leusteanu.....
- From: "Ronin" <Kotyto@xxxxxxxxx>
- Date: 21 Oct 2005 18:59:20 -0700
din sciencenews -
High Times for Brain Growth: Marijuana-like drug multiplies neurons
Christen Brownlee
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, marijuana's 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, Zhang's 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 didn't receive the drug. These results suggest that, while
these new neurons probably don't 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," it's 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.
.
- Prev by Date: Autoritalile il pupa in cur pe Guru
- Next by Date: Re: sarbatoarea cocioabilor
- Previous by thread: Autoritalile il pupa in cur pe Guru
- Next by thread: Predictie
- Index(es):
Relevant Pages
|
Loading
