title: Endogenous L-dopa in the rat dorsal vagal complex: an immunocytochemical study by light and electron microscopy.
abstract: The aim of this work was to examine L-DOPA immunoreactivity (L-DOPA-IR) in the dorsal vagal complex (DVC) of the rat medulla oblongata containing A2/C2 catecholaminergic cell groups, in order to further evaluate the previously proposed hypothesis that various pools of endogenous L-DOPA could be immunocytochemically demonstrated in the mammalian brain. For this purpose, L-DOPA-IR was studied in DVC in comparison with both some other catecholaminergic areas and dopamine immunoreactivity (DA-IR) on adjacent sections of the same brain, by using specific antibodies against glutaraldehyde conjugated L-DOPA and DA. Also, the first preliminary observations of L-DOPA-IR in DVC neurons at the ultrastructural level are reported. The following main results were obtained: (1) bright, intense and homogeneous L-DOPA staining was found in perikarya and proximal neuronal processes situated within the rostrocaudal extension of the DVC; (2) this staining pattern was readily distinct from weak and heterogeneous DA staining; (3) an inverse L-DOPA/DA staining pattern ratio was identified between the DVC and the mesencephalon; (4) L-DOPA-IR at electron microscopic level was roughly similar to that previously observed for DA-IR in mesencephalic cells and their presumptive projections. Although some discrepancies were noticed between L-DOPA staining and data from the literature on tyrosine hydroxylase labeling, our results could not invalidate the hypothesis that, among high L-DOPA/DA ratio containing neurons, some cells in the DVC may contain only L-DOPA.
authors.affiliation: Service de Neurologie, Hôpital Pellegrin, Bordeaux, France.
authors.forename: F
authors.initials: F
authors.lastname: Tison
authors.forename: N
authors.initials: N
authors.lastname: Mons
authors.forename: S
authors.initials: S
authors.lastname: Rouet-Karama
authors.forename: M
authors.initials: M
authors.lastname: Geffard
authors.forename: P
authors.initials: P
authors.lastname: Henry
mesh_terms: D000818:Animals; D000906:Antibodies; D004298:Dopamine / Q000032:analysis; D007150:Immunohistochemistry; D007980:Levodopa / Q000032:analysis*; D008526:Medulla Oblongata / Q000166:cytology* / Q000648:ultrastructure; D008636:Mesencephalon / Q000166:cytology; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000906:Antibodies; D007980:Levodopa; D004298:Dopamine