1Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences; Institutes of Brain Science, Brain Science Collaborative Innovation Center, State Key Laboratory of Medical Neurobiology, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai 200032, China
2WuXi AppTec, Shanghai 200131, China

Abstract 

Accumulating evidence suggests that obesity is associated with chronic pain. However, whether obesity is associated with acute inflammatory pain is unknown. Using a well-established obese mouse model induced by a high-fat diet, we found that: (1) the acute thermal pain sensory threshold did not change in obese mice; (2) the model obese mice had fewer nociceptive responses in formalin-induced inflammatory pain tests; restoring the obese mice to a chow diet for three weeks partly recovered their pain sensation; (3) leptin injection induced significant phosphorylation of STAT3 in control mice but not in obese mice, indicating the dysmodulation of topical leptin–leptin receptor signaling in these mice; and (4) leptin–leptin receptor signaling-deficient mice (ob/ob and db/db) or leptin–leptin receptor pathway blockade with a leptin receptor antagonist and the JAK2 inhibitor AG 490 in wild-type mice reduced their nociceptive responses in formalin tests. These results indicate that leptin plays a role in nociception induced by acute inflammation and that interference in the leptin–leptin receptor pathway could be a peripheral target against acute inflammatory pain.

Keywords

Leptin, Obesity, Formalin test, Nociception

[SpringerLink]