Increased poly-(R)-3-hydroxybutyrate concentrations in streptozotocin (STZ) diabetic rats.

Poly-(R)-3-hydroxybutyrate, a linear polymer of the ketone body, R-3-hydroxybutyric acid, is an amphiphilic, water-insoluble, salt-solvating polymer. In humans, shortchain, complexed polyhydroxybutyrate has been found in a wide variety of tissues and in atherosclerotic plaques. In the circulation, plasma polyhydroxybutyrate concentrations correlate strongly with atherogenic lipid profiles. We compared polyhydroxybutyrate levels in plasma, kidney, eye, sciatic nerve, aorta, and brain of streptozotocin-diabetic and healthy control Sprague-Dawley rats, three weeks after injection. With the exception of brain, which showed only a marginal increase (1.3-fold), polyhydroxybutyrate levels were 3- to 8-fold greater in tissues from diabetic vs. control rats. Increases in polyhydroxybutyrate levels between normal and diabetic rat tissues were in order: sciatic nerve (9.0-fold), kidney (7.2-fold), plasma (6.0-fold), aorta (4.4-fold), and whole eye (2.9-fold). These data indicate a significant increase in polyhydroxybutyrate levels in organs affected by complications of diabetes, and further suggest that plasma polyhydroxybutyrate levels may serve as a marker for the disease.