Pubdate: Fri, 14 Oct 2005
Source: Belfast Telegraph (UK)
Copyright: 2005 Belfast Telegraph Newspapers Ltd.
Contact:  http://www.belfasttelegraph.co.uk/
Details: http://www.mapinc.org/media/42
Author: Jeremy Laurance
Bookmark: http://www.mapinc.org/find?207 (Cannabis - United Kingdom)
Bookmark: http://www.mapinc.org/coke.htm (Cocaine)
Bookmark: http://www.mapinc.org/heroin.htm (Heroin)

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.
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MAP posted-by: Elizabeth Wehrman