Active ingredients in marijuana found to spread and prolong pain
August 13, 2009Imagine that you're working on your back porch, hammering in a nail. Suddenly you slip and hit your thumb instead — hard. The pain is incredibly intense, but it only lasts a moment. After a few seconds (and a few unprintable words) you're ready to start hammering again.
How can such severe pain vanish so quickly? And why is it that other kinds of equally terrible pain refuse to go away, and instead torment their victims for years?
University of Texas Medical Branch at Galveston researchers think they've found at least part of the answer—and believe it or not, it's in a group of compounds that includes the active ingredients in marijuana, the cannabinoids. Interestingly enough, given recent interest in the medical use of marijuana for pain relief, experiments with rodents and humans described in a paper published in the current issue of Science suggest these "endocannabinoids," which are made within the human body, can actually amplify and prolong pain rather than damping it down.
"In the spinal cord there's a balance of systems that control what information, including information about pain, is transmitted to the brain," said UTMB professor Volker Neugebauer, one of the authors of the Science article, along with UTMB senior research scientist Guangchen Ji and collaborators from Switzerland, Hungary, Japan, Germany, France and Venezuela. "Excitatory systems act like a car's accelerator, and inhibitory ones act like the brakes. What we found is that in the spinal cord endocannabinoids can disable the brakes."
To get to this conclusion, the researchers began by studying what happened when they applied a biochemical mimic of an endocannabinoid to inhibitory neurons (the brakes, in Neugebauer's analogy) on slices of mouse spinal cord. Electrical signals that would ordinarily have elicited an inhibitory response were ignored. They then repeated the procedure using slices of spinal cord from mice genetically engineered to lack receptors where the endocannabinoid molecules could dock, and found that in that case, the "brakes" worked. Finally, using electron microscopy, they confirmed that the receptors were in fact on inhibitory, not excitatory neurons. Endocannabinoids docking with them would suppress the inhibitor neurons, and leave pain signals with a straight shot to the brain.
"The next step was to make the leap from spinal slices to test whether this really had anything to do with pain," Neugebauer said. Using anesthetized rats, he recorded the spinal cord electrical activity produced by an injection in the hindpaw of capsaicin- a chemical found in hot peppers that produces a level of pain he compared to a severe toothache. Although the rats were unconscious, pain impulses could be detected racing up their spinal cords. What's more, formerly benign stimuli now generated a significant pain response — a response that stopped when the rats were treated with an endocannabinoid receptor blocker.
"Why was this non-painful information now gaining access to the spinal "pain" neurons?" Neugebauer said. "The capsaicin produced an overstimulation that led to the peripheral nerves releasing endocannabinoids, which activated receptors that shut down the inhibitor neurons, leaving the gates wide open."
Finally, the researchers recruited human volunteers to determine whether a compound that blocked endocannabinoid receptors would have an effect on the increased sensitivity to pain (hyperalgesia) and tendency for normally non-painful stimuli to induce pain (allodynia) often reported in areas of the body near where acute pain had been inflicted. In this case, the researchers induced pain by passing electricity through the volunteers' left forearms, with the intensity of the current set by each volunteer to a 6 on a scale of 1 to 10. At a second session a month later, the volunteers who had received the receptor blocker showed no reduction in perceived acute pain, but had significantly less hyperalgesia and allodynia — a result that matched up well with the endocannabinoid hypothesis.
"To sum up, we've discovered a novel mechanism that can transform transient normal pain into persistent chronic pain," Neugebauer said. "Persistent pain is notoriously difficult to treat, and this study offers insight into new mechanisms and possibly a new target in the spinal cord."
It also raises questions about the efficacy of marijuana in relieving acute pain, given that endocannabinoids and the cannabinoids found in marijuana are so biochemically similar. "If you had a toothache, you probably wouldn't want to treat it with marijuana, because you could actually make it worse," Neugebauer said. "Now, for more pathological conditions like neuropathic pain, where the problem is a dysfunction within the nerves themselves and a subsequent disturbance throughout the nervous system that's not confined to the pain system, marijuana may be beneficial. There are studies that seem to show that. But our model shows cannabinoids over-activating the pain system, and it just doesn't seem like a good idea to further increase this effect."
Source: University of Texas Medical Branch at Galveston (news : web)
Jan 22, 2008 |
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Similar, but not the same. I'd like to see a study done that actually uses cannabis instead of something that is "mostly like" cannabis. Additionally, they only looked at the effects on the spinal nerves, as opposed to a bigger picture of the interactions in the brain that cannabinoids trigger. Completely anecdotal: it seems that cannabis creates a sensation of "forgetfulness" or lack of care about pain as opposed to actually blocking the pain itself.
