title: Increased levels of metallothionein in placenta of smokers.
abstract: Experiments were designed to evaluate and compare metallothionein (MT), zinc and cadmium levels in human placentas of smoking and non-smoking women. Smoking was assessed by self-reported cigarette consumption and urine cotinine levels before delivery. Smoking pregnant women with urine cotinine levels higher than 130 ng/ml were included in the smoking group. Determination of placental MT was performed by western blot analysis after tissue homogenization and saturation with cadmium chloride (1000 ppm). Metallothionein was analyzed with a monoclonal antibody raised against MT-1 and MT-2 and with a second anti mouse antibody conjugated to alkaline phosphatase. Zinc and cadmium were determined by neutron activation analysis and atomic absorption spectrometry respectively. Smokers showed higher placental MT and cadmium levels, together with decreased newborn birth weights, as compared to non-smokers. The semi-quantitative analysis of western blots by band densitometry indicated that darker bands corresponded to MT present in smokers' samples. This study confirms that cigarette smoking increases cadmium accumulation in placental tissue and suggests that this element has a stimulatory effect on placental MT production.
authors.affiliation: Laboratorio de Hormonas y Receptores, Instituto de Nutrición y Tecnología de los Alimentos, INTA, Universidad de Chile, Casilla 138-11, Santiago, Chile. amronco@inta.cl
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Ronco
authors.forename: Graciela
authors.initials: G
authors.lastname: Arguello
authors.forename: Myriam
authors.initials: M
authors.lastname: Suazo
authors.forename: Miguel N
authors.initials: MN
authors.lastname: Llanos
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000187:drug effects; D015153:Blotting, Western; D002104:Cadmium / Q000378:metabolism; D003367:Cotinine / Q000652:urine; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D008431:Maternal-Fetal Exchange; D008668:Metallothionein / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
chemical_list: D002104:Cadmium; D008668:Metallothionein; D015032:Zinc; D003367:Cotinine