HEXOKINASE-II ACTIVITY AND MESSENGER-RIBONUCLEIC-ACID ABUNDANCE IN ADIPOSE-TISSUE AND SKELETAL-MUSCLE DURING PREGNANCY AND LACTATION IN RATS

OBJECTIVE: Our purpose was to investigate the influence of pregnancy a nd lactation on hexokinase II activity and gene expression in adipose tissue and skeletal muscle of rats. STUDY DESIGN: Intraabdominal adipo se tissue and femoral quadriceps muscle were removed from Sprague-Dawl ey rats at various times (6 to 10 animals per group) during pregnancy and lactation. Hexokinase II messenger ribonucleic acid was assayed by quantitative ribonuclease protection analysis, and hexokinase activit y was measured with the glucose-6-phosphate-coupled assay. RESULTS: Th e amount of hexokinase II messenger ribonucleic acid in adipose tissue on day 20 of pregnancy was 55.4% +/- 8.4% (p < 0.01, unpaired Student t test) of the value for nonpregnant control rats; hexokinase II acti vity was also decreased in this tissue at this time (39.34 +/- 3.05 vs 27.81 +/- 3.61 mU . min(-1) . mg protein(-1), p < 0.05). Hexokinase I I activity and messenger ribonucleic acid abundance in skeletal muscle were unaffected by pregnancy and lactation. CONCLUSION: Both hexokina se II messenger ribonucleic acid abundance and enzyme activity are red uced in adipose tissue of pregnant rats near term, possibly contributi ng to the insulin resistance associated with late pregnancy.