Pharmacology
Muscimol is a potent GABAA agonist, activating the receptor for the brain's major inhibitory neurotransmitter, GABA. Muscimol actually binds to the same site on the GABAA receptor complex as GABA itself, as opposed to other GABAergic drugs such as barbiturates and benzodiazepines which bind to separate regulatory sites. GABAA receptors are widely distributed in the brain, and so when muscimol is administered, it alters neuronal activity in multiple regions including the cerebral cortex, hippocampus, and cerebellum.
While muscimol is conventionally thought of as a selective GABAA agonist, it is also a potent partial agonist at the GABAC receptor, and so its range of effects results from a combined action at both targets.
In patients with Huntington's disease and chronic schizophrenia, oral doses of muscimol have been found to cause a rise of both prolactin and growth hormone.
During a test involving rabbits connected to an EEG, muscimol showed a distinctly synchronized EEG tracing. This is substantially different from serotonergic psychedelics, as brainwave patterns will generally show a desynchronization. In higher doses (2 mg/kg), the EEG will show characteristic spikes.
If consumed, muscimol will pass through the human body, and be excreted unchanged in the subject's urine.
The psychoactive dose of muscimol is around 10–15 mg for a normal person. A Guide to British Psilocybin Mushrooms by Richard Cooper published in 1977 recommends a smaller dose, 8.5 mg, and suggests that it is possible for this amount to be present in as little as 1 g of dried A. muscaria. A correct dose may be difficult to determine because potency varies dramatically from one mushroom to the next.
Read more about this topic: Muscimol