Role of the renin–angiotensin system in the development of cataract formation in angiotensin‐II‐induced experimental rats

Abstract

Previously, we established several facts regarding hypertension-associated cataractogenesis. As a follow-on study, we evaluated the role of the renin-angiotensin system (RAS) in angiotensin-II (Ang-II)-induced cataract formation in experimental hypertensive rats. Sprague-Dawley male albino rats (150-180 g) were used for the present experiment. The animals were divided into four groups, with six animals in each group. During the 12 weeks of the experimental protocol, the normal group received sterile water (1 ml/kg/day, subcutaneously (sc), and the Ang-II control group received angiotensin (1 mg/kg/day) subcutaneously. The ARB (O) group received olmesartan (2 mg/kg/day) orally, and the ARB (T) group received two drops of olmesartan (5 mM) topically on the cornea; concurrently, both groups were treated with Ang-II (1 mg/kg/day, sc) to induce hypertension. Biweekly, the systolic and the diastolic blood pressures were recorded, and the eyes were examined; moreover, cataractogenic parameters, such as oxidative stress markers and protein contents in the lenses, were evaluated after completion of the experimental protocol. Twelve weeks of olmesartan administered, orally or topically, significantly reduced the progression of cataract formation and restored antioxidants, lipid peroxidation, nitrite content, and protein contents in the lenses of the mice in groups O and T, respectively, as compared with those in the Ang-II control group. On the basis of our results, we conclude that the ocular RAS exacerbates the lenticular oxidative stress that may lead to cataract formation. The results showed that the RAS has an independent and important role in cataract formation under hypertensive conditions.

Impacts of angiotensin II on retinal artery changes in apolipoprotein E deficient mice

“…These terms have a close relationship to visual function, which suggested that the visual function might be impaired due to Ang II. In fact, RAS plays an important role in visual function from various aspects [30][31][32] . Researchers have found that RAS could promote age-related macular degeneration in mouse models and angiotensin II type 1 receptor (AT1R) blocker could reversed the retinal pigmented epithelial cell condition and visual function [30] .…”

Effects of Angiotensin Receptor Blockers on Streptozotocin-Induced Diabetic Cataracts

“…Additionally, the renin-angiotensin system (RAS) is present in human aqueous humor [15]. The local RAS, operating through this aqueous humor circulation, is involved in cataract formation in angiotensin II-induced rats [16], and ARBs are effective in suppressing oxidative stress in diabetic cataracts [17]. Therefore, the RAS is hypothesized to participate in oxidative stress associated with the formation of diabetic cataracts.…”