CSF monoamine metabolites in melancholia

Dysregulation of striatal dopamine D2/D3 receptor-mediated by hypocretin induces depressive behaviors in rats

BACKGROUND

The dysregulation of the dopamine system contributes to depressive-like behaviors in rats, and the neurological functions regulated by hypocretin are severely affected in depression. However, whether suvorexant plays a role in alleviating depression by affecting the dopamine system is unclear.

METHODS

To preliminarily explore the mechanism of suvorexant (10 mg/kg) in the treatment of depression, the mRNA and protein expression of TH, Drd2, Drd3, GluN2A, DAT, and GluN2B in the striatum of rats was quantified by qPCR and western blotting. The plasma hypocretin-1 and dopamine levels and the striatal dopamine levels were determined by ELISA.

RESULTS

i) Compared to those of the control group, chronic unpredictable mild stress (CUMS) rats showed depressive-like behaviors, which were subsequently reversed by treatment with suvorexant. ii) The mRNA and protein expressions of TH, Drd2, Drd3, GluN2A, and GluN2B in the striatum of CUMS were significantly increased compared with those in the controls, but decreased after suvorexant treatment. iii) Compared with those in the control group, the plasma and striatal dopamine levels of CUMS decreased while plasma hypocretin-1 levels increased, which was reversed after suvorexant treatment.

LIMITATIONS

i) The suvorexant is a dual hypocretin receptor antagonist; however, the responsible receptor is unclear. ii) We only focused on related factors in the striatum but did not explore other brain regions, nor did we directly explore the relationship among these factors.

CONCLUSION

Depressive-like behaviors induced by CUMS can be reversed by suvorexant, and the therapeutic effects of suvorexant may be mediated by affecting the dopamine system.

Potential lethality of suicide attempts in youth

Rates of suicide in youth have increased over the last 50 years, yet our ability to predict suicidal behaviours has not significantly improved during this time. Examining predictors of suicide attempt lethality can enhance our understanding of suicidality in youth, yet research has focused on actual medical lethality (the actual danger to life resulting from a suicide attempt) rather than potential lethality (the potential for death that is associated with a suicide attempt). Thus, the aim of the present study was twofold: first, we quantified the percentage of youth for whom the severity of suicide attempt was misclassified by considering only actual lethality; second, we tested whether key variables that predict the actual lethality of suicide attempts also predict the potential lethality of suicide attempts in youth. We examined these questions in a sample of children and adolescents admitted to a psychiatric inpatient unit following a suicide attempt. Over 70% of youth who made serious suicide attempts would have been misclassified by assessments relying on only actual lethality. Although several variables relevant to the construct of actual lethality significantly predicted potential lethality (e.g., male sex, substance use disorder), others did not. In addition, we found that the subset of youth who would have been misclassified as low risk based on actual lethality had a disproportionately high need for healthcare resources due to future hospital admissions. The present study provides evidence to suggest that considering potential lethality may lead to improved detection and prediction of suicide risk in youth, and in doing so supports recent calls to broaden considerations of the lethality associated with suicide attempts.

Sex and race differences of cerebrospinal fluid metabolites in healthy individuals

INTRODUCTION

Analyses of cerebrospinal fluid (CSF) metabolites in large, healthy samples have been limited and potential demographic moderators of brain metabolism are largely unknown.

OBJECTIVE

Our objective in this study was to examine sex and race differences in 33 CSF metabolites within a sample of 129 healthy individuals (37 African American women, 29 white women, 38 African American men, and 25 white men).

METHODS

CSF metabolites were measured with a targeted electrochemistry-based metabolomics platform. Sex and race differences were quantified with both univariate and multivariate analyses. Type I error was controlled for by using a Bonferroni adjustment (0.05/33 = .0015).

RESULTS

Multivariate Canonical Variate Analysis (CVA) of the 33 metabolites showed correct classification of sex at an average rate of 80.6% and correct classification of race at an average rate of 88.4%. Univariate analyses revealed that men had significantly higher concentrations of cysteine (p < 0.0001), uric acid (p < 0.0001), and N-acetylserotonin (p = 0.049), while women had significantly higher concentrations of 5-hydroxyindoleacetic acid (5-HIAA) (p = 0.001). African American participants had significantly higher concentrations of 3-hydroxykynurenine (p = 0.018), while white participants had significantly higher concentrations of kynurenine (p < 0.0001), indoleacetic acid (p < 0.0001), xanthine (p = 0.001), alpha-tocopherol (p = 0.007), cysteine (p = 0.029), melatonin (p = 0.036), and 7-methylxanthine (p = 0.037). After the Bonferroni adjustment, the effects for cysteine, uric acid, and 5-HIAA were still significant from the analysis of sex differences and kynurenine and indoleacetic acid were still significant from the analysis of race differences.

CONCLUSION

Several of the metabolites assayed in this study have been associated with mental health disorders and neurological diseases. Our data provide some novel information regarding normal variations by sex and race in CSF metabolite levels within the tryptophan, tyrosine and purine pathways, which may help to enhance our understanding of mechanisms underlying sex and race differences and potentially prove useful in the future treatment of disease.

Serotonergic mechanisms and suicidal behavior

Disturbances in central serotonin (5-hydroxytryptamine, 5-HT) were first described in depression. They were inferred to exist based on the finding of lowered baseline and post-probenecid concentrations of 5-HIAA in CSF. Initially, depressed patients with and without deimonstrable disturbances in central 5-H1 seemed psychopathologically indistinguishable. Interpreting the available data, at that time, we introduced in 1971 the concept of biochemical heterogeneity of depression. Some forms, we postulated, are linked to disturbances in 5-HT functions, others are not or, to a much lesser extent. Subsequently, we showed the concept of a separate «5-HT depression» to be untenable. It seems more likely now that 5-HT disturbances in depression are not linked to a particular syndromal depression type, but to particular psychopathological dimensions, i.e. heightened anxiety and disturbed aggression regulation. These dimensions might form a prominent aspect of depression or may be virtually absent. They are moreover not specific for depression, but can occur in other psychiatric disorders as well. This might explain the seemingly capricious occurrence of 5-HT disorders in depression as well as their nosological non-specificity.

Based on the dimensional 5-HT hypothesis one might expect drugs that increase 5-HT availability in the brain to be effective in the various anxiety disorders, in depressions marked by increased anxiety and disturbed aggression regulation and in personality disorders with strong aggressive tendencies.

Biological correlates of personality: considerations on the possible usefulness of central nervous system peripheral markers

Although a great deal of biological research has been carried out on several psychiatric disorders, it is disappointing to see how little progress has been made in the field of the biology of personality. The authors underline the methodological problems that arise in the investigation of biological substrates of human personality and review both currently available and putative peripheral markers of the central nervous system that might be used in further human studies.

