The study investigates the abdominal constriction response in mice and its suppression by analgesic drugs. The response, characterized by a wave of constriction and elongation along the abdominal wall, is elicited by various substances, including acetylcholine, adenosine triphosphate, bradykinin, potassium chloride, and tryptamine. The response is rapid, with 70% or more of mice responding within 2 minutes to these challenge substances. The study also evaluates the effectiveness of 10 analgesic drugs in reducing the incidence of this response, finding that morphine, cyclazocine, aspirin, and others are effective to varying degrees. Paracetamol was only effective against acetylcholine. The antipyretic drugs were more effective against acetylcholine than tryptamine, while narcotic and narcotic antagonist drugs were less effective. The acetylcholine test is useful for rapid initial screening of potential analgesic drugs, though it has the disadvantage of generating many false positives. The study concludes that the acetylcholine-induced abdominal constriction response is a reliable and sensitive method for assessing analgesic activity in mice.The study investigates the abdominal constriction response in mice and its suppression by analgesic drugs. The response, characterized by a wave of constriction and elongation along the abdominal wall, is elicited by various substances, including acetylcholine, adenosine triphosphate, bradykinin, potassium chloride, and tryptamine. The response is rapid, with 70% or more of mice responding within 2 minutes to these challenge substances. The study also evaluates the effectiveness of 10 analgesic drugs in reducing the incidence of this response, finding that morphine, cyclazocine, aspirin, and others are effective to varying degrees. Paracetamol was only effective against acetylcholine. The antipyretic drugs were more effective against acetylcholine than tryptamine, while narcotic and narcotic antagonist drugs were less effective. The acetylcholine test is useful for rapid initial screening of potential analgesic drugs, though it has the disadvantage of generating many false positives. The study concludes that the acetylcholine-induced abdominal constriction response is a reliable and sensitive method for assessing analgesic activity in mice.