title: Biphasic lindane-induced oxidation of glutathione and inhibition of gap junctions in myometrial cells.
abstract: The insecticide lindane (gamma-hexachlorocyclohexane) inhibits gap junction intercellular communication in rat myometrial cells by a mechanism involving oxidative stress. We hypothesized that oxidation of reduced glutathione (GSH) to glutathione disulfide (GSSG) and subsequent S-glutathionylation provide a mechanistic link between lindane-induced oxidative stress and lindane's inhibition of myometrial gap junction communication. Gap junction communication between cultured rat myometrial myocytes was assessed by Lucifer yellow dye transfer after microinjection. A biphasic pattern was confirmed, with dye transfer nearly abolished after 1 h of exposure to 100 microM lindane followed initially by recovery after lindane removal, and then the development 4 h after termination of lindane exposure of a delayed-onset, sustained inhibition that continued for 96 h. As measured by HPLC, cellular GSH varied over a 24-h period in a biphasic fashion that paralleled lindane-induced inhibition of dye transfer, whereas GSSG levels increased in a manner inversely related to GSH. In accordance, GSH/GSSG ratios were depressed at times when GSH and dye transfer were low. Lindane substantially increased S-glutathionylation in a concentration-dependent manner, measured biochemically by GSSG reductase-stimulated release of GSH from precipitated proteins. Furthermore, treatments that promoted accumulation of GSSG (50 microM diamide and 25 microM 1,3-bis(2-chloroethyl)-1-nitrosourea [BCNU]) inhibited Lucifer yellow dye transfer between myometrial cells. Findings that lindane induced GSH oxidation to GSSG with increased S-glutathionylation, together with the diamide and BCNU results, suggest that oxidation of GSH to GSSG is a component of the mechanism by which lindane inhibits myometrial gap junctions.
authors.affiliation: Toxicology Program, Department of Environmental Health, University of Michigan, 1420 Washington Heights, Ann Arbor, Michigan 48109-2029, USA. rlc@umich.edu
authors.forename: Rita Loch
authors.initials: RL
authors.lastname: Caruso
authors.forename: Brad L
authors.initials: BL
authors.lastname: Upham
authors.forename: Craig
authors.initials: C
authors.lastname: Harris
authors.forename: James E
authors.initials: JE
authors.lastname: Trosko
mesh_terms: D000818:Animals; D002330:Carmustine / Q000494:pharmacology; D002450:Cell Communication / Q000187:drug effects*; D002478:Cells, Cultured; D003958:Diamide / Q000494:pharmacology; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D017629:Gap Junctions / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D001556:Hexachlorocyclohexane / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D007546:Isoquinolines / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D009215:Myometrium / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005456:Fluorescent Dyes; D007306:Insecticides; D007546:Isoquinolines; D003958:Diamide; D001556:Hexachlorocyclohexane; C017475:lucifer yellow; D005978:Glutathione; D002330:Carmustine; D019803:Glutathione Disulfide