The role of mitochondrial apoptotic pathway in the apoptosis of cultured bovine retinal capillary pericytes induced by constant and intermittent high glucose / 中华内分泌代谢杂志

ABSTRACT

Objective To study the effects of constant and intermittent high glucose on the apoptosis of cultured bovine retinal capillary pericytes (BRPs), and to investigate the role of mitochondrial apoptotic pathway in the apoptosis of BRPs. Methods After being cultured under glucose with different concentrations tot 6 days, the change of uhrastructure of BRPs was observed under electronmieroscope, the apoptosis of pericytes was detected by TUNEL method, the mitochondrial inner transmembrane potential (△Ψm) was detected by laser scanning confocal microscopy, the change of cytochrome c (cyt-c) was assayed by spectrophotometer and the expression of apoptotic genes was detected by immunohistochemical method and RT-PCR. Results (1) BRPs showed typical changes of apoptosis in constant and intermittent high glucose concentrations. The apoptosis induced by constant high glucose concentration was more obvious than that by intermittent high glucose. (2) Constant and intermittent high glucose concentrations obviously decreased △Ψm compared with control group. The △Ψm of BRPs was correlated negatively with the apoptotie rate of BRPs (r = - 0.89, P < 0.01) ; (3) Constant and intermittent high glucose concentrations increased the release of cyt-c from mitochondria to cytoplasm, and the concentration of cyt-c in the cytoplasm was correlated positively with the apoptotic rate of BRPs (P < 0.01) ; (4) Constant and intermittent high glucose concentrations increased the expression of proapoptotie gene Bax and decreased the expression of prosurvival gene Bcl-2, resulting in increased Bax/Bcl-2 ratio. Bax/Bcl-2 ratio was negative correlatied with the △Ψm of BRPs, and positively eorrclaticd with the concentration of cyt-c in cytoplasm and apoptotic rate (both P < 0.01).Conclusion Constant and intermittent high glucose concentrations could decrease △Ψm, increase the release of cyt-c and induce the apoptosis of BRPs, the effects being stronger with constant high glucose concentration. The mitochondrial apoptotic pathway plays an important role in the apoptosis of BRPs, in which Bax and Bcl-2 are involved.