Data-driven biological subtypes of depression: systematic review of biological approaches to depression subtyping

Research into major depressive disorder (MDD) is complicated by population heterogeneity, which has motivated the search for more homogeneous subtypes through data-driven computational methods to identify patterns in data. In addition, data on biological differences could play an important role in identifying clinically useful subtypes. This systematic review aimed to summarize evidence for biological subtypes of MDD from data-driven studies. We undertook a systematic literature search of PubMed, PsycINFO, and Embase (December 2018). We included studies that identified (1) data-driven subtypes of MDD based on biological variables, or (2) data-driven subtypes based on clinical features (e.g., symptom patterns) and validated these with biological variables post-hoc. Twenty-nine publications including 24 separate analyses in 20 unique samples were identified, including a total of ~ 4000 subjects. Five out of six biochemical studies indicated that there might be depression subtypes with and without disturbed neurotransmitter levels, and one indicated there might be an inflammatory subtype. Seven symptom-based studies identified subtypes, which were mainly determined by severity and by weight gain vs. loss. Two studies compared subtypes based on medication response. These symptom-based subtypes were associated with differences in biomarker profiles and functional connectivity, but results have not sufficiently been replicated. Four out of five neuroimaging studies found evidence for groups with structural and connectivity differences, but results were inconsistent. The single genetic study found a subtype with a distinct pattern of SNPs, but this subtype has not been replicated in an independent test sample. One study combining all aforementioned types of data discovered a subtypes with different levels of functional connectivity, childhood abuse, and treatment response, but the sample size was small. Although the reviewed work provides many leads for future research, the methodological differences across studies and lack of replication preclude definitive conclusions about the existence of clinically useful and generalizable biological subtypes.

Cerebrospinal fluid monoamine metabolite concentrations in depressive disorder: A meta-analysis of historic evidence

Altered monoaminergic functions have been implicated in the pathophysiology of depressive disorder. However, previously reported cerebrospinal fluid (CSF) monoamine metabolite concentrations in major depression have been inconsistent. We performed a meta-analysis of historic evidence to determine whether CSF monoamine metabolite levels were different between patients with depression and normal controls, and could be used as depression biomarkers. Relevant studies that investigated CSF 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels in patients with depression and normal controls were identified in PubMed, Web of Science, PsycINFO, and Embase databases through September 5, 2017, using a synonymous search for depression, CSF, normal, control, and each monoamine metabolite name, and in the reference lists of the acquired articles. Obtained records were individually scrutinized for eligibility. Our search strategy identified 26 studies, including our own. We employed random effects modeling and adopted "Hedges's g" as an index of effect size. In the meta-analyses, no significant difference was observed in CSF 5-HIAA or MHPG levels between patients with depressive disorder and controls. In contrast, CSF HVA was significantly decreased in patients with depression (Hedges's g = -0.30, P = 0.0000025), and these results remained significant after patients with bipolar disorder were excluded (Hedges's g = -0.37, P = 0.000061). In the meta-regression, sex was significantly associated with the Hedges's g of CSF HVA (Q = 4.41, P = 0.036). This meta-analysis revealed that only CSF HVA, and not 5-HIAA or MHPG, levels were decreased in depressive disorder. The reduction in the CSF HVA concentration in patients with depression may guide future studies on depression and serve as a useful biomarker of depressive disorder.

No major influence of regular tobacco smoking on cerebrospinal fluid monoamine metabolite concentrations in patients with psychotic disorder and healthy individuals

Metabolism of the monoamines dopamine, serotonin and noradrenaline, is altered in the central nervous system of people with schizophrenia, and their major metabolites homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG), respectively, have been intensively studied as indirect measures of these neurotransmitters in cerebrospinal fluid (CSF). Regular tobacco smoking has been shown to alter neurotransmitter metabolism in the brain and studies have found CSF monoamine metabolite concentrations to be substantially lower in smokers. However, few studies investigating these monoamines in CSF have controlled for regular tobacco smoking. We investigated if regular tobacco smoking influences CSF HVA, 5-HIAA and MHPG concentrations in patients treated for psychotic disorders (n = 69) and healthy non-psychotic human volunteers (n = 200). After lumbar puncture CSF samples were analyzed with mass fragmentography. CSF HVA, 5-HIAA and MHPG concentrations did not significantly differ between smokers and non-smokers neither in patients, nor in healthy subjects, whereas back-length predicted HVA and 5-HIAA and antipsychotic medication MHPG concentrations. The results indicate that regular tobacco smoking has no significant effect on monoamine metabolite concentrations in CSF. This suggests that lack of controlling for regular tobacco smoking should not substantially violate the results in studies of the major monoamine metabolites in CSF.

Short overview on metabolomic approach and redox changes in psychiatric disorders

Schizophrenia, depression and posttraumatic stress disorder (PTSD) are severe mental disorders and complicated diagnostic entities, due to their phenotypic, biological and genetic heterogeneity, unknown etiology, and poorly understood alterations in biological pathways and biological mechanisms. Disturbed homeostasis between overproduction of oxidant species, overcoming redox regulation and a lack of cellular antioxidant defenses, resulting in free radical-mediated pathology and subsequent neurotoxicity contributes to development of depression, schizophrenia and PTSD, their heterogeneous clinical presentation and resistance to treatment. Metabolomics is a discipline that combines different strategies with the aim to extract, detect, identify and quantify all metabolites that are present in a biological sample and might provide mechanistic insights into the etiology of various psychiatric disorders. Therefore, oxidative stress research combined with metabolomics might offer a novel approach in dissecting psychiatric disorders, since these data-driven but not necessarily hypothesis-driven methods might identify new targets, molecules and pathways responsible for development of schizophrenia, depression or PTSD. Findings from the oxidative research in psychiatry together with metabolomics data might facilitate development of specific and validated prognostic, therapeutic and clinical biomarkers. These methods might reveal bio-signatures of individual patients, leading to individualized treatment approach. In reviewing findings related to oxidative stress and metabolomics in selected psychiatric disorders, we have highlighted how these novel approaches might make a unique contribution to deeper understanding of psychopathological alterations underlying schizophrenia, depression and PTSD.

