PDF(Pubmed)
Abstract：
Transient Receptor Potential Vanilloid 1 (TRPV1) is a nonselective cation channel expressed by pain-sensing neurons and has been an attractive target for the development of drugs to treat pain. Recently, Src homology region two domain-containing phosphatase-1 (SHP-1, encoded by Ptpn6) was shown to dephosphorylate TRPV1 in dorsal root ganglia (DRG) neurons, which was linked with alleviating different pain phenotypes. These previous studies were performed in male rodents only and did not directly investigate the role of SHP-1 in TRPV-1 mediated sensitization. Therefore, our goal was to determine the impact of Ptpn6 overexpression on TRPV1-mediated neuronal responses and capsaicin-induced pain behavior in mice of both sexes. Twelve-week-old male and female mice overexpressing Ptpn6 (Shp1-Tg) and their wild type (WT) littermates were used. Ptpn6 overexpression was confirmed in the DRG of Shp1-Tg mice by RNA in situ hybridization and RT-qPCR. Trpv1 and Ptpn6 were found to be co-expressed in DRG sensory neurons in both genotypes. Functionally, this overexpression resulted in lower magnitude intracellular calcium responses to 200 nM capsaicin stimulation in DRG cultures from Shp1-Tg mice compared to WTs. In vivo, we tested the effects of Ptpn6 overexpression on capsaicin-induced pain through a model of capsaicin footpad injection. While capsaicin injection evoked nocifensive behavior (paw licking) and paw swelling in both genotypes and sexes, only WT mice developed mechanical allodynia after capsaicin injection. We observed similar level of TRPV1 protein expression in the DRG of both genotypes, however, a higher amount of tyrosine phosphorylated TRPV1 was detected in WT DRG. These experiments suggest that, while SHP-1 does not mediate the acute swelling and nocifensive behavior induced by capsaicin, it does mediate a protective effect against capsaicin-induced mechanical allodynia in both sexes. The protective effect of SHP-1 might be mediated by TRPV1 dephosphorylation in capsaicin-sensitive sensory neurons of the DRG.
摘要：
瞬时受体电位香草素1（TRPV1）是一种由疼痛感知神经元表达的非选择性阳离子通道，已成为开发治疗疼痛药物的有吸引力的靶标。最近,含有Src同源区2域的磷酸酶-1（SHP-1，由Ptpn6编码）显示可使背根神经节（DRG）神经元中的TRPV1去磷酸化，这与减轻不同的疼痛表型有关。这些先前的研究仅在雄性啮齿动物中进行，并未直接研究SHP-1在TRPV-1介导的致敏中的作用。因此,我们的目标是确定Ptpn6过表达对TRPV1介导的神经元反应和辣椒素诱导的小鼠疼痛行为的影响.使用过表达Ptpn6（Shp1-Tg）的十二周龄雄性和雌性小鼠及其野生型（WT）同窝。通过RNA原位杂交和RT-qPCR在Shp1-Tg小鼠的DRG中确认Ptpn6过表达。发现Trpv1和Ptpn6在两种基因型的DRG感觉神经元中共表达。功能上,与WT相比,这种过表达导致在来自Shp1-Tg小鼠的DRG培养物中对200nM辣椒素刺激的较低幅度的细胞内钙反应。在体内,我们通过辣椒素足垫注射模型测试了Ptpn6过表达对辣椒素诱导的疼痛的影响。虽然辣椒素注射引起基因型和性别的伤害行为（舔爪）和爪肿胀，只有WT小鼠在注射辣椒素后出现机械性异常性疼痛。我们观察到两种基因型的DRG中TRPV1蛋白表达水平相似，然而,在WTDRG中检测到较高量的酪氨酸磷酸化TRPV1.这些实验表明,而SHP-1不介导辣椒素引起的急性肿胀和伤害性行为，它确实介导对辣椒素诱导的男女机械性异常性疼痛的保护作用。SHP-1的保护作用可能是通过TRPV1去磷酸化介导的辣椒素敏感的DRG感觉神经元。
