Effects of Thyroidectomy and Thyroxine on Glucose Transport Capacity in the Jejunum and Ileum of Rat

Thyroid hormone has been known to alter glucose metabolism. This study was conducted to investigate the effect of thyroidectomy and thyroxine on glucose transport in the small intestine. Forty rats were randomly selected into four groups of ten rats. Groups one and two rats were thyroidectomised to make them hypothyroid after which group two rats received T4 replacement of 10ug/100g b/w for thirty-five days to make them euthyroid. Rats in groups three and four were sham operated thereafter group three rats received 10ug/100g b/w thyroxine for thirty-five days to make them hyperthyroid. 10mg/kg b/w Ketamine was administered intraperitoneally as anesthesia before the surgeries. On the thirty-fifth day post-surgery all the animals were sacrificed and their small intestines were harvested. 10cm length of jejunum and ileum respectively were used to make everted sacs for the in vitro study. Mucosa glucose transfer (MGT), Final glucose concentration gradient (FCG) and Gut glucose uptake (GGU) were significantly higher (P< 0.05) in the hyperthyroid group and lower (P< 0.05) in the hypothyroid group compared with the control with transport in the jejunum greater (P< 0.05) than the ileum in all groups. Serosal glucose transfer (SGT) was Negative in the hyperthyroid group. These findings suggest that thyroidectomy reduced glucose transport while thyroxine increased glucose transport in different segments of the small intestine with the transport in the jejunum greater than that of the ileum. But excess thyroxine may cause reverse glucose transport in the small intestine.