exenatide and Peripheral-Nerve-Injuries

Growing evidences indicate that neuropathic pain is frequently accompanied with cognitive impairments, which aggravate the decrease in the quality of life of chronic pain patients. Furthermore, it has been shown that the activation of Glucagon-like-peptide-1receptor (GLP-1R) improved memory deficit in multiple diseases, including Alzheimer's disease (AD), stroke. However, whether GLP-1R activation could improve memory impairment induced by neuropathic pain and the mechanisms underlying the effect of the activation of GLP-1R on memory protection have not yet been established. The spared nerve injury (SNI) model was established as a kind of neuropathic pain. And novel-object recognition memory (hippocampus-dependent memory) was tested by the novel object recognition test (NORT). The expression levels of GLP-1, GLP-1R, adenosine monophosphate-activated protein kinase (AMPK), p-AMPKThr172, nuclear factor κ B p65 (NF-κB p65), interleukin-1beta (IL-1β), IL-1β p17 (mature IL-1β), tumor necrosis factor-alpha (TNF-α) and the synaptic proteins were tested in the murine hippocampus with memory deficits caused by neuropathic pain. Then, exenatide acetate (Ex-4, a GLP-1R agonist), exendin (9-39) (Ex(9-39), a GLP-1R antagonist) and Compound C dihydrochloride (CC, an AMPK inhibitor) were used to test the effects of the activation of GLP-1R in the mice with neuropathic pain. First, we uncovered that neuropathic pain could inhibit GLP-1/GLP-R axis, disturb inflammatory signaling pathway, increase the expression of IL-1β, IL-1β p17 and TNF-α, downregulate the synaptic proteins (postsynaptic density protein 95 (PSD95) and Arc). Subsequently, we reported that Ex-4 treatment could improve recognition memory impairment, increase the ratio of p-AMPKThr172/AMPK, inhibit the phosphorylation NF-κB p65 and decrease the expression of IL-1β, IL-1β p17 and TNF-α, upregulate the levels of PSD95 and Arc. Moreover, we found that Ex(9-39) and CC treatment could abrogate the memory protection of activation of GLP-1R in mice with neuropathic pain. The results indicated that the activation of GLP-1R could improve recognition memory impairment via regulating AMPK/NF-κB pathway, improving neuroinflammation, reversing the decreased level of synaptic proteins in neuropathic pain mice.

Topics: AMP-Activated Protein Kinase Kinases; Animals; Chronic Pain; Disease Models, Animal; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hippocampus; Interleukin-1beta; Memory Disorders; Mice; Neuralgia; Neuroinflammatory Diseases; Open Field Test; Peptide Fragments; Peripheral Nerve Injuries; Recognition, Psychology; Sciatic Nerve; Transcription Factor RelA; Tumor Necrosis Factor-alpha

Peripheral nerve injury (PNI) is a common clinical disease that causes the partial loss of segmental exercise and sensory and autonomic nervous function, placing a heavy burden on patients and their families. A previous study confirmed that exendin-4 can effectively improve nerve regeneration and functional recovery after PNI. However, the specific mechanisms by which exendin-4-mediates this repair have not been clarified. To explore the mechanism of exendin-4 in the treatment of PNI, we used microarray analysis to detect gene expression in the distal segment of the sciatic nerve after sciatic injury. Bioinformatics analyses were used to predict the roles of differentially expressed genes (DEGs) in nerve damage repair. Schwann cells (SCs) were cultured, and we verified the molecular mechanism of exendin-4 in SCs and the effect of exendin-4 on peripheral nerve regeneration through in vitro molecular biology and cell biology experiments. In vivo, exendin-4 could significantly promote peripheral nerve regeneration. A total of 180 DEGs between the exendin-4 group and the control group were detected. Bioinformatics analysis indicated that these DEGs were mainly enriched in the Jak-STAT signaling pathway. In vitro, exendin-4 could significantly promote the proliferation and migration of SCs by activating the Jak-STAT pathway, which promoted peripheral nerve regeneration. Our results indicate that exendin-4 promotes SC proliferation, migration and nerve regeneration after PNI by activating the Jak-STAT pathway. Our findings provide a basis and direction for further elucidation of the mechanisms of exendin-4 in the repair of PNI and provide a new way to treat PNI.

Topics: Cell Proliferation; Exenatide; Humans; Nerve Regeneration; Peripheral Nerve Injuries; Schwann Cells; Sciatic Nerve