Editing Strychnine (section)

== Mechanism of action ==
Strychnine is a [[neurotoxin]] which acts as an [[receptor antagonist|antagonist]] of [[glycine receptor|glycine]] and [[acetylcholine receptor]]s. It primarily affects the motor nerve fibers in the spinal cord which control muscle contraction. An impulse is triggered at one end of a nerve cell by the binding of [[neurotransmitter]]s to the receptors. In the presence of an inhibitory neurotransmitter, such as [[glycine]], a greater quantity of excitatory neurotransmitters must bind to receptors before an [[action potential]] is generated. Glycine acts primarily as an agonist of the glycine receptor, which is a [[Ligand-gated ion channel|ligand-gated]] chloride channel in neurons located in the spinal cord and in the brain. This [[chloride channel]] allows the negatively charged chloride ions into the neuron, causing a [[Hyperpolarization (biology)|hyperpolarization]] which pushes the membrane potential further from threshold. Strychnine is an antagonist of glycine; it binds noncovalently to the same receptor, preventing the inhibitory effects of glycine on the postsynaptic neuron. Therefore, action potentials are triggered with lower levels of excitatory neurotransmitters. When the inhibitory signals are prevented, the motor neurons are more easily activated and the victim has spastic muscle contractions, resulting in death by asphyxiation.<ref name="sharma" /><ref>{{cite book | vauthors = Waring RH, Steventon GB, Mitchell SC | title = Molecules of death | publisher = Imperial College Press | date = 2007}} {{page needed|date=February 2017}}</ref> Strychnine binds the ''[[Aplysia californica]]'' acetylcholine binding protein (a homolog of [[nicotinic acetylcholine receptor|nicotinic receptors]]) with high affinity but low specificity, and does so in multiple conformations.<ref name="Brams2011">{{cite journal | vauthors = Brams M, Pandya A, Kuzmin D, van Elk R, Krijnen L, Yakel JL, Tsetlin V, Smit AB, Ulens C | title = A structural and mutagenic blueprint for molecular recognition of strychnine and d-tubocurarine by different cys-loop receptors | journal = PLOS Biology | volume = 9 | issue = 3 | pages = e1001034 | date = March 2011 | pmid = 21468359 | pmc = 3066128 | doi = 10.1371/journal.pbio.1001034 | doi-access = free | s2cid = 14123035}}</ref>