Botulinum toxin, produced by the bacterium Clostridium botulinum, is one of the most poisonous biological substances known, but in true' the dose makes the poison' fashion,  Botulinum neurotoxin serotype A , commonly known as Botox - took C. botulinum  from being known for the serious paralytic illness Botulism to smoothing out wrinkles due to its paralytic effect.

It's been used for decades with no serious side effects and outside cosmetic surgery is also useful for the treatment of over-active muscles and spasticity, because it promotes local and long-term paralysis, but a new study has found that some of the toxin is transported via our nerves back to the central nervous system.

University of Queensland  Brain Institute laboratory leader Professor Frederic Meunier says, "The discovery that some of the injected toxin can travel through our nerves is worrying, considering the extreme potency of the toxin. However, to this day no unwanted effect attributed to such transport has been reported, suggesting that Botox is safe to use.

"While no side-effects of using Botox medically have been found yet, finding out how this highly active toxin travels to the central nervous system is vital because this pathway is also hijacked by other pathogens such as West Nile or Rabies viruses. A detailed understanding of this pathway is likely to lead to new treatments for some of these diseases."

Dr. Tong Wang, a Postdoctoral Research Fellow in Professor Meunier's laboratory, discovered that most of the toxin is transported to a cellular dump where it is meant to be degraded upon reaching the central nervous system. "For the first time, we've been able to visualize single molecules of Botulinum toxin travelling at high speed through our nerves.

"We found that some of the active toxins manage to escape this route and intoxicate neighboring cells, so we need to investigate this further and find out how."

Citation: Tong Wang, Sally Martin, Andreas Papadopulos, Callista B. Harper, Timur A. Mavlyutov, Dhevahi Niranjan, Nick R. Glass, Justin J. Cooper-White, Jean-Baptiste Sibarita, Daniel Choquet, Bazbek Davletov, Frédéric A. Meunier, 'Control of Autophagosome Axonal Retrograde Flux by Presynaptic Activity Unveiled Using Botulinum Neurotoxin Type A', The Journal of Neuroscience, 15 April 2015, 35(15):6179-6194; doi:10.1523/JNEUROSCI.3757-14.2015