CSF thyrotropin-releasing hormone gender difference: implications for neurobiology and treatment of depression

In light of the postulated role of thyrotropin-releasing hormone (TRH) as an endogenous anti-depressant, 56 refractory mood-disordered patients and 34 healthy adult control subjects underwent lumbar puncture for cerebrospinal fluid (CSF) TRH analysis. By two-way analysis of variance, there was no difference between CSF TRH in patients (as a group or by diagnostic subtype) and control subjects (n = 90, F = 0.91, df = 2.84, P = 0.41). There was, however, a CSF TRH gender difference (females, 2.95 pg/ml; males, 3.98 pg/ml; n = 90, F = 4.11, df = 1.84, P < 0.05). A post hoc t-test revealed the greatest gender difference in the bipolar group (t = 2.52, P < 0.02). There was no significant difference in CSF TRH in "ill" vs. "well" state (n = 20, P = 0.41). The role of elevated levels of CSF TRH in affectively ill men--or the role of decreased levels of CSF TRH in affectively ill women--remains to be investigated but could be of pathophysiological relevance.