 nM-1 microM预处理以剂量依赖性方式阻断尼古丁的作用。与先前的研究相比，新皮质细胞与小脑颗粒细胞相比，诱导毒性需要更高的乙醇浓度。此外，与小脑细胞相比，较低浓度的MLA但较高浓度的DHBE阻断了新皮质细胞中尼古丁的作用。总体而言，结果表明不同神经元群体对乙醇毒性作用的敏感性不同。此外，尼古丁在不同区域对酒精的保护作用似乎由不同的烟碱受体亚型介导。尼古丁对乙醇诱导的毒性的神经保护作用可能是酗酒者中吸烟率高的一个促成因素。
