Microvascular retinopathy in the Zucker diabetic fatty rat

Abstract

Purpose: To determine if quantifiable morphometric signs of retinopathy occur in the Zucker diabetic fatty rat (ZDF/Gmi-fa, formerly designated ZDF/Drt), a partially inbred strain in which the genetic propensity for diabetes is only expressed in obese males.

Methods: Retired diabetic (ZDF/Gmi-fa) and control lean Zucker (fa/+) breeder rats were examined for quantifiable evidence of microvascular changes of the retinal capillaries by gross examination, trypsin digestion of retinal vessels, and transmission electron microscopy.

Results: Gross examination of retinas and trypsin digestion of capillaries revealed no differences. Quantitative assessment of capillary cell nuclear density showed that diabetic retinas were hypercellular compared to lean rats (3.888 +/- 0.041 versus 3.304 +/- 0.046 nuclei per 100 microns (mean +/- SE), P = 0.0042). Transmission electron microscopic analysis of retinal capillary basement membrane thickness demonstrated thicker measurements in diabetic animals (mean thickness 21% greater in diabetic rats, P = 0.0307).

Conclusions: This model may be useful for pharmacologic intervention studies because it is naturally and severely non-insulin-dependent diabetic, there are quantifiable retinal vascular changes, and same-sex litter mates can be used as controls.