Role And Mechanism Of Adrenomedullin Activated Astrocytes In Pain

Experimental background and significance: Studies in recent years have confirmed that damage to peripheral and central nerves can cause astrocyte activation.Adrenomedullin(AM)consists of 52 amino acids and is a member of the family of calcitonin gene-related peptides.It is a neuropeptide that has been shown to be involved in pain in recent years.Based on previous research results in the laboratory,this study proposes that AM can activate astrocytes and participate in the occurrence of pain.In order to further explore its specific mechanism,I established a primary culture method that can obtain large quantities of astrocytes with good growth and high purity,and then study the activation of astrocytes by AM;Investigate the effects of intrathecal injection of AM-stimulated astrocytes on the mechanical pain sensitivity of rats,and detect the situation of expression signaling pathways,inflammatory factors and chemokines in rat spinal cord by in vivo and ex vivo experiments..Research methods: A primary culture method for obtaining astrocytes with good growth and high purity in large quantities was established.After activating astrocytes with AM to simulate "activation",western blot and immunofluorescence were used.And qRT-PCR and other techniques to comprehensively analyze the effect of AM on astrocyte activation and intrathecal injection of AM-incubated astrocytes on the changes of signaling pathway,inflammatory factors and chemokines in rat spinal cord.The research results are as follows:(1)Astrocytes with good growth and high purity are obtained in large quantities.(2)AM can activate astrocytes,and up-regulate the expression of GFAP,P-JNK,RAMP2,CLR,TNF-?,IL-1? in astrocytes.(3)Intrathecal injection of AM-stimulated astrocytes increased the sensitivity of mechanical pain in rats.Moreover,the expression of GFAP,P-JNK,TNF-? and IL-1? in the spinal cord of rats was up-regulated,which increased the sensitivity of mechanical pain in rats.(4)AM can activate astrocytes and up-regulate the expression of CCL2 in astrocytes;after treatment with D-JNKI-1,it can significantly inhibit the up-regulation of CCL2 expression in astrocytes induced by AM.Up-regulation of mRNA expression of CCL2 in the dorsal horn of the spinal cord increases the sensitivity of mechanical pain in rats.Conclusion: AM can directly activate astrocytes through the action of AM1 receptor,causing changes in astrocyte morphology and function.Intrathecal injection of AM stimulated astrocytes increases the sensitivity of mechanical pain in rats,which is mediated through CCL2 and JNK signaling pathways.