Localization of nicotinic receptor subunit mRNAs in monkey brain by in situ hybridization

Nicotinic receptors are implicated in memory, learning, locomotor activity, and addiction. Identification of the specific receptor subtypes that media te these behaviors is essential for understanding their role in central ner vous system (CNS) function. Although expression of nicotinic receptor trans cript has been studied in rodent brain, their localization in the monkey CN S, which may be a better model for the human brain, is not yet known. We th erefore investigated the distribution of alpha 4, alpha 6, alpha 7, beta 2, beta 3, and beta 4 receptors subunit mRNAs in the monkey brain by using in situ hybridization. alpha 4 and alpha 7 mRNAs were very widely expressed, with a substantial degree of overlap in their distribution, except for the reticular nucleus of the thalamus in which alpha 7 mRNA was much more promi nently expressed. beta 2 and beta 4 mRNA were also widely distributed, alth ough beta 4 was more prominently localized in thalamic nuclei than beta 2. The distribution of alpha 6 and beta 3 mRNA was very distinct from that of the other transcripts, being restricted to catecholaminergic nuclei, the ce rebellum, and a few other areas. Although there were similarities in distri bution of the nicotinic receptor subunit mRNAs in monkey and rodent brain, there were prominent differences in areas such as the caudate, putamen, loc us coeruleus, medial habenula, and cerebellum. In fact, the distribution of alpha 4 and alpha 7 mRNAs in the monkey caudate and putamen was more simil ar to that reported in the human than rodent brain. These findings have imp lications for the development of drug therapies for neurological disorders, such as Alzheimer's and Parkinson's disease, in which nicotinic receptors are decreased. J. Comp. Neurol. 425:58-69, 2000. (C) 2000 Wiley-Liss, Inc.