Pubdate: Sun, 15 Oct 2000
Source: NIDA News Release
Contact: Beverly Jackson or Michelle Muth 301-443-6245
Note: We made the headline up, but it is what we may expect in newspapers 
in the days ahead. The rest of the news release is from the NIDA website -- 
it is posted to DrugNews as an exception to policy. The news release says 
nothing about peer review, or the fact that the results do not match the 
experience of hundreds of millions of humans worldwide. Nor does it say why 
such an early finding, unsupported by other studies, was released to the 
media just weeks before voters in several states vote on marijuana issues. 
We request that readers newshawk any stories which appear in the press as a 
result of this news release.


NIDA Researchers Find That Animals Exposed to Marijuana's Active Component 
Will Self-Administer the Drug

Scientists at the National Institute on Drug Abuse (NIDA) have demonstrated 
that laboratory animals will self-administer marijuana's psychoactive 
component, THC (delta-9-tetrahydrocannabinol), in doses equivalent to those 
used by humans who smoke the drug. Self-administration of drugs by animals, 
long considered a model of human drug-seeking behavior, is characteristic 
of virtually all addictive and abused drugs.

"This study is simple and its findings are clear," says NIDA Director Dr. 
Alan I. Leshner. "Animals will work to get THC. This emphasizes further the 
similarity between marijuana and other abusable, addicting substances. Both 
animals and humans will work to acquire access to marijuana in the same way 
that both animals and humans change their behavior to get other drugs of 
abuse, like cocaine and heroin."

Dr. Steven Goldberg and colleagues at NIDA's Intramural Research Program in 
Baltimore, Maryland, report in the current issue of Nature Neuroscience 
that squirrel monkeys will self-administer intravenous injections of THC.

"This is the first study in which it has been possible to show that monkeys 
or other research animals will self-administer THC. There are many factors 
which may explain this behavior, including the fact that in our study we 
used doses of THC that are directly comparable to doses in marijuana smoke 
inhaled by humans," Dr. Goldberg says.

Before the study began, the scientists first established 
self-administration behavior in squirrel monkeys that received repeated 
intravenous injections of cocaine after pressing a lever 10 times for each 
injection. At the start of the study, the researchers replaced cocaine with 
saline solution and the animals' self-administration stopped. When saline 
was replaced with THC in a solution that would rapidly pass from blood to 
the brain, the animals resumed self-administration, rapidly pressing the 
lever to obtain on average 30 injections of THC during each of a series of 
1-hour sessions. Treatment with a compound that prevented THC from binding 
to cannabinoid receptors on brain cells almost completely eliminated 
self-administration of THC, but had no effect in another group of monkeys 
self-administering cocaine under identical conditions, according to Dr. 

"The drug-seeking behavior in these animals was comparable in intensity to 
that maintained by cocaine under identical conditions, and was obtained 
from a range of doses comparable to those self-administered by humans 
smoking a single marijuana cigarette," Dr. Goldberg says. "This finding 
suggests that marijuana has as much potential for abuse as other drugs of 
abuse, such as cocaine and heroin."

Note to reporters: The full text of the brief communication about this 
study is available in Nature Neuroscience 2000, volume 3, pgs 1073-74 or at

The National Institute on Drug Abuse is a component of the National 
Institutes of Health, U.S. Department of Health and Human Services.  NIDA 
supports more than 85 percent of the world's research on the health aspects 
of drug abuse and addiction.
- ---
MAP posted-by: Richard Lake