How do neurons communicate?
Most neurons communicate with others by releasing one of over 50 different types of neurotransmitter. Each neurotransmitter fits on to its receptor on the surface of the neighbouring neuron. Chemicals that interfere with the signalling may act on the neurotransmitter or on the receptor. Many of these are natural substances, such as nerve poisons produced by plants and animals for self-defence or capturing prey. Others, including nerve gases are man-made substances.
How can nerve gases affect your brain?
Nerve gases are potentially lethal synthetic chemicals developed during the Second World War. They work by blocking the breakdown of the neurotransmitter acetylcholine. As a result it builds up in the synapse and its actions cannot be stopped. Nerve gases are now banned, but can still fall into the wrong hands: in 1995 Tokyo commuters were poisoned by the nerve gas Sarin. The chemical atropine – itself a poison – is found in the plant Deadly Nightshade. It can be used as an emergency antidote as it blocks the action of acetylcholine.
How can poisons affect your brain?
There are many chemicals that are produced in plants, animals or insects which prevent neurons from working properly. One example is strychnine which was used as a rat poison and is obtained from seeds of Strychnos nux–vomica. Strychnine interferes with the neurotransmitter glycine, by preventing it from docking at its receptors. Some snake venoms contain poisons that block acetylcholine, causing paralysis by preventing instructions passing from the nerves to the muscles.