| Aims:The aims of this study were to observe changes of the distal colonic transit and ICC in constipation diabetic rats induced by STZ.Methods:Twenty male Sprague-Dawley rats, weighing 250-300 g were used in the present study. The rats were purchased from Tongji Medical College and housed under normal laboratory conditions (18-22℃,12/12h light-dark cycle) with free access to food and water ad libitum. This study was started after the rats were adapted to the environment, usually after one week. Diabetes was induced with a single intraperitoneal injection of streptozotocin (Alexis Biochemicals, San Diego, CA, USA) 60 mg kg-1 freshly dissolved in 20 mmol 1-1 citrate buffer solution (Sigma, St Louis, MO, USA). Age matched controls were injected with an equal volume of citrate buffer (PH=7.4). Blood glucose, body weight and the distal colonic transit time were measured prior to injection as well as 1 week,4 weeks and 8 weeks after injection. The expression of c-kit (ICC marker) in colon was measured by immunohistochemistry, real-time polymerase chain reaction methods (Real-time PCR) and Western blot.Results:(1) There were no differences in the baseline blood glucose among each group. At the end of 1 week,4 weeks and 8 weeks, the blood glucose level in the diabetic rats was markedly higher than that of the controls (32.0±1.7 mmol L-1 vs 6.2±1.1 mmol L-1,P=0.000; 33.1±0.4 mmol L-1 vs 6.5±1.2 mmol L-1,P=0.000; 32.9±0.7 mmol L-1 vs 5.7±0.9 mmol L-1,P=0.000). (2) No differences in the baseline body weight between two groups. At the end of 4 and 8 weeks, the body weight of the rats in DM group did not increase, whereas the control group gained weight (293.3±10.8 g vs 377.8±9.0 g, P=0.000; 266.5±19.4 g vs 481.5±42.2 g, P=0.000). (3) No differences were noted in the baseline colonic transit time between two groups. At the end of 4 and 8 weeks, the distal colonic transit in DM group were delayed significantly (122.0±6.4 min vs 16.1±3.2 min,P=0.000; 265.7±23.9 min vs 15.1±4.5 min, P=0.000). (4) Real-time polymerase chain reactions studies suggested that the mRNA levels of c-kit in distal colon tissue were decreased markedly in diabetic group compared with control group (0.4±0.1 vs 5.7±1.4, P=0.000). (5) A large number of c-kit positive cells presented in colon tissue in the normal rats, c-kit expression was markedly decreased in diabetic group. In contrast to the control, the expression of c-kit was markedly decreased in DM group (0.144±0.035 vs 0.915±0.071, P=0.000).Conclusions:The data suggested that the distal colonic transit were markedly delayed in constipation diabetic rats induced by STZ, and accompany by the missing of the interstitial cell of Cajal. Aims:The aims of the study were to observe changes of the SCF/Kit signaling in STZ-induced constipation diabetic rats and to study their roles in the maintain of ICC and distal colonic transit.Methods:A total of twenty adult male Sprague-Dawley rats (250-350 g) were used in the present study. Rats were purchased from Experiment Animal Center of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. They were housed under normal laboratory conditions (12/12 h light-dark cycle,18-22℃) and were given water ad libitum. The study was started after 1 week, when the rats were adapted to the environment. Diabetes was induced with a single intraperitoneal injection of streptozotocin (Alexis Biochemicals, San Diego, CA, USA) 60 mg kg-1 freshly dissolved in 20 mmol 1-1 citrate buffer solution (Sigma, St Louis, MO, USA). Age matched controls were injected with an equal volume of citrate buffer (PH=7.4). Animals were sacrificed at the end of 8 weeks. Real-time PCR and Western blot were used to analyze the expressions of mRNA and protein for menbrane-bound SCF (M-SCF). Enzyme linked immunosorbent assay (ELISA) was used to detecte the concentrations of soluble SCF (S-SCF) in serum.Results:(1) Real-time polymerase chain reactions studies suggested that the mRNA levels ofmembrane-bound stem cell factor in colon tissue were decreased markedly in untreated diabetic group compared with control group (0.6±0.2 vs 2.9±0.5, P=0.000); (2) The protein expression of c-kit in untreated diabetic group was markedly decreased compared with control group (0.194±0.016 vs 0.971±0.055, P=0.000); (3) In contrast to control group, soluble stem cell factor was decreased significantly in untreated diabetic group (13.3±4.9 pg ml-1 vs 22.4±2.9 pg ml-1, P=0.000). Conclusions:The expressions of M-SCF in colon tissue and the concentrations of S-SCF in serum decreased markedly in the STZ-induced constipation diabetic rats, both of them were crucial in the maintaining the distal colonic transit and ICC. Aims:A loss in interstitial cells of Cajal (ICC) is associated with diabetic gastrointestinal dysmotility. Electroacupuncture (EA) at ST-36 is an effective therapy to relieve gastrointestinal symptoms. However, potential roles of EA on ICC in diabetic rats are still unknown. To evaluate the effects of EA on ICC in diabetic rats and investigate whether changes in stem cell factor (SCF) pathway was involved in the regulative effect of EA on ICC.Methods:Male Sprague-Dawley (SD) rats were randomly divided into control group, diabetic group (DM), DM-plus-sham stimulation group (SEA), DM-plus-low frequency stimulation group (LEA), DM-plus-high frequency stimulation group (HEA). EA at ST-36 was performed daily for 8 weeks. Body weight and blood glucose were measured prior to streptozotocin injection, one week, four weeks and 8 weeks after injection. Bead expulsion test was used for measuring the distal colonic transit. In vitro contractile response of colonic muscle strips with or without ICC removing were studied. The expression of c-kit (ICC marker) in colon was measured by immunohistochemistry, real-time polymerase chain reaction methods (Real-time PCR) and Western blot. The SCF in colon tissues (M-SCF) was detected by Real-time PCR and Western blot. The SCF in serum (S-SCF) was detected by ELISA.Results:(1) Body weight was elevated in HEA group. Meanwhile, blood glucose remained high and unchanged by different modalities of EA treatment at the end of 4 and 8 weeks. (2) No differences were noted in the baseline colonic transit time among the five groups. At the end of 4 & 8 weeks, the distal colonic transit in DM group were delayed significantly (122.0±6.4 min vs.16.1±3.2 min, P=0.000; 265.7±23.9 min vs.15.1±4.5 min, P= 0.000). While HEA at ST-36 significantly promoted the distal colonic motility at the end of 4 & 8 weeks (36.7±6.6 min vs.122.0±6.4 min, P=0.000; 43.1±4.2 min vs.265.7±23.9 min, P=0.000). (3)%variation of the muscle strips contraction was significantly elevated in LEA and HEA group compared with DM group, and the same as% decrease between before and after ICC removed. (4) In contrast to diabetic rats, the expression of c-kit was markedly increased in LEA and HEA group. (5) In contrast to diabetic rats, the expression of M-SCF was markedly increased in LEA and HEA group. (6) The change in S-SCF paralleled that of c-kit.Conclusions:Electroacupuncture can promote the distal colonic transit and contractility of colonic muscle strips partially through increasing the number of ICC in diabetic rats, and these effects may be mediated by elevated endogenous SCF level. |
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