ACTOPHOTOMETER Standard Operating Pocedure, SOP



It consists of six built in photo sensor and 4 digit digital counter to indicate the loco meter activity. It measures then spontaneous and indicated activity with digital totalize. It also incorporates electric shock of up to 100 volts for activating rats. The stimulus is variable from 0 to 100v & indicating on meter.




Most of the CNS acting drugs influence the locomotor activities in man & animals. The CNS depressant drugs such as barbiturates & alcohol reduce the motor activity while the stimulants such as caffeine & amphetamines increase the activity. In other words, the locomotor activity can be an index of wakefulness (alertness) of mental activity.

The locomotor activity (horizontal activity) can be easily measured using an actophotometer which operates on photoelectric cells which are connected in circuit with a counter. When the beam of light falling on the photo cell is cut off by the animal, a count is recorded. An actophotometer could have either circular or square arena in which the animal moves. Both rats & mice may be used for testing in this equipment.




1. Weigh the animals (20-25 g mice) & number them.

2. Turn on the equipment (check & make sure that all the photo cells are working for accurate recording) and placed individually each mouse in the activity cage for 10 minutes. Note the basal activity score of all the animals (6).

3. Inject the drug chlorpromazine hydrochloride (Dose: 3 mg/kg, ip; make a stock solution containing 0.3 mg/ml of the drug & inject 1 ml/100 g body wt of mouse), and after 30 mins re-test each mouse for activity scores for 10 mins. Note the difference in the activity, before & after chlorpromazine.

4. Calculate percent decrease in motor activity.


· CNS depressants:

Chlorpromazine hydrochloride (3 mg/kg, ip in case of both rat & mice)

Fluoxetine (10 mg/kg, ip in case of rat)

Imipramine (10-20 mg/kg, ip in case both mice & rat)

Phenobarbitone sodium (10 mg/kg, ip in case of both rat & mice)

Alcohol (0.5-2 g, ip, po in case of both mouse & rat)

· CNS stimulants:

Caffeine (8-10 mg/kg, ip in case of mice & 30 mg/kg, ip in case of rat)

Amphetamine (1.5 mg/kg, ip in case of mice & 3-5 mg/kg, sc, ip in case of rat)


S.NO Body weight (g) Treatment Dose (mg/kg) Locomotor activity(Scores) in 10 min


Reduction in the motor activity indicates CNS depressant property of the drug.

Increase in the motor activity indicates CNS stimulant property of the drug.