Sex differences in gastric alcohol dehydrogenase activity in Sprague-Dawley rats

The effects of sex differences and of fasting on gastric alcohol dehydrogenase activity were determined in Sprague-Dawley rats. Gastric alcohol dehydrogenase activity and enzyme protein levels were higher in female than in male rats. Ovariectomy and orchiectomy had no effect on alcohol dehydrogenase and did not alter the sex difference in enzyme activity. Fasting decreased the enzyme activity more in female than in male rats, abolishing the sex difference. Serum gastrin levels measured in female rats decreased on fasting and returned to normal levels within 24 hours of refeeding. Short- and long-term administration of pentagastrin to fasted and fed female rats did not affect the enzyme activity or enzyme protein level, except for a transient increase in enzyme activity but not in enzyme protein level 12 hours after administration to fasted fats. Omeprazole, which increased serum gastrin levels and decreased enzyme activity but not enzyme protein levels, was found to be a competitive inhibitor of the enzyme with a Ki of 0.40 mmol/L. The mechanisms for the sex differences and changes with fasting in rat gastric alcohol dehydrogenase activity remain unknown.