Botox: A Powerful Neurotoxin
Botox is used for banishing crow's feet and tightening sagging jowls. Six million Americans each year and an estimated 75% of celebrities over the age of 35 use it. But did you know that Botox is composed of the same deadly toxin responsible for botulism poisoning that can cause paralysis and respiratory failure?
Botox is the trade name for botulinum toxin, a protein produced by the bacterium Clostridium botulinum. Botulinum toxin is one of the most powerful neurotoxins known today.
Botulism disrupts both voluntary muscle control and the autonomic nervous system. Symptoms of poisoning include double vision, eyelid drooping, loss of facial expression, inability to swallow, constipation, nausea, and difficulty talking. Weakness spreads throughout the body, making it difficult to use the limbs. Eventually, severe botulism can result in paralysis of respiratory muscles, leading to respiratory arrest, coma, and death if untreated.
So...pretty dangerous, right? Though, at this point, you've likely made the connection between Botox and facial paralysis—after all, we've all seen Joan Rivers.
Let's take a look at the mechanism by which botulinum exerts its tenacious control over the nervous system.
The toxin contains two molecule chains, or peptide sequences. The heavy chain is responsible for recognizing the axon terminal—the end of the neuron where neurotransmitter is released (shown magnified in the figure). Once the toxin reaches the axon terminal, the neuron gobbles it up in a process called endocytosis.The other chain of the toxin, called the light chain, disrupts the structure of a protein group called SNARE (shown in purple, blue, and green). Without SNARE, neurotransmitters cannot be released from the axon terminal.
In muscles, release the neurotransmitter acetycholine (shown in red) allows muscle contraction and movement. By the mechanism described, the presence of botulinum toxin blocks acetylcholine release, leading to muscle paralysis—the hallmark of botulism poisoning.
Low doses of botulinum toxin, as used in Botox, paralyzes muscles at the site of injection. That's what makes the wrinkles seemingly disappear. Botox injections are performed by doctors to treat a range of ailments: dystonia, migraine, severe sweating, and cosmetic correction, among others. Effects can last up to four months.
So the next time you see your favorite celebrity post-injection, looking particularly smooth-skinned and pouty-lipped, remember that they injected a deadly toxin into their body—all so that they could look younger just for you, adoring fan.
Arnon, S. (2001). Botulinum Toxin as a Biological Weapon: Medical and Public Health Management JAMA: The Journal of the American Medical Association, 285 (8), 1059-1070
Frevert J (2010). Content of botulinum neurotoxin in Botox®/Vistabel®, Dysport®/Azzalure®, and Xeomin®/Bocouture®. Drugs in R&D, 10 (2), 67-73