Cerebrospinal fluid monoamine metabolite profiles in bipolar disorder, ADHD, and controls

Alterations in monoaminergic signaling are suggested as key aspects of the pathophysiology in bipolar disorder and ADHD, but it is not known if the monoamine metabolic profile differs between these disorders. One method to study monoaminergic systems in humans is to measure monoamine end-point metabolite concentrations in cerebrospinal fluid (CSF). Here, we analyzed CSF monoamine metabolite concentrations in 103 adults with bipolar disorder, 72 adults with ADHD, and 113 controls. Individuals with bipolar disorder had significantly higher homovanillic acid (HVA, 264 ± 112 nmol/L, p < 0.001) and 5-hydroxyindoleacetic acid (5-HIAA, 116 ± 42 nmol/L, p = 0.001) concentration, but lower 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG, 38 ± 8 nmol/L, p < 0.001) concentrations than controls (HVA, 206 ± 70 nmol/L; 5-HIAA, 98 ± 31 nmol/L; and MHPG, 42 ± 7 nmol/L). Higher HVA concentrations were associated with a history of psychosis in the bipolar disorder sample. Subjects with ADHD had higher HVA (240 ± 94 nmol/L, p < 0.001) concentrations compared with controls. In addition, SSRI treatment was associated with lower 5-HIAA concentrations in both patient groups. A power analysis indicated that for within-group comparisons, only large effects would be reliably detectable. Thus, there may be moderate-to-small effects caused by medication that were not detected due to the limited size of the sub-groups in these analyses. In conclusion, the present study suggests disorder-specific alterations of CSF monoamine metabolite concentrations in patients with bipolar disorder and ADHD compared with controls; these differences were independent of acute symptoms and medication effects.

Serotonin receptors in depression: from A to B

The role of serotonin in major depressive disorder (MDD) is the focus of accumulating clinical and preclinical research. The results of these studies reflect the complexity of serotonin signaling through many receptors, in a large number of brain regions, and throughout the lifespan. The role of the serotonin transporter in MDD has been highlighted in gene by environment association studies as well as its role as a critical player in the mechanism of the most effective antidepressant treatments – selective serotonin reuptake inhibitors. While the majority of the 15 known receptors for serotonin have been implicated in depression or depressive-like behavior, the serotonin 1A (5-HT _1A) and 1B (5-HT _1B) receptors are among the most studied. Human brain imaging and genetic studies point to the involvement of 5-HT _1A and 5-HT _1B receptors in MDD and the response to antidepressant treatment. In rodents, the availability of tissue-specific and inducible knockout mouse lines has made possible the identification of the involvement of 5-HT _1A and 5-HT _1B receptors throughout development and in a cell-type specific manner. This, and other preclinical pharmacology work, shows that autoreceptor and heteroreceptor populations of these receptors have divergent roles in modulating depression-related behavior as well as responses to antidepressants and also have different functions during early postnatal development compared to during adulthood.

Strategies for Advancing Disease Definition Using Biomarkers and Genetics: The Bipolar and Schizophrenia Network for Intermediate Phenotypes

It is critical for psychiatry as a field to develop approaches to define the molecular, cellular, and circuit basis of its brain diseases, especially for serious mental illnesses, and then to use these definitions to generate biologically based disease categories, as well as to explore disease mechanisms and illness etiologies. Our current reliance on phenomenology is inadequate to support exploration of molecular treatment targets and disease formulations, and the leap directly from phenomenology to disease biology has been limiting because of broad heterogeneity within conventional diagnoses. The questions addressed in this review are formulated around how we can use brain biomarkers to achieve disease categories that are biologically based. We have grouped together a series of vignettes as examples of early approaches, all using the Bipolar and Schizophrenia Network on Intermediate Phenotypes (BSNIP) biomarker database and collaborators, starting off with describing the foundational statistical methods for these goals. We use primarily criterion-free statistics to identify pertinent groups of involved genes related to psychosis as well as symptoms, and finally, to create new biologically based disease cohorts within the psychopathological dimension of psychosis. Although we do not put these results forward as final formulations, they represent a novel effort to rely minimally on phenomenology as a diagnostic tool and to fully embrace brain characteristics of structure, as well as molecular and cellular characteristics and function, to support disease definition in psychosis.

The 5-HT1A receptor in Major Depressive Disorder

Major Depressive Disorder (MDD) is a highly prevalent psychiatric diagnosis that is associated with a high degree of morbidity and mortality. This debilitating disorder is currently one of the leading causes of disability nationwide and is predicted to be the leading cause of disease burden by the year 2030. A large body of previous research has theorized that serotonergic dysfunction, specifically of the serotonin (5-HT) 1A receptor, plays a key role in the development of MDD. The purpose of this review is to describe the evolution of our current understanding of the serotonin 1A (5-HT1A) receptor and its role in the pathophysiology MDD through the discussion of animal, post-mortem, positron emission tomography (PET), pharmacologic and genetic studies.

Biochemical markers subtyping major depressive disorder

The pathophysiology of major depressive disorder (MDD) remains elusive, and there is no established biochemical marker used in the daily clinical setting. This situation may result in part from the heterogeneity of MDD, which might include heterogeneous subgroups with different biological mechanisms. In this review, we discuss three promising biological systems/markers to potentially subtype MDD: the dopamine system, the hypothalamic-pituitary-adrenal axis, and chronic inflammatory markers. Several lines of evidence suggest that a facet of MDD is a dopamine agonist-responsive subtype. Focusing on the hypothalamic-pituitary-adrenal axis, depressive spectrum disorders show hypercortisolism to hypocortisolism, which could be detected by hormonal challenge tests, such as the dexamethasone/corticotrophin-releasing hormone test. Finally, accumulating evidence suggests that at least some MDD patients show characteristics similar to those of chronic inflammatory diseases, including neuroinflammatory markers and reduced tryptophan due to the increased activation of the tryptophan-kynurenine pathway. Future studies should examine the inter-relations between these systems/markers to subtype and integrate the pathophysiology of MDD.

Biomarker approaches in major depressive disorder evaluated in the context of current hypotheses

Major depressive disorder is a heterogeneous disorder, mostly diagnosed on the basis of symptomatic criteria alone. It would be of great help when specific biomarkers for various subtypes and symptom clusters of depression become available to assist in diagnosis and subtyping of depression, and to enable monitoring and prognosis of treatment response. However, currently known biomarkers do not reach sufficient sensitivity and specificity, and often the relation to underlying pathophysiology is unclear. In this review, we evaluate various biomarker approaches in terms of scientific merit and clinical applicability. Finally, we discuss how combined biomarker approaches in both preclinical and clinical studies can help to make the connection between the clinical manifestations of depression and the underlying pathophysiology.

