Diurnal variation of urinary MHPG in unipolar and bipolar depressives

Saliva levels of 3-methoxy-4-hydroxyphenylglycol and clinical efficacy of mirtazapine or selective serotonin reuptake inhibitors in patients with major depression

OBJECTIVE

This study compared saliva levels of 3-methoxy-4-hydroxyphenylglycol (sMHPG) in patients with major depressive disorder (MDD) to levels in healthy controls and explored whether sMHPG levels in patients with MDD were a predictive marker for antidepressant efficacy.

METHODS

sMHPG levels were compared in 53 patients with MDD and 275 age-matched healthy controls. Patients' depressive symptoms were assessed by the 17-item Hamilton Rating Scale for Depression at baseline and 4 weeks after treatment with selective serotonin reuptake inhibitors (SSRIs, n = 23) or mirtazapine (n = 30), followed by saliva sampling. The mirtazapine group included nine patients who had been treated with an SSRI for more than 4 weeks without any improvement. sMHPG levels were measured by gas chromatography-mass spectrometry.

RESULTS

sMHPG levels in MDD patients were significantly higher than in controls. The responder rate to drug treatment at 4 weeks was 62% for mirtazapine (13/21), 57% for SSRIs (13/23), and 89% (8/9) for SSRI plus mirtazapine. sMHPG at baseline in 13 responders treated with SSRIs, but not mirtazapine, was significantly higher than that in non-responder group and showed consequent reduction 4 weeks after treatment. The area under the receiver operating characteristic (ROC) curves of sMHPG for discrimination of SSRI responders and non-responders was 0.86 ± 0.10 (95% confidence interval: 0.64-1.0, p = 0.005). In contrast, the ROC curve of sMHPG levels for discrimination of mirtazapine responders and non-responders was not significant. Adjunctive treatment with mirtazapine to SSRI non-responders was effective, regardless of baseline sMHPG levels.

CONCLUSION

sMHPG in patients with MDD was higher than in healthy controls. High baseline sMHPG levels in patients with MDD maybe a predictive marker for SSRI response.

Assessment of circadian function in fibroblasts of patients with bipolar disorder

Previous studies have implicated the circadian system in the pathophysiology of bipolar disorder, but conclusive evidence for altered circadian clocks is lacking. Cultured fibroblasts harbor circadian clocks representative of those in the master clock resident in the suprachiasmatic nuclei, providing a new avenue to investigate the core clock machinery in patients with bipolar illness. We examined the rhythmic expression patterns of core clock genes (BMAL1, PER1, PER2, REV-ERBalpha, DEC2, DBP) in fibroblasts from 12 bipolar patients and 12 healthy controls. Although we did not detect differences in the circadian period between bipolar patients and controls, the amplitude of rhythmic expression for BMAL1, REV-ERBalpha and DBP, as well as the overall mRNA expression level for DEC2 and DBP was reduced in fibroblasts from bipolar patients. Bonferroni's correction for multiple comparisons still resulted in significantly reduced DBP expression level, and trends toward reduced overall expression level of DEC2 and circadian amplitude of BMAL1, in fibroblasts from bipolar patients. We next examined an expanded cohort of 18 bipolar patients and 35 healthy controls for mRNA expression levels of four kinases (CKIdelta, CKIepsilon, GSK3alpha and GSK3beta) and the protein and phosphorylation levels of two of them (GSK3alpha and GSK3beta). We did not detect differences in steady-state mRNA levels or protein levels of these kinases between bipolar patients and controls, but the level of GSK3beta phosphorylation was significantly reduced in bipolar patients within an Old Order Amish bipolar kindred. Our results suggest that the reduced amplitudes and overall expression levels of circadian genes, and the decreased phosphorylation level of GSK3beta may lead to dysregulation of downstream genes, which could explain some pathological features of bipolar disorder.

Neurobiological findings in bipolar II disorder compared with findings in bipolar I disorder

OBJECTIVE

To determine whether there are consistent neurobiological differences between patients with bipolar I disorder (BD I) and those with bipolar II disorder (BD II).

METHOD

We reviewed the literature in areas where the most consistent neurobiological findings have been reported for bipolar disorder, specifically, neuroimaging and brain metabolism. The imaging studies reviewed examined structure, using magnetic resonance imaging (MRI), and function, using functional MRI, positron emission tomography, and single photon emission computed tomography. We used magnetic resonance spectroscopy to examine brain chemistry. We reviewed those metabolic studies that examined cell calcium, 3-methoxy-4-hydroxyphenylglycol, and protein kinase C.

RESULTS

Some genetic studies suggest that there may be differences between BD II and BD I patients. However, our review of the imaging and metabolic studies identified few studies directly comparing these 2 groups. In those studies, there were few differences, if any, and these were not consistent.

CONCLUSIONS

While genetic data suggest there may be differences between BD II patients and BD I patients, the neurobiological findings to date do not provide support. However, this may be owing to the small number of studies directly comparing the 2 groups and also to the fact that those carried out have not been adequately powered to detect possible small true differences. This is an important issue because, if there are no neurobiological differences, it would be anticipated that similar treatments would be similarly effective in both groups. Given the importance of understanding whether there are neurochemical differences between these groups, further research in this area is clearly needed.

Circadian rhythms and the pharmacology of affective illness

The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of motor activity, sleep-wake, body temperature (Tb), 3-methoxy-4-hydroxyphenylglycol, cortisol, thyroid hormone, prolactin, growth hormone and melatonin are examined. ADs often lower nocturnal Tb and affect the homeostatic regulation of sleep. ADs often advance the timing and decrease the amount of slow wave sleep, reduce rapid eye movement sleep and increase or decrease arousal. Together, AD effects on nocturnal Tb and sleep may be related to their therapeutic properties. ADs sometimes delay nocturnal cortisol timing and increase nocturnal melatonin, thyroid hormone and prolactin levels; these effects often vary with diagnosis, and clinical state. The effects of ADs on the coupling of the central circadian pacemaker to photic and nonphotic zeitgebers are discussed.

