Aim: To study the anticonvulsant activity of phenytoin against maximal electro shock-induced
convulsion rats.

Principle: Different types of epilepsy i.e., grand mal, petit mal or psychomotor type, can be studied in
laboratory animals. The maximal electroshock (MES) induced convulsions in animals represent
grand mal epilepsy. Similarly chemo- convulsion due to pentylenetetrazole which produce the clonic
type of convulsion in man. These are the two procedures used to study convulsion and to test anticonvulsant drugs in laboratory animals.
In MES- convulsion electroshock is applied through the corneal electrodes. Through optic
stimulation, cortical excitation is produced. The MES convulsion is divided into five phases are

  1. Tonic flexion
  2. Tonic extensor
  3. Clonic convulsion
  4. Stupor
  5. Recovery / death
    A substance is known to posses anti convulsant property if it reduces or abolishes the
    extensor phase of MES convulsions both in rats and mice. It is advised the students should
    have complete background of the pharmacology of anti epileptics drugs before performing
    this experiment.

Requirement:
Animal: Rats (150-200 gm)
Drugs: phenytoin (dose 25 mg/kg); prepare a stock solution
Equipment : electro- convulsiometer, cornel electrode (150 mA current for 0.2 sec) Stop watch

Procedure:

  1. Weigh and number the animals. Divide them into two groups each consisting of 4-5 rats.
    One group is used as control and the other for drugs treatment.
  2. Hold the animals properly , place corneal electrodes on the cornea and apply the
    prescribed current. Note the difference stages of convulsion
  3. Repeat with other animals of control group
  4. Inject phenytoin I.P to group of 4-5 rats. Wait for 30 min and subjected to animals to
    electroconvulsions .
  5. Note the reduction in time or abolition of tonic extensor phase of MES convulsions.

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