title: Cadmium chloride (CdCl2)-induced metallothionein (MT) expression in neonatal rat primary astrocyte cultures.
abstract: Metallothionein (MT) protein and mRNA levels were studied following exposure of rat neonatal primary astrocyte cultures to cadmium chloride (CdCl2). MT mRNA was probed on Northern blots with a 32P labeled synthetic cDNA probe specific for rat MT mRNA. The probe hybridizes to a single mRNA with a size appropriate for MT, approximately 550 bases. Expression of MT-I mRNA in astrocyte monolayers exposed to 2 x 10(-6) M CdCl2 for 6 h was increased approximately 5-fold (9.7 fg/micrograms total RNA) over MT-I mRNA levels in controls (2 fg/micrograms total RNA). MT-I mRNA could also be detected in untreated cells, suggesting constitutive MT expression in these cells. Western-blot analysis revealed a marked increase in MT protein levels upon exposure to CdCl2 (1 x 10(-6) M; 96 h). Consistent with the constitutive expression of MTs both at the mRNA level and protein level, we have also demonstrated a time-dependent increase in MT-immunoreactivity in astrocytes exposed to CdCl2. The present study suggests that astrocytes constitutively express MTs, and that MT-induction by CdCl2 may be an example of a generalized increase in MTs in response to heavy metal exposure, thus protecting astrocytes, and perhaps also indirectly, juxtaposed neurons from the neurotoxic effects of heavy metals.
authors.affiliation: Department of Pharmacology and Toxicology, Albany Medical College, NY, USA.
authors.forename: L
authors.initials: L
authors.lastname: Rising
authors.forename: D
authors.initials: D
authors.lastname: Vitarella
authors.forename: H K
authors.initials: HK
authors.lastname: Kimelberg
authors.forename: M
authors.initials: M
authors.lastname: Aschner
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002104:Cadmium / Q000494:pharmacology*; D019256:Cadmium Chloride; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology*; D015870:Gene Expression; D007150:Immunohistochemistry; D008668:Metallothionein / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002712:Chlorides; D012333:RNA, Messenger; D002104:Cadmium; D008668:Metallothionein; D019256:Cadmium Chloride