Medical marijuana: More states legalizing, but scientific evidence lacking

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Medical marijuana: More states legalizing, but scientific evidence lacking

Medical marijuana has been gaining support among states and doctors, but one pot researcher points out much remains unknown scientifically about what medical conditions the drug can actually help.

Dr. Margaret Haney is the director of the Marijuana Research Laboratory at Columbia University in New York. Her lab is one of a handful that receives government funding for studies on marijuana, including research on potential therapeutic uses of the drug.

“I have no trouble finding volunteers,” she joked to CBS News’ Kera Rennert.

But these studies are crucial, Haney points out, because carefully controlled studies on marijuana’s effects are lacking. When a new drug gets approved by the Food and Drug Administration, researchers have to demonstrate in series of studies that the drug outperforms a placebo pill to cause a therapeutic effect. This is not the case for marijuana in its plant form.

“The testing is critical, because marijuana is the only medication that’s been voted in as a medication, where we have very established procedures for determining whether something is a medication,” she explained.

Marijuana contains about 60 chemical components called cannabinoids. The most well known and well-studied is delta-9-tetrahydrocannabinol, or THC, which is behind the drug’s “stoned” effect.

Scientists like Haney are starting to isolate those other compounds to see what effects they have. But the lack of research hasn’t stopped states from moving forward with legalization.

Medical marijuana is legalized in 20 states in addition to the District of Columbia: Alaska, Arizona, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Massachusetts, Michigan, Montana, Nevada, New Hampshire, New Jersey, New Mexico, Oregon, Rhode Island, Vermont and Washington. Other states are considering legislation.

The medical community also appears to be increasing acceptance. A survey in the New England Journal of Medicine last March found 76 percent of doctors were in favor of the use of medical marijuana when presented with a hypothetical case of a patient with breast cancer that’s spread and caused pain.

Dr. Sanjay Gupta publicly reversed course and came out in support of medical marijuana, and even apologized for being too dismissive of patients’ reports of symptoms improving.

While medical marijuana is approved in some states for conditions including epilepsy, inflammatory bowel disease multiple sclerosis and chronic pain, the scientific evidence has yet to catch up. Haney notes there is solid evidence marijuana can decrease nausea and increase food intake in people with HIV or cancer who are getting chemotherapy. This has also been shown with the pill form of THC, dronabinol.

One experiment suggests one cannabinoid called cannabidiol, when isolated in high levels, might treat neuropathic pain in mice, a type of chronic pain that can be caused by HIV and chemotherapy.

Research is also being done at other ways to isolate and deliver cannabinoids to patients, since smoking can be a respiratory irritant. Researchers have beentesting a marijuana mouth spray Sativex that contains delta 9-THC and cannabidiol. It’s currently approved in some European countries.

Such rigorous trials are necessary, Haney emphasized, to better understand how marijuana might treat medical conditions, if at all. Her tests include having people smoke real marijuana or a placebo so she can disseminate what the drug actually does for appetite, pain or withdrawal from what people think it will do.

But since this research is very much ongoing, she warns people should not believe marijuana is a cure-all as some rent-a-doctors in states with legalization may suggest.

“Just like you’re skeptical of a pharmaceutical industry and what they say a drug does, you have to be just as skeptical about what marijuana does, because people are making enormous profit from it,” said Haney. “That is again why we need carefully controlled studies to demonstrate what it works for and what it doesn’t work for.

  • Ryan Jaslow

    Ryan Jaslow is’s health editor.

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nature highlights
Nature © Macmillan Publishers Ltd.

Endocannabinoids: A link to leptin and food intake

The protein hormone leptin acts to control body weight via effects on hypothalamic centres that control feeding behaviour and hunger, body temperature and energy expenditure. Work in receptor knockout mice now suggests that endogenous hypothalamic cannabinoids may play a role in the regulation of food intake as one component in the leptin signalling cascade, acting on CB1 cannabinoid receptors to maintain food intake.

letters to nature
Leptin-regulated endocannabinoids are involved in maintaining food intake
Nature 410, 822-825 (12 April 2001)
| First Paragraph | Full Text | PDF (177 K) |

news and views
Physiology: A hunger for cannabinoids
Cannabinoids — molecules found naturally in the body, as well as in cannabis — stimulate appetite. Leptin, a hormone produced by body fat, decreases appetite. The effects of these molecules have now been linked.
Nature 410, 763-765 (12 April 2001)
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Cannabis-like compounds in the brain control appetite.


* Original article here.










The endocannabinoid signaling system in cancer

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Trends in Pharmacological Sciences

Available online 17 April 2013

In Press, Corrected ProofNote to users


The endocannabinoid signaling system in cancer

  • 1 Endocannabinoid Research Group, Department of Pharmacy, University of Salerno, Salerno, Italy
  • 2 Endocannabinoid Research Group, Department of Medicine and Surgery, University of Salerno, Salerno, Italy
  • 3 Endocannabinoid Research Group, Institute of Endocrinology and Experimental Oncology, IEOS CNR, Naples, Italy

Changes in lipid metabolism are intimately related to cancer. Several classes of bioactive lipids play roles in the regulation of signaling pathways involved in neoplastic transformation and tumor growth and progression. The endocannabinoid system, comprising lipid-derived endocannabinoids, their G-protein-coupled receptors (GPCRs), and the enzymes for their metabolism, is emerging as a promising therapeutic target in cancer. This report highlights the main signaling pathways for the antitumor effects of the endocannabinoid system in cancer and its basic role in cancer pathogenesis, and discusses the alternative view of cannabinoid receptors as tumor promoters. We focus on new players in the antitumor action of the endocannabinoid system and on emerging crosstalk among cannabinoid receptors and other membrane or nuclear receptors involved in cancer. We also discuss the enzyme MAGL, a key player in endocannabinoid metabolism that was recently recognized as a marker of tumor lipogenic phenotype.

Figures and tables from this article:

Full-size image (112 K)

Figure 1. Highlighted pathways of the antitumor effects of cannabinoid agonists in cancer. The figure depicts the main signaling cascades elicited downstream of CB receptor activation by endocannabinoids and cannabinoids, which affect all the hallmarks of cancer: inhibition of cell proliferation; cell-cycle arrest; induction of cell death (apoptosis and autophagy); prevention of tumor progression (cancer cell vascular adhesiveness, invasiveness, and metastasis formation); inhibition of angiogenesis in tumor environment; and inhibition of the epithelial–mesenchymal transition.

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Endocannabinoid system

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The endocannabinoid system refers to a group of neuromodulatory lipids and their receptors that are involved in a variety of physiological processes including appetite, pain-sensation, mood, and memory; it mediates the psychoactive effects of cannabis and, broadly speaking, includes:

The endocannabinoid system has been studied using genetic and pharmacological methods. These studies have revealed that cannabinoids act as neuromodulators[2][3][4] for a variety of physiological processes, including motor learning,[5] synaptic plasticity,[6] appetite,[7] and pain sensation.[8]




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