Effect of short-term and long-term treatment with a steroidal oral contraceptive on the intestinal absorption of nutrients in vitro in female rats.

The effect of steroidal oral contraceptive (SOC), comprising megestrol acetate (5 mg/kg body weight) plus ethinyl estradiol (0.05 mg/kg body weight), administered daily by stomach tube for 5, 15, 30 and 90 days, on the intestinal uptake of nutrients such as glucose, amino acids and calcium has been investigated in vitro in female rats. The administration of SOC for 5 days did not affect the uptake of nutrients, but treatment for 15, 30 and 90 days led to a progressive and significant increase in the uptake of glucose and amino acids. The calcium uptake was increased in the groups treated for 5 and 15 days, but decreased after 30 and 90 days of treatment. Kinetic studies done on glucose uptake indicated that the steroid contraceptive might be inducing the transport carrier protein of this nutrient, as elevation in Vmax was observed in the group treated for 30 days. There was no change in brush border membrane phospholipid and cholesterol contents after 30 and 90 days of treatment, but a significant increase in phospholipid after 5 and 15 days of treatment was observed. This study suggests that SOC treatment significantly altered the intestinal absorptive functions and the effect appears to be on the carrier-mediated transport of glucose.