Category Archives: Gastrointestinal Disorders

ENDOCANNABINOID SYSTEM: A multi-facet therapeutic target.

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“Cannabis sativa is also popularly known as marijuana. It is being cultivated and used by man for recreational and medicinal purposes from many centuries.

Study of cannabinoids was at bay for very long time and its therapeutic value could not be adequately harnessed due to its legal status as proscribed drug in most of the countries.

The research of drugs acting on endocannabinoid system has seen many ups and down in recent past. Presently, it is known that endocannabinoids has role in pathology of many disorders and they also serve “protective role” in many medical conditions.

Several diseases like emesis, pain, inflammation, multiple sclerosis, anorexia, epilepsy, glaucoma, schizophrenia, cardiovascular disorders, cancer, obesity, metabolic syndrome related diseases, Parkinson’s disease, Huntington’s disease, Alzheimer’s disease and Tourette’s syndrome could possibly be treated by drugs modulating endocannabinoid system.

Presently, cannabinoid receptor agonists like nabilone and dronabinol are used for reducing the chemotherapy induced vomiting. Sativex (cannabidiol and THC combination) is approved in the UK, Spain and New Zealand to treat spasticity due to multiple sclerosis. In US it is under investigation for cancer pain, another drug Epidiolex (cannabidiol) is also under investigation in US for childhood seizures. Rimonabant, CB1 receptor antagonist appeared as a promising anti-obesity drug during clinical trials but it also exhibited remarkable psychiatric side effect profile. Due to which the US Food and Drug Administration did not approve Rimonabant in US. It sale was also suspended across the EU in 2008.

Recent discontinuation of clinical trial related to FAAH inhibitor due to occurrence of serious adverse events in the participating subjects could be discouraging for the research fraternity. Despite of some mishaps in clinical trials related to drugs acting on endocannabinoid system, still lot of research is being carried out to explore and establish the therapeutic targets for both cannabinoid receptor agonists and antagonists.

One challenge is to develop drugs that target only cannabinoid receptors in a particular tissue and another is to invent drugs that acts selectively on cannabinoid receptors located outside the blood brain barrier. Besides this, development of the suitable dosage forms with maximum efficacy and minimum adverse effects is also warranted.

Another angle to be introspected for therapeutic abilities of this group of drugs is non-CB1 and non-CB2 receptor targets for cannabinoids.

In order to successfully exploit the therapeutic potential of endocannabinoid system, it is imperative to further characterize the endocannabinoid system in terms of identification of the exact cellular location of cannabinoid receptors and their role as “protective” and “disease inducing substance”, time-dependent changes in the expression of cannabinoid receptors.”

http://www.ncbi.nlm.nih.gov/pubmed/27086601

Industrial hemp decreases intestinal motility stronger than indian hemp in mice.

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“Indian hemp has shown beneficial effects in various gastrointestinal conditions but it is not widely accepted due to high content of tetrahydrocannabinol resulting in unwanted psychotropic effects.

Since industrial hemp rich in cannabidiol lacks psychotropic effects the aim of research was to study the effects of industrial hemp on intestinal motility.

Although not completely without psychotropic activity cannabidiol could be a potential replacement for tetrahydrocannabinol.

Since industrial hemp infuse rich in cannabidiol reduces intestinal motility in healthy mice cannabidiol should be further evaluated for the treatment of intestinal hypermotility.”

http://www.ncbi.nlm.nih.gov/pubmed/23467947

Role of cannabinoids in gastrointestinal mucosal defense and inflammation.

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“Modulating the activity of the endocannabinoid system influences various gastrointestinal physiological and pathophysiological processes, and cannabinoid receptors as well as regulatory enzymes responsible for the synthesis or degradation of endocannabinoids represent potential targets to reduce the development of gastrointestinal mucosal lesions, hemorrhage and inflammation.

Direct activation of CB1 receptors by plant-derived, endogenous or synthetic cannabinoids effectively reduces both gastric acid secretion and gastric motor activity, and decreases the formation of gastric mucosal lesions induced by stress, pylorus ligation, nonsteroidal anti-inflammatory drugs (NSAIDs) or alcohol, partly by peripheral, partly by central mechanisms.

