Effects of central administration of oxytocin-saporin cytotoxin on chronic inflammation and feeding/drinking behaviors in adjuvant arthritic rats

An increase in the arthritis index as a marker of chronic inflammation and suppression of food intake are observed in adjuvant arthritic (AA) rats. Our previous study demonstrated that central oxytocin (OXT)-ergic pathways were activated potently in AA rats. In the present study, OXT-saporin (SAP) cytotoxin, which chemically disrupts OXT signaling was administered centrally to determine whether central OXT may be involved in the developments of chronic inflammation and alteration of feeding/drinking behavior in AA rats. The arthritis index was significantly enhanced in AA rats pretreated with OXT-SAP administered intrathecally (i.t.) but not intracerebroventricularly (i.c.v.). Suppression of food intake was significantly attenuated transiently in AA rats pretreated with OXT-SAP administered i.c.v. but not i.t. Suppression of drinking behavior was not affected by i.t. or i.c.v. administration of OXT-SAP in AA rats. In addition, intraperitoneal administration of an OXT receptor antagonist did not change the arthritis index or feeding/drinking behavior in AA rats. These results suggest that central OXT-ergic pathways may be involved in anti-inflammation at the spinal level and suppression of feeding behavior at the forebrain-brainstem level in AA rats.