Repetitive motion injury is associated with increased serum cytokines and chemokines and altered psychosocial responses.
Barbe-MF; Harris-MY; Handy-M; Elliott-MB; Barr-AE
Neuroscience 2006, October 14-18, 2006, Atlanta, Georgia. Washington, DC: Society for Neuroscience, 2006 Oct; :372.8/LL58
Psychosocial behavioral changes have been associated with increased levels of circulating proinflammatory cytokines, as has aging. Using our rat model of repetitive motion injury, we have found that tissue injury resulting from upper extremity repetitive tasks leads to increased serum levels of inflammatory cytokines in young adult rats. The purpose of this study was to examine the combined effects of age and performance of repetitive tasks on serum levels of inflammatory mediators and psychosocial behavior. Seventeen aged (17 months old) Sprague-Dawley rats were randomized into one of three groups: high repetition low force (HRLF), trained control (TC; initial shaping only), or normal control. Ten young adult normal control and trained control rats were also used (n=5 each). For the HRLF task, rats grasped and pulled on a handle at a target force level of <15% maximum grip force, and at a target reach rate of 4 reaches/min. This task was performed in 4, 0.5 hour sessions separated by 1.5 hours for 3 days/week for periods of 3 weeks. Animals were euthanized using Nembutal (120 mg/kg body weight) and serum was collected by cardiac puncture and analyzed for 10 inflammatory cytokines and chemokines via a multiplexed ELISA protein analysis technique. Psychosocial and sensory functions were evaluated by task participation (task duration), grooming (forehead sticker removal), social interaction (withdrawal from a juvenile rat), and mechanical sensitivity of paws (VonFrey monofilament sensation test). Results showed that aged HRLF rats had significantly higher serum levels of RANTES, IL-10, MIP3a/CCL9, and Gro-KC compared to controls. Age alone elevated serum levels of IL1-1alpha, IL1-1beta, and MIP2 compared to young controls. There was a significant decline in task duration, social interaction and mechanical sensitivity in the HRLF compared to age-matched controls at 3 weeks. Thus, systemic inflammatory responses are enhanced in aged rats, especially with the performance of a repetitive task, and these inflammatory responses coincide with changes in psychosocial behavior.
Animals; Laboratory-animals; Models; Repetitive-work; Musculoskeletal-system; Musculoskeletal-system-disorders; Age-groups; Force; Tissue-culture; Behavior; Bone-structure; Injuries; Proteins
Neuroscience 2006, October 14-18, 2006, Atlanta, Georgia
Temple University, Philadelphia, Pennsylvania