Exocytosis and the Neuromuscular Junction
Exocytosis and the Neuromuscular Junction: How Does Botox Work? Exocytosis is the process in which secretory vesicles are exported out of the cell membrane. These vesicles contain proteins which are then transported to parts outside the cell (Wilfred D. Stein, 2012). Neurotransmitters are released during this process into the synaptic cleft. These transmitters attract other transmitters to muscle membrane infoldings, which are called junction folds (Etherington & Hong, 2011).
They diffuse across the break between the nerve and muscle to activate contraction. The progression in which signals are sent from motor neurons to skeletal muscle fibres to warrant movement of muscles is called neuromuscular junction (Etherington & Hong, 2011). Motor neurons, Schwann cells, muscle fibres and kranocytes are all the different cell types that make up the neuromuscular junction. Motor neurons send out axons to skeletal muscles where an action potential is passed along the axons.
The axons form a synaptic knob where they send activation signals to muscle ? bres (Etherington & Hong, 2011). Muscles are made up of hundreds of muscle fibres that all contract simultaneously when an action potential signal is transmitted by a motor neuron (Etherington & Hong, 2011). Schwann cells and kranocytes cover the nerve terminal. Schwann cells are a form of glial cells and Kranocytes are a cell that synthesizes the extracellular matrix and collagen (Etherington & Hong, 2011).
Acetylcholine is an important aspect in neuromuscular junction. It is used to transmit signals to muscles to initiate contractions or movement of the muscles. The toxin binds to neurons where it separates. One part cleaves a protein ultimately preventing the deduction process necessary for the release of acetylcholine (Gill, 2004). Botulinum toxin, BOTOX, disrupts the release of acetylcholine so when signals are released to muscles, they can’t attach anywhere on the muscle causing the muscle to not contract, effectively paralyzing the muscle (Gill, 2004).
Because of this process, botulinum toxin has been used to treat many different disorders characterized by muscle contractions. BOTOX is a type of botulinum toxin that is used to treat spastic equinus gait in people with cerebral palsy. It is used due to its ability in decreasing spasticity and improving ambulation in those with cerebral palsy. Botulinum toxins block the release of acetylcholine in the neuromuscular junction which in turn helps people who have cerebral palsy manage their spasticity (Kim, Shin, Kwon, Kim, Jung, Bang, 2010).
Neuronox is another drug used like BOTOX which improves spastic equinus and has been tested to be just as safe and reliable as BOTOX. Neuronox is another botulinum toxin which interrupts the nerve connection to muscles resulting in a localized reduction in muscle activity (Kim, Shin, Kwon, Kim, Jung, Bang, 2010). Overall, exocytosis and BOTOX are both connected to the neuromuscular junction while BOTOX is also connected to the treatment of spastic equinus gate in cerebral palsy.