Abstract
Subcutaneously injected pilocarpine has an anticonvulsant effect against maximal electroshock seizures (MES) in rats consisting of an early phase with peak effect at 1 hour and a weaker, late phase lasting as long as 72 hours. The ED50 of pilocarpine against the MES is 26 mg/kg. In mice the anticonvulsant effect is considerably weaker than in rats and consists only in prolongation of tonic flexion with doses of pilocarpine up to 160 mg/kg. The anticonvulsant effect of pilocarpine is due to supraspinal actions, inasmuch as patterns of spinal cord convulsions were not significantly affected by the drug. Pilocarpine markedly reduces electroshock seizure threshold (EST) in both rats and mice. Atropine antagonizes the actions of pilocarpine on both MES and EST.
Pilocarpine slightly lowers the threshold for pentylenetetrazol convulsions and very markedly reduces the threshold for strychnine convulsions. The latter effect of pilocarpine is not prevented by pretreatment with atropine. Adrenalectomy in rats does not alter the effects of pilocarpine on MES, EST or strychnine convulsions.
The excitatory and depressant effects of pilocarpine appear to be due to direct central actions of the drug. Changes in blood pH, plasma CO2, and plasma electrolytes after pilocarpine are slight and are insufficient to account for the effects described.
Footnotes
- Received December 26, 1962.
- Accepted February 20, 1963.
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