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A. E. Pysczynski, R. Raithel, M. Bobbie, S. Roy, A. Simon, S. Roy; Effect of Sustained Connexin-43 Downregulation on Retinal Vascular Lesions. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5912.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if reduced Connexin 43 (Cx43) expression over time influences the development of acellular capillaries (AC) and pericyte ghosts (PG) in the retinal capillaries of mice.
Retinal vascular network was isolated by the trypsin digest technique from eyes of Cx43+/- knockout mice sacrificed at early (~8 wks), mid (~16 wks), and late time points (~23 wks), and compared to those of wild type mice. Digital images of ten random fields of the retinal vascular network stained with hematoxylin and PAS were recorded and analyzed for AC and PG. To determine the expression of Cx43, Bax, and caspase-3, retinal protein isolated from the contralateral eyes of each animal were subjected to Western blot analysis.
With increased duration of Cx43 downregulation, a significant increase in the number of AC was observed in the retinal capillaries compared to those of control at each time point; early time point: 229±143% of control, p=0.027, mid time point: 386%±179% of control, p=0.0003, and late time point: 286%±143% of control, p=0.004. Similarly, with increased duration of Cx43 downregulation, a significant increase in the number of PG was observed in the retinal vasculature; early time point: 225%±75% of control, p=0.018, mid time point: 300%±198% of control, p=0.015, and late time point: 250%±125% of control, p=0.020. Western blot analysis showed significant increase in Bax protein expression with increased duration of Cx43 downregulation at each time point; early time point: 251±116, p=0.050, mid time point: 288±76, p=0.003, and late time point: 273±113, p=0.03 (reported as % of control). Increased caspase-3 expression was observed in the Cx43 KO mice at mid (130% of control) and late time points (170% of control) compared to that of normal mice.
The findings indicate that the effect of reduced Cx43 expression on retinal vascular lesions is manifested at an early time point. Since high glucose has been shown to downregulate Cx43 expression, this provides further evidence that reduced Cx43 expression may play an early role in the development of vascular lesions associated with diabetic retinopathy.
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