Roles of calcium and IP3 in impaired colon contractility of rats following multiple organ dysfunction syndrome

Investigating Gut Permeability in Animal Models of Disease

A growing number of investigations report the association between gut permeability and intestinal or extra-intestinal disorders under the basis that translocation of gut luminal contents could affect tissue function, either directly or indirectly. Still, in many cases it is unknown whether disruption of the gut barrier is a causative agent or a consequence of these conditions. Adequate experimental models are therefore required to further understand the pathophysiology of health disorders associated to gut barrier disruption and to develop and test pharmacological treatments. Here, we review the current animal models that display enhanced intestinal permeability, and discuss (1) their suitability to address mechanistic questions, such as the association between gut barrier alterations and disease and (2) their validity to test potential treatments for pathologies that are characterized by enhanced intestinal permeability.

Latitude, Vitamin D, Melatonin, and Gut Microbiota Act in Concert to Initiate Multiple Sclerosis: A New Mechanistic Pathway

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). While the etiology of MS is still largely unknown, scientists believe that the interaction of several endogenous and exogenous factors may be involved in this disease. Epidemiologists have seen an increased prevalence of MS in countries at high latitudes, where the sunlight is limited and where the populations have vitamin D deficiency and high melatonin levels. Although the functions and synthesis of vitamin D and melatonin are contrary to each other, both are involved in the immune system. While melatonin synthesis is affected by light, vitamin D deficiency may be involved in melatonin secretion. On the other hand, vitamin D deficiency reduces intestinal calcium absorption leading to gut stasis and subsequently increasing gut permeability. The latter allows gut microbiota to transfer more endotoxins such as lipopolysaccharides (LPS) into the blood. LPS stimulates the production of inflammatory cytokines within the CNS, especially the pineal gland. This review summarizes the current findings on the correlation between latitude, sunlight and vitamin D, and details their effects on intestinal calcium absorption, gut microbiota and neuroinflammatory mediators in MS. We also propose a new mechanistic pathway for the initiation of MS.

IL-6, TNF-α, and iNOS is associated with decreased colonic contraction in rats with multiple organ dysfunction syndrome

BACKGROUND

Gastrointestinal stasis is frequently accompanied by multiple organ dysfunction syndrome (MODS), which may lead to gastrointestinal smooth muscle dysfunction. The aim of this study is to investigate whether MODS initiates an inflammatory response and produces IL-6, TNF-α, and iNOS cytokines, as well as to determine whether these cytokines give rise to gastrointestinal smooth muscle dysfunction.

MATERIALS AND METHODS

Sixty Wistar rats were divided equally into a negative control group, a positive control group, and a MODS group. The number of stool spots, the contractility of muscle strips in the colon, and morphologic changes to the colon smooth muscle were recorded. The mRNA and protein expressions of IL-6, TNF-α, and iNOS in the colon were detected by semiquantitative reverse transcription polymerase chain reaction and immunohistochemistry respectively. In addition, the NO level was observed.

RESULTS

For the MODS group, the colon stool numbers, maximal contractive stress, and spontaneous frequency of muscle strips were, respectively, 0.77 ± 0.52 pill/h, 301g/cm(3), and 11.52 ± 0.38 contractions/min (P < 0.05); for the negative control group, 1.54 ± 0.64 pills/h, 645 g/cm(3), and 19.2 ± 0.71 contractions/min, respectively (P < 0.05); and for the positive control group, 0.94 ± 0.21 pills/h, 415 g/cm(3), and 14.1 ± 0.52 contractions/min, respectively (P < 0.05). In the MODS group, there was a marked up-regulation of expression of IL-6, TNF-α, and iNOS and the contractility of the smooth muscle strips had a negative correlation with the expression of IL-6, TNF-α, and iNOS.

CONCLUSION

We speculate that reduced colon motility in the MODS rats may be related to the increase in iNOS, IL-6, and TNF-α in the colon muscularis.