Rats taking cannabis get taste for heroin

news@nature.com ^ | 5 July 2006 | Michael Hopkin

[neverdem]

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Published online: 5 July 2006; | doi:10.1038/news060703-9

Rats taking cannabis get taste for heroin

Study suggests cannabis-users may be vulnerable to harder drugs.

Michael Hopkin

Neuroscientists have found that rats are more likely to get hooked on heroin if they have previously been given cannabis. The studies suggest a biological mechanism — at least in rats — for the much-publicized effect of cannabis as a 'gateway' to harder drugs.

The discovery hints that the brain system that produces pleasurable sensations when exposed to heroin may be 'primed' by earlier exposure to cannabis, say researchers at the Karolinska Institute in Stockholm, Sweden, who carried out the study.

There has long been a debate about whether exposure to drugs such as nicotine or marijuana might lead to harder habits. Many argue that the most important factors in the equation are social ones: people who get one drug from a dealer are probably more inclined to try another. But researchers are still interested to know whether there is any physiological effect that might additionally predispose users of so-called soft drugs to harder-drug addiction.

To rule out social factors, the researchers turned to an animal model. They dosed some rats with the active ingredient of cannabis and others with a neutral compound during their adolescence (when they were about four to six weeks old). After that, they gave the rats intermittent access to heroin for several weeks, obtained by pressing a lever.

Although all rats helped themselves to heroin, the ones given cannabis's key compound, called -9-tetrahydrocannabinol (THC), during their formative years showed a greater escalation in their self-dosing during the experiment. By the end, rats that'd had cannabis in their 'teens' were pressing the lever that delivered heroin about 1.5 times more than the rats that had previously been drug-free.

We now know that these drugs have an impact on behaviour later in life.  Yasmin Hurd, Mount Sinai School of Medicine, New York

The researchers report the findings in the journal Neuropsychopharmacology¹.

Hard to kick

"It's a nice study, although somewhat preliminary," comments Ian Stolerman, a psychopharmacologist at Kings College London. "It's too early to say there's a consensus, but a small number of studies like this suggest that there is a physiological basis for this effect."

The rat results may be due to the fact that both THC and heroin act on a pleasure pathway in the brain called the opioid system, explains study leader Yasmin Hurd, now at Mount Sinai School of Medicine in New York. Exposure to opiates such as heroin triggers the release of chemical messengers in the brain called opioids that stimulate pleasant sensations.

The receptor molecule to which THC binds is also found on brain cells in the opioid system, Hurd adds. Over-stimulation of these receptors through exposure to cannabis may alter these cells so that the brain either feels intensely rewarded by subsequent heroin exposure, or needs an ever-increasing dose to feel the same pleasure — both of which could lead to addiction.

If so, a similar effect may be seen with drugs such as cocaine and amphetamines, which involve another brain pathway called the dopaminergic system, Stolerman adds. Cells involved in this pathway also have THC receptors, possibly indicating that they could also be modified by cannabis exposure.

A slippery slope

But even if the gateway effect is one day found to also have a biological basis in humans, the effect is undoubtedly complicated by social factors. Some social commentators have ascribed the perceived gateway effect to the simple fact that cannabis is cheaper than many other illegal drugs, meaning that adolescents are more likely to use it before graduating to other substances.

Hurd, however, feels that softening the law against marijuana at this point would be "ridiculous", given the number of unknowns about its effects. She adds that two other drugs that also stimulate opioid cells, and could therefore also feasibly cause a gateway effect, are nicotine and alcohol. "If we turned back the clock with the knowledge we have now, these two drugs would never have been legalized," Hurd says.

The discovery also warns against complacency that cannabis does not have any lasting effect in young people who use the drug. "Lots of mothers say 'oh well, at least it's not cocaine'," Hurd says. "But this is not about the short-term effects. For adults to do it is one thing, but we have to consider the effects on children."

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References

1. Ellgren M.,

   Spano S. M.&

   Hurd Y. L. . Neuropsychopharmacology, . - doi:10.1038/sj.npp.1301127

[TheSpottedOwl]

Yeah? Give them bread on paper plates and the next thing you know, they're eating your bloody clothes! Marlon Perkins brought home kangaroo rats, and they escaped :(

Anyone got any pot or heroin I can borrow? Maybe they'll OD...