A Review of Biomarkers in Mood and Psychotic Disorders: A Dissection of Clinical vs. Preclinical Correlates

Despite significant research efforts aimed at understanding the neurobiological underpinnings of mood (depression, bipolar disorder) and psychotic disorders, the diagnosis and evaluation of treatment of these disorders are still based solely on relatively subjective assessment of symptoms as well as psychometric evaluations. Therefore, biological markers aimed at improving the current classification of psychotic and mood-related disorders, and that will enable patients to be stratified on a biological basis into more homogeneous clinically distinct subgroups, are urgently needed. The attainment of this goal can be facilitated by identifying biomarkers that accurately reflect pathophysiologic processes in these disorders. This review postulates that the field of psychotic and mood disorder research has advanced sufficiently to develop biochemical hypotheses of the etiopathology of the particular illness and to target the same for more effective disease modifying therapy. This implies that a "one-size fits all" paradigm in the treatment of psychotic and mood disorders is not a viable approach, but that a customized regime based on individual biological abnormalities would pave the way forward to more effective treatment. In reviewing the clinical and preclinical literature, this paper discusses the most highly regarded pathophysiologic processes in mood and psychotic disorders, thereby providing a scaffold for the selection of suitable biomarkers for future studies in this field, to develope biomarker panels, as well as to improve diagnosis and to customize treatment regimens for better therapeutic outcomes.

Catecholamine depletion in first-degree relatives of individuals with mood disorders: An [(18)F]fluorodeoxyglucose positron emission tomography study

Catecholamine depletion with alpha-methylparatyrosine (AMPT) has previously been shown to induce depressive symptoms in currently remitted patients with major depressive disorder (MDD) but not healthy controls. Thus sensitivity to catecholamine depletion has been hypothesized to be an endophenotype of MDD. Here we tested this hypothesis in the context of a randomized, double-blinded, placebo-controlled design by measuring changes in mood in a group of psychiatrically-healthy individuals at risk of mood disorders by virtue of family history (high-risk subjects, HRs). In addition, we tested whether HRs differed from healthy controls with no family-history of mood disorders (low-risk controls, LRs) in their cerebral metabolic response when undergoing catecholamine depletion. Eight healthy LRs (6 males, mean age = 34.1 ± 7.1) and 6 healthy HRs (3 males, mean age = 29.3 ± 4.6) participated in two, 3-day-long identical sessions during which they completed standardized measures of depression, anxiety and fatigue and an [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) scan. On one occasion participants received 4 weight-adjusted doses of AMPT and on the other occasion participants received 4 doses of placebo. The LR and HR groups did not differ from each other in their mood during sham depletion. However, during the period of peak catecholamine depletion, the HR group reported significantly more depression, anxiety and fatigue than the LR group. A region-of-interest analysis showed that during catecholamine depletion versus placebo the combined LR and HR groups displayed a significant increase in cerebral metabolic rate in the left and right ventral striata, left and right amygdalae, and left and right hippocampi (FWE-corrected p < 0.05). Whole brain voxel-wise analyses indicated significantly increased glucose metabolism in the left and right putamina (FWE-corrected p < 0.05) in the combined LR and HR groups in the AMPT versus the placebo session. In the LR group, alone, no significant elevation in glucose metabolism was observed in the regions-of-interest in the catecholamine depletion versus placebo condition. In the HR group, alone, the region-of-interest analysis showed a significant increase in cerebral metabolic rate in the left and right ventral striata (FWE-corrected p < 0.05). No regions-of-interest showed significantly different metabolism in the HR group versus the LR group in the placebo condition, however compared with the LR group, the HR group displayed nominally increased glucose metabolism in the left amygdala during catecholamine depletion (SVC-corrected p = 0.05). A region-of-interest analysis for the interaction contrast confirmed that catecholamine depletion had differential effects on HR and LR participants. Compared with the LR group, the HR group displayed significantly increased glucose metabolism in the left ventral striatum, left amygdala, and left lateral orbitofrontal cortex (OFC) (FWE-corrected p < 0.05). Our results suggest that sensitivity to catecholamine depletion may be a phenotypic marker of vulnerability to mood disorders that is characterized at the neurophysiological level by disinhibition of the striatum and its efferent projections comprising the limbic–cortical–striatal–pallidal–thalamic circuitry.

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High-risk subjects were more depressed and fatigued during catecholamine depletion.

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During depletion HR subjects > metabolism in the left striatum, amygdala, and OFC

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Sensitivity to catecholamine depletion may be an endophenotype of depression.

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.

The association of bipolar spectrum disorders and borderline personality disorder

Bipolar disorder (BD) and borderline personality disorder (BPD) are two different entities sharing a variety of common features in a number of fields and, thus, presenting difficulties in their differential diagnosis. The aim of the review is to identify similarities and differences between BD and BPD concerning the symptomatology, causes, course and treatment of the two disorders. A systematic electronic search of Pubmed (Medline) was conducted in order to identify all relevant scientific articles published between 1990 and 2010. The main common clinical features of BD and BPD are affective instability and impulsivity, which, however, present with quality differences in each disorder. In the field of neuroanatomy, BD and BPD demonstrate similarities such as alterations in the limbic system, as well as specific differences, such as the increase in size of the amygdala in BD and the decrease in BPD. Both disorders appear to have a significant percentage of heritability, but environmental factors seem to hold an important role in BPD, in particular. Both BD and BPD are affected by alterations in the dopaminergic and serotonergic system. Fuctionability and prognosis are slightly worse for BPD. Concerning medication treatment, antidepressants are considered effective in BPD, whereas mood stabilizers are the main treatment of choice in BD. The effectiveness of a variety of psychotherapeutic methods is still under research for both disorders. Despite the similarities and differences already being traced in clinical and biological fields, the relationship of the two disorders has not yet been thoroughly defined.

Cerebrospinal fluid metabolome in mood disorders-remission state has a unique metabolic profile

Targeted metabolomics provides an approach to quantify metabolites involved in specific molecular pathways. We applied an electrochemistry-based, targeted metabolomics platform to define changes in tryptophan, tyrosine, purine and related pathways in the depressed and remitted phases of major depressive disorder (MDD). Biochemical profiles in the cerebrospinal fluid of unmedicated depressed (n = 14; dMDD) or remitted MDD subjects (n = 14; rMDD) were compared against those in healthy controls (n = 18; HC). The rMDD group showed differences in tryptophan and tyrosine metabolism relative to the other groups. The rMDD group also had higher methionine levels and larger methionine-to-glutathione ratios than the other groups, implicating methylation and oxidative stress pathways. The dMDD sample showed nonsignificant differences in the same direction in several of the metabolic branches assessed. The reductions in metabolites associated with tryptophan and tyrosine pathways in rMDD may relate to the vulnerability this population shows for developing depressive symptoms under tryptophan or catecholamine depletion.

Serotonergic dysfunction in patients with bipolar disorder assessed by the loudness dependence of the auditory evoked potential

OBJECTIVE

The loudness dependence of the auditory evoked potential (LDAEP) is suggested to be a marker of serotonin system function. This study explored the LDAEP of multiple mood statuses (depression, mania, and euthymia) and its clinical implication in bipolar disorder patients.

