Rapamycin inhibits oxidative and angiogenic mediators in diabetic retinopathy

To evaluate the role of rapamycin in the prevention of diabetic oxidative stress and the regulation of angiogenic factors.

Experimental animal study.

Diabetes was induced in 20 adult male Wistar rats by a single intraperitoneal administration of streptozotocin (60 mg/kg). Rats were randomly assigned into diabetic and rapamycin groups (n = 10). Ten healthy normal adult male rats of same age formed the control group. All groups were followed for 3 months. Rapamycin group received 1 mg/kg rapamycin via orogastric gavage during the last 4 weeks. At the end of 12 weeks, rats were sacrificed and biochemical oxidative stress markers (malondialdehyde and nitrotyrosine), together with vascular endothelial growth factor, hypoxia-inducible factor-1α, and pigment epithelium-derived factor, were measured in the retina. Blood biochemical analyses were also done.

In the diabetic group, retinal malondialdehyde and nitrotyrosine levels were increased in comparison with control and rapamycin groups (p < 0.05). Rapamycin suppressed oxidative stress and showed a beneficial effect. It also decreased all angiomodulator cytokines compared with the diabetic group (p < 0.05). Correspondingly, rapamycin also decreased plasma malondialdehyde levels compared with the diabetic group (p = 0.037).

Rapamycin may have a protective role against diabetes-induced oxidative retinal injury and may decrease angiomodulator cytokines.