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Lower brainstem catecholamine afferents to the rat dorsal raphe nucleus
Author(s) -
Peyron Christelle,
Luppi PierreHervé,
Fort Patrice,
Rampon Claire,
Jouvet Michel
Publication year - 1996
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(19960115)364:3<402::aid-cne2>3.0.co;2-8
Subject(s) - dorsal raphe nucleus , biology , brainstem , serotonergic cell groups , neuroscience , dorsum , raphe , nucleus , raphe nuclei , catecholamine , anatomy , serotonin , serotonergic , biochemistry , receptor
A large body of data suggests that the activation of α 1 receptors by a tonic noradrenergic input might be responsible for the tonic discharge of the serotonergic neurons of the dorsal raphe nucleus (DRN). To test this hypothesis, it was necessary to determine the origin of the noradrenergic and adrenergic innervation of these neurons. For this purpose, we combined small iontophoretic injections of the sensitive retrograde tracer cholera toxin b subunit (CTb) in the different subdivisions of the DRN with tyrosine hydroxylase immunohistochemistry. After CTb injections in the ventral or dorsal parts of the central DRN, a small number of double‐labeled cells was observed in the locus coeruleus (A6 noradrenergic cell group), the A5 noradrenergic group, the dorsomedial medulla (C3 adrenergic cell group), and the lateral paragigantocellular nucleus (C1 adrenergic cell group). After CTb injections in the lateral wings or the dorsal part of the rostral DRN, a similar number of double‐labeled cells was seen in C3. Slightly more double‐labeled cells were seen in A6 and A5. In addition, a substantial to large number of double‐labeled cells appeared in C1, the commissural part of the nucleus of the solitary tract (A2 noradrenergic cell group) and the caudoventrolateral medulla (A1 noradrenergic cell group). These results indicate that the noradrenergic and adrenergic inputs to the DRN arise from all the catecholaminergic cell groups of the lower brainstem except the A7 noradrenergic group. They further reveal the existence of a topographical organization of these afferents to the different subdivisions of the DRN. © 1996 Wiley‐Liss, Inc.