METHODS

A total of 89 subjects, comprising 35 patients with bipolar disorder, 32 patients with schizophrenia, and 22 healthy controls were evaluated. The bipolar disorder cases comprised 10 depressed patients, 15 patients with mania, and 10 euthymic patients. The N1/P2 peak-to-peak amplitudes were measured at 5 stimulus intensities, and the LDAEP was calculated as the slope of the linear regression. Both cortical and source LDAEP values were calculated.

RESULTS

LDAEP varied according to mood statuses, and was significantly stronger in cases of euthymia, depression, and mania. Cortical LDAEP was significantly stronger in patients with bipolar euthymia compared with schizophrenia, stronger in bipolar depression than in schizophrenia, stronger in healthy controls than in schizophrenia patients, and stronger in healthy controls than in patients with bipolar mania. Source LDAEP was significantly stronger in patients with bipolar euthymia, bipolar depression, and bipolar mania compared with schizophrenia, stronger in bipolar euthymia than in bipolar mania. Psychotic features weakened the source LDAEP relative to nonpsychotic features. The severity of the depressive symptom was negatively correlated with source LDAEP.

CONCLUSION

These findings suggest that the serotonin activity of patients with bipolar disorder may vary according to mood status. A longitudinal follow-up study should be pursued using drug-naive subjects.

Association of saliva 3-methoxy-4-hydroxyphenylglycol levels and a later depressive state in older subjects living in a rural community: 3-year follow-up study

OBJECTIVE

The aim of the study was to examine the association of saliva levels of 3-methoxy-4-hydroxyphenylglycol (sMHPG) with a later depressive state in older people living in a rural community.

METHODS

Baseline sMHPG levels were measured in 214 older subjects followed by completion of the Beck Depression Inventory (BDI) from 2004 to 2006 (time A). The same cohort underwent BDI again from 2007 to 2009 (time B).

RESULTS

One hundred forty-four subjects (44 men, 100 women) were reassessed by the BDI. Baseline sMHPG levels in men with a BDI score of ≤9 at time A and a BDI score of ≥10 at time B were significantly higher than those in men with a BDI score of ≤9 at times A and B. In men, there was a significant correlation between baseline sMHPG levels and BDI score at time B (r = 0.40, p = 0.007) but not at time A (r = 0.29, p = 0.06). This association was not significant in women.

CONCLUSION

These data indicate that high sMHPG levels at time A could be associated with a later depressive state in older men living in a community.

Selectively bred rodents as models of depression and anxiety

Stress related diseases such as depression and anxiety have a high degree of co morbidity, and represent one of the greatest therapeutic challenges for the twenty-first century. The present chapter will summarize existing rodent models for research in psychiatry, mimicking depression- and anxiety-related diseases. In particular we will highlight the use of selective breeding of rodents for extremes in stress-related behavior. We will summarize major behavioral, neuroendocrine and neuronal parameters, and pharmacological interventions, assessed in great detail in two rat model systems: The Flinders Sensitive and Flinders Resistant Line rats (FSL/FRL model), and rats selectively bred for high (HAB) or low (LAB) anxiety related behavior (HAB/LAB model). Selectively bred rodents also provide an excellent tool in order to study gene and environment interactions. Although it is generally accepted that genes and environmental factors determine the etiology of mental disorders, precise information is limited: How rigid is the genetic disposition? How do genetic, prenatal and postnatal influences interact to shape adult disease? Does the genetic predisposition determine the vulnerability to prenatal and postnatal or adult stressors? In combination with modern neurobiological methods, these models are important to elucidate the etiology and pathophysiology of anxiety and affective disorders, and to assist in the development of new treatment paradigms.

Tryptophan transport in human fibroblast cells-a functional characterization

There are indications that serotonergic neurotransmission is disturbed in several psychiatric disorders. One explanation may be disturbed transport of tryptophan (precursor for serotonin synthesis) across cell membranes. Human fibroblast cells offer an advantageous model to study the transport of amino acids across cell membranes, since they are easy to propagate and the environmental factors can be controlled. The aim of this study was to functionally characterize tryptophan transport and to identify the main transporters of tryptophan in fibroblast cell lines from healthy controls.

Tryptophan kinetic parameters (V_max and K_m) at low and high concentrations were measured in fibroblasts using the cluster tray method. Uptake of ³H (5)-L-tryptophan at different concentrations in the presence and absence of excess concentrations of inhibitors or combinations of inhibitors of amino acid transporters were also measured. Tryptophan transport at high concentration (0.5 mM) had low affinity and high V_max and the LAT1 isoform of system-L was responsible for approximately 40% of the total uptake of tryptophan. In comparison, tryptophan transport at low concentration (50 nM) had higher affinity, lower V_max and approximately 80% of tryptophan uptake was transported by system-L with LAT1 as the major isoform. The uptake of tryptophan at the low concentration was mainly sodium (Na⁺) dependent, while uptake at high substrate concentration was mainly Na⁺ independent. A series of different transporter inhibitors had varying inhibitory effects on tryptophan uptake.

This study indicates that tryptophan is transported by multiple transporters that are active at different substrate concentrations in human fibroblast cells. The tryptophan transport trough system-L was mainly facilitated by the LAT1 isoform, at both low and high substrate concentrations of tryptophan.

What can post-mortem studies tell us about the pathoetiology of suicide?

Suicide is a major public health concern; however, its neurobiology is unclear. Post-mortem brain tissue obtained from suicide victims and normal controls offers a useful method for studying the neurobiology of suicide. Despite several limitations, these studies have offered important leads in the neurobiology of suicide. In this article, we discuss some important findings resulting from these studies, focusing on serotonergic mechanisms, signal transduction systems, neuroendocrine studies and immune function abnormalities in suicide. These studies suggest that abnormalities of certain receptor subtypes, components of signaling systems such as protein kinase C and protein kinase A, transcription factors such as cyclic AMP response element-binding protein and neurotrophins may play an important role in the pathophysiology of suicide. These studies also suggest abnormalities of hypothalamic-pituitary-adrenal axis system components, feedback mechanisms and cytokines, which are chemical mediators of the immune functions. Post-mortem brain tissue offers an opportunity for future studies, such as genetic and epigenetic studies.

