Neurotoxins Content:- What is Neurotoxins Introduction of neurons Mechanism action of neurotoxins Different neurotoxins and its mode of action Reference The point where your muscles and nervous system meet is called the neuromuscular junction (NMJ) ACh Receptor Channel Opens Scorpions, spiders Contain low molecular weight proteins that affect ion transport along axon Impairs action potential Symptoms include tachycardia, respiratory distress PESTICIDES Malathion , parathion, “nerve gases” like organophosphorous pesticides and DDT like organochlorine like pesticides Inhibits acetyl cholinesterase (AChE) leading to continuous stimulation. Fasciculin inhibits mammalian and fish acetylcholinesterases Neurobehavioral, cognitive, neuromuscular disturbances Death from respiratory distress Acetycholin-esterase AChE hydrolyzes Ach into choline & acetate . Puffer fish Botulinum toxin cleaves SNARE proteins. SNARE proteins are involved with fusing synaptic vesicles to the plasma membrane. Cleaving of SNARE proteins by botulinum toxin therefore inhibits the release of acetylcholine at the neuromuscular junction, and leads to inhibition of neurotransmission. This means acetylcholine isn’t released at the neuromuscular junction, so muscles are paralysed. Both cause poisoning by interfering with they way muscle contractions are regulated. Muscles become very sensitive to stimulation and instead contracting and then releasing, they go into spasm Reference Toxipedia Neuroscience online: An electronic textbook of neuroscience

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2.  What is Neurotoxins
 Introduction of neurons
 Mechanism action of neurotoxins
 Different neurotoxins and its
mode of action
 Reference
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6. Signals sent from your central nervous
system to the NMJ tell muscles to
move
The synapses at the NMJ use a neurotransmitter
called acetylcholine
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7. many poisons are neurotoxins
Most of them work by
interfering with control of
muscle contractions
They cause death because
they stop the heart and
lungs from working
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8. different neurotoxinswork in different ways…
Neurotoxins that work
like this are found in:
some snake and
spider venom;
poison arrow
frogs;
many scorpion
stings
Many neurotoxins cause difficulty to fire the electrical
signal(action potential).
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9. Cobra toxin blocks acetylcholine receptors
Left untreated, a bite from an Indian Cobra
can kill in just 1 hour
Acetylcholine can’t bind to its receptors, so the
signals that control your muscles are blocked and
your muscles, including your heart and
diaphragm, are paralysed
Some interfere with the action of acetylcholine at the
NMJ
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12.  Contain low molecular weight proteins that affect ion transport
along axon
› Impairs action potential
 Symptoms include tachycardia, respiratory distress
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13.  Malathion , parathion, “nerve gases” like organophosphorous
pesticides and DDT like organochlorine like pesticides Inhibits
acetyl cholinesterase (AChE) leading to continuous stimulation.
 Fasciculin inhibits mammalian and fish acetylcholinesterases
 Neurobehavioral, cognitive, neuromuscular disturbances
 Death from respiratory distress
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14. AChE hydrolyzes Ach into choline & acetate .
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15. • The active toxin in the tissues of this
fish is a chemical called tetrodotoxin.
• Tetrodotoxin is a neurotoxin - it affects
nerve cells (neurons).
• Specifically, tetrodotoxin blocks
voltage-gated sodium ion channels.
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17. Puffer fish for sale at
Kuromon Ichiba market,
Osaka, Japan
Puffer fish (or fugu) is a potentially lethal
Japanese treat
One puffer fish contains enough neurotoxin to
kill 30 people
Fugu can only be prepared by specially trained
chefs
who carefully remove all the parts of the fish
that
contain the poison
There is no known antidote
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18. Botulinum toxin (Botox) is a neurotoxin
produced by bacteria called Clostridium
Botulinum.
It is the most powerful and naturally
occurring neurotoxin yet discovered and
causes poisoning that can be fatal
(botulism)
It is used medically to treat muscle
spasms and cosmetically to reduce
wrinkles.
It works by preventing vesicles containing
neurotransmitter from fusing with the pre
synaptic membrane.
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19.  Botulinum toxin cleaves SNARE
proteins. SNARE proteins are involved
with fusing synaptic vesicles to the
plasma membrane. Cleaving of SNARE
proteins by botulinum toxin therefore
inhibits the release of acetylcholine at
the neuromuscular junction, and leads to
inhibition of neurotransmission.
 This means acetylcholine isn’t released
at the neuromuscular junction, so
muscles are paralysed.
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20. Strychnine is a highly toxic, colourless, bitter
crystalline alkaloid used as a pesticide to control rats,
moles, gophers, and coyotes. Strychnine is highly
toxic to most domestic animals.
Its oral LD50 in dogs, cattle, horses, and pigs is 0.5–1
mg/kg, and in cats is 2 mg/kg.
Strychnine was used by the winner of the 1904
Olympic marathon to improve performance It is still
banned in sport, but its use rarely detected.
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21. Tetanus is caused by the neurotoxin
tetanospasmin which comes from a bacterium
called Clostridium tetani are found in soil, dust and
animal feces.
When they enter a deep flesh wound, spores of the
bacteria may produce a powerful toxin,
tetanospasmin, which actively impairs your motor
neurons, nerves that control your muscles.
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22.  Both cause poisoning by
interfering with they way
muscle contractions are
regulated.
 Muscles become very
sensitive to stimulation
and instead contracting
and then releasing, they
go into spasm
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24. Curare is used by some indigenous
South American tribes for poison darts
It comes from the curare plant
Its a antagonist of nicotinic acetylcholine
receptors
Curare paralyses muscles by blocking
acetylcholine receptors
At the right dose, it has medical uses.
It was one of the first chemicals used as
a muscle relaxant in anaesthesia 24

25.  Toxipedia
 Neuroscience online: An electronic
textbook of neuroscience
 www.google.com (images)
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