Purchase this article with an account.
T. Yamagami, T. Sugiyama, H. Oku, A. Komori, M. Kobayashi, T. Ikeda, D.G. Puro; Cell death induced by activation of NMDA receptors in the retinal microvasculature . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3275.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The concentration of glutamate in the vitreous is increased in patients with diabetic retinopathy. Although not previously studied in retinal capillaries, activation of glutamate receptors initiates neuronal cell death in brain and retina. Here, we tested the hypothesis that activation of N–methyl–D–aspartate (NMDA) receptors can also induce cell death in the retinal microvasculature. Methods:We studied pericyte–containing microvessels that were freshly isolated from the adult rat retina. Microvessels were exposed to a glutamate– or NMDA–containing solution for 24 hours. Microvascular cell viability was quantitatively assessed by the trypan blue dye exclusion. We also performed immunocytochemistry using NMDA–R1 receptor antibodies and calcium imaging using fura–2 AM. Results:After a 24–hour exposure to glutamate, microvascular cell death was observed in a concentration–dependent manner (0.5 mM: 16.1±11.9%, 1 mM: 20.8±6.6%, 3 mM: 27.4±9.7%) in contrast with untreated cells (8.0±3.9%) (p <0.0001). Glutamate (1mM)–induced cell death was significantly (p =0.0008) prevented by the application of a selective NMDA receptor antagonist, MK–801, dose–dependently (1 µM: 6.4±6.7%, 10 µM: –0.3±4.1%). NMDA (1 mM) induced more cell death (22.7±6.6%, p =0.0113) than the comparable glutamate concentration. We also observed that glutamate and NMDA increased the intracellular calcium concentration of microvascular cells by a MK–801–dependent mechanism. Further evidence that retinal microvascular cells express NMDA receptors was our finding of immunoreactivity for NMDA–R1 subunits. Conclusions:In the retinal microvasculature activation of NMDA receptors induces cell death. By activating these receptors, glutamate may play a role in the progression of diabetic retinopathy.
This PDF is available to Subscribers Only