In the mechanism of action for BOTOX, when it blocks acetylcholine, does the nerve actually “die” and need to regrow?

Dr. Dean Kane Q & A. Q. In the mechanism of action for BOTOX, when it blocks acetylcholine, does the nerve actually “die” and need to regrow? Or is it just blocked until the botox “wears off” and the neuromuscular junction is free again? If it “kills” the nerves, then what if they do not grow back? Is that not a risk? Thank you. A. Great question! No, the nerve does not die, it is not blocked; it is disabled. ​A motor neuron (nerve cell) has its cell body in the brain or spinal cord and its axon reaching specific muscle fibers. For a muscle cell to contract, acetylcholine is made in the cell body and contained within a synaptic vesicle (cellular bag) which must fuse with the cell membrane and empty onto the muscle fiber’s acetylcholine receptors across a synapse (neuromuscular space). ​ ​Botox or other botuminum neurotoxins are a protein which when injected is endocytically or “absorbed” into the nerve end of the synapse and “cleaves” or breaks a very specific enzyme (also made in the cell body but outside the vesicle) which allows the vesicle to fuse with the nerve end and dump the acetylcholine.  Since the vesicle cannot now fuse, the acetylcholine cannot travel across the synapse to bind with the muscle receptor and therefore, no muscle contraction. ​ The Botox itself does not stay around long. It is broken down fairly quickly in the synaptic space. It is the special enzyme in the nerve cell which must be re-made and travel down the long axon for the neuromuscular activity to begin once again. This takes an average of 3 months. Which is why most patients return to their doctor’s office every 3-4 months for another Botox injection to keep the cosmetic affects going year round. If you don’t come back for the injection, the same frown lines return and you go back to the way you looked before. Many people ask if they would get worse if they didn’t come back and the answer is that aging continues so you just have the same aging effects you would have had if you never injected Botox in the first place. So if do Botox injections and then stop, in essence you have prevented the aging process and the lines from forming for as long as you keep up the injections. ​ ​I hope this has been helpful! Dr. Dean Kane  
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