Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Behavioral responses to atropine in rats exposed to the potent anticholinesterase agents Soman and Sarin were studied. Atropine itself produced limb-shakes and certain stereotyped activities, in a dose-dependent manner. The neurotoxicity elicited by Soman and Sarin was antagonized by atropine, while at the same time the responses induced by the latter were attenuated. In contrast, where rats were challenged with atropine 6-72 h after giving single doses of Soman or Sarin, the limb-shake myoclonus was markedly enhanced. The atropine-induced stereotypies were not, however, significantly affected, except for an increase seen at 24 h after Sarin treatment. Repeated treatment with Soman for 3 wk also led to similar supersensitivity of atropine-induced responses. The peripheral muscarinic receptor antagonist, methylatropine, produced no such hyperactivity on its own or at any time after anticholinesterase exposure. The rapid occurrence of hypersensitivity to antimuscarinic compounds following exposure to these anticholinesterases, therefore, suggests the need for observation of subjects who are poisoned with such agents and treated with antimuscarinics, for adverse reactions such as myoclonus during the critically sensitive period, especially if repeated antimuscarinic therapy is carried out.
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PMID:Hypersensitivity to antimuscarinic agents following brief exposure to Soman and Sarin. 370 76

Following single or repeated treatment with the irreversible anticholinesterase, DFP or, during infusion of the muscarinic receptor agonist, oxotremorine, and the reversible anticholinesterase physostigmine, effects of challenges with muscarinic antagonists were studied in rats. The antagonists, atropine, scopolamine, benztropine, orphenadrine and trihexyphenidyl induced, to a low degree, limb-shakes (myoclonus) and stereotyped behaviors in normal rats. However, within 24-72 hr after the above pretreatments, this myoclonus was significantly enhanced. The anticholinergic-stereotypies were also increased but only by severe cholinergic pretreatment and at a time later than that for the myoclonus. Myoclonus and stereotypies are known to be produced by treatments which directly enhance serotonergic and dopaminergic activities, respectively. It is suggested that during prolonged cholinergic stimulation, the cholinergic-monoaminergic balance in the brain can be altered depending upon the degree of stimulation. This could be responsible for the observed differential onset of changes in the anticholinergic-behavioral responses, which could, in turn, be mediated by different monoaminergic (serotonin and dopamine) systems.
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PMID:Rapid induction of supersensitivity to muscarinic antagonists-induced motor excitation by continuous stimulation of cholinergic receptors. 404 Oct 2