OBJECTIVETo investigate the role of mast cells and gut hormones and their interactions in TNBS-induced ulcerative colitis.

METHODSRat models of ulcerative colitis were established by a single intracolonic injection of 100 mg/kg TNBS (in 0.3 ml 50% ethanol). At 0, 6, 11, 16, 21 days after TNBS injection, the rats were sacrificed to determine the count of the mast cells. Histamine level in the whole blood, and the levels of histamine, substance P (SP), vasoactive intestinal peptide (VIP), and somatostatin (SS) in the distal colons were measured by fluorimetry or radioimmune assay. Immunofluorescence double staining was used to observe the relationship of the mast cells with SP, VIP, and SS positive nerve fibers.

RESULTSOn day 6 after TNBS injection, obvious ulcers occurred in the distal colon of the rats with significantly increased histamine level in the whole blood (P<0.05) but significantly decreased colonic histamine levels (P<0.05). The histamine levels in the whole blood and distal colon gradually recovered the normal levels. The mast cells significantly increased on day 16 (P<0.05) and maintained the high level till day 21. The distribution of mast cells was altered after TNBS injection, and the cells were found to aggregate in the myenteric region. SP levels in the distal colon significantly increased on day 11 (P<0.05) and maintained the high level till day 21. Immunofluorescence double staining revealed numerous mast cells close to the SP- and VIP-positive nerve fibers at different time points after TNBS injection. VIP positivity and the number of VIP-positive nerve fibers in the myenteric region were markedly increased, but no mast cells were observed in association with SP- and VIP-positive nerve fibers. The distribution of MC was not found to associate with the SS-positive nerve fibers.

CONCLUSIONThe mast cells and histamine released by them, as well as parasecretion of SP and VIP, participate in tissue damage by TNBS-induced colitis. Bidirectional neuroimmunomodulation of the mast cells, SP and VIP have important effect on the development of TNBS-induced colitis.

Animals ; Colitis, Ulcerative ; chemically induced ; metabolism ; pathology ; Disease Models, Animal ; Male ; Mast Cells ; secretion ; Rats ; Rats, Sprague-Dawley ; Substance P ; metabolism ; Trinitrobenzenesulfonic Acid ; toxicity ; Vasoactive Intestinal Peptide ; metabolism

BACKGROUND/AIMS: Bone marrow-derived cells (BMDC) contribute to tissue maintenance under many kinds of pathologic conditions. We carried out a study to see how BMDC play a role in the treatment of experimental murine colitis. METHODS: We divided the animals into 3 groups and treated them with 50% ethanol (control group), 2,4,6-trinitrobenzene sulfinic acid colitis (TNBS group), and TNBS+bone marrow transplant (BMT group). To induce colitis, TNBS (5.0 mg/mouse) dissolved in 50% ethanol was injected into anus weekly for two weeks. Bone marrow transplantations were performed using bone marrow of male transgenic mouse (donor) with green fluoresence protein (GFP) into female wild type mouse (recipient) three weeks before TNBS instillation. All animals were sacrificed, and colons were extracted one week after the last TNBS instillation. We measured microscopic scores of mucosal injury and investigated the GFP expression for bone marrow engraftment. The immunostaining of vimentin and alpha-smooth muscle actin (alpha-SMA) for myofibroblasts was performed. RESULTS: The score of mucosal injury in the TNBS group was much more severe than those in control, and reduced significantly by BMT (p<0.05). GFP-positive cells were almost deposited in pericryptal niche of BMT group but not at all in both control and TNBS group. Most of myofibroblasts stained with both vimentin and SMA also infiltrated into pericryptal niche. But, the number of myofibroblasts stained with vimentin and SMA in both control and TNBS group was smaller than that in BMT group. CONCLUSIONS: BMDC deposited on pericryptal niche might have a significant role in repairing acute experimental murine colitis.
Actins/metabolism ; Acute Disease ; Animals ; *Bone Marrow Transplantation ; Colitis/chemically induced/pathology/*surgery ; Female ; Fibroblasts/cytology ; Intestinal Mucosa/cytology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Transplantation, Homologous ; Trinitrobenzenesulfonic Acid/*toxicity ; Vimentin/metabolism

