Max Planck researchers and collaborators from the University in Munich identify the body?s own cannabinoid receptor as a protective system against colon inflammation.

The development of chronic inflammatory diseases of the gastrointestinal tract such as Crohn?s disease and Colitis ulcerosa has not been understood yet, but medication to treat and alleviate these diseases are in high demand. In the current issue of The Journal of Clinical Investigation (15 April 2004) a researcher team from the Max Planck Institute of Psychiatry and from the Ludwig-Maximilans-University Munich were able to show that mutant mice lacking the cannabinoid receptor are much more prone to experimentally induced colon inflammation as compared to wild-type control mice.

Moreover, colon muscle activities become uncontrolled after inflammation in these mutant mice. The treatment with cannabinoids was able to alleviate inflammation in wild-type animals. Thus, these results suggest that the endogenous cannabinoid system represents a promising therapeutic target for the treatment of chronic inflammatory diseases of the gastrointestinal tract.

An important defense mechanism of the body after insults is the induction of an inflammation. However, if this response is too strong a destruction of the tissue may occur. Therefore, a balance between pro- and anti-inflammatory responses is very important for the body. Chronic inflammatory diseases of the gastrointestinal tract such as Crohn?s disease and Colitis ulcerosa constitute a widespread problem in industrialized countries. These diseases are difficult to be treated successfully and the search for novel therapeutic approaches is of high demand.

During centuries, extracts from Cannabis sativa have been used in folk medicine for the treatment of various gastrointestinal diseases. The most active compound of Cannabis sativa is delta-9-tetrahydrocannabinol, also called THC.

The human body contains a receptor for THC and THC-like molecules, the cannabinoid receptor type 1 (CB1). Body?s fatty acid-like compounds, called endocannabinoids, are also able to activate CB1 receptors. CB1 receptors and endocannabinoids are not only present in the brain but also in the enteric nervous system. Recent investigations conducted by researchers of the group of Beat Lutz at the Max Planck Institute in Munich and of Martin Storr at the Medical Department II of the Ludwig Maximilans University Munich suggest that the endogenous cannabinoid system provides a protective mechanism to prevent excessive inflammatory responses after an insult and thus helps to maintain the balance between pro- and anti-inflammatory reactions.

Inflammatory responses were experimentally induced by infusion of a sulfonic acid-containing substance into the colon of mice. In addition to wild-type control mice, also CB1 knock-out mice (i.e. mice, lacking the cannabinoid rececptor) were used. On day three after infusion, the degree of inflammation was determined by different methods. CB1 knock-out mice showed a higher degree of inflammation as compared to wild-type control mice.

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