Effect of psychotropic drugs on condition avoidance response

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BACKGROUND

Psychotropic drugs influence the learning/memory process by modulating central neurotransmitter systems.¹ Cook’s pole climbing apparatus was used to determine the antipsychotic activity and is based on principle of ability of psychotropic drugs to avoid conditioned response. This apparatus was used for inducing stable baseline behavior.² The aim of the study is to evaluate the antipsychotic activity of the given drugs on condition avoidance response.

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REQUIREMENTS

Animals:    Albino rats of either sex weighing 200-250 gms

Drugs:     Saline- 1 ml

Chlorpromazine- 4 mg/kg,
Phenobarbitone sodium- 15 mg/kg.

Instrument:     Cook’s pole climbing apparatus

The Cook’s pole climbing apparatus comprises of a transparent compartment with an electrified floor and a lid to which is attached to the pole. The lid can be moved after the rat has mounted the pole. The entire chamber is enclosed by a wooden box and there is an arrangement for beeper.

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PROCEDURE

Select animals of both sexes and divide them into three groups consisting of 3 animals in each group. Group receiving saline serves as control. The other two groups receives freshly prepared chlorpromazine and phenobarbitone respectively through intraperitoneal route, 2 hours prior to the experiment.³

Learn the rats to jump on a pole to avoid foot shock. Use a tone of 50 Hz as the conditioned stimulus and a foot shock of 1.0 mA as the unconditioned stimuli. Train the animals to climb the pole to escape shock by placing in the apparatus. In the training procedure, initially allow the animal to adapt in the chamber for 1 min then train them how to avoid electric shock by responding promptly to danger signal (buzzer sound) for a period of 15 sec each. End the trial either after the animal respond by jumping on the pole or after 30 secs, whichever was earlier. Give such trial for all selected animals every day for 10 days. Test the animals for learning process before and after drug treatment for retention of memory of painful stimuli developed in the learning process. Response of an animal to a signal is termed as conditioned response (CR) while the response to the noxious stimuli referred as unconditional response (UR). Inject 1 ml of saline to control group and place the animal in pole climbing apparatus and give buzzer sound followed by electric shock and note the response. The same procedure is to be done for the other two groups receiving chlorpromazine and phenobarbitone respectively and the data of avoidance/escape latency in seconds should be taken for 3 days and the readings are compared.

OBSERVATIONS

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CONCLUSION

Animals that received saline shows response to both CR and UR and confirms normal responsiveness in animal. Animals treated with chlorpromazine blocks CR effectively by blocking CR, so that animals forget what they learned but do not interfere in UR. Animals treated with phenobarbitone blocks both CR and UR. From these observations it is evident that chlorpromazine acts as tranquiliser and phenobarbitone as hypnosedative.

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REFERENCES

1. Terry RD, Davis P. Some morphologic and biochemical aspects of Alzheimer’s disease. In: Ageing of the Brain. 1983;22:47-59.
   
2. Chudasama V, Patel M, Suthar K, Rajpurohit B. To study the effect of antipsychotic drugs using Cooks pole climbing apparatus. Experimental Pharmacology. 2015: 39.
   
3. Kale SR, Kale RR, Hasan SA. Practical pharmacology and toxicology. 14^th edition. Pune: Nirali Prakashan; 2008: 62-66.