Department of Anesthesiology and Intensive Care Medicine, Oita University Faculty of Medicine, 1-1 Idaigaoka-Hasamamachi, Yufu, Oita, 879-5593, Japan.
J Anesth. 2011 Jun;25(3):392-7. doi: 10.1007/s00540-011-1142-3. Epub 2011 Apr 29.
Estradiol is a female hormone required for maintaining pregnancy and developing follicles in the ovary. Estradiol has been shown to perform a variety of physiological activities, including pain reduction. In this study, we tested the hypothesis that estradiol exerts antinociceptive effects in a rat model of inflammatory hyperalgesia.
We established a subacute hyperalgesia model using plantar injection of Freund's complete adjuvant (FCA) in Sprague-Dawley rats. We administered estradiol every 24 h, beginning 12 h after FCA administration, and used the plantar test to determine its effect on hyperalgesia. To determine the mechanism of action of estradiol, we evaluated the role of the opioid antinociceptive system using naloxone and the role of the descending pain inhibitory system using the α-2-receptor antagonist yohimbine and the serotonin receptor antagonist methysergide.
Administration of FCA induced hyperalgesia, which was significantly reduced by estradiol treatment compared to controls. Moreover, this effect was not antagonized by naloxone, but was attenuated by α-2-receptor and serotonin-receptor antagonists.
Estradiol is known to perform a variety of physiological functions. Our findings suggest that one such function is antinociception via an interaction with α-2 receptors and serotonin receptors.
雌激素是维持妊娠和卵巢卵泡发育所必需的女性激素。雌激素具有多种生理活性，包括减轻疼痛。在这项研究中，我们测试了这样一个假设，即雌激素在大鼠炎症性痛觉过敏模型中发挥镇痛作用。
我们使用足底注射完全弗氏佐剂（FCA）在 Sprague-Dawley 大鼠中建立亚急性痛觉过敏模型。我们在 FCA 给药后 12 小时开始每 24 小时给予一次雌激素，并使用足底测试来确定其对痛觉过敏的影响。为了确定雌激素的作用机制，我们使用纳洛酮评估了阿片类镇痛系统的作用，使用育亨宾评估了下行疼痛抑制系统的作用，以及使用 5-羟色胺受体拮抗剂美西麦角。
FCA 给药引起痛觉过敏，与对照组相比，雌激素治疗明显减轻了痛觉过敏。此外，这种作用不受纳洛酮拮抗，但被 α-2 受体和 5-羟色胺受体拮抗剂减弱。
已知雌激素具有多种生理功能。我们的研究结果表明，雌激素的一种生理功能是通过与 α-2 受体和 5-羟色胺受体相互作用来发挥镇痛作用。
