Pubdate: Fri, 14 Oct 2005
Source: StarPhoenix, The (CN SN)
Copyright: 2005 The StarPhoenix
Contact:  http://www.canada.com/saskatoon/starphoenix/
Details: http://www.mapinc.org/media/400
Author: Janet French
Bookmark: http://www.mapinc.org/mjcn.htm (Cannabis - Canada)

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.
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MAP posted-by: Elizabeth Wehrman