Kathleen, thought you might like to see this...
- From: "Cytyzens Agaynst Lyme Cryme" <CALC@xxxxxxxxxx>
- Date: Sun, 16 Oct 2005 12:19:18 -0400
....since you have shown an interest in things (like Lithium)
which have neuroprotective properties-
as it relates to neuroborrelosis and the damage it does.
================================================
Pot-Like Drug Multiplies
Neurons In Brain Growth
By Christen Brownlee
Science News Online
Vol. 168, No. 16
10-15-5
In the stoner stereotype, pot smokers and dying brain cells go hand
in hand. However, new research suggests the situation may be more uplifting
than that. A drug that functions as concentrated marijuana does may spur
neurogenesis, the process by which the brain gives birth to new nerve cells.
Previous research had suggested that neurogenesis happens only in
select locations in the brain, such as the hippocampus, a region involved in
learning and memory. Some studies have shown that this process is inhibited
by most illicit drugs, such as cocaine, heroin, and methamphetamine.
However, says Xia Zhang of the University of Saskatchewan in Saskatoon,
marijuanas effect on neurogenesis has not been clear.
He and his colleagues started investigating this mystery by
searching cell surfaces in live, cultured slices of rat hippocampus for
receptors that respond to marijuana and a few other similar drugs, called
cannabinoids. They reasoned that if marijuana affected neurogenesis in the
hippocampus, then cells in that area must have a way to recognize the drug.
Sure enough, 95 percent of hippocampus cells responsible for neurogenesis
showed evidence of cannabinoid 1 (CB1) receptors, one of two receptors that
respond to cannabinoid drugs.
Next, Zhangs team incubated samples of rat hippocampus with a
solution containing HU210, a drug that stimulates CB1 receptors with a
strength 100 times greater than that of pot. Other rat-hippocampus cells
were incubated with the same solution minus the drug or with AM281, a drug
that blocks CB1 receptors. After 2 days, the researchers found a significant
increase in the number of new brain cells in the samples incubated with
HU210, but no significant increase of such cells in the other samples.
Finally, the researchers injected adult rats with various doses of
HU210. A single high-dose injection seemed to make no significant difference
in the number of new nerve cells. However, animals injected with high daily
doses of the drug over the course of 2 weeks had about 30 percent more
newborn nerve cells than did rats given AM281 or a solution without either
drug.
Animals given the 2-week course of HU210 also showed less anxiety
and depressionlike behavior than did rats not given the drug. When the
researchers irradiated the rats hippocampi with X rays, which kill off new
neurons, animals given HU210 responded to these tests much as did animals
that didnt receive the drug. These results suggest that, while these new
neurons probably dont increase intelligence, they could be responsible for
antianxiety and antidepressive effects, says Zhang.
He and his team report their findings in the November Journal of
Clinical Investigation.
While data suggesting that cannabinoid drugs can accelerate
neurogenesis are "interesting and potentially promising," its too early to
tell whether high doses of marijuana over long periods have a similar effect
on depression and anxiety in people, says Ron Duman, a neuroscientist at
Yale University. "There is very little clinical evidence demonstrating that
cannabinoid administration produces an antidepressant response," he says.
.
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