[Know your rights]

Anyone got any pot or heroin I can borrow? Maybe they'll OD...

People can't OD on pot (not sure about rats). Try alcohol instead.

[Know your rights]

Watch out! Here come the "conservatives" who fear liberty but can't logically argue against it!

[Lancey Howard]

"Give me drugs or give me death"?

[funkywbr]

Lets see, a HUMAN gives a RAT pot!

A human then gives a RAT horse.

Hell a RAT will eat anything.

Why didnt they put CRANK in the cages instead of Horse?

Were they afraid of turning the rats into rednecks?

[neverdem]

"If we turned back the clock with the knowledge we have now, these two drugs would never have been legalized," Hurd says.

I doubt that, at least about alcohol. Smarter governments figured out taxation schemes.

Dave Alexander, owner and operator of the Brickskeller in downtown Washington, D.C., argues that "beer is probably the reason for civilization."

[Know your rights]

More like: Give me liberty, including the liberty to decide for myself whether or not to use drugs, or give me death.

[Mike Darancette]

rats are more likely to get hooked on heroin if they have previously been given cannabis

How about Republicans?

[Cedar]

Poor rats, now they are following the Fried Piper.

[USNBandit]

This type of thread always devolves into a poop slinging contest, so I try to get in early with a little humor.

[Ol' Dan Tucker]

By the end, rats that'd had cannabis in their 'teens' were pressing the lever that delivered heroin about 1.5 times more than the rats that had previously been drug-free.

This article is hilarious. Shades of "Reefer Madness", which has been playing on Flix channel lately, btw.

It's clear that all the rats were pressing the lever to get some smack.

But, for every 7.5 times the hippie rats pressed the lever, the ivy-league rats pressed it 5 times. ;)

[Moonman62]

More like: Give me liberty, including the liberty to decide for myself whether or not to use drugs, or give me death.

Move to Amsterdam where you can enjoy your liberty for a few more years before the Muslims take over.

[mysterio]

Pothead rats like heroin, too? Well, shucks. By all means, let's kick in every door in the country and revoke the Bill of Rights to stop them.

The failed war on some drugs proponents have had lots of "studies" over the years. The first "studies" claimed pot made daughters want to engage in intercourse with jazz musicians. Did it have that effect on the rats, too?

[mysterio]

"Give me drugs or give me death"?

Give me nanny statism or give me emotion based slogans?

[stands2reason]

No, but pythons prefer rats on cannabis.

As long as they have a Big Grab bag of Cheetos to go with.

[Sundog]

Do you ever look at stupidvideos.com?

Stupid fellow shows a python a rat, then pulls it away and puts his hand in the same place.

Next moment he has a set of fang marks across his palms.

Then the other guy says, "Yeah, that's what mine looks like too."

http://www.stupidvideos.com/video/animals/Big_Snake_Bite/

Cheers.

[neverdem]

Sativex has a high concentrate of alcohol. Any result might be skewed by the presence of the alcohol to this study.

SATIVEX®contains approximately 50% v/v of ethanol. Each dose contains up to 0.04 g of ethanol. The median daily dose of 5 sprays would be up to 0.2 g ethanol.

v/v represents the volumes of active ingredients to the volume of solution, i.e. an abbreviation for "by volume," used in chemistry and pharmacology to describe the concentration of a substance in a mixture or solution. Thus 2% v/v means that the volume of the substance is 2% of the total volume of the solution or mixture. See also w/v.

According to New Zealand, "One standard drink equals 10 grams of pure alcohol," i.e. one regular can of beer has about 50 times the total daily average dose consumed with Sativex, depending on the actual ethanol content and volume. Give me a break.

[Rightwing Conspiratr1]

Sativex has a high concentrate of alcohol. Any result might be skewed by the presence of the alcohol to this study.

The control group received it as well. Curiously the theory that THC acts on the same pathway as opium in the study supports the medical use of pot.

[The Red Zone]

However, Pubs proved to be resistant.

[Reform4Bush]

Marijuana use has never made me want to try heroin, but reading this post has.

There you have it. Scientific proof that reading BS will make you want to try heroin.