Chaloner A, Greenwood-Van Meerveld Beverley
Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
Age (Dordr). 2013 Feb;35(1):1-10. doi: 10.1007/s11357-011-9323-4. Epub 2011 Nov 18.
Aging has profound yet unpredictable effects on pain perception and incidence of anxiety disorders. However, the mechanisms underlying age-related pathologies are confounded by contradictory observations in rodent models. Therefore, the goal of our study was to test the hypothesis that genetic variability contributes to age-related pain behaviors and susceptibility to anxiety. To address this hypothesis, we examined pain and anxiety-like behavior in young or old Brown Norway (BN), Fisher 344, and BN/F344 (F1), three rat strains used in studies to evaluate the effect of aging. Mechanosensitive thresholds were assessed using the Von Frey assay, and visceral pain sensitivity was measured via the visceromotor response to colorectal distension. Anxiety-like behavior and exploration was quantified in the elevated plus maze. In the BN strain, old rats exhibited increased mechanosensitive thresholds compared to young rats; however, age did not affect visceral sensitivity in this strain. In F344-BN rats, the number of abdominal contractions induced by the highest colonic distension pressure was significantly lower in old rats. However, following colonic sensitization, a difference was no longer apparent. In the F-344 strain, visceral hypersensitivity following afferent sensitization was evident in young rats at all distension pressures but was not observed in older animals at 20 mmHg. Aging significantly reduced maze exploration across all strains. Our data demonstrate that age- and strain-related alterations exist in pain behavior and highlight the effects of aging on exploratory behavior. These findings suggest that strain differences contribute to the controversial data on the effects of aging on pain perception.
衰老对疼痛感知和焦虑症发病率有着深远但不可预测的影响。然而，啮齿动物模型中相互矛盾的观察结果混淆了与年龄相关的病理机制。因此，我们研究的目的是检验遗传变异性导致与年龄相关的疼痛行为和焦虑易感性这一假设。为了验证这一假设，我们检测了年轻或年老的棕色挪威大鼠（BN）、费希尔344大鼠以及BN/F344（F1）大鼠这三种用于评估衰老影响的大鼠品系的疼痛和焦虑样行为。使用von Frey试验评估机械感受阈值，并通过对结肠扩张的内脏运动反应来测量内脏疼痛敏感性。在高架十字迷宫中对焦虑样行为和探索行为进行量化。在BN品系中，老年大鼠与年轻大鼠相比机械感受阈值升高；然而，年龄并未影响该品系的内脏敏感性。在F344-BN大鼠中，老年大鼠在最高结肠扩张压力下诱发的腹部收缩次数显著减少。然而，在结肠致敏后，这种差异不再明显。在F-344品系中，传入致敏后的内脏超敏反应在所有扩张压力下的年轻大鼠中均明显，但在20 mmHg时老年动物中未观察到。衰老显著降低了所有品系在迷宫中的探索行为。我们的数据表明，疼痛行为中存在与年龄和品系相关的改变，并突出了衰老对探索行为的影响。这些发现表明品系差异导致了关于衰老对疼痛感知影响的有争议的数据。
