IACM-Bulletin of April 17, 2005

Science — THC slows development of atherosclerosis in animal study

THC protects arteries against harmful changes that lead to atherosclerosis, hardening of the arteries, researchers of the University of Geneva, Switzerland, found in a study with mice. Atherosclerosis is the primary cause of stroke and heart disease. The study published in the journal Nature revealed that THC can block the process of inflammation, which is largely responsible for the changes in the vessels. Inflammation combines with fatty deposits to narrow the arteries.

The scientists studied a strain of mice that are susceptible to atherosclerosis. The animals were fed a high-cholesterol diet to make them develop atherosclerotic deposits. Adding THC to their diet caused the growth of the obstructions in their arteries to slow markedly after 11 months. The THC doses applied were comparatively low (1 mg/kg of body weight), too low to cause psychological effects in the mice. Lower and higher doses did not produce a protective effect. The effective dose would correspond to moderate doses in humans. However, it is currently unclear how the results translate to humans.

The protective effect were mediated by THC effects on the immune system. The Swiss researchers found that certain blood cells (lymphoid cells) of THC treated mice secreted less interferon-gamma, a molecule that promotes inflammation, and that migration of certain immune cells (macrophages) to the vessel wall was inhibited. In mice that also received a CB2 receptor antagonist, that blocked the effects of THC at this receptor, continued to develop atherosclerosis at a fast rate. The CB2 receptor is mainly found on cells of the immune system. The authors noted that "THC or cannabinoids with activity at the CB2 receptor may be valuable targets for treating atherosclerosis."

In several other diseases THC was shown to reduce inflammation by reducing pro-inflammatory mediators (cytokines), including interferon-gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha) and several interleukins. THC reduced inflammation in several animal models, among them models of arthritis and multiple sclerosis.

(Sources: Times Online of 7 April 2005, Associated Press of 6 April 2005, Steffens S, et al. Low dose oral cannabinoid therapy reduces progression of atherosclerosis in mice. Nature 2005;434(7034):782-6)

News in brief

Spain — Acquittal

A judge acquitted two men accused of drug trafficking since one of them used the confiscated cannabis to treat his chronic back pain that did not respond sufficiently to available drugs. The police had found 17 cannabis plants in their garden in September 2003. After drying the plants they weighed 1.43 kg and contained 3.1 per cent THC. It is the first sentence of this kind in Asturias, one of the autonomic regions of Spain with the capital Oviedo. (Source: La Nueva Espana of 13 April 2005)

Science — Glaucoma

Italian researchers found that the concentrations of endocannabinoids in the ciliary body of the eyes of glaucoma patients are lower than in eyes of healthy people. The findings suggest that these endogenous cannabinoids may have a role in this disease, particularly with respect to regulation of intraocular pressure. (Source: Chen J, et al. Biochem Biophys Res Commun 2005;330(4):1062-7)

Science — Ecstasy and cannabis

British researchers reported that users of ecstasy who did not use cannabis were more aggressive and complained of more somatic symptoms compared with ecstasy users who were smoking cannabis on a monthly or weekly basis. Heavy cannabis use in the past was associated with more paranoid symptoms. The scientists concluded that "moderate cannabis use may help to ameliorate or mask MDMA-induced aggressivity and somatic symptoms. However, this study confirms that heavy cannabis and ecstasy use is associated with several psychobiological problems, which may emerge after a period of abstinence from both drugs." (Source: Milani RM, et al. Hum Psychopharmacol. 2005 Apr 7; [Electronic publication ahead of print])

Science — Brain tumours

Massive increased levels of endocannabinoids were found in the tissue of two brain tumours (glioblastoma and meningioma) compared with human healthy brain tissue. The researchers concluded that the enhanced level of endocannabinoids "detected in the two types of tumour tissue may possibly act as endogenous anti-tumour mediators by stimulation of both cannabinoid and non-cannabinoid receptor-mediated mechanisms." (Source: Petersen G, et al. J Neurochem 2005;93(2):299-309)

Science — Schizophrenia

Hawaiian researchers investigated the question whether the onset of schizotypal symptoms in regular cannabis users preceded the onset of cannabis use or whether these symptoms followed cannabis use. Their study in a large sample of college students (N=189) found that these symptoms generally were present before the start of cannabis use, an observation that does not support the theses of a causal link between cannabis use and schizophrenia. (Source: Schiffman J, et al. Psychiatry Res 2005;134(1):37-42)