PCOL3011 Lecture Notes - Lecture 19: Memantine, Xerostomia, Mescaline
Document Summary
Neurotoxin (1: the blood brain barrier, why are neurons highly sensitive to neurotoxins, neuronopathies, axonopathies, myelinopathies. Toxins can target: action potential, release, mimic or antagonize at receptors, alter re-uptake (& release) of neurotransmitter, interfere with second messenger systems. Many of these drugs don"t cause damage but produce their toxicity by altering synaptic transmission when they are present. Toxins that target the action potential: action potential necessary for synchronized neurotransmitter release. Inhibiting ap results in no or distorted signal to the next cell. Sodium channels produce action potential depolarisation: local anaesthetics (lidocaine)block ap nerve block, some toxins- such as ttx, saxitoxin (shellfish) and ciguatera toxin (fish) . Channels paralytic shellfish toxin: (shellfish bioaccumulate toxins from algal bloom, (plankton toxin accumulates in larger fish, activates na channels) Tetrodotoxin: defence for puffer-fish (fugu, each fish enough toxin to kill 30 people), blue ringed octopus, porucpine fish, resident bacteria produce toxin, doesn"t x bbb, binds to and blocks na+ channels, heat insensitive.