Similarly, indirect activation of cannabinoid receptors through elevation of endocannabinoid levels by globally acting or peripherally restricted inhibitors of their metabolizing enzymes (FAAH, MAGL) or by inhibitors of their cellular uptake reduced the gastric mucosal lesions induced by NSAIDs in a CB1 receptor-dependent fashion.

Dual inhibition of FAAH and cyclooxygenase induced protection against both NSAID-induced gastrointestinal damage and intestinal inflammation.

Moreover, in intestinal inflammation direct or indirect activation of CB1 and CB2 receptors exerts also multiple beneficial effects.

Namely, activation of both CB receptors was shown to ameliorate intestinal inflammation in various murine colitis models, to decrease visceral hypersensitivity and abdominal pain, as well as to reduce colitis-associated hypermotility and diarrhea.

In addition, CB1 receptors suppress secretory processes and also modulate intestinal epithelial barrier functions. Thus, experimental data suggest that the endocannabinoid system represents a promising target in the treatment of inflammatory bowel diseases, and this assumption is also confirmed by preliminary clinical studies.”

http://www.ncbi.nlm.nih.gov/pubmed/26935536

RGS proteins as targets in the treatment of intestinal inflammation and visceral pain: New insights and future perspectives.

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“Regulators of G protein signaling (RGS) proteins provide timely termination of G protein-coupled receptor (GPCR) responses. Serving as a central control point in GPCR signaling cascades, RGS proteins are promising targets for drug development. In this review, we discuss the involvement of RGS proteins in the pathophysiology of the gastrointestinal inflammation and their potential to become a target for anti-inflammatory drugs. Specifically, we evaluate the emerging evidence for modulation of selected receptor families: opioid, cannabinoid and serotonin by RGS proteins. We discuss how the regulation of RGS protein level and activity may modulate immunological pathways involved in the development of intestinal inflammation. Finally, we propose that RGS proteins may serve as a prognostic factor for survival rate in colorectal cancer. The ideas introduced in this review set a novel conceptual framework for the utilization of RGS proteins in the treatment of gastrointestinal inflammation, a growing major concern worldwide.”

http://www.ncbi.nlm.nih.gov/pubmed/26817719

The Endocannabinoid System and Its Role in Regulating the Intrinsic Neural Circuitry of the Gastrointestinal Tract.

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“Endocannabinoids are important neuromodulators in the central nervous system.

They regulate central transmission through pre- and postsynaptic actions on neurons and indirectly through effects on glial cells.

Cannabinoids (CBs) also regulate neurotransmission in the enteric nervous system (ENS) of the gastrointestinal (GI) tract.

The ENS consists of intrinsic primary afferent neurons, interneurons, and motor neurons arranged in two ganglionated plexuses which control all the functions of the gut.

Increasing evidence suggests that endocannabinoids are potent neuromodulators in the ENS.

In this review, we will highlight key observations on the localization of CB receptors and molecules involved in the synthesis and degradation of endocannabinoids in the ENS.

We will discuss endocannabinoid signaling mechanisms, endocannabinoid tone and concepts of CB receptor metaplasticity in the ENS. We will also touch on some examples of enteric neural signaling in relation neuromuscular, secretomotor, and enteroendocrine transmission in the ENS. Finally, we will briefly discuss some key future directions.”

Prevention of Diet-Induced Obesity Effects on Body Weight and Gut Microbiota in Mice Treated Chronically with Δ9-Tetrahydrocannabinol.

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“Acute administration of cannabinoid CB1 receptor agonists, or the ingestion of cannabis, induces short-term hyperphagia. However, the incidence of obesity is lower in frequent cannabis users compared to non-users.

Gut microbiota affects host metabolism and altered microbial profiles are observed in obese states. Gut microbiota modifies adipogenesis through actions on the endocannabinoid system. This study investigated the effect of chronic THC administration on body weight and gut microbiota in diet-induced obese (DIO) and lean mice.

THC reduced weight gain, fat mass gain and energy intake in DIO but not lean mice. DIO-induced changes in select gut microbiota were prevented in mice chronically administered THC.

