ABSTRACT
Objective To observe the role of brain-derived neurotrophic factor (BDNF) in the plasticity of enteric nervous-smooth muscle system,and to investigate the effects of BDNF induced plasticity on gastrointestinal motility in mice.Methods Male hybrid BDNF knockout (BDNF+/) mice and wild type (BDNF+/+) mice were selected,eight in each group.Gastrointestinal motility of BDNF+/+ mice and BDNF+/ mice were tested and compared.Longitudinal muscle strips of mice colon smooth muscle were prepared.The effects of carbachol (1 × 10 5 mol/L) and BDNF (1 × 10 7 mol/L) on contractile function of muscle strips were observed.And the effects of tetrodotoxin (TTX,1 × 10-6 mol/L) on BDNF induced contractile function of muscle strips were also studied.The changes of the density of mice intestinal myenteric plexus and the expression of smooth muscle α-actin (α-SMA) in colon smooth muscle were detected by immunohistochemical techniqne.The ultrastruetural alterations of myenteric plexus,neuromuscular junction (NMJ) and smooth muscle cells were detected by transmission electron microscope (TEM).T-test or Rank sum test was performed for comparison between groups.Results Number of feces particles and water content in feces of BDNF+/-mice ((3.80±0.75) and (39.60±1.47)％) were both lower than those of BDNF+/+ mice ((6.30± 1.03) and (51.00± 1.61) ％),and the differences were statistically significant (t=4.792,12.827;both P＜0.05).Carbachol (1 × 10-5 mol/L) could significantly increase contraction activity of smooth muscle of BDNF+/+ mice (R =3.26 ± 0.43) and BDNF+/-mice (R=2.15 ± 0.36),and the difference was statistically significant (t=15.754,9.632;both P＜0.05).The effects on contraction exciting of smooth muscle strips of BDNF+/+ mice were more significant than BDNF+/ mice,and the difference was statistically significant (t =5.972,P＜0.05).BDNF could significantly increase contraction of muscle strips of BDNF+/+ mice and R value increased from 1 to 1.41±0.09,and the differences were statistically significant (t=13.674,P＜0.05).TTX could obviously inhibit the excitatory effects of BDNF,R value decreased from 1.41 ± 0.09 to 1.03 ± 0.04 (t=11.692,P＜0.05).The density of myenteric plexus of BDNF+/ mice (median 5.8％,interquartile range 4.2％-7.0％) was significantly lower than that of BDNF+/+ mice (median 9.0％,interquartile range 7.1％-10.8％),and the difference was statistically significant (Z =3.730,P＜ 0.05).The expression of α-SMA of BDNF+/-mice (median 33.4％,interquartile range 28.8％-38.5％) was significantly lower than that of BDNF+/+ mice (median 44.6％,interquartile range 39.2％-48.8％),and the difference was statistically significant (Z=4.565,P＜0.05).The results of TEM indicated ultrastructural alterations of myenteric plexus,NMJ and smooth muscle in BDNF+/-mice.Conelusionss BDNF could induce the plasticity of morphology and function in enteric nervous-smooth muscle system,which may play an important role in mice gastrointestinal motility.
ABSTRACT
Objective To investigate the assessment methods and mechanisms of nonsteroidal antiinflammatory drugs (NSAID)-induced injury in rat small intestinal epithelial barrier,and to explore the protective effects of mucosal protective agents and antacids on it.Methods A total of 96 rats were evenly divided into the morphologic observation group and the mechanism research group,and 48 in each group.Then each group was evenly divided into eight subgroups:the healthy control group,the model group (model established with indomethacin),the teprenone prevention group,the rabeprazole prevention group,the treatment control group,the teprenone treatment group,the rabeprazole treatment group and the teprenone and rabeprazole combined group (combined group),six in each group.Exfoliated cells gap density of small intestine of each subgroup was determined by confocal laser endomicroscopy.Serum level of tumor necrosis factor-α (TNF-α)was measured with enzyme-linked immunosorbent assay (ELISA). The expression of nuclear factor-κB (NF-κB),caspase-3,zonula occludens-1 (ZO-1 )and occludin at protein level was detected by Western blotting.The LSD-t test or Hamhane′s T2 test was performed for statistical analysis.Results The exfoliated cells gap densities of the teprenone prevention group and the rabeprazole prevention group were (57.43 ± 24.55 )/1 000 and (59.80 ± 21 .14 )/1 000,respectively, which were both lower than that of the model group ((110.93±50.58)/1 000),and the differences were statistically significant (t= 53.50 and 54.13,both P < 0.01 ).The exfoliated cells gap density of the combined group was (40.53 ±15 .39)/1 000,which