Aberrant amino acid transport in fibroblasts from patients with bipolar disorder

Aberrant tyrosine transport is a repeated finding in fibroblasts from schizophrenic patients. The transport aberration could lead to disturbances in the dopaminergic and noradrenergic neurotransmitter systems. Tyrosine and tryptophan are the precursors of the neurotransmitters dopamine and serotonin. Disturbed dopaminergic, noradrenergic and serotoninergic systems are implicated as causes of bipolar disorder. Hence, the aim of this study was to explore whether patients with bipolar disorder have an aberrant transport of tyrosine and/or tryptophan. Fibroblast cell lines from patients with bipolar type-1 disorder (n=10) and healthy controls (n=10) were included in this study. All patients fulfilled the DSM-IV diagnostic criteria. The transport of amino acids across the cell membranes was measured by the cluster tray method. The kinetic parameters, maximal transport velocity (V(max)) and affinity constant (K(m)) were determined. A significantly lower V(max) for tyrosine (p=0.027) was found in patients with bipolar type-1 disorder in comparison to healthy controls. No significant differences in K(m) for tyrosine and in the kinetic parameters of tryptophan between patients with bipolar type-1 disorder and healthy controls were observed. The decreased tyrosine transport (low V(max)) found in this study may indicate less access of dopamine in the brain, resulting in disturbed dopaminergic and/or noradrenergic neurotransmission, that secondarily could lead to disturbances in other central neurotransmitter systems, such as the serotoninergic system. However, as sample size was small in this study and an age difference between patients and controls existed, the present findings should be considered as pilot data. Further studies with larger sample number are needed to elucidate the transport aberration and the significance of these findings.

Anxiety is associated with reduced central serotonin transporter availability in unmedicated patients with unipolar major depression: a [11C]DASB PET study

Serotonergic dysfunction may contribute to negative mood states in affective disorders. Some in vivo imaging studies showed reduced availability of serotonin transporters (5-HTT) in the brainstem and thalamus of patients with major depression. We tested the hypothesis that 5-HTT availability is reduced in unmedicated unipolar patients with major depression compared to healthy control subjects matched for gender, age, genotype and smoking status. Availability of 5-HTT was measured in vivo with positron emission tomography and [(11)C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile (DASB) in the midbrain, thalamus and amygdala. DASB binding was correlated with the severity of depression (Beck's Depression Inventory), anxiety (Spielberger's State-Trait Anxiety Inventory) and personality traits (Temperament and Character Inventory). Patients with major depression displayed reduced 5-HTT availability in the thalamus (P=0.005). In patients, low serotonin transporter availability correlated with high anxiety (thalamus: r=-0.78, P=0.004; midbrain: r=-0.78, P=0.004; amygdala: r=-0.80, P=0.003). Correlations with severity of depression were weaker and did not survive correction for multiple testing. These results support the hypothesis that central serotonergic dysfunction is associated with negative mood states in affective disorders. In the thalamus, a low serotonin reuptake capacity may interfere with thalamic control of cortical excitability and contribute to anxiety rather than depression per se in major depression.

Dehydroepiandrosterone and monoamines in the limbic system of a genetic animal model of childhood depression

Monoamines and dehydroepiandrosterone (DHEA) levels were measured in a genetic animal model for childhood depression in four subcortical structures: nucleus accumbens (Nac), ventral tegmental area (VTA), amygdala and hypothalamus. The "depressive-like" strain was the Flinders Sensitive Line (FSL), compared to their controls, Sprague-Dawley (SD) rats. Prepubertal FSL rats showed abnormal levels of only a few monoamines and their metabolites in these brain regions. This is in contrast to former studies, in which adult FSL rats exhibited significantly higher levels of all the monoamines and their metabolites measured. These different abnormal monoamine patterns between the "depressed" prepubertal rats and their adults, may help to explain why depressed children and adolescents fail to respond to antidepressant treatment as well as adults do. On the other hand, FSL prepubertal rats exhibited the same pattern of abnormal DHEA basal levels as was found in adults in previous experiments. The results from the current study may imply that treatment with DHEA could be a promising novel therapeutic option for depressed children and adolescents that fail to respond to common (monoaminergic) antidepressant treatments.

Major depression as a disorder of serotonin resistance: inference from diabetes mellitus type II

The multifactorial nature of depression resembles that of other complex disorders such as diabetes mellitus or coronary artery disease. However, while for the latter disorders predisposing and risk factors have been identified, such knowledge is still scarce in depression. In this review we propose to use diabetes mellitus, for which characteristic milestones have been condensed to obesity-hyperinsulinaemia-insulin resistance-diabetes mellitus, as a conceptual analogical model. Based on this model we hypothesize that depression develops according to a similar pattern: prolonged psychological stress-hyperserotonism-serotonin resistance-major depression. We review extensive supporting evidence from human studies and animal models of depression, including stress involvement in the aetiology of depression, evidence for increased synaptic serotonin and decreased 5-HT1A receptor activity. Conceptualizing the pathogenesis of depression as a multi-step process may inspire new concepts, which will eventually lead to delineation of additional preventive and therapeutic interventions similar to those currently practised in diabetes.

Monoamine metabolites level in CSF is related to the 5-HTT gene polymorphism in treatment-resistant depression

The serotonin (5-hydroxytryptamine) transporter (5-HTT) is considered to affect the pathogenesis of mood disorders. Large number of genetic association studies between 5-HTT functional polymorphisms and vulnerability of mood disorders and therapeutic response to antidepressants has been carried out. We investigated the influence of 5-HTT-linked polymorphic region (5-HTTLPR) and 5-HTT 17 bp variable number of tandem repeat polymorphism (5-HTTVNTR) polymorphisms on concentrations of monoamine metabolites in cerebrospinal fluid (CSF) among treatment-resistant patients with mood disorders. Subjects were 119 Swedish patients with persistent mood disorders and 141 healthy subjects. In 112 of these patients, we measured 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol in CSF. Genotyping for 5-HTT polymorphisms from genomic DNA was carried out by PCR. There was no significant difference in allele/genotype frequency between patients and healthy subjects. In patients with mood disorders, we found significant difference in mean 5-HIAA concentration between 5-HTTLPR genotypes (p=0.03). Although the 5-HIAA concentration showed a tendency to be higher in short (S) carriers than in non-S carriers of the 5-HTTLPR in patients (p=0.06), when considering patients with major depressive disorder (MDD), the 5-HIAA concentration was significantly higher among S carriers than among non-S carriers (p=0.02). Moreover, the 5-HIAA concentration was higher in S/S subjects compared to long (L)/L (p=0.0001) and L/S (p=0.002) subjects in patients with MDD. Similarly, there was higher HVA concentration in S/S subjects compared to L/L (p=0.002) and L/S subjects (p=0.002). There was no effect of 5-HTTVNTR. Our findings show that the 5-HTTLPR polymorphism affects 5-HIAA and HVA concentrations among treatment-resistant patients with mood disorders.

