GPER promotes nuclear translocation of SP1 to regulate NLRP3 transcription and polarization of microglia in a chronic migraine model

Background The pathogenesis of chronic migraine remains to be explored. Studies have confirmed that the incidence of chronic migraine is significantly higher in female patients than in male patients. The Estrogen receptor GPER is a G protein-coupled receptor and a member of the estrogen-related receptor family, which has been proven to regulate inflammation. Therefore, this study explores the exact role of the GPER receptor in chronic migraine and its mechanisms. Method Chronic migraine models were established by repeatedly stimulating the lateral ventricle with inflammatory soup. Mechanical and thermal pain thresholds were evaluated using von Frey filaments and radiant heat. The mRNA and protein expression levels of dopamine GPER receptor were analyzed by qRT-PCR and western blotting. Immunofluorescence was used to observe the co-localization of dopamine GPER and microglial Iba-1, as well as SP1 and microglial Iba-1. A GPER receptor antagonist (G15) and receptor agonist (G1), an SP1 inhibitor (AV37193-100UG), and an NLRP3 antagonist (MCC950) were used to investigate the specific mechanisms. Serum samples were collected from chronic migraine patients aged 18 to 74 years and 9 male controls without a family history of chronic migraine. The levels of 17β-estradiol and testosterone in the serum of the two groups were compared. Result Inflammatory soup stimulation significantly reduced the pain threshold in rats, accompanied by a decrease in the expression of GPER receptor at the TNC site, an increase in the expression of nuclear transcription factor SP1, and NLRP3 in microglia. In the TNC, GPER and SP1 were co-localized with microglia, and the antagonism of GPER mediated an increase in the nuclear translocation of SP1, aggravating the pain hyperalgesia in CM rats, which was reversed by NLRP3 activation in CM rats. Finally, the serum level of 17β-estradiol in male patients with chronic migraine was higher than that in the control group. Conclusion GPER may be involved in the pathogenesis of chronic migraine in rats by mediating the nuclear translocation of SP1 and regulating the transcriptional level of NLRP3 and central sensitization. GPER may be a valuable candidate for the treatment of chronic migraine.