Abstract
Purpose: :
To test the hypothesis that low dose periocular delivery of insulin to the retina of diabetic rats, may be neuroprotective in early diabetic retinopathy.
Methods: :
Regular human insulin in a dose of 0.0325IU/100g body weight or vehicle (1xPBS) was injected subconjunctivally for 4 consecutive days in control and 1 month diabetic male Sprague Dawley rats. The biological effects of subconjunctival insulin on retinal neurodegeneration were analyzed by evaluating pro-survival Akt-1 signaling. Retinal cell death was assessed by TUNEL staining of flat mounted whole retinas.
Results: :
Low dose subconjunctival insulin injections for 4 consecutive days did not have any effect on systemic blood glucose levels or animal weights. However, it restored pro-survival Akt-1 kinase activity (p<0.04) in the retina and reduced the rate of apoptosis (p=0.0004) seen in early diabetic retinopathy.
Keywords: diabetic retinopathy • neuroprotection • apoptosis/cell death