Biochemical effects of antidepressant treatment--studies of monoamine metabolites in cerebrospinal fluid and platelet [3H]imipramine binding

Two putative markers of serotonergic function, the concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and the binding parameters of [3H]imipramine to blood platelets, are discussed. Pretreatment concentrations of 5-HIAA in the cerebrospinal fluid (CSF) are lower in depressed patients than in normal controls, and a low concentration of the metabolite is associated with an increased risk of suicide. Many studies have attempted to use pretreatment concentrations of 5-HIAA, of the noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) and of the dopamine metabolite homovanillic acid (HVA) as predictors of therapeutic effect. On the whole, HVA appears to predict the effects of diverse treatments rather better than 5-HIAA. Treatment with antidepressant drugs changes the amine metabolite concentrations in the CSF in a relatively predictable way. Thus, administration of selective inhibitors of serotonin uptake has a more profound effect on CSF 5-HIAA, while noradrenaline uptake inhibitors preferentially reduce CSF MHPG concentrations. The Bmax of [3H]imipramine binding to blood platelets has been found to be lower in untreated depressed patients than in healthy controls in several studies. In a study from our group, three weeks' treatment with the serotonin uptake blockers zimeldine and alaproclate increased Bmax, while neither nortriptyline nor electroconvulsive treatment caused any change in Bmax after this time period. One year after initiation of treatment, patients who had clinically recovered and were no longer taking drugs still had a low Bmax of [3H]imipramine platelet binding. Prophylactic lithium caused a significant, but transient decrease in the Bmax of platelet [3H]imipramine binding in euthymic bipolar patients.

Do concentrations of neurotransmitters in lumbar CSF reflect cerebral dysfunction in depression?

Concentrations of the amines and amine metabolites dopamine (DA), noradrenaline (NA), adrenaline (A), serotonin (5-HT), homovanillic acid (HVA), 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA) and of the peptides, vasopressin (AVP), vasoactive intestinal polypeptide (VIP), thyrotropin releasing hormone (TRH) and cholecystokinin (CCK) were measured in lumbar cerebrospinal fluid (CSF) in patients with depression and compared with that of controls. Diagnostic classifications were performed according to ICD-9 and the Newcastle Rating Scales for Depression. The severity of depression was measured by Bech-Rafaelsen melancholia scale. Significantly decreased concentrations of CSF-A and AVP were found in as well endogenous as in non-endogenous depression, whereas reduced levels of CSF-VIP were found only in the non-endogenous group. CSF-5-HT and DA were significantly increased in endogenously depressed patients. In these studies patients with non-endogenous depression were not included. No relationship between severity of depression and concentrations of neurotransmitters was found. For most of the neurotransmitters no correlation between concentrations measured at the lumbar and at the ventricular level seems to exist. This finding indicates that measurements on CSF collected from the lumbar sack not necessarily are indicative for concentrations measured at more central levels. Although several transmitter systems most likely are disturbed in depression, results from studies on lumbar CSF should be interpreted with precaution, until further information about origin and distribution of neurotransmitters in CSF has been obtained.

Links between depression and substance abuse in adolescents: neurobiological mechanisms

Adolescence is a high-risk period for development of both depressive and substance use disorders. These two disorders frequently co-occur in adolescents and are associated with significant morbidity and mortality. Given the added economic and psychosocial burden associated with the comorbid condition, identification of risk factors associated with their co-occurrence is of great public health importance. Research with adult animals and humans has indicated several common neurobiological systems that link depressive and addictive disorders. Given the ongoing maturation of these systems throughout adolescence and early adult life, it is not clear how these neurobiological processes influence development and progression of both disorders. A better understanding of the pathophysiological mechanisms leading to the onset and course of these disorders during adolescence will be helpful in developing more effective preventive and treatment strategies, and thereby allow these youth to reach their full potential as adults.

Lower cerebrospinal fluid homovanillic acid levels in depressed suicide attempters

BACKGROUND

Studies suggest that the dopaminergic system is involved in the pathogenesis of major depression, Axis II disorders, and suicidal behavior. Depressed suicide attempters constitute a heterogenous group and important differences may exist between depressed suicide attempters with or without Axis II disorders. Therefore, we compared demographic and clinical parameters, and cerebrospinal fluid (CSF) homovanillic acid (HVA) levels in depressed suicide attempters without comorbid Axis II disorders, depressed non-attempters without comorbid Axis II disorders, and normal controls.

METHODS

Thirty-one depressed subjects with a history of a suicide attempt, 27 depressed subjects without a history of a suicide attempt, and 50 healthy controls were included in the study. Subjects with comorbid Axis II disorders were excluded. Demographic and clinical parameters, and CSF HVA levels were examined.

RESULTS

The two depressed groups did not differ with regard to depression, aggression, hopelessness, and total hostility scale scores. Depressed suicide attempters had higher current suicidal ideation scores compared to depressed non-attempters. Depressed suicide attempters had lower CSF HVA levels compared to depressed non-attempters (t = 4.4, df = 56, p < 0.0001) and to controls (t = -4.09, df = 79, p < 0.0001). There was no difference in CSF HVA levels between depressed non-attempters and controls (t < 1, df = 75, NS).

CONCLUSIONS

Dopaminergic abnormalities are associated with suicidality but not with depression. The variability in the rates of comorbid Axis II disorders and in the prevalence of suicide attempters in different patient populations may affect both clinical and biological results of studies of mood disorders.

CSF 5-HIAA and the rorschach test in patients who have attempted suicide

Two independent measures, 5-HIAA and the Rorschach Suicide Constellation (S-CON), both related to suicide, were studied in an attempt to explore any relationship between the two. Lumbar puncture and the Rorschach were performed in standardized manner on 38 consecutive psychiatric inpatients, who had made a recent suicide attempt. Low CSF 5-HIAA was significantly related to the S-CON (rs = -.517, p = .033) and the Vista variable in the S-CON appeared to play an important role for the correlation. The results indicate that suicide attempters with low CSF 5-HIAA in this sample tended to experience more discomfort and pain during self-inspection. These results raise questions whether shame may be involved in the psychobiology of suicide.

Major affective disorders and schizophrenia: a common molecular signature?

Psychiatric disorders, including affective disorders (AD) and schizophrenia (SZ) are among the most common disabling brain diseases in Western populations and result in high costs in terms of morbidity as well as mortality. Although their etiology and pathophysiology is largely unknown, family-, twin-, and adoption studies argue for a strong genetic determination of these disorders. These studies indicate that there is between 40 and 85% heritability for these disorders but point also to the importance of environmental factors. Therefore, any research strategy aiming at the identification of genes involved in the development of AD and SZ should account for the complex nature (multifactorial) of these disorders. During the last decade, molecular genetic studies have contributed a great deal to the identification of genetic factors involved in complex disorders. Here we provide a comprehensive review of the most promising genes for AD and SZ, and the methods and approaches that were used for their identification. Also, we discuss the current knowledge and hypotheses that have been formulated regarding the effect of variations on protein functioning as well as recent observations that point to common molecular mechanisms.

