EFFECTS OF HYDRAZINE, PHENELZINE, AND HYDRALAZINE TREATMENT ON RAT HEPATIC AND RENAL DRUG-METABOLIZING ENZYME EXPRESSION

The hepatic and renal toxicity associated with hydrazine treatment has been linked to free radical damage resulting from oxidative metabolis m by cytochrome P4502E1 (CYP2E1). Despite this association, there has been little characterization of the effects of hydrazine treatment on the expression of hepatic and renal CYP2E1 or glutathione-S-transferas e-alpha (GST-alpha), an enzyme responsible for catalyzing the conjugat ion of free radicals with reduced glutathione. Therefore, the effects of treatment with hydrazine or one of the therapeutic hydrazines phene lzine and hydralazine on rat hepatic and renal CYP2E1 and GST-alpha ex pression were investigated. Adult male Sprague-Dawley rats were treate d with 0.9% saline vehicle (1 dose ip), hydrazine (100 mg/kg ip), phen elzine (100 mg/kg ip), or hydralazine (25 mg/kg ip). CYP2E1 mRNA and p rotein levels were monitored by Northern and immunoblot analyses, resp ectively, and GST-alpha Ya and Yc subunit levels were determined by im munoblot analysis. Hydralazine administration caused a significant (si milar to 159%) increase in renal GST-alpha Yc subunit expression. In a ddition, hydrazine and phenelzine treatment produced substantial eleva tions (similar to 464% and 566%, respectively) in renal CYP2E1 protein , whereas hydralazine administration did not alter renal CYP2E1 expres sion. Changes in rat hepatic GST-alpha Ya or Yc subunit levels after t reatment with hydrazine, phenelzine, or hydralazine were not statistic ally significant. Similarly, hepatic CYP2E1 levels were not significan tly altered after treatment with hydrazine, phenelzine, or hydralazine . Northern-blot analysis revealed that the observed increases in renal CYP2E1 protein levels after treatment with hydrazine or phenelzine we re not accompanied by concomitant increases in CYP2E1 mRNA. These resu lts suggest that treatment with hydrazine or the therapeutic hydrazine phenelzine significantly increases the expression of rat renal CYP2E1 protein, and that the molecular mechanisms responsible for these effe cts are posttranscriptional in nature.