Central sensitization is essential in maintaining chronic pain induced by chronic pancreatitis (CP), but cortical modulation of painful CP remains elusive. Here, we examined the role of the anterior cingulate cortex (ACC) in the pathogenesis of abdominal hyperalgesia in a rat model of CP induced by intraductal administration of trinitrobenzene sulfonic acid (TNBS). TNBS treatment resulted in long-term abdominal hyperalgesia and anxiety in rats. Morphological data indicated that painful CP induced a significant increase in FOS-expressing neurons in the nucleus tractus solitarii (NTS) and ACC, and some FOS-expressing neurons in the NTS projected to the ACC. In addition, a larger portion of ascending fibers from the NTS innervated pyramidal neurons, the neural subpopulation primarily expressing FOS under the condition of painful CP, rather than GABAergic neurons within the ACC. CP rats showed increased expression of vesicular glutamate transporter 1, and increased membrane trafficking and phosphorylation of the N-methyl-D-aspartate receptor (NMDAR) subunit NR2B and the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) subunit GluR1 within the ACC. Microinjection of NMDAR and AMPAR antagonists into the ACC to block excitatory synaptic transmission significantly attenuated abdominal hyperalgesia in CP rats, which was similar to the analgesic effect of endomorphins injected into the ACC. Specifically inhibiting the excitability of ACC pyramidal cells via chemogenetics reduced both hyperalgesia and comorbid anxiety, whereas activating these neurons via optogenetics failed to aggravate hyperalgesia and anxiety in CP rats. Taken together, these findings provide neurocircuit, biochemical, and behavioral evidence for involvement of the ACC in hyperalgesia and anxiety in CP rats, as well as novel insights into the cortical modulation of painful CP, and highlights the ACC as a potential target for neuromodulatory interventions in the treatment of painful CP.
Animals ; Anxiety/etiology* ; Chronic Pain/etiology* ; GABAergic Neurons ; Gyrus Cinguli/metabolism* ; Hyperalgesia/metabolism* ; Pancreatitis, Chronic/pathology* ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Trinitrobenzenesulfonic Acid/toxicity*

BACKGROUNDThalidomide could relieve clinical symptoms and intestinal mucosal lesions effectively in children with refractory inflammatory bowel disease (IBD) from the pre-clinical study. This study aimed to observe the therapeutic effect of thalidomide by the established animal model of IBD model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in Sprague-Dawley (SD) rats and to investigate the possible mechanism of action.

METHODSA total of 82 SD rats of about 4-5 weeks were randomly divided into three groups: the control group (25 rats), TNBS-treated group (29 rats), and thalidomide treatment group (28 rats). Daily activities were recorded. At least eight rats from each group were killed on the 4th, 7th, and 14th days. Morphological and histological changes in the colon were individually assessed. Serum was collected and the levels of TNF-α and interleukins (IL-1β and IL-10) were assayed by ELISA method. The expression of colonic mucosal nuclear factor (NF)-κB was assayed with the immunohistochemical method.

RESULTS(1) In the control group, diarrhea and rectal bleeding recovered rapidly and no death was recorded. In the TNBS-treated group, diarrhea and rectal bleeding persisted for a longer time. The mortality rate was 10.34% during the observation period. In the thalidomide treatment group, diarrhea and rectal bleeding persisted for a significantly shorter time than the TNBS-treated group (P < 0.01). The rats of this group also exhibited faster weight gain on day 7 compared with the TNBS-treated group but still lower than that of the control group. The mortality rate of the thalidomide treatment group was 3.57%. (2) Macroscopic and microscopic scores of the thalidomide-treated group were significantly lower than those of the TNBS model group on the 14th day (P < 0.01). These results suggested faster and better colonic recovery in the thalidomide-treated group. (3) NF-κB expression in the colonic mucosa of the control group was lower than in the others, mainly distributed in the cytoplasm. A large amount of intra-nuclear and cytoplasm staining was observed (more prominently intra-nuclear) in the TNBS model group and the thalidomide treatment group. On the 7th and 14th days, intra-nuclear NF-κB-containing cells in the thalidomide treatment group were still significantly lower than those in the TNBS model group (P < 0.01). (4) In the control group, the cellular inflammatory factors (TNF-α, IL-1β, and IL-10) were expressed at a low level while in the other two groups they were already expressed at a significantly higher level on day 4. On day 7 the expressions of TNF-α and IL-1β in the thalidomide treatment group were lower than in the TNBS model group. On day 14, the expressions of TNF-α and IL-1β in the thalidomide treatment group were significantly lower than in the TNBS model group (P < 0.05). On day 4, the IL-10 levels of the thalidomide treatment group became significantly elevated. The levels gradually decreased but still remained at a higher level. In the TNBS model group, the IL-10 expression peaked later than in the thalidomide treatment group.

CONCLUSIONSThalidomide was effective in the management of TNBS-induced colitis in young rats. This may be due to the suppression and down-regulation of NF-κB and the expression of the downstream inflammatory mediators (TNF-α and IL-1β). There is also indication that the expression of the anti-inflammatory cytokine (IL-10) is concomitantly up-regulated as well.

Animals ; Colitis ; chemically induced ; drug therapy ; metabolism ; Cytokines ; metabolism ; Inflammatory Bowel Diseases ; chemically induced ; drug therapy ; metabolism ; Interleukin-10 ; metabolism ; Interleukin-1beta ; metabolism ; NF-kappa B ; metabolism ; Rats ; Rats, Sprague-Dawley ; Thalidomide ; therapeutic use ; Trinitrobenzenesulfonic Acid ; toxicity ; Tumor Necrosis Factor-alpha ; metabolism