Functional effects of dextran sulphate sodium (DSS) treatment on the longitudinal muscle of rat distal colon

VSL#3 probiotics exerts the anti-inflammatory activity via PI3k/Akt and NF-κB pathway in rat model of DSS-induced colitis

VSL#3 probiotics can be effective on induction and maintenance of the remission of clinical ulcerative colitis. However, the mechanisms are not fully understood. The aim of this study was to examine the effects of VSL#3 probiotics on dextran sulfate sodium (DSS)-induced colitis in rats. Acute colitis was induced by administration of DSS 3.5 % for 7 days in rats. Rats in two groups were treated with either 15 mg VSL#3 or placebo via gastric tube once daily after induction of colitis; rats in other two groups were treated with either the wortmannin (1 mg/kg) via intraperitoneal injection or the wortmannin + VSL#3 after induction of colitis. Anti-inflammatory activity was assessed by myeloperoxidase (MPO) activity. Expression of inflammatory related mediators (iNOS, COX-2, NF-κB, Akt, and p-Akt) and cytokines (TNF-α, IL-6, and IL-10) in colonic tissue were assessed. TNF-α, IL-6, and IL-10 serum levels were also measured. Our results demonstrated that VSL#3 and wortmannin have anti-inflammatory properties by the reduced disease activity index and MPO activity. In addition, administration of VSL#3 and wortmannin for 7 days resulted in a decrease of iNOS, COX-2, NF-κB, TNF-α, IL-6, and p-Akt and an increase of IL-10 expression in colonic tissue. At the same time, administration of VSL#3 and wortmannin resulted in a decrease of TNF-α and IL-6 and an increase of IL-10 serum levels. VSL#3 probiotics therapy exerts the anti-inflammatory activity in rat model of DSS-induced colitis by inhibiting PI3K/Akt and NF-κB pathway.

Nicotine-induced neurogenic relaxation in the mouse colon: changes with dextran sodium sulfate-induced colitis

Nicotine has been shown to reduce both tone and muscular activity in the human colon by releasing nitric oxide (NO) from nerves. To our knowledge, however, the effect of nicotine on mouse colon has not been elucidated, and the response in tissue from ulcerative colitis (UC) has not been investigated. We examined nicotine-induced responses in colon from control mice and mice with dextran sodium sulfate (DSS)-induced UC. In controls, bath application of nicotine caused a transient relaxation in longitudinal preparations from the transverse and distal colons but not from the rectum. The response was observed in the presence of bethanechol, abolished by treatment with tetrodotoxin and hexamethonium, and mediated partially (>50%) by the NO pathway. In longitudinal preparations of the distal colon from DSS-treated mice, spontaneous contractions decreased markedly, and nicotine caused contraction without relaxation in half of the preparations tested. Nicotine-induced relaxation in the presence of bethanechol was significantly decreased in the DSS-treated distal colon without changing bethanechol-induced contractions. These data suggest that 1) responses to nicotine differ dependent on colon regions, 2) DSS treatment predominantly caused nicotine-sensitive neurogenic changes in distal colon, and 3) DSS treatment may reverse the direction of nicotine-evoked responses in the colon, in mice.

Blockade of colony stimulating factor-1 (CSF-I) leads to inhibition of DSS-induced colitis

BACKGROUND

Intestinal inflammation associated with inflammatory bowel disease (IBD) is typically characterized by an inflammatory cell infiltrate and pro-inflammatory cytokine production. Of particular interest, the frequency of colony stimulating factor-1 (CSF-l)-expressing cells is increased in active lesions. In this study, we have investigated the role of CSF-1 in mucosal inflammation, using a murine model of colitis induced by dextran sulfate sodium (DSS).

METHODS

A neutralizing anti-CSF-1 antibody was administered to Balb/c mice that received DSS in their drinking water. Signs of colitis, such as clinical disease score, cellular infiltrate, and cytokine production, were assessed.

RESULTS

Administration of a neutralizing anti-CSF-1 antibody significantly inhibited DSS-induced colitis. Clinical symptoms, such as weight loss and the appearance of diarrhea or fecal blood, were reduced by CSF-1 blockade; histologic scores were also improved. The cellular infiltrate of macrophages and T cells was inhibited and a trend toward reduced production of pro-inflammatory cytokines was noted.

CONCLUSIONS

This is the first study to demonstrate that CSF-1 plays an important role in mediating intestinal mucosal inflammation and therefore may prove to be an attractive therapeutic target for intestinal diseases such as inflammatory bowel disease.

Neurogenic and non-neurogenic mechanisms in response of rat distal colon muscle to dextran sulphate sodium treatment

We studied, by organ bath methodology, how experimental colitis in rat, induced by the administration of dextran sulphate sodium (DSS) in the drinking water (3% for 3 or 7 days, or 5% for 7 days; Controls received ordinary tap water), may influence spontaneous, contractile activity of the longitudinal muscle layer. DSS treatment caused a dose-dependent increase in phasic contractile activity of the colon muscle. This effect needed an optimal preload of the tissues to be evident, and was non-neurogenic (i.e. myogenic and/or paracrine) in nature. Moreover, the DSS treatment appeared to impair a neurogenic, nitric oxide (NO)-dependent, relaxant response to the stretch (i.e. preload) applied to the tissues. Inducible NO synthase was localized by immunohistochemistry to infiltrating mononuclear cells in the colon wall. We propose that NO, via the inducible pathway, exerts marked effects on the neuromuscular apparatus in the DSS model of experimental colitis.