Research Centre for Brain & Behaviour, Liverpool John Moores University, Liverpool, UK.
Laboratory of Stress Neurobiology, Faculty of Sciences, Center for Integrative Neurobiology and Pathophysiology, Institute of Physiology, Universidad de Valparaíso, Valparaíso, Chile.
Eur J Neurosci. 2022 May;55(9-10):2925-2938. doi: 10.1111/ejn.14951. Epub 2020 Sep 15.
Affiliative tactile interactions buffer social mammals against neurobiological and behavioral effects of stress. The aim of this study was to investigate the cutaneous mechanisms underlying such beneficial consequences of touch by determining whether daily stroking, specifically targeted to activate a velocity/force tuned class of low-threshold c-fiber mechanoreceptor (CLTM), confers resilience against established markers of chronic unpredictable mild stress (CMS). Adult male Sprague Dawley rats were exposed to 2 weeks of CMS. Throughout the CMS protocol, some rats were stroked daily, either at CLTM optimal velocity (5 cm/s) or outside the CLTM optimal range (30 cm/s). A third CMS exposed group did not receive any tactile stimulation. The effect of CMS on serum corticosterone levels, anxiety- and depressive-like behaviors in these three groups was assessed in comparison to a control group of non-CMS exposed rats. While stroking did not mitigate the effects of CMS on body weight gain, CLTM optimal velocity stroking did significantly reduce CMS-induced elevations in corticosterone following an acute forced-swim. Rats receiving CLTM optimal stroking also showed significantly fewer anxiety-like behaviors (elevated plus-maze) than the other CMS exposed rats. In terms of depressive-like behavior, whereas the same velocity-specific resilience was observed in a forced-swim test and social interaction test both groups of stroked rats spent significantly less time interacting than control rats, though they also spent significantly less time in the corner than non-stroked CMS rats. Together, these findings support the theory CLTMs play a functional role in regulating the physiological condition of the body.
亲和性触觉相互作用可缓冲社交哺乳动物的神经生物学和行为应激效应。本研究旨在通过确定日常梳理（专门针对激活速度/力调谐类低阈值 c 纤维机械感受器 (CLTM)）是否能赋予对慢性不可预测轻度应激 (CMS) 的既定标志物的弹性，来研究触摸产生这些有益后果的皮肤机制。成年雄性 Sprague Dawley 大鼠接受了 2 周的 CMS 处理。在整个 CMS 方案中，一些大鼠每天进行梳理，梳理速度分别为 CLTM 最佳速度（5cm/s）或不在 CLTM 最佳范围（30cm/s）。第三个 CMS 暴露组未接受任何触觉刺激。与未暴露于 CMS 的对照组大鼠相比，评估了 CMS 对三组大鼠血清皮质酮水平、焦虑和抑郁样行为的影响。虽然梳理并没有减轻 CMS 对体重增加的影响，但 CLTM 最佳速度梳理显著降低了急性强迫游泳后 CMS 引起的皮质酮升高。接受 CLTM 最佳梳理的大鼠也表现出明显较少的焦虑样行为（高架十字迷宫）比其他 CMS 暴露的大鼠。在抑郁样行为方面，虽然在强迫游泳和社交互动测试中都观察到了相同的速度特异性弹性，但两组梳理大鼠与对照组大鼠相比，互动时间明显减少，尽管它们在角落的时间也明显少于非梳理 CMS 大鼠。总之，这些发现支持了 CLTM 在调节身体生理状况方面发挥功能作用的理论。
