Elimination of wrinkles with botulinum toxin preparations: how does it work?

The mechanism of action of  botulinum toxin preparations is to  impact on motor neurons, which reduces muscle activity. This results in a temporary correction of moderately or severely pronounced vertical frown lines in patients younger than 65 years of age. The elimination of wrinkles, which by their severity had a strong psychological impact on the patient, can significantly improve his quality of life.

Botulinum Toxin Wrinkle Removal: Impulse Transmission Mechanism

When a botulinum toxin preparation is injected into the presynaptic nerve terminal, the neurotransmitter acetylcholine accumulates in the form of vesicles, which are transported to the presynaptic membrane. When transmitting a nerve impulse & nbsp; a chain of reactions is activated, as a result of which the vesicles containing the neurotransmitter merge with the membrane of the nerve ending. This process is due to the interaction of proteins located on the membranes of vesicles and cells, which together form the SNARE complex.

Membrane fusion during exocytosis results in the release of acetylcholine into the synaptic cleft. Acetylcholine, penetrating through the synaptic cleft, eventually binds to the receptors of the muscle fiber, causing it to contract.

How Botulinum Toxin works inside the muscle

Botulinum toxin preparation is injected directly into the target muscle to eliminate wrinkles. After the injection of the drug, the botulinum toxin molecule weighing 150 kilodaltons is separated from the protective complexing proteins surrounding it. The binding domain of the neurotoxin molecule to the presynaptic membrane of the neuromuscular synapse is the free C-terminus of the heavy chain. The botulinum toxin molecule penetrates into the neuron cytoplasm by the mechanism of receptor cell-mediated endocytosis.

Botulinum toxin accumulates in membrane vesicles within the cell. The light chain is then released into the cytoplasm of the nerve ending, where it catalyzes the cleavage of one of the SNARE proteins. In motor neurons, the botulinum toxin light chain blocks the release of acetylcholine by cleaving SNAP25, which is an important component of the SNARE complex. If acetylcholine is not released, then muscle contraction does not occur.

Thus, intramuscular injections of botulinum toxin in therapeutic doses provide partial muscle chemodenervation, which leads to a localized decrease in muscle activity and to the elimination of wrinkles. Evidence-based evidence supports subsequent restoration of muscle innervation.