Aug. 3, 2009 -- Researchers said they had pinpointed the biochemical pathway by which cannabis causes memory loss in mice. The discovery could help open the way to drugs that have marijuana's desired pain-killing properties but without its amnesic side effects, according to the paper, published in the journal Nature Neuroscience. It has long been known that cannabis produces memory loss by acting on the hippocampus, the region in the brain that governs most of our cognitive functions. But whether that impact was long-term or lasted only during the drug's use, as well as how the drug acted biochemically, has been intensely debated. Rafael Maldonado and and Andres Ozaita at Pompeu Fabra University in Barcelona believe they can help answer both questions. The scientists first created a new measure of cognitive impairment so that they could easily assess the impact of cannabis use on memory in normal mice. Related Content:
Marijuana's active ingredient, THC, acts on cannabinoid receptor neurons called CB1. While found in several locations within the brain, there are two concentrations of CB1-type cells in the hippocampus. To explore how each of these neural networks might affect memory loss, the researchers created two groups of genetically modified mice, each missing the CB1 receptors in either of the two regions. One of the groups reacted in the well-known forgetful fashion when required to do memory tests. The other mouse group -- whose CB1 had been removed from the so-called GABAergic neurons -- was unaffected by the drug. "Not only were the behavioral effects abolished, the biochemical responses that are directly responsible for the amnesic-like effect were abolished too," Maldonado said in a phone interview. This should make it possible to develop a molecule that will produce cannabis' positive effect without affecting the GABAergic brain cells that govern memory, he said by phone. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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