Cold receptor TRPM8 as a target for migraine-associated pain and affective comorbidities

BACKGROUND: Genetic variations in the Trpm8 gene that encodes the cold receptor TRPM8 have been linked to protection against polygenic migraine, a disabling condition primarily affecting women. Noteworthy, TRPM8 has been recently found in brain areas related to emotional processing, suggesting an unrecognized role in migraine comorbidities. Here, we use mouse behavioural models to investigate the role of Trpm8 in migraine-related phenotypes. Subsequently, we test the efficacy of rapamycin, a clinically relevant TRPM8 agonist, in these behavioural traits and in human induced pluripotent stem cell (iPSC)-derived sensory neurons.

FINDINGS: We report that Trpm8 null mice exhibited impulsive and depressive-like behaviours, while also showing frequent pain-like facial expressions detected by an artificial intelligence algorithm. In a nitroglycerin-induced migraine model, Trpm8 knockout mice of both sexes developed anxiety and mechanical hypersensitivity, whereas wild-type females also displayed depressive-like phenotype and hypernociception. Notably, rapamycin alleviated pain-related behaviour through both TRPM8-dependent and independent mechanisms but lacked antidepressant activity, consistent with a peripheral action. The macrolide ionotropically activated TRPM8 signalling in human sensory neurons, emerging as a new candidate for intervention.

SIGNIFICANCE: Together, our findings underscore the potential of TRPM8 for migraine relief and its involvement in affective comorbidities, emphasizing the importance of addressing emotional symptoms to improve clinical outcomes for migraine sufferers, especially in females.