Department of Anatomy, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P. 500, Trois-Rivières, QC, Canada, G9A 5H7; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P. 500, Trois-Rivières, QC, Canada, G9A 5H7.
Department of Anatomy, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P. 500, Trois-Rivières, QC, Canada, G9A 5H7; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P. 500, Trois-Rivières, QC, Canada, G9A 5H7.
Neuroscience. 2019 Oct 15;418:37-49. doi: 10.1016/j.neuroscience.2019.08.035. Epub 2019 Aug 28.
It is well established that early blindness results in brain plasticity and behavioral changes in both humans and animals. However, only a few studies have examined the effects of blindness on pain perception. In these studies, pain hypersensitivity was reported in early, but not late, blind humans. The underlying mechanisms remain unclear, but considering its key role in pain perception and modulation, the amygdala may contribute to this pain hypersensitivity. The first aim of this study was to develop an animal model of early blindness to examine the effects of blindness on pain perception. A mouse cross was therefore developed (ZRDBA mice), in which half of the animals are born sighted and half are born anophthalmic, allowing comparisons between blind and sighted mice with the same genetic background. The second aim of the present study was to examine mechanical and thermal pain thresholds as well as pain behaviors and pain-related c-Fos immunoreactivity induced by the formalin test in the amygdalas of blind and sighted mice. Group differences in amygdala volume were also assessed histologically. Blind mice exhibited lower mechanical and thermal pain thresholds and more pain behaviors during the acute phase of the formalin test, compared with sighted mice. Moreover, pain hypersensitivity during the formalin test was associated with increased c-Fos immunoreactivity in the amygdala. Furthermore, amygdala volume was larger bilaterally in blind compared with sighted mice. These results indicate that congenitally blind mice show pain hypersensitivity like early blind individuals and suggest that this is due in part to plasticity in the amygdala.
众所周知，早期失明会导致人类和动物的大脑可塑性和行为变化。然而，只有少数研究探讨了失明对疼痛感知的影响。在这些研究中，报告称早期失明的人类存在疼痛敏感性增加，但晚期失明的人类则没有。其潜在机制尚不清楚，但考虑到杏仁核在疼痛感知和调节中的关键作用，它可能是导致这种疼痛敏感性增加的原因之一。本研究的第一个目的是开发一种早期失明的动物模型，以研究失明对疼痛感知的影响。因此开发了一种小鼠杂交品种（ZRDBA 小鼠），其中一半的动物出生时视力正常，另一半出生时眼球缺失，允许对具有相同遗传背景的盲鼠和正常鼠进行比较。本研究的第二个目的是检查盲鼠和正常鼠的机械和热痛阈值以及福尔马林试验引起的疼痛行为和疼痛相关 c-Fos 免疫反应，并评估杏仁核的体积差异。与正常鼠相比，盲鼠在福尔马林试验的急性阶段表现出较低的机械和热痛阈值以及更多的疼痛行为。此外，福尔马林试验期间的疼痛敏感性增加与杏仁核中 c-Fos 免疫反应的增加有关。此外，盲鼠的杏仁核体积比正常鼠双侧都更大。这些结果表明，先天性失明的小鼠表现出与早期失明个体相似的疼痛敏感性增加，并表明这部分是由于杏仁核的可塑性所致。
