Experimental Study On The Effects Of 1,25(OH)₂D₃ On Diabetes

Objective: To study the prophylactic effects of vitamin D₃ and 1,2 5-dihydroxyvitamin D₃ on Sprague-Dawley diabetes rat induced by streptozotocin at several low doses.Methods: To Sprague-Dawley rats oral 1,2 5-dihydroxy vitamin D3 (lμg/kg/day) or vitamin D₃ 150 000U/kg/month were administered by intramuscular injection 4 weeks before streptozotocin was intraperitoneally given in order to study the prophylactic effects of vitamin D₃ and 1,25-dihydroxyvitamin D₃ on Sprague-Dawley diabetes rat, inclusing the incidence of diabetes, glucose and insulin AUC. TNFa expression on islets was examined by immuhistochemical technique. BAX-mRNA and BCL-2-mRNA expression were also investigated by RT-PCR technique.Results: (1) The incidence of diabetes in the 1,25-dihydroxyvitamin D₃ group was 6/10 ,much less than 10/10 in STZ group (P<0.05) while glucose AUC in the 1,25-dihydroxyvitamin D3 group was also smaller than that in the STZ group(P<0.05). Insulin AUC in the 1,25-dihydroxyvitamin D3 group was higher than that of in the STZ group (P<0.05). No differences in the indices as mentioned above were found between vitamin D3 group and STZ group. But blood glucose level in vitamin D3 group at the first week right after streptozotocin intraperitoneally delivered and at 2 hour after oral glucose loading was much lower than that in the STZ group. (P<0.05) (2)TNFα and BAX-mRNA expression of 1,25-dihydroxyvitamin D₃ group were declined in comparison with that in STZ group (P<0.05). No differences in the expression of BCL-2-mRNA between the three treated groups. (3)Negative correlation was found...