Strain-, Sex- and Species-Related Differences of Acetohexamide Reductase and 20β-Hydroxysteroid Dehydrogenase Activities in Liver Microsomes of Experimental Animals

Abstract

We examined physiological and genetic factors affecting acetohexamide reductase (AHR) and 20β-hydroxysteroid dehydrogenase (20β-HSD) activities in liver microsomes of experimental animals. Pronounced strain-related differnces were found in both activities of AHR and 20β-HSD present in liver microsomes of male rats. Among rat strains tested in this study, even though a Wistar-Imamichi (WIM) rat strain was taken to lack AHR activity, it exhibited a significant 20β-HSD activity. These findings appeared to be in conflict with our conclusion reported so far, which AHR and 20β-HSD present in liver microsomes of male rats are identical enzymes. Thus the reason for this discrepancy was discussed. Furthermore, AHR and 20β-HSD activities were little or not observed in liver microsomes of female rats or male experimental animals other than the rat, indicating the existence of sex- and species-related differences in these two enzyme activities.