Neurotoxins

Do you know what some spiders, snakes, scorpions, bees, mussels, and pufferfish have in common? Well, besides, scaring you, these animals have poisons that act on the nervous system. These poisons (called neurotoxins) are used by the animals for protection against predators or for capturing prey. The table below indicates 1) the names of the neurotoxins, 2) the animals from which the neurotoxin comes from and 3) the action of the neurotoxin on a neuron. The word "channel" refers to a type of protein molecule that different ions use to cross the neuronal membrane.
Now if you ever get bitten or stung by one of these animals, at least you will know what is happening to your nervous system!!

NameSourceNeuronal Action
AgatoxinFunnel Web SpiderBlocks calcium channels
AgitoxinScorpionBlocks potassium channels
alpha-bungarotoxinKrait (snake)Blocks acetylcholine (nicotinic) receptor
AnatoxinAlgaeAcetylcholine receptor agonist
ApaminHoney beeBlocks potassium channels
AtracotoxinBlue Mountains Funnel Web SpiderBlocks voltage-gated calcium channels
ATX IISea AnemoneActivates voltage-gated sodium channels
BatrachotoxinPoison Arrow FrogPrevents sodium channels from closing
beta-bungarotoxinKrait (snake)Inhibits release of ACh at neuromusuclar junction and blocks potassium channels
Botulinum toxinBacteriaBlocks acetylcholine release
BrevetoxinRed Tide DinoflagellateActivates sodium channels
CalcicludineEastern Green MambaBlocks voltage-gated calcium channels
CalciseptineBlack MambaBlocks voltage-gated calcium channels
CapsaicinCayenne PepperExcites peripheral nerve endings
CharybdotoxinScorpionBlocks potassium channels
CiguatoxinDinoflagellate Opens sodium channels
CobrotoxinCobraBlocks nicotinic receptors
ConotoxinMarine SnailSeveral types: one blocks voltage-sensitive calcium channels;
one blocks voltage-sensitive sodium channels;
one blocks ACh receptors.
CrotoxinS. American RattlesnakeReduces acetylcholine release
DendrotoxinGreen MambaBlocks voltage-gated potassium channels
Domoic acidBlue musselGlutamate/kainate receptor agonist
ErabutoxinSea SnakeBlocks acetylcholine (nicotinic) receptors
rErgtoxin-1Mexican ScorpionBlocks potassium channels
Fasciculin-IEastern Green MambaBlocks action of acetylcholinesterase
Grammotoxin SIASouth American Rose TarantulaBlocks calcium channels
GonyautoxinDinoflagellateBlocks sodium channels
HolocyclotoxinAustralian paralysis tickInhibits release of acetylcholine
Homobatrachotoxin Pitohui (bird)Activates sodium channels
rHongotoxin-1Central American ScorpionBlocks potassium channels
HWTX-IChinese bird spiderBlocks calcium channels
IberiotoxinScorpionBlocks potassium channels
Joro spider toxinJoro spiderBlocks glutamate receptors
KaliotoxinScorpionBlocks potassium channels
KurtoxinSouth African ScorpionBlocks calcium channels
LatrotoxinBlack Widow SpiderEnhances acetylcholine release
MaculotoxinBlue-Ringed OctopusBlocks sodium channels
MargatoxinScorpionBlocks potassium channels
MaurotoxinScorpionBlocks potassium channels
NoxiustoxinScorpionBlocks sodium channels
PalytoxinSoft coralPoisons sodium/potassium pump; opens channels
PhilanthotoxinPredaceous WaspBlocks glutamate receptors
PhoneutriatoxinBanana spiderSlows sodium channel inactivation
PhrixotoxinChilean fire tarantulaBlocks potassium channels
PompilidotoxinSolitary WaspActivates voltage-gated sodium channels
RobustotoxinFunnel web spiderOpens sodium channels
SaxitoxinDinoflagellateBlocks sodium channels
ScyllatoxinScorpionBlocks potassium channels
SNX-482African TarantulaBlocks calcium channels
Stichodactyla ToxinSea AnemoneBlocks voltage-gated potassium channels
rStromatoxin-1African TarantulaBlocks voltage-gated potassium channels
TaicatoxinAustralian Taipan snakeInhibits voltage-gated calcium channels
TaipoxinAustralian Taipan snakeInhibits release of acetylcholine
rTamapinIndian Red ScorpionBlocks potassium channels
TertiapinHoney beeBlocks potassium channels
Tetrodotoxin (TTX)PufferfishBlocks sodium channels
TextilotoxinAustralian common brown snakeBlocks release of acetylcholine
Tityustoxin-KBrazilian ScorpionBlocks potassium channels
VersutoxinFunnel web spiderOpens sodium channels

A good reference on Neurotoxins is: Trends in Neuroscience, June 1996, supplement.

Also see venoms (Society for Neuroscience) and the International Venom and Toxin Database for more information about neurotoxins. There are many chemicals that are also toxic to the nervous system.

Just in case you encounter a poisonous snake, make sure you know how to treat and prevent a venomous bite. Find out more about venomous animals at Victims of Venom from PBS.

Did you know?

Even though the pufferfish contains the neurotoxin called tetrodotoxin, it is eaten as a delicacy in Japan. In Japan, this dish is called "fugu." Each fugu chef must have a special license to make this food. Nevertheless, a few people do get poisoned from eating the pufferfish if it is prepared incorrectly. Tetrodotoxin is found in the liver, skin and eggs of the pufferfish. Tetrodotoxin has also been detected in other animals such as the tropical goby, blue ringed octopus, and some species of crabs, starfish, newts and frogs. [Fugu Recipes]
Venomous snakes can be dangerous even after they are dead. In a study published in the New England Journal of Medicine, it was reported that 14.7% of the people envenomed by rattlesnakes were "bitten" by snakes that were dead or thought to be dead.

Try it!

Think you know your neurotoxins? Try this "Match the Toxin" worksheet. If you have trouble or want to check your answers, here is an answer sheet. Note: both of these pages require the free Adobe Acrobat Reader

BACK TO: Exploring the Nervous System Table of Contents

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