DECREASED EXPRESSION OF MCT1 IN STREPTOZOTOCIN INDUCED DIABETIC RATS

Abstract

We investigated whether the expression of MCT1(Monocarboxylate Transporter 1) is changed in streptozotocin (STZ) induced diabetic rats, when carbohydrate metabolism is decreased. In experiment 1, rats were injected with STZ at 85 mg/g BW. Seven days after the injection of STZ, soleus was taken to measure GLUT4 and MCT1 concentration and oxidation of lactate in incubated soleus strip. STZ diabetic rats showed significantly reduced protein expression of GLUT4 and MCT1 in soleus. Oxidation of lactate was also significantly reduced in the soleus of STZ diabetic rats compared with control rats. In experiment 2, rats were injected with STZ at 50 mg/g BW. Diabetic training rats ran at a speed of 27 m/min for 30 min for 3 weeks with daily injection of Na-lactate (10 mg). The STZ diabetic control rats, without exercise and injection of lactate, showed significantly reduced MCT1 in soleus and plantaris. The protein expression of MCT1 in the endurance trained diabetic rats was significantly higher than that in the diabetic control rats. Daily injection of lactate alone into the diabetic rats without exercise did not increase the content of MCT1. These results show that the expression of MCT1 in soleus and plantaris is reduced in STZ induced diabetic rats with concomitant reduction of oxidation of lactate. Endurance training and injection of lactate can increase the expression of MCT1 in the STZ diabetic rats.