The Role Of Soy Isoflavones In Expression Of α-MSH Protein,POMC MRNA And Ob-Rb MRNA Of Diet-induced Obesity Rats

Objectives:To observe the role of oral SIF on DIO rats with respects to body weight and histologic morphology of abdominal adipocytes, detect expression levels of a-MSH protein,Ob-Rb mRNA, POMC mRNA in some tissues, discusse the possibility of Ob-Rb-POMC pathway induced by SIF, and provid morphology basis of the corresponding mechanisms.Methods:Eighty SPF sexually male rats weight140±10g aged4-5weeks old,feed with high fat and sugar diet for8weeks to copy DIO rats model, then randomly divided into four groups, respectively lavage with low (50mg/kg-BW), med (150mg/kg-BW), high (450mg/kg-BW) dose SIF and solven for4weeks, set standard control group (lavage with solvent) always. Measure body weights every week,then fixe the rats by perfusing4%paraformaldehyde and make frozen sections of abdominal fat, brain, pituitary gland, heart, lung, kidney, jejunum and stomach. Sudan Ⅲ dyeing is used to observe abdominal adipocyte, immunohistochemical SABC method to detect distribution and expression of a-MSH protein,oligonucleotide probe in situ hybridization method to distribution and expression of POMC mRNA and Ob-Rb mRNA.Achieved microscopic images and measured values of IOD.Results:(1) An average DIO rats weighed363.91±2.46g (n=54), higher than based control group (273.00+5.37g, n=12) plus1.4times of standard deviation,suggested succeed in copying DIO rats model;150and450mg/kg dose SIF significantly reduced DIO rats’weight; in DIO rats,abdomen adipocytes were significantly increased in area, various in morphological and distributed unevenly,150and450mg/kg SIF significantly decreased area of adipocytes,maintainedniformity of the distribution and morphological,shown a certain therapeutic effect on obesity.(2) Expression of a-MSH protein, POMC mRNA, Ob-Rb mRNA in ARC of DIO rats decreased,150and450mg/kg SIF significantly resisted the decline;a-MSH and a little POMC mRNA positive signal was detected in pituitary, SIF enhanced the expression.(3) Expression of a-MSH protein in lungs of DIO rats decreased,while Ob-Rb mRNA and POMC mRNA Increased,450mg/kg SIF regulated the expression to levels of based control rats.(4) Expression of Ob-Rb mRNA in gastric gland of DIO rats decreased, SIF significantly enhanced its expression; POMC mRNA positive signal was only detected in gastric gland of obese control rats.(5) Positive signals of a-MSH protein and POMC mRNA were detected in lamina propria of jejunum villi,which were weaker of obese rats than based control rats. SIF significantly increased the expression; Ob-Rb mRNA positive singal was only detected in jejunum villi of med and high dose groups.(6)Only a-MSH positive signal was detected in kidneys, specifically located at the glomerular,proximal and distal convoluted tubule, and decreased in obese rats,reversed by oral administration of SIF.(7) a-MSH positive signal was detected in myocardial cell nuclei and cardiovascular, its level decreased in obese rats, reversed by oral administration of SIF. Conclusions:Oral SIF regulated expression expression of a-MSH protein, POMC mRNA and Ob-Rb mRNA expression, thereby improving leptin resistance of DIO rats, down-regulated the level of obesity. And a-MSH protein and POMC mRNA, Ob-Rb mRNA may participate in Initiation of high-fat and high-sugar diet-induced gastric mucosal injury, obesity-related respiratory dysfunction and kidney disease, simultaneously play a role in maintain normal blood pressure and so on.