Flores C M, DeCamp R M, Kilo S, Rogers S W, Hargreaves K M
Department of Restorative Sciences, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Neurosci. 1996 Dec 15;16(24):7892-901. doi: 10.1523/JNEUROSCI.16-24-07892.1996.
The identification of a family of neuronal nicotinic receptor subunit genes establishes the potential for multiple subtypes with diverse physiological functions. Virtually all of the high affinity nicotinic receptors measured to date in the rodent CNS are composed of alpha4 and beta2 subunits only. However, the demonstration of other subunit transcripts in a variety of central and peripheral nervous tissues suggests a greater degree of receptor subtype heterogeneity than so far has been elucidated. The purpose of the present studies was to determine at the mRNA and protein levels which neuronal nicotinic receptor subunits are expressed by sensory neurons of the rat trigeminal ganglion and in what combinations these gene products associate to form neuronal nicotinic receptor subtypes in this tissue. Radioreceptor binding analysis indicated that in the adult rat trigeminal ganglion there exist at least two nicotinic receptor binding sites with differing affinities for [3H]-epibatidine. In situ hybridization histochemical studies revealed the existence of mRNA encoding the alpha3, alpha4, alpha5, beta2, and beta4 subunits, but not the alpha2 subunit. Immunoprecipitation with subunit-specific antisera demonstrated that each of the subunits present in the ganglion at the mRNA level is a constituent of nicotinic receptors capable of binding 3H-epibatidine. Various applications of these approaches yielded strong evidence that, in addition to alpha4beta2, which is thought to be the predominant neuronal nicotinic receptor subtype in the rodent CNS, trigeminal sensory neurons express as the principal subtype alpha3beta4, which has not been demonstrated previously in mammalian nervous tissue.
一类神经元烟碱样受体亚基基因的鉴定表明，可能存在具有多种生理功能的多种亚型。实际上，迄今为止在啮齿动物中枢神经系统中检测到的所有高亲和力烟碱样受体仅由α4和β2亚基组成。然而，在各种中枢和外周神经组织中其他亚基转录本的证实表明，受体亚型的异质性程度比迄今所阐明的要高。本研究的目的是在mRNA和蛋白质水平上确定大鼠三叉神经节感觉神经元表达哪些神经元烟碱样受体亚基，以及这些基因产物以何种组合在该组织中形成神经元烟碱样受体亚型。放射受体结合分析表明，成年大鼠三叉神经节中存在至少两个对[3H] - 埃博霉素具有不同亲和力的烟碱样受体结合位点。原位杂交组织化学研究显示存在编码α3、α4、α5、β2和β4亚基的mRNA，但不存在α2亚基的mRNA。用亚基特异性抗血清进行免疫沉淀表明，神经节中mRNA水平上存在的每个亚基都是能够结合3H - 埃博霉素的烟碱样受体的组成部分。这些方法的各种应用产生了强有力的证据，表明除了被认为是啮齿动物中枢神经系统中主要的神经元烟碱样受体亚型的α4β2之外，三叉神经感觉神经元还表达α3β4作为主要亚型，这在哺乳动物神经组织中以前尚未得到证实。
