P11 (S100A10), a member of the S100 family of proteins, is expressed widely throughout the body and is involved in major depressive disorder and antidepressant response.
The etiology of major depression remains unknown, but dysfunction of serotonergic signaling has long been implicated in the pathophysiology of this disorder. p11 is an S100 family member recently identified as a serotonin 1B [5-hydroxytryptamine 1B (5-HT(1B))] and serotonin 4 (5-HT(4)) receptor-binding protein.
We examined the peripheral blood mononuclear cell (PBMC) P11 mRNA of patients with PTSD (n=13), major depressive disorder (MDD, n=16), bipolar disorder (BP, n=24), and schizophrenia (SCZ, n=12) or controls (n=14) using quantitative real-time PCR and the circulating levels of cortisol in blood plasma and saliva of PTSD using radioimmunoassay kit CORT-CT2.