Rapid antidepressant response after nocturnal TRH administration in patients with bipolar type I and bipolar type II major depression.

BACKGROUND: Thyrotropin-releasing hormone (TRH) is a tripeptide that produces endocrine and behavioral effects in animals and humans. Some studies have shown transient antidepressant activity after morning administration of TRH. We hypothesized that nocturnal administration of TRH, when the circadian sensitivity of the TRH receptor is at its peak, may result in a more robust antidepressant effect. METHODS: Twenty patients with bipolar (BP) type I or BP type II major depressive episode (MDE) were given nocturnal intravenous TRH 500 microg (n = 10) or saline (n = 10) at midnight in a randomized, double-blind fashion. Antidepressant activity was assessed using the Hamilton Depression Rating (HAM-D), Young Mania Rating (YMR), and Profile of Mood (POMS) scales over a 48-hour period. Thyrotropin (TSH), total T4, and free T3 concentrations were measured before and after TRH administration. Data were analyzed using chi test, Fisher exact test, and repeated-measures ANOVA. RESULTS: Sixty percent of the TRH group and 10% of the saline group showed a > or =50% reduction in baseline total HAM-D score within 24 hours (P = 0.03). HAM-D ratings fell by an average of 52% after TRH administration versus 12% after saline administration (P = 0.038). There was a modest increase in YMR scores after TRH compared with saline (P < 0.032). No manic or hypomanic episodes were observed. Antidepressant effects of TRH lasted up to 48 hours. There was no correlation between DeltaTSH, DeltaT4, or DeltaT3 measures after TRH (or saline) administration and the change in HAM-D scores. CONCLUSIONS: Nocturnal TRH administration may produce a rapid antidepressant effect in some patients with BP I and BP II MDE.

Comparative effects of mirtazapine and fluoxetine on sleep physiology measures in patients with major depression and insomnia.

BACKGROUND: Sleep complaints are common in patients with major depressive disorder (MDD). Both MDD and antidepressant drugs characteristically alter objective sleep measures. This study compares the effects of mirtazapine and fluoxetine on sleep continuity measures in DSM-IV MDD patients with insomnia. METHOD: Patients (N = 19) received initial baseline polysomnography evaluations over 2 consecutive nights. Subjects were randomly assigned to either fluoxetine (20-40 mg/day) or mirtazapine (15-45 mg/day) treatment for an 8-week, double-blind, double-dummy treatment trial. Single-night polysomnograms were conducted at weeks 1, 2, and 8, with depression ratings assessed at baseline and weeks 1, 2, 3, 4, 6, and 8. Statistical analysis was performed by repeated-measures analysis of variance followed by Dunnet's post hoc analyses. RESULTS: Patients receiving mirtazapine (N = 8) had significant improvement in objective sleep physiology measures at 8 weeks. Improvements in sleep latency, sleep efficiency, and wake after sleep onset were significant after only 2 weeks of mirtazapine treatment. No significant changes in sleep continuity measures were observed in the fluoxetine group (N = 11). Both groups improved clinically in mood and subjective sleep measures from baseline, with no differences between groups. CONCLUSION: These data demonstrate the differential effects of mirtazapine and fluoxetine, with significant improvement in favor of mirtazapine, on objective sleep parameters in MDD patients with insomnia.

The thyrotropin-releasing hormone (TRH) hypothesis of homeostatic regulation: implications for TRH-based therapeutics.

The functions of thyrotropin-releasing hormone (TRH) in the central nervous system (CNS) can be conceptualized as performed by four anatomically distinct components that together comprise a general TRH homeostatic system. These components are 1) the hypothalamic-hypophysiotropic neuroendocrine system, 2) the brainstem/midbrain/spinal cord system, 3) the limbic/cortical system, and 4) the chronobiological system. We propose that the main neurobiological function of TRH is to promote homeostasis, accomplished through neuronal mechanisms resident in these four integrated systems. This hypothesis offers a unifying basis for understanding the myriad actions of TRH and TRH-related drugs already demonstrated in animals and humans. It is consistent with the traditional role of TRH as a regulator of metabolic homeostasis. An appreciation of the global function of TRH to modulate and normalize CNS activity, along with an appreciation of the inherent limitations of TRH itself as a therapeutic agent, leads to rational expectations of therapeutic benefit from metabolically stable TRH-mimetic drugs in a remarkably broad spectrum of clinical situations, both as monotherapy and as an adjunct to other therapeutic agents. The actions of TRH are numerous and varied. This has been viewed in the past as a conceptual and practical impediment to the development of TRH analogs. Herein, we alternatively propose that these manifold actions should be considered as a rational and positive impetus to the development of TRH-based drugs with the potential for unique and widespread applicability in human illness.