Effect of the ACE inhibitor Zofenopril on the Oxidative Status of the Eye in Animals with Experimental Glaucoma

Overview

Aims: To evaluate the effect of zofenopril on oxidative stress markers and antioxidant enzyme activity in ocular tissues of rabbits with experimentally induced glaucoma.

Materials and Methods: An experimental model of adrenaline-induced glaucoma (AIG) was developed in 2–2.5-year-old rabbits. Zofenopril, an angiotensin-converting enzyme (ACE) inhibitor, was administered orally as an aqueous suspension (1 mg/kg body weight) daily for three months. Oxidative stress was assessed by measuring malondialdehyde (MDA) levels as a marker of lipid peroxidation (LPO), hydroxyl and superoxide radical generation, and the activity of antioxidant enzymes (glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT)). Intraocular pressure (IOP) in rabbits was measured using an applanation tonometer under local anesthesia with 0.5% Alcaine. Spectrophotometric analysis was performed on the retina, optic nerve, and drainage zone tissues.

Results: In the AIG modeling group, a dynamic increase in IOP was observed: by 28.3% after 30 days, by 34.2% and 46.7% after 60 and 90 days, respectively, compared to baseline data. Oral administration of zofenopril suspension during AIG modeling resulted in a milder elevation of IOP –⁠ by 17.4% on day 30 (p < 0.05) –⁠ followed by a gradual decline to 110.1% and 105.4% of baseline values on days 60 and 90, respectively. On day 90 of the study, rabbits with AIG exhibited significant activation of LPO and elevated MDA levels in ocular tissues: by 54.1% in the retina, 39.9% in the optic nerve, and 70.1% in the drainage zone, compared to controls (intact animals) (p < 0.01). Enhanced free radical generation was observed: hydroxyl radical levels increased by 71.3% in the retina, 58.9% in the optic nerve, and 81.8% in the drainage zone; superoxide radical levels increased by 78.4%, 64.4%, and 94.2%, respectively. Antioxidant enzyme activity declined in the retina, with GPx decreasing by 35.9%, SOD by 42.4%, and CAT by 30.7%, compared to the controls. Zofenopril administration during glaucoma modeling resulted in reduced MDA levels: by 19.3% in the retina, 16.1% in the optic nerve, and 28.1% in the drainage zone, compared to the untreated AIG group. Hydroxyl radical generation also decreased by 23.0% in the retina, 21.9% in the optic nerve, and 23.9% in the drainage zone. Superoxide radical levels were reduced by 20.3% in the retina and 24.9% in the drainage zone. In contrast, antioxidant enzyme activity increased in the retina: GPx rose by 33.6%, SOD by 26.2%, and CAT by 21.6%, compared to the untreated AIG group.

Conclusion: Prolonged systemic administration of zofenopril in a rabbit model of glaucoma effectively attenuated oxidative stress and stabilized intraocular pressure. Zofenopril prevented a progressive rise in IOP observed in untreated animals, maintaining IOP values close to physiological levels throughout the experiment. The treatment resulted in a marked decrease in LPO and MDA accumulation within the retina, optic nerve, and drainage zone, along with reduced generation of hydroxyl and superoxide radicals and a significant restoration of antioxidant enzyme activity.

Keywords:

glaucoma – Rabbits – Retina – Optic nerve – oxidative stress – experimental model – drainage zone tissues – ACE inhibitor zofenopril – free radical processes – antioxidant enzymes