Most acute and chronic animal models of pain rely heavily on reflexive assays for evaluating levels of nociception, which involves removing the animal from its normal social environment. Here, we examine and characterize the influence of social interactions on inflammatory pain-evoked changes in movement in two different mouse strains. To produce inflammatory nociception, we injected CFA bilaterally into the hind paws of Balb/c and C3H mice and then recorded exploratory locomotor activity using an automated detector system to first evaluate the effects of social behavior on nociception. Secondly, we determined if carprofen administration altered the effects of social behavior on nociceptive-evoked movement. This methodology was expanded to create a novel thermal activity assay to objectively measure the effect of heat and cold on CFA-evoked animal movement in paired animals. Paired Balb/c and C3H mice exhibited significant hyper-locomotion that lasted for 3 h post-injection in Balb/c, but only 1 h post-injection in C3H. Single Balb/c mice only showed increased activity for 1 h post-injection, while single C3H mice showed no increase. This CFA-induced increase in activity in paired animals was highly inversely correlated with mechanical allodynia as measured using standard Von Frey filaments. Carprofen administration completely blocked this CFA-induced hyperlocomotor activity. Both heat and cold induced a significant increase in locomotor activity in paired mice injected with CFA, while having no effect on activity in control mice injected with saline. The results presented here indicate that social interactions greatly influence inflammatory pain-induced changes in locomotor activity and indicate that the use of movement-based assays to evaluate nociception in paired mice may provide an alternative and more sensitive method to quantify nociception and characterize novel analgesic effects over time in the context of social interactions in rodent models of pain.
|Original language||English (US)|
|Number of pages||8|
|Journal||Brain Research Bulletin|
|State||Published - Sep 2017|
Bibliographical noteFunding Information:
This study was funded by NIH grant CA84233 and Minnesota AES grant MIN-63-071. The author B.A.S. is supported by a NIH/NIAMS T32 AR050938 ?Musculoskeletal Training Grant?. The authors would like to thank Dr. Alice Larson for her helpful comments and advice during the preparation of this manuscript.
© 2017 Elsevier Inc.