Objective: Our purpose was to investigate the influence of pregnancy and lactation on hexokinase II activity and gene expression in adipose tissue and skeletal muscle of rats.
Study design: Intraabdominal adipose tissue and femoral quadriceps muscle were removed from Sprague-Dawley 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 activity was measured with the glucose-6-phosphate-coupled assay.
Results: The 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 activity was also decreased in this tissue at this time (39.34 +/- 3.05 vs 27.81 +/- 3.61 mU x min(-1) x mg protein(-1), p < 0.05). Hexokinase II activity and messenger ribonucleic acid abundance in skeletal muscle were unaffected by pregnancy and lactation.
Conclusion: Both hexokinase II messenger ribonucleic acid abundance and enzyme activity are reduced in adipose tissue of pregnant rats near term, possibly contributing to the insulin resistance associated with late pregnancy.