title: Differential regulation of glutamic acid decarboxylase mRNA and tyrosine hydroxylase mRNA expression in the aged manganese-treated rats.
abstract: Recent studies have implicated chronic elevated exposures to environmental agents, such as metals (e.g. manganese, Mn) and pesticides, as contributors to neurological disease. Eighteen-month-old rats received intraperitoneal injections of manganese chloride (6 mg Mn/kg/day) or equal volume of saline for 30 days in order to study the effect of manganese on the dopamine- and GABA-neurons. The structures studied were substantia nigra, striatum, ventral tegmental area, nucleus accumbens and globus pallidus. First, we studied the enzymatic activity of mitochondrial complex II succinate dehydrogenase (SDH). We found an overall decrease of SDH in the different brain areas analyzed. We then studied the mRNA levels for tyrosine hydroxylase (TH) and the dopamine transporter (DAT) by in situ hybridization. TH mRNA but not DAT mRNA was significantly induced in substantia nigra and ventral tegmental area following Mn treatment. Correspondingly, TH immunoreactivity was increased in substantia nigra and ventral tegmental area. Manganese treatment significantly decreased GAD mRNA levels in individual GABAergic neurons in globus pallidus but not in striatum. We also quantified the density of glial fibrillary acidic protein (GFAP)-labeled astrocytes and OX-42 positive cells. Reactive gliosis in response to Mn treatment occurred only in striatum and substantia nigra and the morphology of the astrocytes was different than in control animals. These results suggest that the nigrostriatal system could be specifically damaged by manganese toxicity. Thus, changes produced by manganese treatment on 18-month-old rats could play a role in the etiology of Parkinson's disease.
authors.affiliation: Departamento de Bioquímica, Bromatología y Toxicología, Facultad de Farmacia, Universidad de Sevilla, C/Prof. García González s/n, Seville, Spain.
authors.forename: Mayka
authors.initials: M
authors.lastname: Tomás-Camardiel
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Herrera
authors.forename: José L
authors.initials: JL
authors.lastname: Venero
authors.forename: Mari
authors.initials: M
authors.lastname: Cruz Sánchez-Hidalgo
authors.forename: Josefina
authors.initials: J
authors.lastname: Cano
authors.forename: Alberto
authors.initials: A
authors.lastname: Machado
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D001253:Astrocytes / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D030161:Avian Proteins; D051926:Basigin; D001798:Blood Proteins; D003342:Corpus Striatum / Q000166:cytology / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D005917:Globus Pallidus / Q000166:cytology / Q000201:enzymology; D005968:Glutamate Decarboxylase / Q000235:genetics*; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000235:genetics; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000032:analysis; D009474:Neurons / Q000187:drug effects / Q000201:enzymology; D009714:Nucleus Accumbens / Q000166:cytology / Q000201:enzymology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013378:Substantia Nigra / Q000166:cytology / Q000201:enzymology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics*; D017557:Ventral Tegmental Area / Q000166:cytology / Q000201:enzymology
chemical_list: D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D001798:Blood Proteins; C102624:Bsg protein, Gallus gallus; C079432:Bsg protein, rat; D005904:Glial Fibrillary Acidic Protein; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D051926:Basigin; D008345:Manganese; D014446:Tyrosine 3-Monooxygenase; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1