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Increased vasodilatory prostaglandin production in the diabetic rat retinal vasculature
E I Johnson1, M E Dunlop, R G Larkins
1Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia. e.johnson@medicine.unimelb.edu.au
Purpose:
This study was undertaken in order to investigate whether the production of vasodilatory prostaglandins is increased in the retinal vasculature of the diabetic rat.
Methods:
Diabetes was induced in male Sprague-Dawley rats using streptozotocin. Diabetic rats were left uncontrolled for 3-4 weeks or were treated with insulin replacement throughout the period of diabetes. Control rats were age-matched. Retinal vessels extracted from retinae removed at sacrifice were incubated in a physiological salts solution. Prostaglandin E and prostaglandin I2 were measured in collected medium.
Results:
The production of both prostaglandin E and prostaglandin I2 by blood vessels isolated from the retina was increased by approximately 40% in streptozotocin-diabetic rats, compared to controls, within 4 weeks of the onset of diabetes. This increase was reversed by treatment of streptozotocin-diabetic rats with insulin. The increase in prostaglandin production was not due to alteration in the maximal capacity of cyclooxygenase enzyme.
Conclusions:
Increased production of vasodilatory prostaglandins occurs in the rat retinal vasculature early in diabetes. Prostaglandins may contribute to altered retinal hemodynamics in early diabetic retinopathy.