Botox, a potent neurotoxin which is used to paralyse nerves to smooth out wrinkles and treat several illnesses, can reach the brain without causing side effects, which shows its use is safe, Australian researchers report in the Journal of Neuroscience.
"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,” said study leader Professor Frederic Meunier from the UQ Queensland Brain Institute Laboratory.
Apart from its age-defying cosmetic uses, Botox is now used to treat several nerve and muscle-related disorders, including spasticity, migraines, muscle spasm and excessive sweating.
“Botox has several therapeutic benefits and is approved to treat cervical dystonia (severe spasms in the neck muscles), muscle spasms in the arms and hands, severe underarm sweating (hyperhidrosis) and nerve disorders, Botox is used to treat cervical dystonia (severe spasms in the neck muscles), muscle spasms in the arms and hands, and severe underarm sweating (hyperhidrosis), uncontrolled blinking or spasm of the eyelids, overactive bladder and incontinence (urine leakage) caused by nerve disorders such as spinal cord injury or multiple sclerosi, and chronic migraine headaches,” says Dr Pushpendra Renjen, consultant neurologist.
Botulinum Toxin Type A blocks nerve activity in the muscles, causing a temporary reduction in muscle activity. “Because of the nature of the toxin, several safety studies of Botulinum Toxin Type A have been done since it was approved in 1989, and all have found it safe,” he adds.
In the new study, researchers are excited to identify the neural pathway this highly active toxin takes to travel to the central nervous system because the same pathways are hijacked by other disease-causing viruses and bacteria 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," said Meunier.
For the first time, Meunier’s team was able to visualise single molecules of Botulinum toxin travelling at high speed through the nerves to a cellular dump where it is meant to be degraded upon reaching the central nervous system.
The degradation, however, did not happen. The researchers found that some of the active toxins manage to escape this route and intoxicate neighbouring cells, but said further research was needed to understand how it happened.