title: Mitochondrial-dependent manganese neurotoxicity in rat primary astrocyte cultures.
abstract: Chronic exposure to excessive levels of Mn results in a movement disorder termed manganism, which resembles Parkinson's disease (PD). The pathogenic mechanisms underlying this disorder are not fully understood. Several lines of evidence implicate astrocytes as an early target of Mn neurotoxicity. In the present study, we investigated the effects of Mn on mitochondrial function. Primary astrocyte cultures were prepared from cerebral cortices of one-day-old Sprague-Dawley rats. We have examined the cellular toxicity of Mn and its effects on the phosphorylation of extracellular signal-regulated kinase (ERK) and activation of the precursor protein of caspase-3. The potentiometric dye, tetramethyl rhodamine ethyl ester (TMRE), was used to assess the effect of Mn on astrocytic mitochondrial inner membrane potential (DeltaPsi(m)). Our studies show that, in a concentration-dependent manner, Mn induces significant (p<0.05) activation of astrocyte caspase-3 and phosphorylated extracellular signal-regulated kinase (p-ERK). Mn treatment (1 and 6 h) also significantly (p<0.01) dissipates the DeltaPsi(m) in astrocytes as evidenced by a decrease in mitochondrial TMRE fluorescence. These results suggest that activations of astrocytic caspase-3 and ERK are involved in Mn-induced neurotoxicity via mitochondrial-dependent pathways.
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, TN, USA.
authors.forename: Zhaoobao
authors.initials: Z
authors.lastname: Yin
authors.forename: Judy L
authors.initials: JL
authors.lastname: Aschner
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: dos Santos
authors.forename: Michael
authors.initials: M
authors.lastname: Aschner
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D002712:Chlorides / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D017895:Manganese Compounds; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000502:physiology*; D009498:Neurotoxins / Q000633:toxicity*; D009942:Organometallic Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; D009498:Neurotoxins; D009942:Organometallic Compounds; D013778:Tetrazolium Salts; D013844:Thiazoles; C110932:tetramethyl rhodamine ethyl ester; D007770:L-Lactate Dehydrogenase; D048049:Extracellular Signal-Regulated MAP Kinases; D053148:Caspase 3; C022616:thiazolyl blue; C025340:manganese chloride