SLUD (Salivation, Lacrimation, Urination, Defecation [and emesis]) is a syndrome of pathological effects indicative of massive discharge of the parasympathetic nervous system. Unlikely to occur naturally, SLUD is usually encountered only in cases of drug overdose or exposure to nerve gases. Nerve gases irreversibly inhibit the enzyme acetylcholinesterase; this results in a chronically high level of acetylcholine at cholinergic synapses throughout the body, thus chronically stimulating acetylcholine receptors throughout the body. The symptoms of SLUD are due to chronic stimulation of muscarinic acetylcholine receptors, in organs and muscles innervated by the parasympathetic nervous system:
- Salivation: stimulation of the salivary glands
- Lacrimation: stimulation of the lacrimal glands
- Urination: relaxation of the internal urinary sphincter, and contraction of the detrusor muscles
- Defecation: relaxation of the internal anal sphincter
- Emesis: stimulation of brainstem emesis center
One common cause of SLUD is exposure to organophosphorus insecticides, including parathion, malathion, and diazinon. These agents phosphorylate acetylcholinesterase, thereby raising the acetylcholine levels and causing SLUD.
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