A STUDY ON DRUG-INDUCED “WRITHING” IN THE MOUSE

The "writhing" response in the mouse is a characteristic body movement and postural change caused by certain drugs following their intraperitoneal administrations. The purpose of this experiment was to study the mechanism of "writhing" in the mouse. The following results were obtained: 1.Various irritants tested, such as alkali, acids, salts of heavy metals and others, all caused "writhing", but non-irritants were ineffective. 2. The measures of reducing irritation of drugs could abolish the activity of drugs to cause "writhing". 3. "Writhing" was produced by mechanical irritation to the tissues in the centre of the abdominal cavity. 4. When the chemical or the mechanical irritation only acted on the serosa of the intestine, "writhing" was also caused. 5. "Writhing" response was inhibited selectively by a prior administration of analgesics. According to the results obtained, it is considered that "writhing" is a visceralsomatic reflex caused by the irritation of drugs to thc serosa of the intestine or the mesentery.