was lower than that of the treatment control group ((93.80±40.65 )/1 000 ),and the difference was statistically significant (t =44.27,P <0.01 ).The serum levels of TNF-α of the teprenone prevention group and the rabeprazole prevention group were (25 .80±8.97)ng/L and (22.74 ±7.15 )ng/L,repsectively,which were both lower than that of the model group ((44.48 ± 7.42 )ng/L),and the differences were statistically significant (t = 18.68 and 21 .74,both P <0.01 ).The serum level of TNF-αof the combined group ((13.66 ±4.98)ng/L)was lower than that of the treatment control group ((24.67±6.70)ng/L),and the difference was statistically significant (t = 9.02,P < 0.01 ).The caspase-3 levels of teprenone prevention group and rabeprazole prevention group were 1 .47 ±0.35 and 1 .58 ±0.34,and the NF-κB levels of these two groups were 1 .27±0.14 and 1 .21 ± 0.10,respectively.Compared with those of model group (2.44 ± 0.45 and 1 .69±0.13),the differences were statistically significant (t =0.97,0.86,0.42 and 0.48,respectively, all P <0.01 ).The levels of caspase-3 and NF-κB of the combined group were 0.66±0.06 and 0.44 ± 0.21 ,respectively,which were lower than those of the treatment control group,and the differences were statistically significant (t=0.34 and 0.56,both P <0.01).The expressions of occludin at protein level of the teprenone prevention group and the rabeprazole prevention group were 0.69 ±0.16 and 0.74 ±0.11 , and the levels of ZO-1 were 0.81 ± 0.08 and 0.84 ± 0.12.Compared with those of the model group (0.45 ±0.22 and 0.64±0.07 ),the differences were statistically significant (t =0.24,0.29,0.17 and 0.21 ,respectively,all P <0.01 ).The levels of occludin and ZO-1 of the combined group were 2.50 ± 0.46 and 1 .76±0.18,which were higher than those of the treatment control group,and the differences were statistically significant (t =1 .50 and 0.76,both P <0.01 ).Conclusions The exfoliated cells gap density may be a valuable indicator to predict the degree of inflammation response and permeability of epithelial barrier as well as to evaluate efficacy of medication.Teprenone and rabeprazole have prevention and treatment effects on NSAID-induced injury in rat small intestine.
ABSTRACT
Objective To investigate the correlation between the expression changes of brain-derived neurotrophic factor (BDNF) in colon mucosa and abdominal pain in irritable bowel syndrome (IBS). The density of nerve fiber in colon mucosa and ultrastructural alterations of nerve fiber in IBS were also observed. Methods From September 2008 to January 2010,the IBS patients who visited the department of gastroenterology of our hospital and met the Rome Ⅲ diagnosis criteria were selected and divided into IBS with diarrhea (D-IBS) and IBS with constipation (C-IBS) according to their clinical features. The patients with colon polyps detected by colonoscopy in our hospital were selected as control group. All subjects were asked to fill in Self-Rating abdominal pain or abdominal uncomfortable Scale according to abdominal symptom in the last 2 weeks before visit and underwent colonoscopy. Four biopsy specimens were taken from the colon mucosa of rectosigmoid junction. Ofwhich,two specimens were for protein isolation and detection of BDNF expression level,one specimen was used for PGP 9. 5 immunohistochemistry staining in paraffin slices. Another specimen was used to observe the ultrastructure changes of nerve fiber in colon mucosa under transmission electron microscopy. Results Total 40 IBS patients were enrolled in this study,of those 21 were D-IBS patients,19 were C-IBS patients,and 21 were controls. The abdominal pain severity score and frequency score of IBS patients were (2. 3±0. 8) and (2. 1±0. 7),which were significantly higher than those of control group (0. 4±0. 7 and 0. 3±0. 5,P＜0. 001). Compared with the control group,the BDNF expression in colon mucosa was significantly elevated in IBS patients (P= 0. 003 ),and which correlated with the severity and frequency of abdominal pain/discomfort (r=0. 57,P＜0. 001and r=0. 46,P= 0. 003,respectively). The immunohistochemistry result indicated that the nerve fiber density in colon mucosa of IBS patients was significantly higher than that of controls,and there were ultrastructural changes of colon mucosal nerve fibers in IBS patients. Conclusion Increased colon mucosal BDNF expression may be associated with abdominal pain symptom in IBS patients. The impaired ultrastructural of mucosal nerve fibers may cause the increased BDNF expression in colon mucosa,and result in the increased mucosal nerve fiber density in IBS patients.