Arginine vasopressin is associated with hypercortisolemia and suicide attempts in depression

Molecular Changes Associated with Suicide

Suicide is a serious global public health problem, with a worrying recent increase in suicide rates in both adolescent and adult populations. However, it is essential to recognize that suicide is preventable. A myriad of factors contributes to an individual's vulnerability to suicide. These factors include various potential causes, from psychiatric disorders to genetic and epigenetic alterations. These changes can induce dysfunctions in crucial systems such as the serotonergic, cannabinoid, and hypothalamic-pituitary-adrenal axes. In addition, early life experiences of abuse can profoundly impact an individual's ability to cope with stress, ultimately leading to changes in the inflammatory system, which is a significant risk factor for suicidal behavior. Thus, it is clear that suicidal behavior may result from a confluence of multiple factors. This review examines the primary risk factors associated with suicidal behavior, including psychiatric disorders, early life adversities, and epigenetic modifications. Our goal is to elucidate the molecular changes at the genetic, epigenetic, and molecular levels in the brains of individuals who have taken their own lives and in the plasma and peripheral mononuclear cells of suicide attempters and how these changes may serve as predisposing factors for suicidal tendencies.

Targeting the Arginine Vasopressin V1b Receptor System and Stress Response in Depression and Other Neuropsychiatric Disorders

A healthy stress response is critical for good mental and overall health and promotes neuronal growth and adaptation, but the intricately balanced biological mechanisms that facilitate a stress response can also result in predisposition to disease when that equilibrium is disrupted. The hypothalamic-pituitary-adrenal (HPA) axis neuroendocrine system plays a critical role in the body's response and adaptation to stress, and vasopressinergic regulation of the HPA axis is critical to maintaining system responsiveness during chronic stress. However, exposure to repeated or excessive physical or emotional stress or trauma can shift the body's stress response equilibrium to a "new normal" underpinned by enduring changes in HPA axis function. Exposure to early life stress due to adverse childhood experiences can also lead to lasting neurobiological changes, including in HPA axis function. HPA axis impairment in patients with depression is considered among the most reliable findings in biological psychiatry, and chronic stress has been shown to play a major role in the pathogenesis and onset of depression and other neuropsychiatric disorders. Modulating HPA axis activity, for example via targeted antagonism of the vasopressin V_1b receptor, is a promising approach for patients with depression and other neuropsychiatric disorders associated with HPA axis impairment. Despite favorable preclinical indications in animal models, demonstration of clinical efficacy for the treatment of depressive disorders by targeting HPA axis dysfunction has been challenging, possibly due to the heterogeneity and syndromal nature of depressive disorders. Measures of HPA axis function, such as elevated cortisol levels, may be useful biomarkers for identifying patients who may benefit from treatments that modulate HPA axis activity. Utilizing clinical biomarkers to identify subsets of patients with impaired HPA axis function who may benefit is a promising next step in fine-tuning HPA axis activity via targeted antagonism of the V_1b receptor.

Blood hormones and suicidal behaviour: A systematic review and meta-analysis

This study was to evaluate the relationship between blood hormone levels and suicidal behaviour. We reviewed Web of Science, PubMed and Embase for literature published up to 10 April 2022. Studies were restricted to English-language articles. Studies measuring blood hormone levels in suicidal and non-suicidal subjects were eligible. Standardized mean differences (SMDs) were applied to evaluate group differences. Overall, 57 studies were eligible, of which 51 evaluated suicide attempts, and 9 assessed suicidal ideation. Random-effects meta-analysis indicated that levels of thyrotropin stimulating hormone (TSH) (SMD = 0.50; 95% CI, 0.27-0.72), leptin (SMD = -1.16; 95% CI, -1.94 to -0.38) and dehydroepiandrosterone sulfate (DHEAS) (SMD = -0.67; 95% CI, -1.13 to -0.21) were related to suicide attempts, whereas progesterone levels (SMD = 0.22; 95% CI, 0.03-0.41) were related to suicidal ideation. This analysis offers evidence linking abnormalities of blood hormones with suicidal behaviour, which may be essential for identifying individuals with suicide attempts and suicidal ideation. Large prospective studies are needed for further clarification of roles of hormones in suicidal behaviour.

