Toxicological complement - amino acid transmitters
Beside drugs, toxic agents act while modifying directly or indirectly activity of GABA or glutamate. We will give some examples of them:
GABAmimetic agents
Muscimol
- isolated from mushrooms of type fly agaric, Amanita muscaria and Amanita pantherina (which contain other biologically active compounds than muscinol)
- muscinol is chemically close to ibotenic acid
- agonist of GABA-A receptors
- is used as pharmacological reagent
GABA antagonists
Picrotoxine
- found in certain plants
- is an antagonist of GABA-A receptors
- convulsive agent
Bicuculline
- found in certain plants
- antagonist of GABA-A receptors
- convulsive agent
Alpha-thujone
- present in essential oil of wormwood, Artemisia absinthium, which was used as drink, in particular in Paris about 1900, before being prohibited
- antagonist of GABA-A receptors
- has stimulant and convulsive effects
Fipronil
Noncompetitive inhibitor of GABA, fipronil inhibits chloride entry into cells of insects but has little or no effect in vertebrates. This inhibition of chloride entry creates a cellular depolarization in insects. It is used in external applications against fleas in dog and cat and ticks in dog.
Glycine antagonists
Strychnine
- alkaloid present in vomic nut, Strychnos nux-vomica
- is an antagonist of glycine receptors ,
- was formerly used in medicine as stimulant
- was used as mole killer
- in human poisoning causes: muscular hyperreflexia, anxiety, seizures, tensions, poisoning which can be treated by a benzodiazepine.
Glutaminomimetic
Called sometimes EAA for Excitory Amino Acids.
Domoic a cid
- is an agonist of ionotropic receptors of glutamate
- can contaminate certain edible shells where it could be produced by microorganisms. Consumption of these shells can cause poisoning with various disorders such as loss of memory
Oxalyl diaminopropionic acid
Present in various plants, of which Lathyrus sativus; poisoning by these plants causes lathyrism.
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