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Week_11_-_Specific_examples_of_neurotoxi - Week 11 Specific...

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Week 11 - Specific examples of neurotoxicants Organophosphate pesticides Organophosphate pesticides (OPs) , such as malathion and parathion , are widely used in agriculture for insect control. OPs bind tightly to acetylcholinesterase , the enzyme that breaks down acetylcholine in the synapse. Acetylcholinesterase inhibition results in excessive ACh in the synapse, leading to symptoms such as slowed heart rate, pupil constriction, airway constriction, and increased secretion of saliva, tears, urine and feces. At the neuromuscular junction, excessive ACh results in muscle twitching and cramps. In the CNS, elevated ACh creates anxiety, restlessness and coma. Death is usually due to respiratory failure resulting from paralysis of respiratory muscles and inhibition of the CNS system controlling respiration. To treat OP poisoning, patients are treated with atropine (to block muscarinic ACh receptors) and pralidoxime (to accelerate reversal of the acetylcholinesterase inhibition). Botulinum toxin Botulinum toxin is actually a highly neurotoxic group of at least seven distinct toxic proteins produced by seven different strains of the bacteria Clostridium botulinum . Botulinum toxin poisoning is commonly known as botulism , and is most commonly caused by consumption of bacteria-contaminated food. Botulinum toxins are amongst the most toxic substances known, with an estimated LD 50 in humans of 1 ng/kg.
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  • Summer '11
  • hess
  • Neurotransmitter, Botulinum toxin, MPTP, bacteria Clostridium Botulinum, Acetylcholinesterase inhibition results, excessive ACh

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