Comparative anatomical distribution of 5-HT1A receptor mRNA and 5-HT1A binding in rat brain--a combined in situ hybridisation/in vitro receptor autoradiographic study.
The present study examined the comparative distribution of 5-HT1A receptor mRNA and 5-HT1A receptors in rat brain using a combination of in situ hybridisation histochemistry and in vitro receptor autoradiography. 5-HT1A mRNA was visualized using a 910 bp cRNA probe synthesised from a BalI-PvuII fragment of the rat 5-HT1A reetor gene, while 5-HT1A receptors were labelled with the 5-HT1A-selective ligand 8-OH-DPAT. In general terms, there was a complementary distribution of cells expressing 5-HT1A receptor mRNA and 5-HT1A receptor sites. High levels of both 5-HT1A mRNA and 5-HT1A receptors were evident in the hippocampal formation (CA1, CA3, dentate gyrus), entorhinal cortex, and raphe nuclei and lower levels in neocortex and thalamus. Although 5-HT1A mRNA was not expressed in any regions which did not also exhibit 5-HT1A receptors, within both the diagonal band and the medial septal nucleus mRNA levels were proportionately higher than 5-HT1A receptor levels, possibly reflecting receptor transport or a heterogeneity in 5-HT1A receptor turnover mechanisms. 5-HT1A receptor mRNA and 5-HT1A binding sites were undetectable in caudate/putamen and cerebellar regions. The present data indicate the synthesis of 5-HT1A receptors both in raphe serotonergic cells and anatomically specific serotonergic projection areas, further supporting both a presynaptic autoregulatory and postsynaptic modulatory role for this receptor in serotonergic transmission.
Chalmers
D T
DT
Mental Health Research Institute, University of Michigan, Ann Arbor 48109.
Watson
S J
SJ
D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism*; D003720:Densitometry / Q000379:methods; D004027:Diencephalon / Q000378:metabolism; D008297:Male; D008636:Mesencephalon / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D015347:RNA Probes; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000235:genetics / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D013687:Telencephalon / Q000378:metabolism
D015347:RNA Probes; D012333:RNA, Messenger; D011985:Receptors, Serotonin; D012701:Serotonin