This undated file photo shows a person is receiving botulinum toxin injection. A public interest group has petitioned the U.S. authorities to press tougher warnings on wrinkle-eliminating cosmetic drug, media reported Monday. (file Photo) Photo Gallery>>>

    WASHINGTON, April 4 (Xinhua) -- Researchers have found that botulinum neurotoxin type A, which is more commonly known as Botox, the popular wrinkle eraser, can migrate into the central nervous system after it's injected into the skin, according to latest issue of The Journal of Neuroscience available on Friday.

    The discovery by Italian researchers has raised new concerns about how the toxin works and what unintended consequences it may have.

    The botulinum toxin cuts off communication between nerve cells by destroying a protein named SNAP-25. The disruption paralyzes the muscles controlled by the nerve cells. These paralyzing properties allow doctors to treat some diseases such as strabismus(or "crossed" eyes). Plastic surgeons also use small doses to paralyze facial muscles, thereby making lines and wrinkles less visible.

    A team of Italian researchers were evaluating another potential use of the toxin: treating epilepsy. But when studying its effects on epileptic mice, they noticed evidence of the toxin on both sides of the animals' brains, even though they had injected it on only one side.

    Using doses analogous to those prescribed in humans, researchers then injected botulinum into the eyes, whisker pads, and brains of normal mice and rats. They traced the toxin's wreckage -- the cleaved SNAP-25 -- to see where and how it moved through the nervous system.

    In the case of botulinum type A, the kind used in Botox, they found that wreckage along nerves originating from the injection site and in neighboring nerves. The toxin even reached part of the brain stem.

    "A significant portion of the toxin is active where it's not intended to be," said Matteo Caleo, the lead researcher.

    The experiment is the first to show that botulinum migrates.

    However, Christopher von Bartheld, a neuroscientist from University of Nevada, said there's no need for alarm. "Botox has been used for more than 25 years with very few complications, unless you overdose."

    He added that the toxin's ability to spread might have an upside, allowing doctors to treat brain-based disorders such as epilepsy.