Histamine and substance P in synovial fluid of patients with temporomandibular disorders

Summary Although psychosocial factors and malocclusion are regarded as potential causes of temporomandibular disorders ( TMD ), the underlying pathogenesis is poorly understood. Recent studies suggest that substance P ( SP ), which has been associated with both psychosocial factors and malocclusion, and histamine, whose release can be induced by SP , may be implicated in the pathogenetic process. This study was designed to measure the concentration of histamine and SP in synovial fluid ( SF ) of both 38 patients with TMD and 11 healthy controls, and analyse the correlation between histamine and SP . Patients with TMD were divided into three subgroups: displaced disc with reduction ( DDR ), displaced disc without reduction ( DDNR ) and osteoarthritis ( OA ), with 10, 13, 15 subjects in every subgroup, respectively. After collecting SF samples, histamine and SP levels were measured by enzyme‐linked immunosorbent assay analysis ( ELISA ) and calibrated by bicinchoninic acid ( BCA )‐quantified protein level in the samples. The results suggest that OA group presented a significantly higher level of both histamine and SP than DDNR , DDR and healthy control groups. Histamine or SP in DDR and DDNR groups tend to be higher than control group, but no significance was found. Painful TMJ s show higher histamine and SP than painless TMJ s. Correlation analysis reveals a significant correlation between histamine and SP concentrations. Collectively, this study showed the changes of histamine and SP in the SF from different stages of TMD and found a significant correlation between the two substances, suggesting their potential implication in the pathogenesis of TMD .