Chronic THC treatment reduced energy intake and prevented high fat diet-induced increases in body weight and adiposity; effects that were unlikely to be a result of sedation or altered gastrointestinal transit. Changes in gut microbiota potentially contribute to chronic THC-induced actions on body weight in obesity.”

http://www.ncbi.nlm.nih.gov/pubmed/26633823

“Prevention of Diet-Induced Obesity Effects on Body Weight and Gut Microbiota in Mice Treated Chronically with Δ9-Tetrahydrocannabinol… To follow up on our hypothesis that exposure to THC may produce weight loss, in the current study we investigated whether chronic THC inhibits weight gain in lean and diet-induced obese (DIO) mice… We present data showing that chronic administration of the CB1/CB2 receptor partial agonist, THC, prevents weight gain in DIO mice. Furthermore, we show evidence that DIO-mediated modifications in gut microbiota are prevented in chronically THC treated mice… In conclusion, we present data showing the CB1/CB2 receptor partial agonist THC, induces hypophagia and prevents weight gain in obesity and suggest these actions may be mediated in part by modifications of the gut microbiota.”  http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0144270

Endocannabinoids and the Digestive Tract and Bladder in Health and Disease.

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“Components of the so-called endocannabinoid system, i.e., cannabinoid receptors, endocannabinoids, as well as enzymes involved in endocannabinoid synthesis and degradation, have been identified both in the gastrointestinal and in the urinary tract.

Evidence suggests that the endocannabinoid system is implicated in many gastrointestinal and urinary physiological and pathophysiological processes, including epithelial cell growth, inflammation, analgesia, and motor function.

A pharmacological modulation of the endocannabinoid system might be beneficial for widespread diseases such as gastrointestinal reflux disease, irritable bowel syndrome, inflammatory bowel disease, colon cancer, cystitis, and hyperactive bladder.

Drugs that inhibit endocannabinoid degradation and raise the level of endocannabinoids, non-psychotropic cannabinoids (notably cannabidiol), and palmitoylethanolamide, an acylethanolamide co-released with the endocannabinoid anandamide, are promising candidates for gastrointestinal and urinary diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/26408170

In vitro and non-invasive in vivo effects of the cannabinoid-1 receptor agonist AM841 on gastrointestinal motor function in the rat.

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“Cannabinoids have been traditionally used for the treatment of gastrointestinal (GI) symptoms, but the associated central effects, through cannabinoid-1 receptors (CB1R), constitute an important drawback. Our aims were to characterize the effects of the recently developed highly potent long-acting megagonist AM841 on GI motor function and to determine its central effects in rats…

The CB1R megagonist AM841 may potently depress GI motor function in the absence of central effects. This effect may be mediated peripherally and may be useful in the treatment of GI motility disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/26387676

[Cannabis – therapy for the future?]

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“Despite all the progress achieved in the treatment of chronic gastrointestinal diseases, in some patients the treatment does not reach long-term optimum effectiveness. Therefore a number of patients have turned to complementary and alternative medicine (CAM).

Of the different types of CAM patients with GIT diseases tend to prefer in particular homeopathy, acupuncture and not least phytotherapy, where therapeutic use of cannabis may also be included.

The pathophysiological basis of therapeutic effect of curative cannabis has not been fully clarified so far.

Many scientists in many fields of medicine and pharmacology have been engaged in the study of effects of cannabinoids on the body since the beginning of the 20th century with the interest significantly increasing in the 1980s.

The discovery of CB receptors (1988) and endogenous molecules which activate these receptors (1992) led to the discovery of the endocannabinoid system.

Pharmacological modulation of the endogenous cannabinoid system offers new therapeutic possibilities of treatment of many illnesses and symptoms including the GIT disorders, including of nausea, vomiting, cachexia, IBS, Crohns disease and some other disorders.

Cannabinoids are attractive due to their therapeutic potential – they affect a lot of symptoms with minimum side effects.

Experience of patients with GIT disorders show that the use of cannabis is effective and helps in cases where the standard therapy fails.”

http://www.ncbi.nlm.nih.gov/pubmed/26375695