The researchers have uncovered the precise molecular process by which Botox toxin is able to gain entry into the neurons in the brain.
In a remarkable study, the researchers Professor Frederic Meunier and Dr. Merja Joensuu from University of Queensland, Australia have been able to unravel how the Botox toxin, which can block nerve functions and lead to muscular and respiratory paralysis, is able to enter the brain.
Millions of individuals across the world use Botox every day, making it one of the most popular cosmetic procedures. However, a small percentage of those procedures result in adverse reactions.
This does not come as a surprise as Botox, also known as botulinum toxin type A, is the most toxic biological compound known which is produced by the bacterium Clostridium botulinum. The bacteria is commonly found in soil, water, on plants as well as in the intestinal tracts of animals. In fact, the toxin or the ‘miracle poison’ is so potent that just a few teaspoons of it would be enough to kill millions of people.
Botox entry in the Brain
The study which was published in The EMBO Journal sheds light on how the toxin may be able to accomplish this. The scientists discovered that this ability is conferred to the toxin by its ability to hijack a receptor complex.
With the help of super-resolution microscopy, the researchers were able to show that a receptor called Synaptotagmin 1 binds to two other earlier known clostridial neurotoxin receptors to form a small complex that sits on the plasma membrane of neurons, as explained by Professor Fredric Meunier, the neurobiologist of University of Queensland.
This complex formed of the three receptors, is hijacked by the toxin, which then enters the synaptic vesicles that store the neurotransmitters necessary for the communication between neurons. Mainly, the release of the neurotransmitter acetylcholine is inhibited post the infection, causing the communication between nerves and muscle cells to be disrupted by Botox, which eventually results in paralysis. The symptoms of botulism include but are not limited to dilated pupils, double vision, hazy vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness.
The triple combination
The researchers demonstrated that this triple receptor combination is necessary for the Botox toxin to enter the neuron and get access into the brain. The toxin was unable to enter when it was bound to only one of the receptors. The cell developed a tube to let in the toxin but never broke from the surface when the scientists completely eliminated one of the receptors -the Syt1 receptor. One can imagine it to be similar to blowing bubbles, but with the bubble remaining attached to the wand.
The grave news is that it isn’t like only the individuals opting for such cosmetic procedures are the only ones at risk due to a dosage of Botox injection, but anybody can be prone to this infection as the bacteria that produces this toxin can be present in the food, or can be breathed in through soil particles or water. It can also possibly enter the wounds in case of unfortunate events.
Though currently there are antitoxins available, nevertheless the disease known as botulism still claims the lives of about 7% of those who contract it.
How the study may be helpful
The research team is hopeful that the new findings may lead to more effective disease therapies. Professor Meunier explained that now interactions between any two of the three receptors can be inhibited to prevent the lethal toxins from entering neurons since a better understanding of how this complex permit toxin internalization has been developed.
