Adipocyte dysfunction in rats with streptozotocin–nicotinamide‐induced diabetes

Abstract

Administration of streptozotocin (STZ) and nicotinamide (NA) to adult rats allows for the induction of mild diabetes. However, this experimental model has not been fully characterized. This study was undertaken to determine the metabolic and secretory activity of adipose tissue in rats with STZ-NA-induced diabetes. Experiments were performed using epididymal adipocytes isolated from control and mildly diabetic rats. Lipogenesis, glucose transport as well as glucose and alanine oxidation, lipolysis, anti-lipolysis, cAMP levels and adipokine secretion were compared in cells isolated from the control and diabetic rats. Lipogenesis, glucose transport and oxidation were diminished in the adipocytes of diabetic rats compared with the fat cells of control animals. However, alanine oxidation appeared to be similar in the cells of non-diabetic and diabetic animals. Lipolytic response to low epinephrine concentrations was slightly increased in the adipocytes of diabetic rats; however, at higher concentrations of the hormone, lipolysis was similar in both groups of cells. The epinephrine-induced rise in cAMP levels was higher in the adipocytes of STZ-NA-induced diabetic rats, even in the presence of insulin. Lipolysis stimulated by dibutyryl-cAMP did not significantly differ, whereas anti-lipolytic effects of insulin were mildly decreased in the cells of diabetic rats. Secretion of adiponectin and leptin was substantially diminished in the adipocytes of diabetic rats compared with the cells of control animals. Our studies demonstrated that the balance between lipogenesis and lipolysis in the adipose tissue of rats with mild diabetes induced by STZ and NA is slightly shifted towards reduced lipid accumulation. Simultaneously, adiponectin and leptin secretion is significantly impaired.

Coadministration of alloxan and nicotinamide in rats produces biochemical changes in blood and pathological alterations comparable to the changes in type II diabetes mellitus

“…It is more likely that this choice reflects the preference of researchers because there is a lack of reports suggesting that one method is superior over the other. [24][25][26][27] In these studies, rats are usually administered with NA 15 min before STZ injection because STZ causes pancreatic -cell destruction, while the administration of NA prior to STZ can partially protect -cell against STZ, resulting in partial loss of glucose metabolism and only moderate insulin deficiency. 28 Several reports have demonstrated that this DM model is useful to explore the efficacy of various diabetogenic drugs.…”

Cyclohexane extract of walnut leaves improves indices of oxidative stress, total homocysteine and lipids profiles in streptozotocin‐induced diabetic rats

“…In the diabetic rats treated with walnut leaves extract levels of TC, HDL-c, TG, VLDL-c, and LDL-c improved and did not show significant difference with the control group. It was previously observed that STZ-nicotinamide induced diabetic rats develop significant disturbances in lipid metabolism in the rat adipose tissue (Szkudelska, Nogowski, & Szkudelski, 2014). It is known that insulin exerts an anti-lipolytic effect via phosphorylation of cGMP-inhibited cAMP phosphodiesterase which leads to reduction in cAMP in the adipocytes (Czech, Tencerova, Pedersen, & Aouadi, 2013).…”

Resveratrol loaded glycyrrhizic acid-conjugated human serum albumin nanoparticles for tail vein injection II: pharmacokinetics, tissue distribution and bioavailability

“…Studies have shown that RES has a variety of protective effects on human health such as an analgesia (Bazzo et al, 2013), age defying (Hsu et al, 2014), regulation of lipoprotein metabolism, platelet aggregation inhibitor and vasodilator (Wang et al, 2008). In the pancreatic tissues, RES increases antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase, and glutathione peroxidase to improve the activity of antioxidant defenses and protects pancreatic cells from free radical damage (Szkudelska et al, 2014). Several studies have shown that RES administration increases insulin sensitivity in patients with T2DM and diabetic rats (Zhu et al, 2017).…”