Study turns pot wisdom on its head

[apothecary]

http://www.theglobeandmail.com/servlet/sto...ienceandHealth/

CALGARY — Forget the stereotype about dopey potheads. It seems marijuana could be good for your brain.

While other studies have shown that periodic use of marijuana can cause memory loss and impair learning and a host of other health problems down the road, new research suggests the drug could have some benefits when administered regularly in a highly potent form.

Most "drugs of abuse" such as alcohol, heroin, cocaine and nicotine suppress growth of new brain cells. However, researchers found that cannabinoids promoted generation of new neurons in rats' hippocampuses.

Hippocampuses are the part of the brain responsible for learning and memory, and the study held true for either plant-derived or the synthetic version of cannabinoids.

"This is quite a surprise," said Xia Zhang, an associate professor with the Neuropsychiatry Research Unit at the University of Saskatchewan in Saskatoon.

"Chronic use of marijuana may actually improve learning memory when the new neurons in the hippocampus can mature in two or three months," he added.

The research by Dr. Zhang and a team of international researchers is to be published in the November issue of the Journal of Clinical Investigation, but their findings are on-line now.

The scientists also noticed that cannabinoids curbed depression and anxiety, which Dr. Zhang says, suggests a correlation between neurogenesis and mood swings. (Or, it at least partly explains the feelings of relaxation and euphoria of a pot-induced high.)

Other scientists have suggested that depression is triggered when too few new brain cells are created in the hippocampus. One researcher of neuropharmacology said he was "puzzled" by the findings.

As enthusiastic as Dr. Zhang is about the potential health benefits, he warns against running out for a toke in a bid to beef up brain power or calm nerves.

The team injected laboratory rats with a synthetic substance called HU-210, which is similar, but 100 times as potent as THC (delta-9-tetrahydrocannabinol), the compound responsible for giving marijuana users a high.

They found that the rats treated regularly with a high dose of HU-210 -- twice a day for 10 days -- showed growth of neurons in the hippocampus. The researchers don't know if pot, which isn't as pure as the lab-produced version, would have the same effect.

"There's a big gap between rats and humans," Dr. Zhang points out.

But there is a lot of interest -- and controversy -- around the use of cannabinoids to improve human health.

Cannabinoids, such as marijuana and hashish, have been used to address pain, nausea, vomiting, seizures caused by epilepsy, ischemic stroke, cerebral trauma, tumours, multiple sclerosis and a host of other maladies.

There are herbal cannabinoids, which come from the cannabis plant, and the bodies of humans and animals produce endogenous cannabinoids. The substance can also be designed in the lab.

Cannabinoids can trigger the body's two cannabinoid receptors, which control the activity of various cells in the body.

One receptor, known as CB1, is found primarily in the brain. The other receptor, CB2, was thought to be found only in the immune system.

However, in a separate study to be published today in the journal Science, a group of international researchers have located the CB2 receptor in the brain stems of rats, mice and ferrets.

The brain stem is responsible for basic body function such as breathing and the gastrointestinal tract. If stimulated in a certain way, CB2 could be harnessed to eliminate the nausea and vomiting associated with post-operative analgesics or cancer and AIDS treatments, according to the researchers.

"Ultimately, new therapies could be developed as a result of these findings," said Keith Sharkey, a gastrointestinal neuroscientist at the University of Calgary, lead author of the study.

(Scientists are trying to find ways to block CB1 as a way to decrease food cravings and limit dependence on tobacco.)

When asked whether his findings explain why some swear by pot as a way to avoid the queasy feeling of a hangover, Dr. Sharkey paused and replied: "It does not explain the effects of smoked or inhaled or ingested substances."

[Thelema]

warning:

you gotta remember that an increase in physiological rates does not necessarily mean a phallic (loving) action.

I am reminded of the effect of garlic on red blood cell manufacture. Consumtion produces an analogous effect in increasing the production of red blood cells. But upon investigation, it is found that garlic actually stimulates the increased production of red blood cells by acting as a poison that destroys them, alerting the body to produce more in defence.

Could MJ act as a poison to neural formation in the hippocampus, thereby stretching the homeostatic mechanism for all it's worth to counteract with neural growth in that area?

[faustus]

However, in a separate study to be published today in the journal Science, a group of international researchers have located the CB2 receptor in the brain stems of rats, mice and ferrets.

i thought you can't OD on cannabis because there are so few cannabinoid receptors in the brain stem, as opposed to heroin, because there's a high density of opioid receptors? or are we talking about CB1 vs CB2?

and good point horatio-thelema, cannabinoids inhibit release of glutamate don't they?

haven't watched it myself, but any one seen that stoner flick "how high" about that bud that makes you smarter, so the college kids smoke their way to the top of the class!

[Dodie]

I've heard rumours that it's possible to O.D if mj is ingested, or kids can O.D because of their age, i don't know if there is any truth in these statments..

Oh and "how high" watched that plenty of times...one of thier mates dies and they put his ashes in one of their plants and they dub the plant "ivory" when they smoke this their mate appears in ghost form which the person/s smoking can only see and they pretty much cheat their way in....

[ShiningPlain]

you can't overdose on weed man! god...

Horatio Churchmouse - i highly doubt it.

[faustus]

you can't overdose on weed man! god...

just because nobody's ODed on it doesn't mean you can't.

it does have an LD50.

i can't remember exactly, but i worked it out once. it's in the vicinity of 50,000+ cones.

(then again, this is assuming that animal data holds true for humans)

[ShiningPlain]

this all means you can't overdose on it! you'd have to smoke something like 5000 pounds in 30 minutes to kill yourself. and if you did manage to pull that off (highly improbable), you wouldn't die from a "drug overdose". you would die from something like lung collapse.

[apothecary]

Yah I think the amount you would have to smoke is literally impossible.

However, ingesting too many hash cookies will definitely make you wish you didn't.