Effects of chronic administration of fruit extract (Citrus unshiu Marc) on endothelial dysfunction in streptozotocin-induced diabetic rats.

We investigated the effects of chronic administration of fruit extract (Citrus unshiu MARC) on the endothelial dysfunction seen in aortae from streptozotocin (STZ)-induced diabetic rats. A ten-week administration of this fruit extract preserved acetylcholine (ACh)-induced endothelium-dependent relaxation, but not sodium nitroprusside (SNP)-induced endothelium-independent relaxation, in the diabetic aorta. In age-matched control rats, chronic administration of the fruit extract had no influence on the ACh- or SNP-induced aortic relaxation. The increased total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride levels seen in STZ-induced diabetic rats were not normalized by fruit-extract treatment. These results suggest that Citrus unshiu MARC extract preserves endothelial function in the aorta in STZ-induced diabetic rats without lowering plasma cholesterol. This beneficial effect may be due to this extract protecting of nitric oxide against inactivation by oxygen free radicals.