Try smoking some weed instead of regurgitating what you see in the movies.
Vel and Simon highlighted the major, absolutely obscene flaws in this study, but I find it hard to argue that MJ does not enhance "feelings."
"This research funded by the Pharmaceutical Industry of America."
Experience tells me this is not accurate because sitting there sober with a toothache vs stoned with a toothache anyone willing to be stoned would tell you their choice (its not like any toothache isn't already hurting before you've smoked, and after you can at least relax a little). Plus these studies where they try and figure out marijuana is bad without actually using it are more designed to make it look as though marijuana is so dangerous it can't even be studied directly, yet opiates and cocaine derivatives are available at any pharmacy across the world with a prescription. Its available in California basically and if you really want to do actual science with real data there are ways to make a real study happen. To play with other models vs the real thing at this point is like observing the milky way exclusively through binoculars while the Hubble's in orbit over your head, hardly advancing any science.
It may well be true, in its own limited context, however,
I found it to be misleading, and to perhaps contradict a
lot of personal testimony of people with those kinds of
chronic "neuropathic pain" who say that they benefited.
This study admits that kind of chronic pain
might well be treated by medical marijuana.
However, like most other sensationalized
anti-pot propaganda, the report tended to
be presented to cast bad aspersion on pot.
In the end, this study seems to me to merely be another
confirmation of general effects of getting high, that when
you get high, both the good and the bad experiences
tend to be amplified, so that food tastes better, and
music sounds better, and so on and so forth, and so,
it would seem to make also make good sense that if
"you hit your thumb with a hammer," then it would
tend to hurt worse when you were high, than if
you were not high when you hit your thumb ...
Life is generally a package deal,
& the good comes with the bad.
The price of getting high may well be
that good sex is better, however, the
bad sex ends up being worse, etc. ...
Personally I would not attempt treating pain with marijuana because in my case it greatly enhances every sensation and I would expect the pain to get worse (though I admit my expectation may be wrong here it is enough to stop me from even trying).
There is however plenty of evidence that it does help people with chronic pain.
One possible explanation is that cannabinoids present in marijuana compete with endocannabinoids for those same receptors but due to chemical differences do not work as well in shutting down inhibitory neurons. This way a person whose spinal cord already produces endocannabinoids may experience some pain relief due to plant cannabinoids preventing natural cannabinoids from exerting their full effect and completely blocking inhibitory neurons. In other words marijuana endocannabinoids may only "half-block" the inhibitory neurons. If your inhibitory neurons were not blocked before you would experience increase in pain, if they were already blocked completely you would experience pain relief.
This is just one possible mechanisms but there are many other possibilities, for example overstimulation with cannabinoids may activate some sort of negative feedback mechanism which downregulates receptors for example by degrading them. Finally the pain relief effects may stem from some other part of the nervous system.
All in all, I think the article is incredibly misleading as THC is the active ingredient in marijuana, however it is not the be all - end all of cannibinoids.
http://www.theden...ail.html
Looks like the drug propaganda war is still going strong.
Then there was the time I pranged up my hang-glider, and broke my leg as a result... triple-compound fracture, and the mediquacks that shoved a rod into it and patched it all up were all saying that it'd be a good half-year at least before I'd be walking normally again - so; I got hauled back home to my cabin, and then immediately stocked up on several more bags of cannabis so I could stay stoked-up on a more-or-less continual basis... and after five weeks I was walking perfectly well again, without crutches. No undue pain, and back to work as normal - thus making my employer less nervous about shift coverage.
And the moral of this story is: umm... errr... ahh; I forgot. Make up one yourself then, if you really need such - I'm going to go roll a joint now.
years and years. If I remember right you're a tobacco guy? That explains your vitriol. It's your NERVES my friend. Maybe you're just freakin me out.
blue? Aw you musta hit a vein dude
ah poetry. I like poetry. Especially when it's BLACK METAL!!!!!! AAAAHHHHHHHHHH!!!
Mr. Neugebauer, I don't have a medical degree or anything but I'll bet if you'd get a patient suffering from toothache to smoke a joint, he could tell you first hand if it releaves his pain or not.
if you could actually have someone smoke MJ you wouldn't need words like "probably", "could" and "seem" in your results.