Muscimol-induced myoclonic jerks in mice

Abstract

Muscimol produced myoclonic jerks in mice. The manifestation of this response required a minimum dose of 2 mg/kg (i.p.). These jerks, involving the hind quarter of the animals, commenced after a latent period of 6–10 min, were more or less rhythmic, peaked between 27 and 45 min and slowly tapered off thereafter. The maximum responses seen after 2 and 3 mg/kg (i.p.) doses of muscimol were 48 and 76 jerks per min, respectively. It is not known whether the response to muscimol is spinal in origin or whether a metabolite is involved. This effect of muscimol was not blocked by subconvulsive doses of picrotoxin or bicuculline. Drug interaction studies showed that treatments which resulted in decreased activity of the central norepinephrine system, or which enhanced the activity of the central serotoninergic system, effectively blocked the response to muscimol. The present study has not only brought to light a new aspect of the central action of muscimol, but it also seems that this response may prove to be valuable as an animal model for the evaluation of antimyoclonic drugs. One interesting aspect of this response is that it is strain-specific.