Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, 1971 Commonwealth Ave, St. Paul, MN 55108, United States.
Department of Veterinary Physiology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Republic of Korea.
Brain Res Bull. 2017 Sep;134:47-54. doi: 10.1016/j.brainresbull.2017.06.017. Epub 2017 Jun 23.
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 3h post-injection in Balb/c, but only 1h post-injection in C3H. Single Balb/c mice only showed increased activity for 1h 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.
大多数急性和慢性动物疼痛模型严重依赖反射性测定来评估痛觉水平，这涉及将动物从其正常的社会环境中移除。在这里，我们研究并描述了社会互动对两种不同小鼠品系炎症性疼痛引起的运动变化的影响。为了产生炎症性疼痛，我们将 CFA 双侧注射到 Balb/c 和 C3H 小鼠的后爪中，然后使用自动检测系统记录探索性运动活动，首先评估社会行为对疼痛的影响。其次，我们确定 carprofen 给药是否改变了社会行为对疼痛诱发运动的影响。这种方法被扩展为创建一种新的热活动测定法，以客观测量热和冷对 CFA 诱发的动物运动的影响在配对动物中。配对的 Balb/c 和 C3H 小鼠表现出显著的过度运动，在 Balb/c 中持续 3 小时，而在 C3H 中仅持续 1 小时。单独的 Balb/c 小鼠仅在注射后 1 小时内表现出活动增加，而单独的 C3H 小鼠则没有增加。这种 CFA 诱导的配对动物活动增加与使用标准 Von Frey 细丝测量的机械性痛觉过敏高度负相关。Carprofen 给药完全阻断了这种 CFA 诱导的过度运动活性。热和冷都能显著增加注射 CFA 的配对小鼠的运动活性，而对注射生理盐水的对照小鼠的活动没有影响。这里呈现的结果表明，社会互动极大地影响了炎症性疼痛引起的运动活性变化，并表明使用基于运动的测定法来评估配对小鼠的痛觉可能提供一种替代且更敏感的方法来在疼痛的啮齿动物模型中，在社会互动的背景下，随着时间的推移量化痛觉和描述新的镇痛效果。
