Stress and Saliva

You can buy your very own ladder safety poster from Stan's Safety Posters, found here. 

I received this excellent question from Gill recently:

Incidentally, is saliva production halted when there is major stress?  Have noticed a marked difference, for instance, today I was frightened that I was about to fall off the top of a step ladder and the saliva vanished........When the stressful situation is over, back comes the saliva.

First of all, I was really impressed with Gill's ability to evaluate Sjogren's symptoms AS THIS PERSON WAS ABOUT TO FALL OFF A LADDER.

Wow. That's amazing. See, I would be all flailing around and screaming and just freaking out in general. But Gill? Thinking probably calmly, "Drat. I'm falling off a ladder......Hm. My mouth is really dry right now. I wonder where the saliva went?"

This is the kind of person that I aspire to be. Seriously.

But back to the excellent question: Does stress influence saliva production?

Yep. It sure does.

The production of saliva is controlled by several factors, one being a very complex neurological network, two components of which I'll discuss here. Please note that I'm simplifying things dramatically. It's the only way that my brain can handle this kind of stuff anymore.

The answer to the question lies in describing the sympathetic and parasympathetic nervous systems.  Simply put, the parasympathetic nervous system is responsible for the "rest and digest" functions of the body. The sympathetic creates the "fight or flight" response in a reaction to stimulus outside of the body, such as the stress created by a wobbly stepladder. And the fear that one may be crashing one's body onto a hard surface.

Here's an explanatory graph created by Dr. Sumaiya Khan, found here.

Parasympathetic Nervous System	Sympathetic Nervous System
Constriction of pupils	Dilation of pupils
Stimulation of secretion of saliva	Inhibition of secretion of saliva
Decreases the heart rate, thus, causing a drop in the blood pressure	Increases the heart rate, thus, causing an increase in the blood pressure
Constricts the bronchi and thus, decreasing the diameter of airway	Dilates the bronchi, thus, increasing the diameter of airway
Stimulates activity of the digestive system, like stimulation of peristalsis	Inhibits activity of the digestive system, like inhibition of peristalsis
Stimulates gallbladder secretions	Decreases gallbladder secretions
Contract urinary bladder	Relaxes urinary bladder
Relaxes rectum	Contracts rectum

Note in the second row that the sympathetic nervous system (the one that is triggered as one falls off a ladder) when stimulated inhibits the production of saliva.

The parasympathetic and sympathetic nervous system cannot both be active simultaneously. Dr. Khan explains, "Thus, as can be inferred from the above given table, the responses and effects of both the systems are complementary in nature, rather than being antagonistic. The sympathetic division acts as the accelerator and the parasympathetic division acts as a decelerator of the human body. Thus, these two systems try and maintain the body in a normal state of homeostasis for the maximum possible time. At a time, only one of the two systems are activated in the body, depending on the type of innervation brought about and the hormones released."

In other words, a Yikes-I'm-Going-To-Fall experience will inhibit the secretion of saliva.

So, yes, Gill, acute stress does temporarily halt saliva production. That is, until the parasympathetic nervous system kicks in once the stressful incident has passed, and resumes it's normal messages to the salivary glands to produce saliva.

But wait -- there's more!

The nervous system uses special biochemicals -- or neurotransmitters -- to facilitate stimulus transmission through it's network of nerves. Sjoggies should be particularly interested in the neurotransmitter acetylcholine, which is used by the parasympathetic nerves to send their messages, including the ones that stimulate the production of saliva.

The two most commonly used drugs which increase the production of saliva, Evoxac (civemeline), and Salagen (pilocarpine), are considered cholinergic agonists, which means that the drugs enhance the effects of acetylcholine.

If you take either of these medications, you probably have noticed that they do cause an increase in saliva (if your salivary glands have functioning tissue) but that they do also have side effects, which may include increased sweating and some gastro-intestinal symptoms. This is because acetylcholine is instrumental in these body functions too, and these functions will also increase along with salivation.

If you are experiencing side effects while taking civemeline or pilocarpine, talk to your doctor.

Enough biochemistry for the day. My brain is strained.

See y'all tomorrow.