Increased Levels of Cortisol in Individuals With Suicide Attempt and Its Relation With the Number of Suicide Attempts and Depression

BACKGROUND

Abnormalities in the hypothalamic-pituitary-adrenal axis (HPA) have been reported in individuals with suicide behavior. The aim of the study was to evaluate cortisol levels in peripheral plasma of individuals with more than one suicide attempt.

METHODS

Cortisol concentrations in peripheral plasma were measured using the ELISA technique. Suicide attempts were evaluated by the Columbia Suicide Severity Rating Scale, while depression was evaluated by the Hamilton Depression Rating Scale.

RESULTS

We found elevated cortisol levels in the suicide attempt group when compared with healthy controls (F = 7.26, p-value = 0.008), but no statistical differences with the psychiatric diseases group (F = 1.49, p-value = 0.22). Cortisol levels were higher in individuals with depression (F = 8.99, P = 0.004) and in individuals with two or more suicide attempts (F = 13.56, P < 0.001).

CONCLUSIONS

Cortisol levels are increased in individuals who attempt suicide and higher of cortisol concentrations in plasma regard to depression and more attempts of suicide.

Imaging pituitary vasopressin 1B receptor in humans with the novel PET radiotracer 11C-TASP699

Arginine vasopressin (AVP) is a hormone that is mainly synthesized in the hypothalamus and stored in the posterior pituitary. Receptors for vasopressin are categorized into at least three subtypes (V_1A, V_1B, V₂). Among these subtypes, the V_1B receptor (V_1BR), highly expressed in the pituitary, is a primary regulator of the hypothalamic-pituitary-adrenal axis activity, and thus a potential target for the treatment of neuropsychiatric disorders, such as depression and anxiety. ¹¹C-TASP699 is a novel PET radiotracer with high affinity and selectivity for the V_1BR. The purpose of this study was to characterize the pharmacokinetic and binding profiles of ¹¹C-TASP699 in human and determine its utility in an occupancy study of a novel V_1BR antagonist, TS-121. Methods: Six healthy subjects were scanned twice with ¹¹C-TASP699 to determine the most appropriate kinetic model for analysis of imaging data and test-retest reproducibility of outcome measures. Nine healthy subjects were scanned before and after administration of TS-121 (active component: THY1773) to assess V_1BR occupancy. Metabolite-corrected arterial input functions were obtained. Pituitary time-activity curves were analyzed with one- and two-tissue compartment (1TC, 2TC) models and multilinear analysis 1 (MA1) to calculate distribution volumes (V _T). Relative test-retest variability (TRV) and absolute test-retest variability (aTRV) were calculated. Since no brain region could be used as a reference region, percent change in V _T after TS-121 administration was computed to assess its receptor occupancy and correlate with plasma concentration of the drug. Results: ¹¹C-TASP699 showed high uptake in the pituitary and no uptake in any brain regions. The 2TC model provided better fits than the 1TC model. The MA1 V _T estimates were very similar to the 2TC V _T estimates, so MA1 was the model of choice. TRV of V _T was good (TRV: -2 ± 14%, aTRV: 11%). THY1773 reduced VT in a dose-dependent fashion, with IC50 of 177 ± 52 ng/mL in plasma concentration. There were no adverse events resulting in discontinuation from the study. Conclusion: ¹¹C-TASP699 was shown to display appropriate kinetics in human with substantial specific binding and good reproducibility of V _T Therefore, this tracer is suitable for measurement of the V_1BR in human pituitary and V_1BR occupancy of TS-121, a novel V_1BR antagonist.

Community-based participatory research: Suicide prevention for youth at highest risk in Guyana

Studied mostly in developed countries, the increased prevalence of suicide among youth, worldwide, is a preventable public health concern. Guyana, a developing country in South America, has the highest rate of youth death by suicide. Based on the diathesis-stress model, this community-based study aimed to identify both psychiatric and biological factors associated with repeated suicide attempts among high-risk youth.

