Therapeutic effects of the tripeptide protirelin (thyrotropin-releasing hormone) have been postulated in the affective disorders, but direct assessment in humans has been hindered by poor blood-brain barrier permeability.
Eight medication-free inpatients with refractory depression received 500 μg of protirelin via a lumbar intrathecal injection and an identical sham lumbar puncture procedure, separated by 1 week, in a doubleblind crossover design.
Five of eight patients responded to intrathecal protirelin, defined as a 50% or greater reduction in an abbreviated Hamilton Rating Scale for Depression score. Suicidality also was reduced significantly (P<.05). Responses were rapid and clinically robust, but shortlived.
Administration of protirelin by an intrathecal route induced a rapid improvement in mood and suicidality in these refractory depressed patients, supporting the hypothesis that thyrotropin-releasing hormone could be a positive modulator of mood.