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Wrinkle, Wrinkle



“I just love the feeling of paralyzed muscles in the morning.” This is what I imagine people are saying to themselves as they willingly, nay, enthusiastically receive Botox injections. The rumors you’ve heard are true; Botox does in fact contain a deadly neurotoxin that is more potent than any snake or spider venom you’ll come across. The same neurotoxin that causes botulism and consequently kills about 145 people a year in the states.

The Botox injections that are used for various cosmetic and medical procedures are a derivative of a botulinum toxin (hence the creative name Bo-Tox). The toxin is produced by Clostridium botulinum, a bacterium commonly found in food products like poorly packaged meat and canned foods. When I say it’s potent what I really mean is POTENT—think LD50 around 1ng/kg in rats. That means that a 150 pound person would only need to receive about .000000068 grams of the stuff in order to give him a 50% chance of dying. This toxin is so potent that the DNA sequence of the newest strain of Clostridium botulinum is being safe-guarded by the scientists who discovered it, for fear it would be used in biological warfare. Although the idea of injecting this stuff into my face is intriguing to say the least, it’s not as fascinating as the way botulinum toxin affects your neuromuscular system.

As you well know, your body relies on muscles to get lots of things done. Doing a bicep curl, blinking your eyes, digesting your lunch, even maintaining your posture all require carefully timed expansion and contraction of your muscles. There is a distinct difference between a bicep curl and an exhale though. You can think of this distinction in terms of decision making: you usually decide to do a bicep curl, while it sounds silly to talk about deciding to digest that sandwich you just ate. In general, if you decide to do it, it’s a voluntary movement but if you just do it, it’s Nike. Just kidding, it’s an involuntary movement.

All these muscle motions depend on a common factor: stimulation from your brain. Neurons that terminate at a muscle are called motoneurons and they are responsible for telling your muscles when to expand and contract. The signal comes in the form of a small molecule called acetylcholine. This neurotransmitter gets released by motoneurons and binds to receptors on your muscles, preparing them for contraction. The release of acetylcholine from motoneurons however is no small feat.

Just inside the terminal end of the neuron is a crowd of vesicles full of acetylcholine. Vesicles are basically little balloon-like structures with flexible membranes that can contain any number of things—proteins, neurotransmitters, cellular debris, etc. The tricky part of neurotransmitter release is getting the small molecule out of the tip of the neuron where it will find a receptor on a muscle cell. Now, the entire vesicle can’t just pop out of the neuron because that would leave a gaping hole in the neuron’s cell membrane. The acetylcholine can’t just pop out of the vesicle because then it would just float around aimlessly inside the neuron. Acetylcholine release requires that the vesicle membrane actually fuse with the neuron membrane, maintaining the integrity of the neuron’s membrane while simultaneously opening the vesicle to the extracellular space.


This is the process that scientists think botulinum toxins inhibit. And this is why Botox gives you that perfect, wrinkle-free forehead you’ve always wanted. If your forehead muscles can’t contract then you can’t get frown lines. Coincidentally if your heart muscles can’t contract then you die.

Botox rarely has terribly adverse side effects and almost never kills anyone, because it is delivered in a very controlled manner. But if you happen to ingest botulinum toxin from that can of spam that’s been in your cupboard for 12 years your entire body will feel the effects—including your heart, diaphragm and gastrointestinal muscles.


Sources and Further Reading

Dressler, D.; Saberi, F.A. (2005) Botulinum Toxin: Mechanisms of Action. European Neurology (53), pp 3-9. 

Centers for Disease Control and Prevention. Foodborne, Waterborne, and Mycotic Diseases: Botulism. http://www.cdc.gov/nczved/divisions/dfbmd/diseases/botulism/#how_common (accessed Oct 24, 2013)

Roos, Robert. (2013) Scientists find new botulinum toxin, withhold genetic details. CIDRAP News, University of Minnesota.http://www.cidrap.umn.edu/news-perspective/2013/10/scientists-find-new-botulinum-toxin-withhold-genetic-details (accessed Oct 24, 2013)

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