The effects of systemic pro-inflammatory mediators on pain sensitization and psychosocial behavior in response to a repetitive motion injury.
Elliott-MB; Barr-AE; Amin-M; Harris-M; Barbe-MF
FASEB J 2007 Apr; 21(6):A1272
Pro-inflammatory cytokines were found in serum and distal forelimb tissues in our rat model of repetitive motion injury (RMI). The purpose of this study was to compare serum cytokines and chemokines to nociceptive neurochemicals in the spinal cord and psychosocial activity in a model of RMI. Both young and aged rats were randomized into high repetition low force (HRLF) or control (Cont) groups. Rats in the HRLF group performed a low force reaching and grasping task at a reach rate of 4 reaches/min. This task was performed in 4, 0.5 hr sessions separated by 1.5 hrs for 3 d/wk for 8 wks. Following euthanasia using Nembutal (120 mg/kg), serum was collected and analyzed for inflammatory cytokines/chemokines via multiplex protein analysis. Animals were perfusion fixed for immunohistochemical analysis of substance P and neurokinin 1 in the spinal cord dorsal horn. Psychosocial function was evaluated by task duration, forehead sticker removal, social interaction, and VonFrey monofilament sensation test. Results of this study showed rats in the HRLF group had significant changes in both serum cytokines levels and spinal cord neurochemicals compared to controls, as well as a significant decline in psychosocial activity in the HRLF animals. The results of this study suggest that systemic inflammation as a result of peripheral tissue injury may enhance inflammatory pain and sickness behavior particularly in aged rats.
Animals; Laboratory-animals; Models; Repetitive-work; Musculoskeletal-system; Musculoskeletal-system-disorders; Age-groups; Force; Proteins; Tissue-culture; Behavior; Cumulative-trauma; Cumulative-trauma-disorders
The FASEB Journal
Temple University, Philadelphia, Pennsylvania