Relevance of heat-shock protein 70 expression as histological marker of paraquat-induced damage to rat liver cells

Heat-shock protein 70 (HSP70) is expressed in response to various stressful stimuli, and generally used as a histological marker of cell damage. While paraquat has previously been shown to cause HSP70 expression as a result o f the oxidative cell damage, recent study has shown that HSP70 expression i nduced by paraquat poisoning is no longer observed at 18 hr after the drug administration in the senescence-accelerated mouse liver, thereby raising t he question whether the cell damage is always accompanied by elevated HSP70 expression. To affirm the relevance of HSP70 expression as a marker of the cell damage, the expression of HSP70 immunoreactivity and lipid peroxidati on in paraquat-poisoned rat liver were examined, The immunostaining of HSP7 0 was still clearly detected at 24 hr after the drug administration. Lipid peroxidation, a biochemical maker of the oxidative cell damage, was also el evated by the same treatment, suggesting that the expression of HSP70 immun oreactivity observed here may reflect the oxidative-damage to liver cells. These results seem to provide evidence supporting the relevance of HSP70 ex pression as a histological marker of paraquat-induced damage to rat liver c ells.