muszkarin

Muscarine, also known as muszkarin in some contexts, is a naturally occurring toxin found in several mushroom species, most notably Inocybe and Clitocybe, with smaller amounts reported in some Amanita species. It is a quaternary ammonium alkaloid that acts as a selective agonist of muscarinic acetylcholine receptors, producing stimulation of the parasympathetic nervous system.

Muscarine binds to M1–M5 muscarinic receptors, leading to increased exocrine secretions and reductions in heart rate and blood pressure. Because it is a quaternary ammonium compound, muscarine does not readily cross the blood–brain barrier, so central nervous system effects are minimal and peripheral effects predominate. Common symptoms after ingestion include excessive sweating, salivation, lacrimation, bronchial secretions, miosis, bradycardia, abdominal cramps, nausea, and diarrhea. Onset is typically 15 to 60 minutes after exposure, and symptoms can persist for several hours depending on dose.

Toxicity varies with the amount ingested; muscarine-containing mushroom poisoning is considered rare but potentially dangerous, particularly for children. Treatment is supportive and includes atropine, a muscarinic antagonist, to counteract cholinergic effects. Decontamination may be considered if the patient presents early.

In mushrooms, muscarine co-occurs with other toxins, but the classic hallucinogenic toxins of Amanita muscaria, such as muscimol and ibotenic acid, are not muscarinic and require different management in poisoning. The study of muscarine highlights the diversity of mushroom-derived alkaloids and their pharmacological actions.