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Teruyo Kida, Hidehiro Oku, Taeko Horie, Tsunehiko Ikeda; Vasoactive factors and chorioretinal blood flow in spontaneous hypertensive rats. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4263.
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© ARVO (1962-2015); The Authors (2016-present)
Systemic hypertension is a risk factor for retinal vein occlusion (RVO) in humans, and the RVO can lead to retinal ischemia. The purpose of this study was to investigate whether vasoactive factors such as endothelin-1 (ET-1), nitric oxide (NO), and vascular endothelial growth factor (VEGF) are involved in the retina of spontaneous hypertensive rats (SHR).
Retinas from SHR and age-matched normotensive Wistar-Kyoto rats (WKY) were fixed by perfusion under deep anesthesia with pentobarbital. The retinal tissues were removed, and retinal sections were immunostained for the ET-A and ET-B receptors, VEGF, and iNOS (induced NO synthase). The protein levels of both ET-1 receptors, HIF-1 (hypoxia-inducible factor 1), VEGF, and iNOS were also determined in the retinal tissues by western blot analysis. In addition, the chorioretinal blood flow was assessed by laser speckle flowgraphy before and after an intravenous injection of ET-1 to examine whether these vasoactive factors were associated with the blood flow in the eyes of SHRs.
The immunoreactivities to both ET-1 receptors, VEGF, and iNOS were significantly higher than in the SHR retinas than in the WKY retinas. The protein levels of both ET-1 receptors, HIF-1, VEGF, and iNOS were also significantly higher in SHR retinas than in WKY retinas. The chorioretinal blood flow was significantly decreased in the retinas of SHRs after the injection of ET-1.
Systemic hypertension induces an increase in the expression of the ET-1 receptors which can then cause vasoconstriction and ischemia mediating HIF-1 in the retina, while the VEGF and iNOS are associated with the vasodilation in the retina. The increase in the level of vasoactive factors in the retina of SHRs suggests that these factors could be the inducers of the pathomechanisms leading to RVO.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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