Nature Medicine

If a cocaine addict can be persuaded to enter a treatment program, he or she could be placed on a regime of methadone replacement as a substitute for cocaine. However, relapse amongst addicts is common and much research is currently dedicated to finding ways to prevent relapse.

In the October issue of Nature Medicine, scientists at Vrije University in The Netherlands report that a treatment for cocaine relapse may come from a surprising source-marijuana.

The brain contains two receptors for cannabinoid molecules, and naturally occurring chemicals that act on these receptors (endocannabinoids) have been linked to the phenomenon of cocaine addiction. Using a rat model of addiction, Taco De Vries and colleagues found that the compound HU210 which stimulates cannabinoid receptors, caused rats to relapse whereas SR141716A, which blocks cannabinoid receptors, decreased the tendency to relapse.

These data reveal an important link between the cocaine and the cannabinoid systems in the brain and suggest that the use of compounds that interact with cannabinoid receptors-such as marijuana-may be useful in treating cocaine addiction.

Daniele Piomelli of the University of California, Irvine, explains the findings in an accompanying News & Views article and writes, "As with other chronic diseases, it is reasonable to expect that treatment of drug craving and relapse will involve the use of more than one drug."

Nature Medicine

With an ever increasing percentage of the worlds population becoming obese, treatments for this condition are desperately needed. Scientists at McGill University in Canada have taken a step toward combating obesity by identifying a protein that can make white fat (a reserve of energy), take on the properties of brown fat (a source of heat generation).

Nahum Sonenberg and colleagues found that mice lacking the gene for the protein 4E-BP1, had less white fat tissue and a higher metabolic rate. They discovered that the white fat present in these mice had taken on the properties normally associated with brown fat, such as dispersed fat droplets within fat cells and increased amounts of the UCP-1 protein which is involved in the production of energy in cells.

Robert Farese & Hubert Chen from the University of California, San Fransisco, explain the molecular intricacies of the work and its implications for human energy balance and weight regulation in an accompanying News & Views article.

Nature Medicine

Cancerous cells express proteins that are foreign to the hosts body and which should therefore be recognized by the immune system and attacked, thus destroying the tumor. Oftentimes this system fails: the cancerous cell escape immune attack. Understanding how tumor cells are able to avoid detection is important to developing new anti-cancer treatments.

Richard Flavell and colleagues at Yale University have discovered that the cytokine molecule TGF-beta is key to suppressing the immune response to tumors, thus allowing cancers to thrive. Blocking the effects of TGF-beta could form the basis of a new therapy for cancer.

Using transgenic mice engineered so that the T lymphocyte cells of their immune systems were insensitive to TGF-beta, the researchers found that these mice did not develop tumors when injected with cancerous cells, unlike normal mice which went on to develop tumors and die.

The authors conclude that if human T cells could also be made insensitive to the signaling effects of TGF-beta, then these findings "can be readily adapted to clinical situations to improve existent T-cell-mediated antitumor interventions."