1,2-Diacylglycerol has been proposed to be a secondary messenger; therefore, in this study we evaluated the amount of
1,2-diacylglycerol in heart tissue from
streptozocin-induced diabetic rats and examined the effect of
insulin treatment on
1,2-diacylglycerol content. Diabetic rats had lower body and ventricular weights and higher ratios of ventricular to
body weight, all of which shifted toward normal values after 4 wk of untreated diabetes followed by 4 wk of
insulin treatment. The contents of major
phospholipids were significantly depressed in the diabetic rat hearts. In contrast, the
triglyceride and
cholesterol contents in the myocardium were increased by
streptozocin injection and completely normalized by
insulin treatment, and
glucose levels returned to normal. The
1,2-diacylglycerol content in the myocardium was also significantly elevated in the diabetic rats compared with age-matched controls. Moreover, the
1,2-diacylglycerol content was significantly higher in rats with 4 wk of diabetes than in those with 8 wk of diabetes.
Insulin treatment in the diabetic rats, however, did not produce any decrease in
1,2-diacylglycerol content. The results of this study suggest that the development of
cardiomyopathy induced by
streptozocin injection is associated with a high
1,2-diacylglycerol level, which may result in the activation of
protein kinase C.
Insulin is one of the agonists that generates
1,2-diacylglycerol in myocytes; however, the relationship between the sustained
1,2-diacylglycerol level and the normalization of diabetes by
insulin administration is unclear.