RESUMO
BacKground:The mechanism of diabetic gastrointestinaI dysmotiIity is stiII uncIear. More and more studies showed that gastrointestinaI smooth muscIe derived factors pIay an important roIe in gastrointestinaI dysmotiIity. RecentIy,the roIe of RhoA/ROCK signaIing pathway in diabetic compIications become a research hotspot. Aims:To investigate the possibIe roIe of RhoA/ROCK signaIing pathway in diabetic coIon dysmotiIity by examining the expressions of major signaIing moIecuIes in diabetic coIon muscIe. Methods:NormaI coIon tissue sampIes taken from patients undergoing radicaI surgery for coIonic cancer from Sept. 2012 to Dec. 2013 at the First AffiIiated HospitaI of Nanjing MedicaI University were coIIected. According to gIycated hemogIobin IeveI,the patients were divided into diabetes meIIitus( DM)group and controI group. The expressions of major signaIing moIecuIes in RhoA/ROCK1 signaIing pathway incIuding RhoA,ROCK1,MYPT1 and p-MYPT1 were determined by immunohistochemistry or Western bIotting. Results:Immunohistochemistry showed that expression of RhoA protein in DM group was significantIy Iower than that in controI group(P0. 05). Conclusions:The inhibition of RhoA/ROCK signaIing pathway in diabetic coIon muscIe may have some correIation with diabetic coIon dysmotiIity.
RESUMO
Background:Myopathy due to smooth muscle cells( SMC)abnormalities is involved in the pathogenesis of diabetic gastroparesis(DGP),however,the relationship between myopathy and advanced glycation end products(AGEs)is not fully clarified. Aims:To investigate the ultrastructural changes of gastric SMC in patients with diabetes mellitus( DM)and the relationship between expressions of contractile proteins and AGEs. Methods:Full-thickness gastric specimens from 30 gastric neoplasm patients undergoing gastrectomy from July 2012 to December 2012 at the First Affiliated Hospital with Nanjing Medical University were collected. Of them 15 patients had DM( DM group)and the other 15 patients without ( control group). Ultrastructure of SMC was observed by transmission electron microscopy. Expressions of three contractile proteins[ myosin heavy chains( MHC),α-actin and calponin]and Nε-carboxymethyllysine( CML),the key component of AGEs in gastric muscular layer were determined by Western blotting,and expressions of MHC,α-actin and calponin mRNA were determined by real-time PCR. Correlations of mRNA expressions of three contractile proteins with protein expression of CML were analyzed by Pearson correlation coefficient. Results:In DM group,significant ultrastructural changes were found in gastric SMC,including disruption of gap junction,swelling of mitochondria,occurring of lipofuscin in cytoplasm,increase in cell membrane alveolae,and thickening of basal lamina. Protein and mRNA expressions of muscular MHC,α-actin and calponin were significantly lower in DM group than in control group(P all ﹤0. 01),while protein expression of CML was significantly higher in DM group(P ﹤0. 01). In gastric muscular layer of DM group, negative correlations were found between expressions of MHC,calponin mRNA and CML protein(r= -0. 59,P=0. 02;r= -0. 63,P=0. 01),but no correlation was seen between α-actin mRNA and CML protein(r= -0. 49,P=0. 06). Conclusions:Disruption of SMC ultrastructure,decrease in contractile proteins and increase in AGEs are existed in gastric muscular layer of DM patients,and there is a negative correlation between contractile proteins and AGEs. These changes may cause impaired contractility of SMC,and subsequently lead to gastric motility disorders in diabetic patients.