Definition for Neurotoxin
From Biology Forums Dictionary
Neurotoxin effectively means "nerve poison". Neurotoxins act directly on neurons, or nerve cells, by interfering with membrane proteins and ion channels. Frequently, venoms and other toxins used by living organisms are neurotoxins. Scorpion and spider venom and some forms of bee venom are neurotoxins.
The most common effect of the neurotoxins used by organisms is rapid-setting paralysis, useful to snakes and other venomous predators as it keeps the prey from running away.
Other neurotoxins include carbon monoxide, mercury and other heavy metals, ethanol and various other chemical substances. Chemical weapons make use of neurotoxins to impair or kill their enemies.
The effect of various neurtoxins on the brain's neurons depends primarily on the dosage, but typically results in loss of muscle control, loss of mental abilities, loss of feeling and, sometimes loss of consciousness. Low levels of ethanol, for instance, are mildly neurotoxic and result only in drunkenness, not poisoning; but prolonged exposure to it weakens and kills neurons.
Several neurotoxins are also produced by the body, such as glutamate. A high level of glutamate around a neuron causes the cell to kill itself. This is because glutamate acts to excite the nerve, and too much cellular stimulation causes processes in the cell that destroy it.