The effects of an oral contraceptive on plasma growth hormone and glucose tolerance in two strains of rats.

Effects of an oral contraceptive on plasma growth hormone and glucose tolerance were studied in two strains of rats, Sprague-Dawley, a normal strain, and BHE, a carbohydrate-sensitive strain. Ethynyl estradiol and norgestrel, combined in a dose representative of the clinical preparation of Ovral were given for 21 days. Plasma growth hormone was measured following sodium pentobarbital stimulation. In both strains fasting blood glucose levels were unchanged following oral contraceptive therapy, however, a strain difference in response to a glucose load was found. With contraceptive steroid treatment, Sprague-Dawley rats developed an impaired tolerance to glucose during the latter part of the glucose tolerance test. BHE control animals had an abnormal response to a glucose load which improved with oral contraceptive therapy. No significant correlation between growth hormone changes and changes in glucose tolerance during contraceptive steroid treatment were observed. Both strains of rats receiving oral contraceptives gained less weight than their controls, however, the difference was statistically significant only in the Sprague-Dawley strain.