Dietary regulation of glycolytic enzymes IX. The effect of oral, intramuscular and conjugated sex steroids on jejunal glycolytic enzyme activities in normal and castrated male and female rats

Abstract

1. 1. The effects of oral, intramuscular and conjugated sex hormones (estradiol, progesterone and testosterone) on the activities of three glycolytic enzymes (phosphofructokinase (ATP : D-fructose-6-phosphate 6-phosphotransferase, EC 2.7.1.11), pyruvate kinase (ATP : pyruvate phosphotransferase, EC 2.7.1.40) and fructose diphosphate aldolase (fructose-1,6-diphosphate D-glyceraldehyde-lyse, EC 4.1.2.13) were studied in the jejunum of both non-castrate and castrate male and female rats. 2. 2. These studies demonstrate that the oral sex hormones (estradiol in females, testosterone in males) produce adaptive increases in the activity of jejunal pyruvate kinase in both non-castrate and castrate rats, while intramuscular sex hormones are effective only in castrate rats. Sex hormones also produced adaptive increases in phosphofructokinase activities in castrate rats. Oral conjugated sex hormones are nearly as effective as the non-conjugated sex hormones in producing adaptive increases in the activity of jejunal pyruvate kinase. No significant changes were seen in fructose-1,6-phosphate alsolase activities. 3. 3. We postulate that a sex hormone-dependent binding site in jejunum accounts for the differences in action between intramuscular and oral sex steroids in castrate and non-castrate rats.