Objective: To determine whether activation and/or inhibition of α-adrenoreceptors influences substance P (SP) release from dorsal root ganglion (DRG) primary sensory neurons in vitro.
Methods: DRGs were dissected from 15-day embryonic Wistar rats. DRG neurons were dissociated and cultured for 2 d and then exposed to noradrenaline (NA) alone (1×10(-4) mol/L), or along with the α1-adrenoreceptor antagonist prazosin (1×10(-6) mol/L) or the α2-adrenoreceptor antagonist yohimbine (1×10(-5) mol/L) for 4 d. Then, RT-PCR was used to determine the levels of preprotachykinin (PPT) mRNA encoding for SP and Western blot to assess the protein levels of SP. Basal and capsaicin (CAP)-evoked SP release were measured by enzyme-linked immunosorbent assay (ELISA).
Results: CAP-evoked SP release was sensitized by NA and this effect was inhibited by pre-incubation with prazosin but not with yohimbine. The levels of PPT mRNA, SP peptide, and basal SP release did not change significantly in any of the experimental conditions.
Conclusion: NA may significantly increase CAP-evoked SP release through activation of α-adrenoreceptors, which may contribute to noradrenergic pain modulation.
目的: 观察激活或抑制α-肾上腺素受体是否影响体外培养的背根神经节(dorsal root ganglion, DRG)神经元 P物质(substance P, SP)的释放。
方法: 胎龄15天的Wistar大鼠DRG神经元培养2天后, 分别用去甲肾上腺素(noradrenaline, NA)(1×10−4 mol/L)、 α1-受体拮抗剂哌唑嗪(1×10−6 mol/L)+NA(1×10−4 mol/L)、 α2-受体拮抗剂育亨宾(1×10−5 mol/ L)+NA(1×10−4 mol/L)孵育4天。 用RT-PCR法检测DRG神经元编码SP蛋白的PPT mRNA表达水平, 用Western blot 法检测DRG神经元SP蛋白的表达水平, 用酶联免疫吸附测定法检测SP的基础释放量和辣椒素刺激后的释放量。
结果: NA单独孵育显著增加了DRG神经元辣椒素刺激后的SP释放量, α1-受体拮抗剂哌唑嗪预处理可阻断NA的效应, 而α2-受体拮抗剂育亨宾不产生此作用。 在各种实验条件下, PPT mRNA水平、 SP蛋白表达水平和SP的基础释放量没有显著性差异。
结论: NA通过激活α1-受体增加了DRG神经元辣椒素刺激后的SP释放量, 这一作用可能与去甲肾上腺素能的疼痛调节有关。