Exposure to chronic stress can influence nociception and further induce hyperalgesia. Whether stress modulation of pain in female animals occurs in an estrous cycle-specific manner is still unclear. We profiled the changes in nociception (thermal, mechanical, formalin-evoked acute and inflammatory pain) of female Sprague-Dawley rats after treatment with chronic unpredictable mild stress (CUMS) and investigated whether these changes occur in an estrous cycle-dependent manner. The results showed that CUMS female rats exhibited a lower mechanical withdrawal threshold in proestrus and estrus, a longer formalin-evoked licking time in metestrus and diestrus, but no changes in the latency time on the tail-flick test. The present study findings suggest that chronic stress induces mechanical and formalin-evoked acute hyperalgesia of female rats in an estrous cycle-dependent manner.

• SUMMARY

• Our studies showed that chronic stress increased nociceptive sensitivity of female rats. Furthermore females had different stress-induced pain responses in different estrous phases: mechanical hyperalgesia in proestrus and estrus, formalin-evoked acute hyperalgesia in metestrus and diestrus.

暴露于慢性应激会影响伤害感受并进一步引起痛觉过敏。雌性动物疼痛的应激调节是否以发情周期特异性的方式发生尚不清楚。我们分析了慢性不可预测的轻度应激（CUMS）治疗后雌性Sprague-Dawley大鼠的伤害感受（热，机械，福尔马林诱发的急性和炎性疼痛）的变化，并调查了这些变化是否以发情周期依赖性方式发生。结果表明，CUMS雌性大鼠在发情期和发情期表现出较低的机械退缩阈值，在肠胃和发情期的福尔马林诱发的舔ing时间更长，而甩尾试验的潜伏时间没有变化。

• 概要

• 我们的研究表明，慢性应激会增加雌性大鼠的伤害感受敏感性。此外，雌性在不同的发情阶段具有不同的压力诱发的疼痛反应：发情和发情期的机械性痛觉过敏，福尔马林诱发的发情期和二头肌的痛觉过敏。