Yang Ke-chun, Jin Guo-zhang, Wu Jie
Divisions of Neurology, Barrow Neurological Institute, St Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
Acta Pharmacol Sin. 2009 Jun;30(6):740-51. doi: 10.1038/aps.2009.63.
Neuronal nicotinic acetylcholine receptors (nAChRs) are the superfamily of ligand-gated ion channels and widely expressed throughout the central and peripheral nervous systems. nAChRs play crucial roles in modulating a wide range of higher cognitive functions by mediating presynaptic, postsynaptic, and extrasynaptic signaling. Thus far, nine alpha (alpha2-alpha10) and three beta (beta2, beta3, and beta4) subunits have been identified in the CNS, and these subunits assemble to form a diversity of functional nAChRs. Although alpha4beta2- and alpha7-nAChRs are the two major functional nAChR types in the CNS, alpha6*-nAChRs are abundantly expressed in the midbrain dopaminergic (DAergic) system, including mesocorticolimbic and nigrostriatal pathways, and particularly present in presynaptic nerve terminals. Recently, functional and pharmacological profiles of alpha6*-nAChRs have been assessed with the use of alpha6 subunit blockers such as alpha-conotoxin MII and PIA, and also by using alpha6 subunit knockout mice. By modulating DA release in the nucleus accumbens (NAc) and modulating GABA release onto DAergic neurons in the ventral tegmental area (VTA), alpha6*-nAChRs may play important roles in the mediation of nicotine reward and addiction. Furthermore, alpha6*-nAChRs in the nigrostriatal DAergic system may be promising targets for selective preventative treatment of Parkinson's disease (PD). Thus, alpha6*-nAChRs may hold promise for future clinical treatment of human disorders, such as nicotine addiction and PD. In this review, we mainly focus on the recent advances in the understanding of alpha6*-nAChR function, pharmacology and pathophysiology.
神经元烟碱型乙酰胆碱受体(nAChRs)是配体门控离子通道超家族,广泛表达于中枢和外周神经系统。nAChRs通过介导突触前、突触后和突触外信号传导,在调节广泛的高级认知功能中发挥关键作用。迄今为止,已在中枢神经系统中鉴定出9种α(α2-α10)亚基和3种β(β2、β3和β4)亚基,这些亚基组装形成多种功能性nAChRs。虽然α4β2-和α7-nAChRs是中枢神经系统中两种主要的功能性nAChR类型,但α6*-nAChRs在中脑多巴胺能(DAergic)系统中大量表达,包括中脑皮质边缘和黑质纹状体通路,尤其存在于突触前神经末梢。最近,已使用α6亚基阻滞剂如α-芋螺毒素MII和PIA,以及通过使用α6亚基敲除小鼠来评估α6*-nAChRs的功能和药理学特征。通过调节伏隔核(NAc)中的多巴胺释放以及调节腹侧被盖区(VTA)中多巴胺能神经元上的GABA释放,α6*-nAChRs可能在尼古丁奖赏和成瘾的介导中发挥重要作用。此外,黑质纹状体多巴胺能系统中的α6*-nAChRs可能是帕金森病(PD)选择性预防性治疗的有前景的靶点。因此,α6*-nAChRs可能为尼古丁成瘾和PD等人类疾病的未来临床治疗带来希望。在本综述中,我们主要关注对α6*-nAChR功能、药理学和病理生理学理解的最新进展。