AIM:To investigate whether insulin glargine has the protective effect on
apoptosis induced by free fatty acid(FFA),and compare
the interventional effect with those of regular insulin and insulin-like growth factor-1(IGF-1) in pancreatic beta(β) cells. METHODS:The experiment was carried out in the Lin Bai-Xin Medical Scientific Research Center of the Second Affiliated Hospital of Sun Yat-sen University from May to October 2004.RIN-m cell was cultured and kept in routine passages.Cells were inoculated in 6-well or 96-well plates for 2 days,and used for determination of
apoptosis at about 70%confluence.The medium was removed and replaced with that supplemented with 10 g/L bovine serum albumin(BSA),10 mL/L ethanol,20 mL/L fetal bovine serum(FBS) in absence(normal
control group) or presence of 0.3 mmol/L palmitic acid(apoptosis control group) and 100 nmol/L insulin glargine(glargine group) or regular insulin(regular insulin group) or 10 nmol/L insulin-like growth factor-1(IGF-1 group).After incubation for 24 hours,the cells were inoculated to the 6-well plate for induction of apoptosis.RIN-m apoptosis in each group was detected with Hoechst33342 staining,flow cytometry and enzyme-linked immunoadsordent assay(ELISA),and the apoptic DNA fragmentation was determined quantitatively.Absorbance,which stood for the number of nucleosome in cell lysate,that was the number of DNA fragmentation,was determined at double wavelength of 405 nm against 492 nm. RESULTS:After incubation in 0.3 mmol/L Morphological analysis of nuclei of RIN-m cells incubated with 0.3 mmol/L palmitic acid,RIN-m cells showed chromosome condensation and fragmentation of nuclei.①The percentages of hypodiploid cells(SubG1) in the insulin glargine group,regular insulin group and IGF-1 group<(32.00±3.08)%,(35.97±3.14)%,(25.25±1.66)%> were obviously higher than that in the normal control group<(3.28±1.44)%>(P< 0.01),but markedly lower than that in the apoptosis control group<(42.10%±4.24)%>(P< 0.01).②The numbers of nucleosome in cell lysates(absorbance value) in the insulin glargine group,regular insulin group and IGF-1 group(2.372±0.21,2.758±0.20,1.704±0.16) were obviously lower than that in the normal control group(0.341±0.023)(P< 0.01),but markedly lower than that in the apoptosis control group(3.333±0.23)(P< 0.01),and it was remarkably lower in the insulin glargine group and IGF-1 group than in the regular insulin group(P< 0.05). CONCLUSION:Insulin glargine plays a role in inhibiting apoptosis induced by FFA in pancreatic βcells,which is stronger than that of regular insulin.