目的:脊髓是参与疼痛传递和调节的关键结构。垂体腺苷酸环化酶激活肽(PACAP)和血管活性肠肽(VIP),在脊髓中表达。这些肽激活G蛋白偶联受体(PAC1,VPAC1和VPAC2),可以为开发新型疼痛治疗提供靶标。然而,目前尚不清楚这些受体中的哪一种在脊髓内表达,以及这些受体如何发出信号。
方法:分离的大鼠脊髓培养物用于检查激动剂和拮抗剂受体药理学。确定了五种信号传导途径的信号传导谱。然后在小鼠中研究了不同PACAP和VIP受体的表达,使用免疫印迹和免疫荧光的大鼠和人脊髓。
结果:PACAP,但不是VIP,强力刺激cAMP,脊髓培养中IP1的积累和ERK和cAMP反应元件结合蛋白(CREB),但不是Akt磷酸化。信号由M65和PACAP6-38拮抗。PACAP-27比PACAP-38或VIP更有效地拮抗。PAC1和VPAC2受体样免疫反应性的模式在脊髓中似乎是不同的。
结论:脊髓中的药理作用表明,PAC1受体是存在的主要功能受体亚型,因此可能介导PACAP肽家族在脊髓中的伤害性作用。然而,PAC1和VPAC2受体在脊髓中的潜在表达强调了这些受体可能发挥不同的作用,并且都是可能的治疗靶点.
OBJECTIVE: The spinal cord is a key structure involved in the transmission and modulation of pain. Pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP), are expressed in the spinal cord. These peptides activate G protein-coupled receptors (PAC1, VPAC1 and VPAC2) that could provide targets for the development of novel pain treatments. However, it is not clear which of these receptors are expressed within the spinal cord and how these receptors signal.
METHODS: Dissociated rat spinal cord cultures were used to examine agonist and antagonist receptor pharmacology. Signalling profiles were determined for five signalling pathways. The expression of different PACAP and VIP receptors was then investigated in mouse, rat and human spinal cords using immunoblotting and immunofluorescence.
RESULTS: PACAP, but not VIP, potently stimulated cAMP, IP1 accumulation and ERK and cAMP response element-binding protein (CREB) but not Akt phosphorylation in spinal cord cultures. Signalling was antagonised by M65 and PACAP6-38. PACAP-27 was more effectively antagonised than either PACAP-38 or VIP. The patterns of PAC1 and VPAC2 receptor-like immunoreactivity appeared to be distinct in the spinal cord.
CONCLUSIONS: The pharmacological profile in the spinal cord suggested that a PAC1 receptor is the major functional receptor subtype present and thus likely mediates the nociceptive effects of the PACAP family of peptides in the spinal cord. However, the potential expression of both PAC1 and VPAC2 receptors in the spinal cord highlights that these receptors may play differential roles and are both possible therapeutic targets.