ISSN No. 1606-7754                   Vol.8 No.3 December 2000

Effects of Insulin Insufficiency and High Glucose on Cell Survival of Dog Retinal Capillary Pericytes

Masatoshi Murata, Shinichi Sakurai, Peter F. Kador and Sanai Sato

Laboratory of Ocular Therapeutics, National Eye Institute, National Institute of Health, Bethesda, Maryland, U.S.A.

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Abstract

The selective loss of capillary pericytes has been well established as a hallmark of diabetic retinopathy. In this study, using cultured dog retinal capillary pericytes, the effects of insulin and high glucose on the viability of pericytes have been investigated. Dog retinal capillary pericytes were cultured in DMEM medium supplemented with 20% fetal calf serum (FCS). Cell viability was evaluated in medium containing 1% FCS. The expression levels of the insulin receptor and bcl-2 were examined by RT-PCR. Mitogen-activated protein (MAP) kinase was assayed by Western blot using monoclonal antibody against phospho-Elk-1 (ser383). Cell viability of the cultured retinal pericytes was significantly higher when cultured in medium containing insulin for 7 days than when cultured without insulin. Cells treated with insulin increased the expressions of both the insulin receptor and bcl-2. Activation of MAP kinase was also detected. In contrast, cell viability and the expression levels of the insulin receptor and bcl-2 were all down-regulated when 50 mM glucose was added to the culture medium. The data suggest that insulin is of importance in maintaining dog pericytes. The data also suggest that, under hyperglycemic conditions, pericytes become more susceptible to the various insults that initiate the process of apoptosis

Key words: Retinal pericyte; dog; retinopathy; insulin; insulin receptors

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