The Straight Toke - THE Marijuana Blog

I don't know if you've covered this or not, but I've been wondering about the whole cottonmouth phenomenon.

For the longest time I always assumed cottonmouth was directly related to the act of smoking, but then when I got more into edibles I discovered it can be just as bad if not worse. Is there something in cannabis that shuts off salivary glands?

Well I haven't covered it, but I don't see why I shouldn't. ;-)

Short Answer

Your guess is likely correct. Recent research suggests that various compounds in cannabis actively impede the production of saliva. It's not a sign of dehydration, simply a (mostly) harmless physiological response. Since this is due not to the heat caused by smoking cannabis, but is rather a physiological response to the compounds in marijuana, the method of ingestion doesn't make a difference.

Wanna know why? Read on

Long Answer

Most mammalian tissue contains two types of cannabinoid receptors, CB₁ and CB₂. CB₁ receptors are found in nervous tissue (primarily in the brain, but also in other locations throughout the body) and CB₂ receptors are found in hematopoietic cells and throughout the immune system (specifically in T cells, B cells, and macrophages.) Cannabis, as you likely know, contains THC (delta9-tetrahydrocannabinol). THC is a CB₁ agonist. But THC isn't the only cannabinoid receptor agonist -- there are a number of other cannabinoids found in common marijuana, at least 66 have been discovered thus far. While the actions of these cannabinoids on CB₁ and CB₂ receptors are beyond the scope of this article, it can safely be assumed that there are likely more CB₁/CB₂ agonists in cannabis than just THC.

So how does this tie in to "cottonmouth"? Well as it turns out, the salivary system appears to respond to CB₁ and CB₂ agonists. In a study on the subject¹, it was found that the submandibular glands of male rats contain CB₁ and CB₂ receptors. When researchers injected anandamide (an endocannabinoid with a high affinity for the CB₁ and CB₂ receptors) into rats' submandibular saliva glands, they found that it appeared to inhibit saliva production. The study concluded that anandamide "decreases saliva secretion in the SMG acting through CB₁ and CB₂ receptors."

Now while anandamide was chose by Prestifilipo et al., the inhibition of saliva production does not appear to be specific to anandamide. Instead, it is assumed that the activation of CB₁ and CB₂ in the submandibular gland was what caused the decrease in saliva production. If the inhibitory effect is indeed substance independent (i.e. not unique to the anandamide), then we might assume that any sufficiently strong CB₁/CB₂ agonist could cause a reduction in saliva production. Since marijuana contains a number of CB₁ and CB₂ agonists, and since CB₁/CB₂ agonists appear to have an effect on saliva production, it may well be that "cottonmouth" is due to the activation of CB₁ and CB₂ in saliva glands. Of course this conclusion is dependent on 1) the presence of CB₁ and CB₂ receptors in the saliva glands of humans 2) the presence of strong CB₁ and CB₂ agonists in recreationally-used marijuana and 3) human salivary secretion sharing certain similarities with the salivary secretion of rats.

So that's my guess -- based on the work of Prestifilippo et al., I'd be willing to be that "cottonmouth" is caused by the activation of CB₁ and CB₂ receptors in the salivary glands.

1. Prestifilippo et al. 2006. Inhibition of Salivary Secretion by Activation of Cannabinoid Receptors. Experimental Biology and Medicine 231:1421-1429

This post answers the questions:
Why do I get cotton mouth after I smoke weed?
Why is my mouth dry after I smoke pot?
Why does my mouth feel dry after I smoke marijuana?
Why do I get a dry mouth after smoking pot?

This entry was posted on Saturday, June 7th, 2008 at 7:50 pm and is filed under Health/Medicine, Q/A. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.