Relationship between chronobiological thyrotropin and prolactin responses to protirelin (TRH) and suicidal behavior in depressed patients

Our results suggest that central TRH secretion is not altered in depressed patients with SBD in early remission. The findings that current SBDs exhibit both decreased FT4B levels and decreased evening TSH responses (and consequently, decreased ΔΔTSH values) support the hypothesis that hypothalamic TRH drive is reduced-leading to an impaired TSH resynthesis in the pituitary during the day after the morning TRH challenge. In violent suicide attempters, the marked abnormalities of TRH test responses might indicate a greatest reduction in hypothalamic TRH drive. These results further strengthen the possibility that a deficit in central TRH function may play a key role in the pathogenesis of suicidal behavior.