The Effect of Intraperitoneal Histamine Administrationon the Anxiety in Rats

Aim and Background. It has been suggested that histamine has modulatory influence on anxiety-relatedbehaviors both in animals and humans.Materials and Methods.Intraperitoneal histamine administration (5, 10 and 20mg/kg) decreased %OAT (OpenArm Times) and but not locomotor activity, thus showing an anxiogenic response. Subcutaneous administration of ranitidine, a H2 histamine receptor antagonist at doses of 12.5, 25 and 50 mg/kg beforehistamine (20 mg/ kg) increased %OAT (Open Arm Times) and %OAE (Open Arm Entries) but not locomotor activity, thus showing an anxiolytic responses.Conclusions. This effect showed that ranitidine antagonizes histamine anxiolytic effects.Our results indicated that the anxiogenic-like effects induced by histamine in the intraperitoneal reverse inpresence of ranitidine.