Marijuana In Detail Essay Research Paper

Marijuana In Detail Essay, Research Paper

"Marijuana causes long-term changes in the brain similar to those seen with

other drugs of abuse . . ." Back in the 1970s, animal experiments led to

groundless fears that marijuana blew holes in brain tissue. The experiments

organisations like NIDA now fund are more sophisticated but the controversy

still rages. George Koob, an addiction researcher from The Scripps Research

Institute in La Jolla, California, claims the new message from the animals is

simple: "The more we discover about the neurobiology of addiction the more

common elements we’re seeing between THC (tetrahydrocannabinol, the main active

ingredient in cannabis) and other drugs of abuse." And for Koob, one of

these newly discovered "common elements" is marijauna’s ability to

trigger chemical changes in the brain that lead to strong withdrawal symptoms.

In humans, some researchers claim to see clear evidence of insomnia, anxiety and

even flu-like symptoms in heavy cannabis users who abstain. But if there’s a

consensus, it’s that symptoms are mild and variable. By contrast, Koob’s rats

are shivering wrecks. Does this mean marijuana is more addictive than we think.

Not a bit of it, says Roger Pertwee, a university pharmacologist and president

of the Cannabinoid Research Society. That’s because those symptoms aren’t so

much observed as manufactured. The animals are injected with high doses of THC,

then injected with a second chemical to block cannabis receptors in the brain.

Without the block, the sharp withdrawal symptoms can’t be seen because cannabis

clears so slowly that even heavily doped rats are likely to experience a gentle

wind down. Another debate rages over animal studies into the short-term effects

of marijuana on brain chemistry. Heroin, cocaine, alcohol and nicotine all

trigger a surge in the chemical dopamine in a small midbrain structure called

the nucleus accumbens. Many researchers regard this as a hallmark of an

addictive substance. Last year, experiments showed that cannabis presses the

same dopamine button in rats, leading to claims that the drug must be more

addictive than previously thought. To critics, it is just another example of

those old exaggerated fears. What nobody tells you, says John Morgan, a

pharmacologist at City University of New York Medical School, is that rats don’t

like cannabis. It’s easy for them to get hooked on heroin or cocaine — but not

marijuana. Nor, Morgan claims, are researchers exactly open about awkward

observations, such as the fact that there are plenty of nonaddictive drugs that

stimulate dopamine in the brain. It’s easy to understand why biologists want to

find simple chemical traits that are shared by all addictive drugs.

Unfortunately, the differences are as important as the similarities when it

comes to weighing the relative risks and pleasures involved in taking drugs. And

subjectively at least, the intense rush of cocaine and orgasm-like high of

heroin have little in common with dope’s subtler effects. A compound related to

the active ingredient in marijuana may be accumulating in the spinal fluid of

people with schizophrenia. This might explain why many sufferers smoke pot. Many

researchers blame schizophrenia on an overactive dopamine system in the brain.

Daniele Piomelli and colleagues at the University of California at Irvine

already knew that making rats. dopamine receptors hyperactive caused a surge in

anandamide, a lipid that binds to the same receptors in the brain as marijuana.

Now Piomelli.s group has examined cerebrospinal fluid from 10 schizophrenic

patients, taken for diagnostic purposes at the Medical College of Hannover in

Germany. They found that fluid from schizophrenic patients had on average twice

as much anandamide as fluid from people who didn.t have schizophrenia (NeuroReport,

vol 10, p 1665). One explanation for the higher levels in schizophrenics is that

the brain is attempting to compensate for a hyperactive dopamine system. .It.s

the brain.s response to bring this dopamine activity down,. says Piomelli. But

the brain cannot keep the amount of anandamide high enough to lower dopamine

levels, he says. This might also explain why schizophrenics often smoke

marijuana. The drug.s active agent, THC, and anandamide both bind to the same

receptor, so patients might be treating themselves, he says. But because pot

does not act selectively in the brain, Piomelli does not consider it a useful

treatment for schizophrenia. .I don.t think the patient wants to be high,. he

says. .I think the patient wants to feel better.. One weakness in the data so

far is that five of the patients were taking medication for their symptoms and

three others were using marijuana daily. The effects of these drugs on

endogenous cannabinoid levels is not known. .It is imperative to continue with

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