Sustained pharmacological blockade of NK1 substance P receptors causes functional desensitization of dorsal raphe 5-HT 1A autoreceptors in mice

Antagonists at NK1 substance P receptors have demonstrated similar antidepressant properties in both animal paradigms and in human as selective serotonin reuptake inhibitors (SSRIs) that induce desensitization of 5-HT 1A autoreceptors within the dorsal raphe nucleus (DRN). We investigated whether this receptor adaptation also occurs upon NK1 receptor blockade. C57B/L6J mice were treated for 21 days with the selective NK1 receptor antagonist GR 205171 (10 mg/kg daily) through subcutaneously implanted osmotic mini pumps, and DRN 5-HT 1A autoreceptor functioning was assessed using various approaches. Recording of DRN serotonergic neurons in brainstem slices showed that GR 205171 treatment reduced (by approximately 1.5 fold) the potency of the 5-HT 1A receptor agonist, ipsapirone, to inhibit cell firing. In parallel, the 5-HT 1A autoreceptor-mediated [35S]GTP-gamma-S binding induced by 5-carboxamidotryptamine onto the DRN in brainstem sections was significantly decreased in GR 205171-treated mice. In vivo microdialysis showed that the cortical 5-HT overflow caused by acute injection of the SSRI paroxetine (1 mg/kg) was twice as high in GR 205171-treated as in vehicle-treated controls. In the DRN, basal 5-HT outflow was significantly enhanced by GR 205171 treatment. These data supported the hypothesis that chronic NK1 receptor blockade induces a functional desensitization of 5-HT 1A autoreceptors similar to that observed with SSRIs.

Distinctions between bipolar and unipolar depression

This is a review of the studies comparing unipolar and bipolar depression, with focus on the course, symptomatology, neurobiology, and psychosocial literatures. These are reviewed with one question in mind: does the evidence support diagnosing bipolar and unipolar depressions as the same disorder or different? The current nomenclature of bipolar and unipolar disorders has resulted in research that compares these disorders as a whole, without considering depression separately from mania within bipolar disorder. Future research should investigate two broad categories of depression and mania as separate disease processes that are highly comorbid.

The Flinders Sensitive Line rat: a selectively bred putative animal model of depression

The Flinders Sensitive Line (FSL) rats were originally selectively bred for increased responses to an anticholinesterase agent. The FSL rat partially resembles depressed individuals because it exhibits reduced appetite and psychomotor function but exhibits normal hedonic responses and cognitive function. The FSL rat also exhibits sleep and immune abnormalities that are observed in depressed individuals. Neurochemical and/or pharmacological evidence suggests that the FSL rat exhibits changes consistent with the cholinergic, serotonergic, dopaminergic, NPY, and circadian rhythm models but not the noradrenergic, HPA axis or GABAergic models of depression. However, evidence for the genetic basis of these changes is lacking and it remains to be determined which, if any, of the neurochemical changes are primary to the behavioral alterations. The FSL rat model has been very useful as a screen for antidepressants because known antidepressants reduced swim test immobility when given chronically and psychomotor stimulants did not. Furthermore, rolipram and a melatonin agonist were shown to have anti-immobility effects in the FSL rats and later to have antidepressant effects in humans. Thus, the FSL rat model of depression exhibits some behavioral, neurochemical, and pharmacological features that have been reported in depressed individuals and has been very effective in detecting antidepressants.

More tryptophan hydroxylase in the brainstem dorsal raphe nucleus in depressed suicides

Deficient serotonin neurotransmission in suicide is indicated by reduced brainstem serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), fewer 5-HT(1A) autoreceptors and reduced cortical serotonin transporter binding in suicide victims. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of 5-HT, and alterations in TPH could explain some of these findings. We sought to determine the amount of TPH immunoreactivity (TPH-IR) in the dorsal (DRN) and median (MRN) raphe nuclei in suicides and controls. Brainstems of suicide victims and controls (n = 11 pairs) were collected at autopsy, matched for age, sex and postmortem interval, frozen and sectioned (20 microm). Immunoautoradiography, using an antibody to label TPH, was performed, slides exposed to film and autoradiograms quantified by a computer-based image analysis system. We examined sections every 1000 microm throughout the whole length of the nucleus, performing statistical analysis only on those subjects for whom the raphe was complete (n = 8 pairs). TPH-IR (microCi/g) was higher in suicides than controls (S: 300.8 +/- 70.8 vs. C: 259.6 +/- 40.7, t = 2.57, df = 7, P = 0.04) in the dorsal raphe nucleus (DRN), and not different between suicides and controls (S: 251.3 +/- 44.2 vs. C: 235.9 +/- 27.4, t = 1.49, df = 7, P = 0.18) in the MRN. DRN TPH-IR was higher in male suicide victims (MS) compared to male controls (MC; MS: 318.4 +/- 54.4 vs. MC: 271.9 +/- 22.5, t = 2.66, df = 6, P = 0.03). The analysis of TPH-IR area and density at each DRN rostrocaudal levels showed higher area and density in suicides compared to controls in the rostral DRN and lower area and density in the caudal DRN. TPH-IR, an index of the amount of TPH enzyme, in the DRN is higher in depressed suicides. More TPH may be an upregulatory homeostatic response to impaired serotonin release or less autoreceptor activation. Alternatively, the serotonin impairment in suicide may be due to hypofunctional serotonin-synthesizing enzyme.

A controlled, prospective study of neuropsychological outcomes post parathyroidectomy in primary hyperparathyroid patients

BACKGROUND

There is an increasing number of primary hyperparathyroidism (PHPT) patients with neuropsychological or psychiatric symptoms. Many of these patients do not have osseous or renal complications to satisfy the criteria for parathyroidectomy according to the NIH guidelines.

OBJECTIVE

To assess whether there is any improvement in neuropsychological and mood symptoms following parathyroidectomy.

PATIENTS AND DESIGN

Twenty PHPT patients undergoing parathyroidectomy and 20 orthopaedic controls matched for age, gender and estimated intelligence were subjects to pre and postoperative assessment of cognition and mood with a mean surgery-retest interval of 3 months.

RESULTS

Using two tests of attentional flexibility [the Stroop test, the Digit symbol test of the Wechsler Adult Intelligence Scale-Revised (WAIS-R)], and two memory tests for prose and nonverbal material, no significant change was found between the groups when comparing scores before and after surgery. There was no improvement between pre and postoperative measures of verbal (dominant hemisphere) as opposed to visuo-spatial (nondominant hemisphere) function when compared to controls. There was no relationship between the reduction in serum calcium and the change in the neuropsychological measures postoperatively.

CONCLUSION

This controlled, prospective study demonstrates no significant improvement in neuropsychological indices using objective, validated psychometric tools in an unselected cohort of PHPT patients. No relationship was found between serum calcium level and the degree of neuropsychological deficit. More studies are needed to assess whether the effect of parathyroidectomy is beneficial and sustainable in PHPT patients with neuropsychological symptoms alone.