Increased central and peripheral inflammation and inflammatory hyperalgesia in Zucker rat model of leptin receptor deficiency and genetic obesity

This study investigated whether sensitivity to nociceptive stimuli is altered in obese rats using established models of inflammatory pain, and using real-time PCR, profiled alterations in expression of key adipokine and inflammatory mediator mRNA (adiponectin, tumor necrosis factor-a, interleukin-1ß, cyclooxygenase-2, inducible nitric oxide synthase (iNOS)) in spinal cord with obesity. Responses to thermal and mechanical stimulation of the hindpaw and paw oedema were assessed in adult male Zucker fatty rats (fa/fa) and their lean littermates (fa/–; n = 6–9 per group) in the absence of inflammation (acute nociception), then in response to intradermal hindpaw injection of carrageenan (3%; 50 µl) or capsaicin (10 µg; 50 µl) or hindpaw incision.