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.