PO-85 | Alterations in gut microbiota and the endocannabinoid system in an animal model of chronic migraine

Sara Facchetti,^1,2 Chiara Demartini,¹ Miriam Francavilla,^1,2 Rosaria Greco,¹ Cristina Tassorelli^1,2 | ¹Section of Translational Neurovascular Research, IRCCS Mondino Foundation, Pavia, Italy; ²Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy

Background: The endocannabinoid system (ECs) with its receptors and ligands is a complex cell-signalling system widely present in the nervous system and in the gastrointestinal tract. The ECs regulates inflammatory responses and intestinal homeostasis through its interactions with the gut microbiota, ultimately influencing brain function both indirectly, via gut-derived circulating factors, and directly, through vagus nerve signalling. Increasing evidence points to a role for the ECs in chronic migraine. The aim of this study was to assess whether gut dysbiosis is associated with alterations in the ECs, both centrally and peripherally, in a chronic migraine-like animal model induced by repeated nitroglycerin (NTG) administration.

Methods: Adult male Sprague-Dawley rats were treated with NTG (5 mg/kg i.p.) or vehicle every two days over nine days (5 total injections). On day nine, four hours after the last administration of NTG or vehicle, rats were tested for migraine-like hyperalgesia (orofacial formalin test). The intestine and trigeminal ganglion were collected to assess the gene expression of ECs components using real-time PCR. Fecal 16S ribosomal RNA gene sequencing was used to assess alterations in the gut flora.

Results: Chronic NTG administration significantly increased face rubbing time during phase II of the orofacial formalin test, confirming the development of trigeminal hyperalgesia. Gut microbiota analysis revealed significant differences in beta-diversity between NTG-treated and vehicle groups, confirming an alteration in the microbial population. Furthermore, analysis of intestinal gene expression showed a significant decrease in monoacylglycerol lipase (MAGL) mRNA expression, with no changes observed in the mRNA expression of fatty acid amide hydrolase, N-acylethanolamine acid amidase, N-acyl phosphatidylcholine phospholipase D, cannabinoid receptor-1, and cannabinoid receptor-2. Accordingly, reduced MAGL mRNA expression was also detected in the trigeminal ganglion of NTG-treated rats compared to the vehicle group. 

Conclusion: These findings suggest that microbiota dysbiosis associated with trigeminal hyperalgesia may be linked to altered 2-arachidonoylglycerol metabolism, suggesting a potential role for the gut-brain-endocannabinoid axis in migraine-related pain.