Protective effects of Ginkgo biloba extract EGb 761 on the myocardium of experimentally diabetic rats - II. Ultrastructural and immunohistochemical investigation on microvessels and interstitium

Interstitial and microvascular disorders are known as a characteristic part of the diabetic cardiomyopathy and to resist partly insulin therapy. Aim o f this study was to demonstrate structure-protecting effects of Ginkgo Extr act EGb 761 known as a natural radical scavenger in streptozotocin-diabetic rats on the microvascular compartment. Wistar rats (n = 5) were made diabetical by i.p. injection of 60 mg/kg body mass streptozotocin for 4 months. Rats of the protected group (n = 5) rece ived daily 100 mg/kg body mass EGb 761 for 3 months, starting 1 month after induction of diabetes. 5 age-matched rats served as control. The volume fraction of interstitium was slightly but significantly increase d only in the unprotected diabetic group. Diminishing of the capillary to t he myocyte ratio was seen in the diabetic but not in the protected group. Immunostaining of collagen revealed a slight increase of type Ill, type IV, and type VI fibres in the interstitium, more expressed in the unprotected group. Ultrastuctural morphometry revealed significant thickening of endoth elial and muscular basement membranes in diabetic animals, less expressed i n the EGb- protected group. The capillary diameter was slightly increased i n the diabetic and slightly decreased in the protected group. The number of plasmalemmal vesicles was tendentially more decreased, that of lysosomes m ore increased in the diabetic than in the protected group. It is concluded that EGb 761 can diminish partly interstitial fibrosis and reduce endothelial and muscular basement membrane thickening of the diabeti c myocardium. It may contribute to prevent late diabetic complications.