CANNABIS STIMULATES GROWTH OF BRAIN

Discussion in 'Medical Marijuana' started by Alfa, Oct 17, 2005.

  1. Alfa

    Alfa Productive Insomniac Staff Member Administrator

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    HIGH-DOSE CANNABIS STIMULATES GROWTH OF BRAIN CELLS IN RATS


    Cannabis, the third most popular recreational drug after alcohol and tobacco, yesterday won an unlikely accolade from scientists who said that it could boost brain power.


    Experiments on rats given a potent cannabinoid have shown the drug stimulates the growth of new brain cells. Canadian researchers found that the drug caused neurons to regenerate in the hippocampus, an area that controls mood and emotions, after one month of treatment.


    Its effect was similar to that of the antidepressant drug Prozac, which also stimulates nerve growth in the hippocampus. The rats were less anxious and more willing to eat in a novel environment that would normally make them fearful.


    Most drugs, including alcohol, heroin, cocaine and nicotine, have been shown to destroy nerve cells in the hippocampus, the researchers from the University of Saskatchewan, Canada, say. "The present study suggests that cannabinoids are the only illicit drug that can promote adult hippocampal neurogenesis following chronic administration,"


    they write in the Journal of Clinical Investigation.


    The finding runs counter to previous research highlighting the risks of cannabis use, including a heightened degree of psychosis in vulnerable users, and an increased risk of lung cancer similar to that in tobacco smokers. The authors say regular cannabis users are known to suffer acute memory impairment, as well as dependency and withdrawal symptoms.


    The new research suggests that the size of the dose may be crucial.


    The results showed that regular injections of high, but not low, doses of the artificial cannabinoid HU210 were associated with anti-anxiety and antidepressive effects.


    "These complicated effects of high and low doses of acute and chronic exposure to cannabinoids may explain the seemingly conflicting results observed in clinical studies regarding the effects of cannabinoid on anxiety and depression," the scientists say.


    The study emerged from the recent discovery that, unlike other parts of the brain, the hippocampus can generate neurons throughout the lifespan of mammals, including humans.


    Natural selection has conserved cannabinoid receptors in animals that have been separated by evolution for 500 million years, suggesting they have an important biological role. Cannabinoids appear to alter the effects of pain, nausea, tumours, sclerosis and other disorders in both animals and humans, the team says.


    The experiment involved giving rats regular injections of HU210 for a month. At the end of this time, hungry animals showed significantly less reluctance to eat in a novel environment. Rats are normally neophobic - wary of new situations.


    Cannabis, the third most popular recreational drug after alcohol and tobacco, yesterday won an unlikely accolade from scientists who said that it could boost brain power.


    Experiments on rats given a potent cannabinoid have shown the drug stimulates the growth of new brain cells. Canadian researchers found that the drug caused neurons to regenerate in the hippocampus, an area that controls mood and emotions, after one month of treatment.


    Its effect was similar to that of the antidepressant drug Prozac, which also stimulates nerve growth in the hippocampus. The rats were less anxious and more willing to eat in a novel environment that would normally make them fearful.


    Most drugs, including alcohol, heroin, cocaine and nicotine, have been shown to destroy nerve cells in the hippocampus, the researchers from the University of Saskatchewan, Canada, say. "The present study suggests that cannabinoids are the only illicit drug that can promote adult hippocampal neurogenesis following chronic administration,"


    they write in the Journal of Clinical Investigation.


    The finding runs counter to previous research highlighting the risks of cannabis use, including a heightened degree of psychosis in vulnerable users, and an increased risk of lung cancer similar to that in tobacco smokers. The authors say regular cannabis users are known to suffer acute memory impairment, as well as dependency and withdrawal symptoms.


    The new research suggests that the size of the dose may be crucial.


    The results showed that regular injections of high, but not low, doses of the artificial cannabinoid HU210 were associated with anti-anxiety and antidepressive effects.


    "These complicated effects of high and low doses of acute and chronic exposure to cannabinoids may explain the seemingly conflicting results observed in clinical studies regarding the effects of cannabinoid on anxiety and depression," the scientists say.


    The study emerged from the recent discovery that, unlike other parts of the brain, the hippocampus can generate neurons throughout the lifespan of mammals, including humans.


