A pilot study on mechanisms of hyperadiponectinemia in two rat models with different in vivo insulin sensitivity |
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| Authors: | RAN Jian-min LAO Gan-cheng ZHANG Yang LIU Wei FENG Qiong XIONG Xiao-qing XIE Bin GUO Jian |
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| Institution: | Department of Endocrinology, Guangzhou Red Cross Hospital, The Fourth Affiliated Hospital of Medical College, Jinan University, Guangzhou 510220, China.E-mail:ranjm@163.com |
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| Abstract: | AIM:To explore the possible mechanisms of hyperadiponectinemia in the insulin-resistant Zucker fatty rats (ZF) and insulin-sensitive nephrotic syndrome rats induced by puromycin aminonucleoside (PA).METHODS:8-week old Zucker rats were fed with standard rat chow for 4 weeks and Wistar rats were intraperitoneally injected single dose of PA 10 d before experiments.Blood samples and 24 h urines were collected for detecting the lipid profiles, adiponectin (ADPN), albumin and urine albumin excretion rate (UAER).A frequently sample intravenous glucose tolerance test (FSIVGTT) was conducted.The insulin sensitivity index (SI) and glucose effectiveness index (SG) were calculated according to Bergmans minimal model.Epididymal white adipose tissues were then extracted for weighting.Correlations between ADPN and other parameters were analyzed by Pearsons correlation.RESULTS:Both ZF rats and PA-injected rats showed significantly higher plasma ADPN levels compared with their own controls ［(7.44±1.23)mg/L vs (2.44±0.33)mg/L and (8.64±0.88)mg/L vs (2.95±0.46)mg/L, respectively, P<0.01］.SI and SG were markedly decreased and negatively correlated to ADPN in Zucker rats, but not changed and correlated to ADPN in Wistar rats.Hyperlipidemia was observed in either ZF rats or PA-injected rats and was positively correlated to ADPN levels.Two hyperadiponectinemic rats showed markedly higher UAER ［(64.8±14.2)mg/24 h vs (14.9±14.6)mg/24 h and (275.1±64.5)mg/24 h vs (15.4± 4.5)mg/24 h, respectively, P<0.01］ and positively correlated with ADPN.The ratio of white adipose tissue to body weight was higher in ZF rats than that in their control rats despite its disproportion with ADPN, while it was comparable between PA-injected and normal rats.The renal creatinine clearance rate was not altered in both strains of rats.CONCLUSION:Hyperadiponectinemia is a common property in ZF rats and PA-induced nephrotic syndrome rats, and it cant be interpreted by changes of in vivo insulin sensitivity.Markedly increased UAER in both rats is the key mechanism of hyperadiponectinemia. |
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