www.newscientist.com/news/news.jsp?id=ns99996055
com news service Rats snorting a modified virus into their brains show some immunity from the effects of cocaine, a new study has shown. Existing therapies that aim to help addicts conquer their dependence use antibodies to block cocaine before it reaches the brain and produces a "high". But this approach means that some of the highly addictive drug may still slip into the brain, says Kim Janda, a chemical biologist at the Scripps Research Institute, California, US. "These approaches are not completely foolproof in terms of drugs getting into the central nervous system," he explains. Now Janda his colleagues have shown that cocaine-binding proteins can be delivered directly to the brain by engineering the required genes into a special kind of virus called a phage, which is then breathed in through the nose. Rats given the modified virus before cocaine showed far fewer physical signs of a drug hit than rats given a control virus. And importantly, there seemed to be no side-effects, says Janda. He believes the technique could be a "powerful tool" to help beat various drug addictions. And in the future, enzymes or neuronal peptides which act on addiction pathways in the brain, as well as the drug itself, could also be added to the phages. Sniffing and rearing The team engineered phages to produce a cocaine-binding antibody and then injected them into the rats' noses twice a day for three days. The rats were given a shot of cocaine on the fourth day. Rats pre-treated with the phage showed less of the physical activity and "stereotyped" behaviours associated with a cocaine high than control rats. Stereotyped behaviour includes repetitive movements like sniffing and rearing. Their movement was monitored by their breaking two infra-red beams which criss-crossed each rat's box.
Proceedings of the National Academy of Sciences Janda says that viruses can enter the brain directly from the nose using receptor neurons. "These neurons project axons and basically the virus can hook into this and use it as a highway to get into the central nervous system." However, unlike cocaine vaccines which harness the body's immune response, the effects of the new approach may be short-lived. "The only thing about this is it's only around for a few days, maybe a week, and then it's gone," Janda told New Scientist. He believes the approach could be used in conjunction with other therapies.
|
http://csua.com/feed/