title: Comparative sensitivity of rat cerebellar neurons to dysregulation of divalent cation homeostasis and cytotoxicity caused by methylmercury.
abstract: The objective of the present study was to determine the relative effectiveness of methylmercury (MeHg) to alter divalent cation homeostasis and cause cell death in MeHg-resistant cerebellar Purkinje and MeHg-sensitive granule neurons. Application of 0.5-5 microM MeHg to Purkinje and granule cells grown in culture caused a concentration- and time-dependent biphasic increase in fura-2 fluorescence. At 0.5 and 1 microM MeHg, the elevations of fura-2 fluorescence induced by MeHg were biphasic in both cell types, but significantly delayed in Purkinje as compared to granule cells. Application of the heavy-metal chelator, TPEN, to Purkinje cells caused a precipitous decline in a proportion of the fura-2 fluorescence signal, indicating that MeHg causes release of Ca(2+) and non-Ca(2+) divalent cations. Purkinje cells were also more resistant than granule cells to the neurotoxic effects of MeHg. At 24.5 h after-application of 5 microM MeHg, 97.7% of Purkinje cells were viable. At 3 microM MeHg there was no detectable loss of Purkinje cell viability. In contrast, only 40.6% of cerebellar granule cells were alive 24.5 h after application of 3 microM MeHg. In conclusion, Purkinje neurons in primary cultures appear to be more resistant to MeHg-induced dysregulation of divalent cation homeostasis and subsequent cell death when compared to cerebellar granule cells. There is a significant component of non-Ca(2+) divalent cation released by MeHg in Purkinje neurons.
authors.affiliation: Department of Pharmacology and Toxicology, Michigan State University, B331 Life Sciences Building, East Lansing, MI 48824-1317, USA.
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Edwards
authors.forename: M Sue
authors.initials: MS
authors.lastname: Marty
authors.forename: William D
authors.initials: WD
authors.lastname: Atchison
mesh_terms: D000393:Air Pollutants / Q000737:chemistry / Q000633:toxicity; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent / Q000378:metabolism* / Q000633:toxicity; D018929:Cell Culture Techniques / Q000379:methods; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D002531:Cerebellum / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D002614:Chelating Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D005029:Ethylenediamines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D005333:Fetus / Q000473:pathology; D016257:Fura-2 / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D008767:Methylmercury Compounds / Q000633:toxicity*; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D011689:Purkinje Cells / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D051381:Rats
chemical_list: D000393:Air Pollutants; D002413:Cations, Divalent; D002614:Chelating Agents; D005029:Ethylenediamines; D008767:Methylmercury Compounds; D016202:N-Methylaspartate; C044387:N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine; D002118:Calcium; D016257:Fura-2