Effects Of Insulin On Adiponectin Secretion In Human Omental Adipocytes And Intervention Study

OBJECTIVE: To observe the effects of insulin concentration andculture time on omental adiponectin secretion and the influences ofrosiglitazone(RSG) on them in cultured adipocytes of type 2 diabetes andnon-diabetes controls.METHODS: Human Omental and subcutaneous abdominal adiposetissues were obtained from 12 patients undergoing selective surgery,including 6 type 2 diabetes and 6 non-diabetic patients, and adipocyteswere separated and purified through collagenase treatment. The purifiedadipocytes were cultured for 6,12,24 hours in different culture mediawith various final concentrations range (0.1,1,10,100,1000nmol/l)of insulin or/and RSG. The concentrations of adiponectin in culturemedia were detected by enzyme-linked immuno assay (ELISA).RESULTS: 1. Compared with the control, the treatment of omentaladipocytes with 100 nM insulin for various periods(6,12,24, 30, 36hours)decreased adiponectin secretion,and the maximal inhibition wasobserved when the adipocytes were cultured in insulin-containingmedium for 36 hours.2.Through the treatment of omental adipocytes of non-diabetic caseswith various concentrations of insulin-containing medium(0.1,1,10, 100,1000nmol/l) for 24 hours, significant 31% inhibition of adiponectinsecretion was detectable at insulin concentrations as low as 100 nmol/L,and a maximal 43% decrease was found at 1000 nmol/L insulin (allp＜0.05).3. The level of adiponectin secreted by the omental adipocytes oftype 2 diabetes is lower than non-diabetic group (p＜0.05). However thelevel of adiponectin secreted by the subcutaneous adipocytes of type 2diabetes is insignificantly lower than non-diabetic group (p＞0.05).4. The treatment of omental adipocytes of non-diabetic patients with100 nM insulin for 24 hours significantly decreased adiponectin secretionto 69％of control levels (p＜0.05). Cotreatment with RSG induced areversion of adiponectin secretion, and RSG 5umol/l to 83％and10umol/1 to 95％of control cells (p＜0.05).5. The treatment of omental adipocytes of type 2 diabetes with 100nM insulin for 24 hours significantly decreased adiponectin secretion to71％of control levels(p＜0.05). Cotreatment with RSG induced areversion of adiponectin secretion, and RSG 10umol/l to 91％of controlcells (p＜0.05).6. There was no significant difference of the effects of insulin or/andRSG on the secretion of adiponectin in omental adipocytes between type2 diabetes and non-diabetes controls. CONCLUSION: 1. Cultured in vitro, The insulin of high level decreasedthe secretion of adiponectin in a dose-and time-dependent fashion in thecultured omental adipocytes of non-diabetic cases.2. The level of adiponectin secreted by the omental adipocytes oftype 2 diabetes is significant lower than non-diabetic group.3. The inhibitory effect of insulin was reversed by cotreatment withRSG in a dose-dependent fashion. There was no significant difference ofthe effects of insulin or/and RSG on the secretion of adiponectin inomental adipocytes between type 2 diabetes and non-diabetic controls.