Hypertension potentiates cataractogenesis in rat eye through modulation of oxidative stress and electrolyte homeostasis.

PURPOSE: To evaluate modes of cataractogenesis in the hypertensive state by using different hypertensive animal models, including fructose, cadmium chloride (CdCl2), N ω-nitro-l-arginine methyl ester (l-NAME), and two-kidney, one clip (2K1C) method.

METHODS: Male Sprague-Dawley albino rats (150-180 g) were divided into different groups, each group containing six animals. Hypertension was induced in animals via six weeks administration of fructose (10% solution in drinking water), CdCl2 (0.5 mg/kg/day, i.p.), and l-NAME (20 mg/kg/day, p.o.) in their respective groups and NaCl (0.9% solution in drinking water) in the 2K1C group. The Ramipril-treated group (2 mg/kg/day, orally) served as a standard group for the 2K1C animal model. Blood pressure was measured biweekly using non-invasive blood pressure system. The biochemical parameters in serum and eye lenses were evaluated after six weeks of the experimental protocol.

RESULTS: Hypertensive animal models showed significant induction of systolic and diastolic blood pressure and modulation of oxidative stress through depletion of antioxidants, including glutathione peroxidase, catalase, superoxide dismutase, glutathione, and elevation of malondialdehyde in serum and eye lenses. A significant elevation of ionic contents (Na(+) and Ca(2+)) and reduction of total protein and Ca(2+) ATPase activity in eye lenses were observed in all hypertensive animal models except l-NAME when compared with the normal group. The significant restoration of the antioxidants, Malondialdehyde (MDA) total protein, and ionic contents in the eye lenses concomitant with reduction of blood pressure were observed in the ramipril-treated group as compared to the 2K1C animal model. The results indicate that the fructose, CdCl2, and 2K1C models showed pronounced cataractogenic effects in the rat eye lenses.

CONCLUSION: Based on our findings, it can be concluded that systemic hypertension significantly increases the risk of cataract formation in the rat eyes via modulation of the antioxidant defense mechanism and electrolyte homeostasis.