DIFFERENTIAL EXPRESSION OF NEUROTENSIN RECEPTOR MESSENGER-RNA IN THE DOPAMINERGIC CELL GROUPS OF THE RAT DIENCEPHALON AND MESENCEPHALON

Several lines of evidence support interactions between neurotensin (NT ) and dopaminergic (DAergic) neurons in the brain. In order to obtain further knowledge about the anatomical substrate for such interactions , the distribution of cells expressing the cloned neurotensin receptor (NTR) mRNA was examined in relation to tyrosine hydroxylase (TH) mRNA -expressing cells within different subnuclei of the diencephalon and v entral mesencephalon of the male rat, In situ hybridization was perfor med on consecutive sections labeled with P-33-labeled oligonucleotide probes, In the hypothalamus, NTR mRNA signals were mostly found in the suprachiasmatic, dorsomedial, dorsal premammillary, and supramammilla ry nuclei, On the other hand, DAergic cells of the periventricular nuc leus of the hypothalamus and dorsal aspect of the arcuate nucleus, rev ealed by TH in situ hybridization, did not exhibit NTR mRNA even thoug h dense NT binding sites have been previously described in this nuclei . In the zona incerta, TH mRNA-containing cells were concentrated in t he medial part, with little overlap with NTR mRNA-expressing cells loc ated mainly in its mediolateral extent, In contrast, the distribution of both markers was superimposable within the different subdivisions o f the ventral tegmental area and substantia nigra, as previously sugge sted, but also in the retrorubral field. These anatomical data further support the NT-dopamine interactions on both mesocorticolimbic and ni grostriatal DAergic systems. Moreover, the results suggest that dience phalic DAergic neurons do not synthesize the cloned NTR mRNA or expres s it at considerably lower levels than DAergic mesencephalic cells. (c ) 1995 Wiley-Liss, Inc.