Diurnal neuroendocrine and autonomic function in acute and remitted depressed male patients

This study evaluated diurnal data gathered hourly (1000 to 1800 hours) in males during acute depression and during remission of depression and in age-range/gender-matched normal controls. Mean, peak, variability, and time-course of the noradrenergic metabolite, plasma 3-methoxy, 4-hydroxyphenylglycol [MHPG]), plasma cortisol, and autonomic (mean arterial blood pressure [MAP] and heart rate) variables were examined. Compared to controls, acutely depressed, but not remitted depressed, patients had 1) an earlier plasma MHPG peak, 2) a greater intragroup variability of plasma MHPG, 3) a higher plasma cortisol concentration, 4) a lower MAP, and 5) tended to increase MAP more slowly than did the normal controls. The time course of diurnal heart rate also differed in acutely depressed patients from controls: acutely depressed patients started higher and converged by midday to normal levels. These diurnal data lend limited support to the dysregulation hypotheses of depression that suggest normal circadian rhythmicities are altered or disrupted in acute depression and that peripheral manifestations of central dysregulation normalize in remission of depression.

Disruption of circadian MHPG rhythmicity in major depression

Plasma concentrations of total (free plus conjugated) 3-methoxy-4-hydroxyphenylglycol (MHPG) were determined every 3 hr for a 24-hr period in 32 unipolar depressed patients, 11 bipolar depressed patients, and 12 healthy subjects. Each subject's circadian MHPG rhythmicity was modeled by a sinusoidal function. Temporal parameters were estimated by linear least squares regression with a fixed 24-hr period. The variabilities associated with estimates of circadian amplitude and acrophase were roughly twice as large in the patients compared to healthy subjects. Phase advances were associated most significantly with the agitated rather than the retarded subtype of depression, and with first episode depressions. Treatment with desipramine (n = 26) did not alter significantly any of the model parameters and had no effect on circadian variability in any patient group. The data overall support a dysregulation theory for depressive illness with phase advances representing one manifestation of such dysregulation.

Clinical and biochemical aspects of depressive disorders: II. Transmitter/receptor theories

The present document is the second of three parts in a review that focuses on recent data from clinical and animal research concerning the biochemical bases of depressive disorders, diagnosis, and treatment. Various receptor/transmitter theories of depressive disorders are discussed in this section. Specifically, data supporting noradrenergic, serotonergic, cholinergic, dopaminergic, GABAergic, and peptidergic theories, as well as interactions between noradrenergic and serotonergic, or cholinergic and catecholaminergic systems are presented. Problems with the data and future directions for research are also discussed. A previous publication, Part I of this review, dealt with the classification of depressive disorders and research techniques for studying the biochemical mechanisms of these disorders. A future publication, Part III of this review, discusses treatments for depression and some of the controversies in this field.

[Lithium, manic depressive psychoses and biological rhythms]

Lithium is one of the rare substances capable of disturbing the body's “biological clock”. Clinical, biochemical and physiological observations allow us to view the Manic Depressive Illness pathogeny and the mechanism of lithium action in terms of biological rhythm modification.

The 24-hour pattern of urinary MHPG excretion in depressives and normals

The 24-h pattern of urinary 3-methoxy-4-hydroxy-phenylglycol (MHPG) was studied in 15 depressives and 15 healthy controls. MHPG was measured at 3-h intervals over two consecutive 24-h periods. The shape of the MHPG excretion pattern of the depressed group was different from that of the control group. However, both the consistency and shape of the individual 24-h MHPG patterns exhibited a high interindividual variability. Therefore it is difficult to speculate on a circadian phase difference between depressives and healthy controls. Major factors that may have influenced our results are discussed.

Urinary MHPG, platelet 3H-imipramine binding and symptomatology in depression: an exploratory study of clinical heterogeneity

Urinary MHPG concentrations and platelet 3H-imipramine binding (Bmax, Kd) were measured in 20 psychiatric inpatients with diagnoses of major depressive disorder. Clinical assessments were performed using the Present State Examination (PSE) interview, and several dimensions of symptomatology were constructed on the basis of the PSE items. There was a significant positive relationship between Bmax and items reflecting both psychomotor retardation and anxiety. Urinary MHPG bore a comparatively complex nonlinear relationship to Bmax and to the psychomotor retardation symptom dimension. Urinary MHPG also showed an inverse, curvilinear correlation with certain neurotic symptoms. The implications of these findings are briefly discussed in the light of the "dysregulation" hypothesis of affective disorder.

Circadian symptom fluctuations in people with anxiety disorders

Circadian rhythm abnormalities have been demonstrated in people with depression, including a tendency toward maximal symptom severity in the morning. Although a few studies have suggested that symptoms in people with anxiety are worse later in the day, no detailed study of this observation has been reported. In 86 patients with anxiety disorders (63 with panic disorder or agoraphobia with panic attacks), anxiety symptoms tended to be more severe in the afternoon or evening than in the morning, with no abnormalities of heart rate or oral temperature. This is the first systematic demonstration of a circadian fluctuation of mood in any disorder other than depression.

Clinical and biological correlates of sleep deprivation in depression

Sleep deprivation is reported to have therapeutic effectiveness in depressive illness. Furthermore, the response to sleep deprivation has important research implications. Recent conceptual advances, resulting in increased understanding of the role of abnormal biological rhythms and neurotransmitter function of the pathophysiology of affective disorder, highlight the future role of sleep deprivation in the research and treatment of these disorders.