TNF and rheumatoid arthritis: Accordingly, the aim of this study was to investigate the expression of GPR30 in the hippocampus, synovial tissue and cartilage during different stages of pristane-induced arthritis in Dark Agouti (DA) rats, an animal model of RA, and to determine the associations with hippocampal microglia, IL-17A and TNF serum levels, degree of joint inflammation and clinical score in both sexes.