Dietary caloric restriction modifies inflammatory responses in the livers of streptozotocin-induced diabetic rats

Chronic systemic low-grade inflammation plays a key role in the development of insulin resistance, a hallmark of type 2 diabetes. Caloric restriction has been shown to improve glycemic control in diabetes and moderate expression of some markers of inflammation that are up-regulated during aging. Forty male Wistar rats were subjected to 30% caloric restriction (20 animals) and ad libitum feeding (20 animals) for 9 weeks before induction of diabetes by intraperitoneal administration of 35 mg/kg body weight streptozotocin. Caloric restriction significantly increased the concentrations of haptoglobin, interleukin (IL)-1β, IL-10, and reduced the tumor necrosis factor-α, IL-4, and IL-6 levels in the nondiabetic and diabetic animals when compared with their counterparts. The results presented show that caloric restriction was able to down-regulate the proinflammatory mediators and up-regulate the antiinflammatory cytokines implicated in inflammatory responses during diabetes. These changes are probably attributed to the reduction in deposition of adipose tissues in the liver and concomitant decrease in organ weights.