Insulin-like growth factor I (IGF-1) supplementation prevents diabetes-induced alterations in coenzymes Q9 and Q10.

Diabetes, which causes enhanced oxidative stress, is a multifactorial disease that leads to deleterious effects in many organ systems within the body. Ubiquinones (coenzyme Q(9) and Q(10)) are amphipathic molecular components of the electron transport chain that function also as endogenous antioxidants and attenuate the diabetes-induced decreases in antioxidant defense mechanisms. Insulin-like growth factor 1 (IGF-1) is considered to be an "essential surviving factor", the level and function of which are compromised in diabetes. This study investigated the impact of IGF-1 supplementation on ubiquinone levels in a rat model of type I diabetes. Adult male Sprague-Dawley rats were divided into four groups: control, control plus IGF-1, diabetic and diabetic plus IGF-1. Diabetic animals received a single intravenous injection of streptozotocin (STZ, 55 mg/kg). IGF-1 supplementation groups received a daily intraperitoneal dose of 3 mg IGF-1 per kilogram body weight for 7 weeks. Coenzyme Q(9) and Q(10) levels were assessed by ultraviolet detection on high pressure liquid chromatography. STZ caused a significant reduction in body weight and an elevation in blood glucose level, which were not prevented by IGF-1 supplementation. In addition Q(9) and Q(10) levels in diabetic liver were significantly elevated. IGF-1 supplementation prevented liver alterations in Q(10) but not Q(9) levels. Q(9) and Q(10) levels in diabetic kidney were significantly depressed, and these deleterious effects were abolished by IGF-1 treatment. These data suggest that IGF-1 antagonizes the diabetes-induced alterations in endogenous antioxidants including coenzyme Q(10), and hence may have a therapeutic role in diabetes.