Effect of Insulin on Adiponectin and Adiponectin Receptor-1 Expression in Rats with Streptozotocin-induced Type 2 Diabetes

Abstract

The present study was designed to investigate the effect of insulin on insulin resistance (IR), plasma adiponectin level and expression of adiponectin receptors 1 (AdipoR1) in obese and streptozotocin-induced type 2 diabetic rats. Male Sprague-Dowley rats were randomized to control group and 3 obese experimental groups. Type 2 diabetic mellitus was induced in the 3 rd and 4 th experimental groups by given 30 mg/kg of a single dose streptozotocin via intraperitoneal injection (i.p.). Fourth group was treated with i.p. 1 IU insulin/kg/day for 6 days before end of the experiment which lasts for 8 weeks while same amount of normal saline was i.p. given to other group. At the end of the study (8 weeks), plasma levels of adiponectin, triglycerides (TG), cholesterol, fasting blood glucose and insulin were measured. Obesity index (OI) and IR were calculated. AdipoR1 mRNA levels in the soleus muscle tissue were semi-quantitated. Hyperlipidemia, hyperinsulinemia and hyperglycemia were observed in both obese and diabetic rats, which were accompanied by hypoadiponectinemia and down regulation of AdipoR1 expression as compared to the control rats. Adiponectin was negatively correlated with all the biochemical parameters assessed. Insulin treatment significantly improved these metabolic abnormalities and effectively restored adiponectin and AdipoR1 to the control level. In conclusion, adiponectin and its receptor-associated cascade may be aberrantly regulated in both obesity and type 2 diabetes and targeting adiponectin and its receptors may offer a novel therapy against obesity and type 2 diabetes.

Elevated Plasma Adiponectin Level and Peripheral Blood Leukocyte Adiponectin Receptor Expression in Dogs Suffering from Insulin Deficiency

“…Moreover, this reduction in adiponectin receptor expression may be related to alteration in systemic inflammation status, due to insulin, which may be reflected by plasma FFA levels. FFAs are known potent physiological inducers of TNF-production in adipocytes [33] and a pro-inflammatory response in -cell islets [34]. Obese animals demonstrated 2x more plasma FFA as compared to control animals; whereas ID animals demonstrated 50% higher plasma FFA pre-insulin treatment, and 50% less plasma FFA post-insulin treatment, as compared to control animals.…”

Spirulina Reverses Histomorphological Changes in Diabetic Osteoporosis in Pioglitazone Treated Rats

“…Blood samples were drawn at weekly intervals on the day 7, 14, 21 the animals were anesthetized with ether, and blood was collected from retro-orbital puncture. About 30 µl serum was then separated for the estimation of Glucose [21], Triglyceride [22], HDL [23] LDL [24], adiponectin levels [25] (Rat adiponectin ELISA kit; Linco Research Inc.) and serum insulin was estimated by radio immuno assay kit purchased from Stat Diagnostics (Linco Research Inc.), Mumbai, India. All other reagents and chemicals used in the study were of analytical grade.…”