Study Of Drugs On Locomotor Activity Using Actophotometer

Aim: To study the central nervous system depressant property of chlorpromazine on the locomotor activity of mice using an actophotometer.

Principle: Most of the central nervous system acting drugs influencing the locomotor activities in man and animals. The CNS depressant drugs such as barbiturates and alcohol reduce motor activity while the stimulants such as caffeine, amphetamines increase the activity. In other words, the locomotor activity can be an index of wakefulness of mental activity. The locomotor activity can be easily measured using an actophotometer. which operates on photoelectric cells which are connected in a circuit with a counter, when the beam of light falling on the photocell is cut off by the animal, a count is recorded. An actophotometer could have either a circular or square arena in which the animal moves. Both rats and mice may be used for testing in this equipment.


Animal: Mice (20-25gm)
Drugs: Chlorpromazine hydrochloride
Equipment : Actophotometer


  • Weigh the animals and number them.
  • Turn on the equipment and place individually each mouse in the activity cage for 10 min. Note the basal activity score of all the animals.
  • Inject chlorpromazine and after 30 min re-test each mouse for activity scores for 10 min. Note the difference in the activity before and after chlorpromazine.
  • Calculate percent decrease in motor activity.

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