VPT 321: Veterinary Neuropharmacology (2+1)

Procedure for convulsions induced by chemicals

INTRODUCTION

• In medical practice anticonvulsants are used to control the convulsions occurring in epilepsy, tetanus, cerebral hemorrhage, eclampsia and in poisoning with convulsants. The greatest use is in epileptic disorders characterized as petitmal and grandmal and psychomotor seizures.
• Epilepsy: According to neurological theory epilepsy is a paraoxysmal, self-limited, cerebral dysrhythmia. It is accompanied by abnormal patterns on the electroencephalograph, and severe seizures may cause loss of consciousness.
• Most of the experimental methods for detection anticonvulsant activity involve the artificial induction of convulsions and their inhibition with organic compounds. These tests have another principal use: to detect myorelaxant activity.

Convulsions induced by chemicals

• Pentylenetetrazol: A drug used as a stimulant of the central nervous system is pentylenetetrazol. The test substance (anticonvulsant drug) is given in adult rats. Forty five minutes later an intramuscular injection of pentylenetetrazol is given at a dose of 112 mg/kg. The convulsion begins with jerks of the head and body, consisting of clonic contractions. The seizures end fatally or are followed by depression and other seizures before death or recovery finally takes place. The criterion of anticonvulsant activity is complete protection against convulsions of any kind. Tremors are disregarded. Observations are made for at least 60 minutes after the administration of pentylenetetrazol
• Strychnine: Intraperitoneal injection of 2 mg/kg of strychnine sulfate in mice produces stimulant action and the animal is thrown into convulsion. Test substance (anticonvulsant) are introduced at a time interval before the strychnine so that they are at peak activity. The end-point is the measure of the substance’s ability to prolong life beyond the usual time of death. It would be better to use enough test substance to save the animal’s life and thus demonstrate a more pronounced antagonism to strychnine.
• Calculate the percentage of protection given by the test substanace ( anticonvulsant)

Results:                    Date:                             Route:

S.No	Sex of the animal	Weight of the animal	Dose of the test substance	Time of administration of test substance	Status of animal survival / death	% of protection
1
2
3
4
5
6

% of protection = - (Experimental/Control) X 100