Serum Omentin In Diet-induced Obese Rats And Its Biologic Effects After Exogenous Omentin Injections

Objective: To investigate serum omentin level and its mRNAexpression in omental adipose tissue in rats fed with high fat diet, anddocument biological effects of exogenous recombinant omentin afterinjections in obese rats.Material and methods: Forty male adult Sprague-Dawley rats wererandomly divided into2groups:10rats in nomal group fed with normaldiet,30rats in experimental group with high fat diet (HFD). Body weightwas measured weekly. After6weeks, rats fed HFD and ranged in top20weight gain were randomly divided into2groups:10rats in control groupand10rats in intervention group. Saline was injected into rats of normaland control groups, while recombinant human omentin were injected viatail vein for rats in intervention group at a dosage of6μg per rat. Rats innormal group (n=10) were fed with normal diet and ones in control andintervention groups were fed with the HFD until end of the study. At10weeks, omentin injection was carried out once again at a dose of3μg perrat. At end of our study, only9rats were left in each group. Blood samples were taken from heart for the measurements of serum glucose, lipids,insulin, and omentin. Adipose tissue samples were taken for determinationof mRNA expression of omentin by RT-PCR. Carotid artery was taken todetect the thickness of the arterial intima.Results:(1) After12weeks of HFD feeding, body weight, weightgain and the obesity index were significantly higher in rats fed HFD thanthose in control group (591.71vs525.98g,286.59vs211.89g,0.049vs0.027, P<0.05for all comparisons).(2) LDL was significantly higher in thecontrol and the intervention groups, i.e. fed with HFD, than those in controlgroup as well (0.29vs0.20mmol/L,0.30vs0.20mmol/L, P<0.05).(3)Significant higher serum omentin level and its mRNA expression inomental adipose tissue were found in obese rats compared with the normalrats (99.68vs56.98μg/L,1.25vs1.06, P<0.05for all).(4) Obesity-relatedindicators and arterial intima-media thickness didn’t significantly differbetween the intervention and control groups.Conclusions: According to our knowledge, it is the first time todocument that serum omentin and its mRNA expression in omental adiposetissue are increased in high fat diet-induced obese rats. Our findings areinconsistent with the results found in population-based studies. No effectswere observed in obese rats after omentin intervention.