CHANGES IN GAP JUNCTION PERMEABILITY, GAP JUNCTION NUMBER, AND CONNEXIN43 EXPRESSION IN LINDANE-TREATED RAT-LIVER EPITHELIAL-CELLS

The pesticide lindane (gamma-hexachlorocyclohexane) is a mammalian neu rotoxin and hepatocarcinogen. Lindane can inhibit gap junctional inter cellular communication (GJIC) and this effect may contribute to its to xic properties. The mechanism of inhibition of GJIC by lindane in WB-F 344 rat liver epithelial cells was studied to determine if altered gap junction permeability, gap junction number, and/or gap junction prote in (connexin43) expression were involved. GJIC was monitored by fluore scent Lucifer Yellow CH dye microinjection (dye-coupling). Gap junctio n number was quantified visually after indirect immunostaining of gap junctions using an anti-connexin43 monoclonal antibody. Connexin43 mRN A and protein levels were determined by Northern and Western blotting, respectively. Short-term treatment (10-30 min) with lindane (50 mu M) resulted in the rapid (within 10 min), nearly complete loss of dye-co upling but no changes in gap junction number or connexin43 mRNA or pro tein levels. Medium-term treatment (1-4 hr) resulted in the loss of dy e-coupling, gap junctions, and phosphorylated connexin43 proteins. Lon g-term treatment (1-14 days) led to reductions in dye-coupling, total connexin43 protein, and connexin43 mRNA. Nuclear run-on assays indicat ed that transcription of the connexin43 gene was reduced nonspecifical ly by lindane. These data indicate that reductions in gap junction per meability, number, and expression may be involved in the inhibition of GJIC depending on pesticide treatment duration. (C) 1995 Academic Pre ss, Inc.