GLP-1 and its derived peptides mediate pain relief through direct TRPV1 inhibition without affecting thermoregulation
The 2024 MSC Emerging Science Contest for Early-Career Investigators took place on December 9, 2024. Below is a written summary of one of the presentations from the contest. (A recording of the event is available here).
Category: Pharmacology
Winner: Eun Jin Go, Gachon University, College of Medicine
Title: GLP-1 and its derived peptides mediate pain relief through direct TRPV1 inhibition without affecting thermoregulation
Hypothesis, methodology, findings and conclusions
Our research focused on understanding if glucagon-like peptide-1 (GLP-1), a hormone released after eating, could help reduce pain by acting on a specific receptor in nerves called TRPV1, which detects pain signals from heat and inflammation. We hypothesized that GLP-1 and its derivatives might relieve pain by blocking this receptor without causing common side effects, such as issues with body temperature regulation.
To test this, we conducted a series of experiments using cell models and animal pain models. First, we isolated pain-sensitive neurons and exposed them to GLP-1 peptides to see how they interacted with TRPV1. Using electrophysiological techniques like the patch-clamp method, we measured the electrical signals produced when capsaicin – a TRPV1 activator – was applied, and observed how GLP-1 derivatives, especially exendin 9–39 and exendin 20–29, reduced these currents, indicating an inhibitory effect. To further verify the effect, we used calcium imaging to measure calcium influx (a sign of nerve activation), which also decreased when these peptides were applied, confirming inhibition of TRPV1.
In more detailed single-channel recordings, we observed that exendin 9–39 binds to the outer (extracellular) side of TRPV1 and acts as a noncompetitive inhibitor of capsaicin. This means it selectively blocked TRPV1 activation by capsaicin without affecting other pathways, like those activated by acidic conditions. We then moved to animal models to assess pain relief behaviorally. Mice treated with GLP-1 peptides in acute and chronic pain models (such as inflammatory and neuropathic pain) showed reduced pain behaviors, without changes in body temperature, unlike other TRPV1 inhibitors. Finally, binding assays confirmed that exendin 9–39 and exendin 20–29 interact directly with TRPV1, further supporting our findings.
Our results showed that GLP-1 peptides, especially exendin 9–39 and exendin 20–29, significantly reduced pain behaviors in animal models by inhibiting TRPV1 in a targeted manner without disrupting body temperature. This was particularly effective in both acute pain and chronic pain models, such as inflammatory and neuropathic pain, demonstrating a strong analgesic effect with minimal risk of temperature-related side effects.
This study reveals a novel use for GLP-1-derived peptides in pain management. By targeting the TRPV1 receptor specifically, GLP-1 peptides, especially exendin 20–29, offer a potential way to relieve pain without the side effects commonly seen with other TRPV1 inhibitors. This could provide clinicians with a safer, more effective option for managing chronic and inflammatory pain, giving patients relief without the risks of temperature dysregulation and other adverse effects. This research thus opens the door to developing a new class of pain medications that could improve patient quality of life with fewer side effects.
Implications for understanding migraine disease and/or its comorbidities, or how the research holds promise as a new avenue of future migraine study.
Migraines are a neurological disorder characterized by severe, recurrent headaches often accompanied by nausea, visual disturbances, and sensitivity to light and sound. This condition is also associated with several comorbidities, including metabolic syndrome, obesity, cardiovascular issues, gastrointestinal problems, and mood disorders like anxiety and depression. A key mechanism in migraine pathology is neurogenic inflammation, where pain-sensing neurons release inflammatory neuropeptides, such as calcitonin gene-related peptide (CGRP), leading to pain and other migraine symptoms. The TRPV1 receptor on these neurons plays a critical role in this process by responding to inflammatory stimuli and promoting the release of these neuropeptides.
Our research into GLP-1-derived peptides, particularly exendin 20–29, offers new insights into migraine treatment by showing that these peptides can inhibit TRPV1 activity without affecting body temperature regulation. This selective inhibition is important because traditional TRPV1 inhibitors can cause adverse effects like hyperthermia. By blocking TRPV1 activation that leads to neuropeptide release, GLP-1- derived peptides could reduce the neurogenic inflammation central to migraine attacks, potentially alleviating migraine pain with fewer side effects.
Furthermore, since GLP-1 plays a role in metabolic regulation and GLP-1 analogs are already used to treat conditions like diabetes and obesity, our findings suggest a dual benefit. These peptides could address migraine pain while also helping manage metabolic comorbidities common in migraine sufferers. This dual action could be particularly valuable for patients whose migraines are exacerbated by metabolic issues or for those who also struggle with obesity or glucose regulation.
Our study opens promising new avenues for migraine research by linking GLP-1 pathways with migraine mechanisms. Future studies could focus on testing GLP-1 peptides like exendin 20–29 in migraine models to confirm their effectiveness in reducing neurogenic inflammation and pain. Additionally, exploring the broader effects of GLP-1 on other migraine-related pathways and comorbidities could lead to more comprehensive treatments that not only alleviate migraine symptoms but also improve overall health in patients with complex migraine profiles. This approach has the potential to transform migraine management by offering targeted therapies that are both effective and well-tolerated.