Abstract
BACKGROUND: While disruption of acid-base homeostasis has been pathoetiologically implicated in panic disorder (PD), the mechanism by which pH imbalance is translated to panic pathophysiology is poorly understood. Recently, in a translational rodent model of PD, we reported a role of microglial acid sensing G-protein coupled receptor, T cell death associated gene-8 (TDAG8) in panic-associated behavior and physiology. However, the clinical validity of the TDAG8 receptor has not been investigated. OBJECTIVE: To assess TDAG8 in PD, we evaluated TDAG8 receptor expression in adolescents and young adults with PD and healthy comparison subjects. METHODS: Relative expression of TDAG8 mRNA was determined in peripheral blood mononuclear cells from patients with PD, and compared to expression in healthy subjects. Linear models were utilized to evaluate the relationship between TDAG8 expression and panic disorder symptom severity scale (PDSS) score as well as other potential explanatory variables (e.g., CRP, body mass index, sex, age). Models were refined based on the estimated parameter significance, evidence of omitted variable bias and Bayesian/Akaike information criteria. RESULTS: Relative to healthy comparison subjects (n=17), expression of TDAG8 mRNA was significantly increased in patients with PD (n=15) (1.60±0.65 vs. 1.01±0.50, p=0.008). TDAG8 mRNA expression predicted PD symptom severity in a fixed effect model incorporating age and sex (p=0.003). CONCLUSIONS: Collectively, our results suggest greater TDAG8 expression in patients with PD compared to healthy subjects, and directly link TDAG8 expression and the severity of the PD symptoms. Further investigation of the TDAG8 receptor in panic pathophysiology is warranted.