title: Vesicular glutamate transporter DNPI/VGLUT2 mRNA is present in C1 and several other groups of brainstem catecholaminergic neurons.
abstract: The mouse glutamate vesicular transporter VGLUT2 has recently been characterized. The rat homolog of VGLUT2, differentiation-associated Na(+)/P(i) cotransporter (DNPI), was examined using a digoxigenin-labeled DNPI/VGLUT2 cRNA probe in the present study to determine which, if any, of the various groups of pontine or medullary monoaminergic neurons express DNPI/VGLUT2 mRNA and, thus, are potentially glutamatergic. DNPI/VGLUT2 mRNA was widely distributed within the brainstem and seemed exclusively neuronal. By using a double in situ hybridization method, the presence of the mRNA for DNPI/VGLUT2 and glutamic acid decarboxylase (GAD)-67 was mutually exclusive. By combining DNPI/VGLUT2 mRNA detection and conventional immunohistochemistry, DNPI/VGLUT2 mRNA was undetectable in lower brainstem cholinergic and serotonergic cells, but it was present in several tyrosine hydroxylase-immunoreactive (TH-ir) cell groups. DNPI/VGLUT2 mRNA was detected in most of the adrenergic neurons of the C1, C2, and C3 groups (75-80% of TH-ir neurons), in the A2 noradrenergic group (80%), and in vast numbers of area postrema cells. Within the A1 region, many fewer TH-ir cells contained DNPI/VGLUT2 (16%). Finally, DNPI/VGLUT2 mRNA was undetectable in the pontine noradrenergic cell groups (A5 and A6/locus coeruleus). In conclusion, the general pattern of DNPI/VGLUT2 expression and its exclusion from GABAergic, cholinergic, and serotonergic neurons supports the notion that DNPI/VGLUT2 mRNA identifies a subset of glutamatergic neurons in the lower brainstem. Within this region several catecholaminergic cell groups appear to be glutamatergic, including but not limited to the adrenergic cell groups C1-C3. Based on the present evidence, the noradrenergic cell groups of the pons (A5 and A6) do not contain either known vesicular glutamate transporter and are most likely not glutamatergic.
authors.affiliation: Department of Pharmacology, University of Virginia Health System, Charlottesville, Virginia 22908-0735, USA. rs3j@virginia.edu
authors.forename: Ruth L
authors.initials: RL
authors.lastname: Stornetta
authors.forename: Charles P
authors.initials: CP
authors.lastname: Sevigny
authors.forename: Patrice G
authors.initials: PG
authors.lastname: Guyenet
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics*; D002395:Catecholamines / Q000378:metabolism*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism; D026901:Membrane Transport Proteins; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011149:Pons / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D014018:Tissue Distribution; D050599:Vesicular Glutamate Transport Protein 2; D033921:Vesicular Transport Proteins
chemical_list: D002352:Carrier Proteins; D002395:Catecholamines; D007527:Isoenzymes; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; C493475:Slc17a6 protein, rat; D050599:Vesicular Glutamate Transport Protein 2; D033921:Vesicular Transport Proteins; D012701:Serotonin; D002795:Choline O-Acetyltransferase; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1