    Natural selection has conserved cannabinoid receptors in animals that have been separated by evolution for 500 million years, suggesting they have an important biological role. Cannabinoids appear to alter the effects of pain, nausea, tumours, sclerosis and other disorders in both animals and humans, the team says.


    The experiment involved giving rats regular injections of HU210 for a month. At the end of this time, hungry animals showed significantly less reluctance to eat in a novel environment. Rats are normally neophobic - wary of new situations.
     
  2. Alfa

    Alfa Productive Insomniac Staff Member Administrator

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    POT-LIKE DRUGS REDUCE ANXIETY, U OF S TEAM FINDS


    Drug Also Helps Depression Symptoms


    A University of Saskatchewan team has shown that a potlike drug reduces the symptoms of anxiety and depression in rats.


    Using injections of a synthesized substance called HU210, which mimics one of the active ingredients in marijuana, Dr. Xia Zhang, an associate professor of psychiatry, and his colleagues showed new growth of brain cells increased in rats.


    Other recent studies have linked that growth, or so-called neurogenesis, to a reduction in anxiety and depression.


    The results were published Thursday on the website of the Journal of Clinical Investigation.


    "The implication of this paper is that smoking marijuana is a good thing," Zhang said with a hearty laugh in his office.


    Well, good for rats anyway.


    "We hypothesize cannabis or marijuana can produce a similar effect,"


    Zhang said.


    The group, including researchers at Xijing Hospital in China and at the University of Maryland in Baltimore, have yet to test the effect of marijuana itself on rats' neurogenesis, Zhang said.


    He also cautions against the assumption the drug will have the same effect on humans.


    "There is a big gap between rats and humans," Zhang said.


    "Realistically, we cannot judge these results from rats and apply them to a human situation.


    "There's a huge difference. Our results can give (only) some indication or implication."


    Although previous studies have shown alcohol, nicotine, opiates and cocaine reduce the growth of new brain cells, Zhang's paper is the first to show marijuana could have the opposite effect.


    Because rats can't say how depressed they are, researchers used tests such as putting the rats in a swimming pool with no escape to see how quickly they would give up swimming and resign themselves to a likely fate of drowning. (The rats were plucked out of the pool before they could drown.)


    What's more exciting to researchers than the potential connection between smoking pot and easing lethargy and frayed nerves is the possibility a component of marijuana could be the next blockbuster antidepressant.


    "Prozac is great, but it does have its problems, and its mechanism of action is similar to antidepressants we were using 40, 50 years ago,"


    said Dr. Lisa Kalynchuk, a Canada Research Chair in behavioural neuroscience and associate professor of psychology at the University of Saskatchewan. "What we really need in the field is to develop new antidepressant drugs that are acting in new ways. Certainly, if we could get a drug that would act on these (cannabis) receptors and could actually alleviate depressive symptoms, that would be fantastic. It would be the next Prozac -- the next company to make billions of dollars."


    There are problems with antidepressants currently on the market, she said, including side-effects such as dizzy spells, insomnia and impaired sex drive. Some drugs take a month to start working and others don't work on some people at all, she said.


    But researchers would have to develop a better understanding of the mechanism by which HU210 or cannabis works in the brain before they package them into pills, Zhang said.


    Kalynchuk also questions whether the cannabislike drug would have an effect on anxiety, since only one major study has shown a connection between increased neurogenesis and the reduction of anxiety.


    Another surprise in the result is that smoking marijuana sometimes causes anxiety attacks in users.


    The discrepancy is a matter of dosage, Zhang said. Although a large amount of marijuana in the short term can cause anxiety, he hypothesizes that a lower dose over time could help reduce it instead.


    HU210 is a purified substance, concentrated 100 times stronger than marijuana's active ingredient tetrahydrocannabinol (THC) would be in a joint.


    Michael Corcoran, a professor in anatomy and cell biology at the University of Saskatchewan, studies cannabinoids, the chemicals that act on receptors that detect cannabis in the brain.


    "In a sense, it's a very artificial situation, because when somebody's smoking dope, they're getting THC, they're getting a whole host of other cannabinoids and other chemicals into their nervous system, and we don't know what the interactions are amongst those," he said.


    Zhang agrees, saying the next step is to test the effect of THC on rats' brain cell growth and behaviour.


    Studying the effect in humans could take much longer, since such research requires strict ethical guidelines and bureaucratic approvals.