GENDER-DEPENDENT REGULATION OF GLUTAMATE-DEHYDROGENASE EXPRESSION IN PERIPORTAL AND PERICENTRAL ZONES OF RAT-LIVER LOBULES

We studied the level(s) at which glutamate dehydrogenase (GDH; EC 1.4. 1.2) expression is regulated in the livers of fed male and female rats . The cellular content of GDH mRNA, protein, and enzyme activity was d etermined quantitatively using image analysis for measurement of the a bsorbance in consecutive serial sections that were processed for in si tu hybridization, immunohistochemistry, and enzyme histochemistry. In both males and females, GDH protein and activity patterns were similar , with pericentral values being twice as high as periportal values. GD H mRNA distribution patterns in female liver lobules reflected those o f GDH protein and activity, but GDH mRNA distribution patterns in male rat livers were found to be homogeneous owing to a more than twofold lower cellular mRNA content in pericentral zones than in female rats. We conclude that gender affects GDH expression selectively in pericent ral zones at posttranscriptional and pretranslational levels.