5.4.3. Stimulation of hollow organs

In hollow organs such as rat colon, formalin is injected, and a complex biphasic type of 'true visceral pain' is exhibited in two phases. In first phase, contraction and stretching of body and in second phase, abdominal licking and nibbling behaviour is shown by the animal. Intravesical administration of capsaicin or turpentine produce bladder pain, glycerol produces abdominal constrictions and intrauterine injections of mustard oil show complex behaviour patterns in a number of models including rats. Another mean of stimulus for colorectal distension in rat is an inflatable balloon [75, 76].
