Department of Physiology, Shanghai Second Military Medical University, Shanghai, 200433, People's Republic of China,
Purinergic Signal. 2011 Mar;7(1):73-83. doi: 10.1007/s11302-010-9212-9. Epub 2011 Jan 6.
There is evidence that gonadal hormones may affect the perception of painful stimulation, although the underlying mechanisms remain unclear. This investigation was undertaken to determine whether the adenosine 5'-triphosphate (ATP) receptor subunit, P2X(3), is involved in the modulatory action of estrogen in peripheral pain signal transduction in dorsal root ganglion (DRG). The mechanical pain behavior test, real-time quantitative reverse transcription-polymerase chain reaction analysis, and Western blot methods were used to determine the mean relative concentrations and functions of P2X(3) receptors in DRG in sham, ovariectomized (OVX), and estradiol replacement (OVX+E(2)) female rats and in sham and orchiectomized male rats. The mechanical hyperalgesia appeared after ovariectomy, which was subsequently reversed after estradiol replacement, whereas it was not observed after orchiectomy in male rats. Plantar injection of 2'(3')-O-(2,4,6-trinitrophenyl) ATP (TNP-ATP), a P2X(3) and P2X(2/3) receptor antagonist, resulted in an increase of the pain threshold force in OVX rats while had no effect on sham rats. Furthermore, A-317491, a selective P2X(3)/P2X(2/3) receptor antagonist, significantly reversed the hyperalgesia of OVX rats. Injection of ATP into the plantars also caused a significant increase of the paw withdrawal duration in OVX rats compared with that seen in the sham group, which became substantially attenuated by TNP-ATP. P2X(3) receptors expressed in DRG were significantly increased in both mRNA and protein levels after ovariectomy and then reversed after estrogen replacement, while a similar increase was not observed after orchiectomy in male rats. Furthermore, P2X(3) mRNA was significantly decreased 24 h after the application of 17β-estradiol in a concentration-dependent manner in cultured DRG neurons. ICI 182,780, an estrogen receptor antagonist, blocked the reduction in the protein level. These results suggest that the female gonadal hormone, 17β-estradiol, might participate in the control of peripheral pain signal transduction by modulating P2X(3) receptor-mediated events in primary sensory neurons, probably through genomic mechanisms.
有证据表明，性腺激素可能会影响痛觉刺激的感知，尽管其潜在机制尚不清楚。本研究旨在确定三磷酸腺苷（ATP）受体亚单位 P2X(3) 是否参与了雌激素对背根神经节（DRG）外周痛觉信号转导的调节作用。采用机械性疼痛行为测试、实时定量逆转录聚合酶链反应分析和 Western blot 方法，检测 sham、卵巢切除（OVX）、雌激素替代（OVX+E(2)）雌性大鼠以及 sham 和去势雄性大鼠的 DRG 中 P2X(3) 受体的平均相对浓度和功能。卵巢切除后出现机械性痛觉过敏，随后雌激素替代后恢复，而雄性大鼠去势后则未观察到这种现象。足底注射 P2X(3) 和 P2X(2/3) 受体拮抗剂 2'（3'）-O-（2,4,6-三硝基苯）-ATP（TNP-ATP）可增加 OVX 大鼠的痛阈力，而对 sham 大鼠则无影响。此外，选择性 P2X(3)/P2X(2/3) 受体拮抗剂 A-317491 可显著逆转 OVX 大鼠的痛觉过敏。向足底注射 ATP 也可使 OVX 大鼠的足底回缩持续时间明显增加，与 sham 组相比，这一现象在注射 TNP-ATP 后明显减弱。OVX 大鼠的 DRG 中 P2X(3) 受体的 mRNA 和蛋白水平均显著增加，随后在雌激素替代后恢复正常，而雄性大鼠去势后则未观察到类似的增加。此外，在培养的 DRG 神经元中，17β-雌二醇以浓度依赖的方式在应用 24 小时后显著降低 P2X(3)mRNA。雌激素受体拮抗剂 ICI 182,780 阻断了蛋白水平的降低。这些结果表明，女性性腺激素 17β-雌二醇可能通过调节初级感觉神经元中 P2X(3) 受体介导的事件来参与外周痛觉信号转导的控制，可能通过基因组机制。
