IACM-Bulletin of April 15, 2001

Canada — Health Minister wants to facilitate the medical use of cannabis

Canada plans to make it easier to possess and cultivate marijuana for medical purposes, Canadian Health Minister Allan Rock said on 6 April. The government intends the new rules to apply by 31 July.

Rock first allowed Canadians to apply for the medical use of cannabis in May 1999, and 220 people have received such exemptions from the law. But Ontario's highest court ruled in July 2000 that the federal government should make the process more transparent, particularly in defining who can apply.

Under the proposed new rules, people would still have to apply for exemptions from the general ban, but the regulations would eliminate the current fixed limits on how much cannabis someone can possess. This would be replaced with individual recommendations by a physician -- in effect, a prescription for marijuana.

Patients would also be able to choose a friend to grow marijuana for them. Renewals of exemptions would be granted on an annual basis instead of the current six months.

(Source: Reuters of 6 April 2001)

Science — Endocannabinoids are involved in the regulation of appetite

New research suggests that endocannabinoids are part of the brain's complex system for controlling when and how much to eat. It is known for some time that leptin is the key hormone for the regulation of the circuit in the hypothalamus responsible for appetite control.

Leptin reduces food intake by upregulating appetite-reducing factors and downregulating appetite-stimulating factors. The finding that endocannabinoids (anandamide and 2-arachidonyl glycerol) are involved in this process helps explain why people get hungry after using cannabis or THC and why it helps patients with loss of appetite and weight.

In the study published in the journal Nature, researchers found that mice without CB1 cannabinoid receptors ate less than normal mice did. And when ordinary mice were given the cannabinoid receptor antagonist SR141716A that blocked endocannabinoids from acting at these receptors, they ate less than normal as well. Furthermore, reduced levels of leptin were associated with elevated levels of endocannabinoids in the hypothalamus, and application of leptin reduced endocannabinoid levels.

These findings indicate that endocannabinoids in the hypothalamus may activate CB1 receptors to maintain food intake, and that they can act independently of the level of certain other appetite-triggering substances.

(Sources: Di Marzo V, et al. Leptin-regulated endocannabinoids are involved in maintaining food intake. Nature 2001;410:822-825; AP of 11 April 2001)

News in brief

IACM — Frequently asked questions:

A new service on the IACM web site offers the possibility to ask questions and have a look at answers to frequently asked questions. The first question is: "Pregnancy: Does cannabis/THC do harm to the fetus if it is used during pregnancy?" The next questions to be answered are: "Interactions: Does cannabis/THC interact with other drugs used for the treatment of diseases?" and "Asthma: How should cannabis or THC be taken to treat asthma?" More at: http://www.cannabis-med.org/

Science — HIV/AIDS study:

Am 3. April begann die erste von der US-Regierung genehmigte Studie zur medizinischen Verwendung von Marihuana in Kalifornien. Das Gesundheitszentrum des Kreises San Mateo wird Cannabiszigaretten an 60 HIV- und Aids-Patienten abgeben, die an neurologischen Störungen leiden. Dr. Dennis Israelski, Leiter für Infektionskrankheiten an den Kreiskrankenhäusern und ?kliniken, wird die 12-wöchige Studie leiten. Die US-Drogenbehörde DEA genehmigte die Studie am 22. November 2000. (Quellen: AP vom 4, April 2001, IACM-Informationen vom 26. November 2000)

Science — Nausea and vomiting

animal model of anticipatory nausea and vomiting that THC is able to prevent this form of nausea. Their study based on the emetic reactions of the musk shrew is published in Neuroreport. Retching caused by an injection of lithium chloride was completely suppressed by pre-treatment with a moderate dose of THC. This provides the first experimental evidence in support of reports that THC suppresses anticipatory vomiting. (Source: Parker LA, Kemp SW. Tetrahydrocannabinol (THC) interferes with conditioned retching in Suncus murinus: an animal model of anticipatory nausea and vomiting (ANV). Neuroreport 2001;12(4):749-751.)

Science — Pain

Researchers of the Virginia Commonwealth University in Richmond, USA, examined the effect of short-term exposure to THC, morphine, or both drugs in combination on receptor density in a mouse model. They demonstrated that all three types of opioid receptors were significantly decreased in morphine-tolerant mouse, while this reduction was not seen in combination-treated animals. The scientists concluded that a combination of THC and morphine retains high pain mitigating properties without causing changes in receptors that may contribute to tolerance. (Source: Cichewicz DL, et al. Changes in opioid and cannabinoid receptor protein following short-term combination treatment with delta(9)-tetrahydrocannabinol and morphine. J Pharmacol Exp Ther 2001;297(1):121-127.)

Science — Blockade of THC effects

SR141716, a CB1 cannabinoid receptor antagonist developed in 1994, was given to humans now for the first time. 63 healthy men received different doses of SR141716 or a placebo and smoked a marijuana cigarette 2 hours later. SR141716 produced a dose-dependent blockade of marijuana effects. Lead researcher Dr. Marilyn Huestis of NIDA (National Institute on Drug Abuse), said the findings help point the way toward possible treatment for people addicted to marijuana, for treating obesity and schizophrenia and improving memory. (Source: Huestis M, et al. Blockade of effects of smoked marijuana by the CB1-selective cannabinoid receptor antagonist SR141716. Arch Gen Psychiatry 2001;58:322-328.)