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Regional and cellular distribution of serotonin 5‐hydroxytryptamine 2a receptor mRNA in the nucleus accumbens, olfactory tubercle, and caudate putamen of the rat
Author(s) -
Mijnster M. Janneke,
Raimundo Anabela G.V.,
Koskuba Katerina,
Klop Henri,
Docter Gerrit J.,
Groenewegen Henk J.,
Voorn Pieter
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19971208)389:1<1::aid-cne1>3.0.co;2-6
Subject(s) - olfactory tubercle , biology , nucleus accumbens , putamen , caudate nucleus , neuroscience , serotonin , receptor , central nervous system , genetics
This paper describes the regional and cellular distribution of serotonin 5‐hydroxytryptamine 2a (5‐HT 2a ) receptor mRNA in (sub)regions of the rat striatum by using in situ hybridization. Our results indicate that 5‐HT 2a mRNA is distributed heterogeneously in this brain region. Regional densitometry of autoradiograms from striatal sections hybridized with isotope‐labeled cRNA probes showed that mRNA levels were highest in the olfactory tubercle, lower in the nucleus accumbens, and lowest in the caudate‐putamen. In the nucleus accumbens, the average mRNA levels in the shell were higher than those in the core. These data suggest a particular relevance for the 5‐HT 2a receptor for olfactory tubercle‐ and shell‐related functions. Therefore, in the nucleus accumbens and the olfactory tubercle, the cellular localization of 5‐HT 2a mRNA was investigated by determining the colocalization of 5‐HT 2a mRNA with enkephalin mRNA or dynorphin mRNA. 5‐HT 2a mRNA was found in enkephalinergic as well as dynorphinergic neurons. Thus, there does not seem to be a differential distribution of this receptor in the output routes of the ventral striatum. In all of the subregions investigated (core, medial shell, and lateral shell of the nucleus accumbens and the olfactory tubercle), only subpopulations of the total enkephalinergic and dynorphinergic populations were found to contain 5‐HT 2a mRNA. For enkephalin, the percentage colocalization was higher in the lateral shell (61%) compared with the other subregions (38–45%). For dynorphin, the percentage colocalization was higher in the olfactory tubercle (68%) than in the other subregions (34–43%). The differences in (sub)regional mRNA levels and in colocalization with opioids suggest a considerable regional differentiation in the effects of 5‐HT 2a ‐mediated neurotransmission in the striatum. J. Comp. Neurol. 389:1–11, 1997. © 1997 Wiley‐Liss, Inc.