OBJECTIVE

We measured psychiatric symptoms, childhood traumas, and cortisol to identify correlates with recurrent suicide attempts.

METHOD

Poisson regression tested the association between psychiatric symptoms, trauma, and cortisol levels on number of suicide attempts among 50 youths from three child welfare orphanages in Guyana. Sixty-six percent were female, and the average age was 14 years. DSM-5 symptom measure was administered and saliva samples collected.

RESULTS

Fifty percent of the youth endorsed suicide attempt. Within this subsample, a minimum of one and maximum of five suicide attempts were self-reported. Participants' number of suicide attempts was positively associated with number of past traumas, psychosis, and depression symptoms.

CONCLUSION

Suicide prevention screening among at-risk youth should target severity of psychosis and depression reports and number of traumatic life experiences.

Vasopressin V1B Receptor Antagonists as Potential Antidepressants

Accumulating evidence shows that certain populations of depressed patients have impaired hypothalamus-pituitary-adrenal (HPA) axis function. Arginine-vasopressin (AVP) is one of the primary factors in HPA axis regulation under stress situations, and AVP and its receptor subtype (V1B receptor) play a pivotal role in HPA axis abnormalities observed in depression. Based on this hypothesis, several non-peptide V1B receptor antagonists have been synthesized, and the efficacies of some V1B receptor antagonists have been investigated in both animals and humans. V1B receptor antagonists exert antidepressant-like effects in several animal models at doses that attenuate the hyperactivity of the HPA axis, and some of their detailed mechanisms have been delineated. These results obtained in animal models were, at least partly, reproduced in clinical trials. At least 2 V1B receptor antagonists (TS-121 and ABT-436) showed tendencies to reduce the depression scores of patients with major depressive disorder at doses that attenuate HPA axis hyperactivity or block the pituitary V1B receptor. Importantly, TS-121 showed a clearer efficacy for patients with higher basal cortisol levels than for those with lower basal cortisol levels, which was consistent with the hypothesis that V1B receptor antagonists may be more effective for patients with HPA axis hyperactivity. Therefore, V1B receptor antagonists are promising approaches for the treatment of depression involving HPA axis impairment such as depression.

The role of peripheral cortisol levels in suicide behavior: A systematic review and meta-analysis of 30 studies

Cortisol can be considered as one biomarker for diagnosis of suicide; nevertheless, several studies have shown conflicting results. This study aimed to evaluate the levels of cortisol in individuals with suicide behavior and controls (healthy or with other psychiatric disorders). Published articles were searched on online databases (PubMed, Scopus and EBSCO). Standardized mean differences (SMD), heterogeneity, publication bias and sensitivity were assessed using the Comprehensive Meta-Analysis (CMA) statistical software. The meta-analysis comprised 30 studies that provided 1775 cases, and 2162 controls (696 healthy individuals and 1465 individuals with other psychiatric diagnoses). The pooled results revealed that cortisol levels were higher in individuals with suicide behavior (SMD = 0.92, 95%CI = 0.26; 1.57, P = 0.006; I² = 88%, Q < 0.001) than healthy controls. However, individuals with suicide behavior showed decreased levels of cortisol in the morning. Additionally, individuals with suicide behavior showed lower levels of cortisol than psychiatric controls (SMD = -1.79, 95%CI = -3.01; -0.58, P = 0.004, I² = 89%, Q < 0.001). Morning cortisol levels in individuals with suicide behavior were higher than morning cortisol levels in psychiatric controls. Our updated meta-analysis suggests that peripheral levels of cortisol have a role in suicide behavior.

Sex differences in stress-related disorders: Major depressive disorder, bipolar disorder, and posttraumatic stress disorder

Stress-related disorders, such as mood disorders and posttraumatic stress disorder (PTSD), are more common in women than in men. This sex difference is at least partly due to the organizing effect of sex steroids during intrauterine development, while activating or inhibiting effects of circulating sex hormones in the postnatal period and adulthood also play a role. Such effects result in structural and functional changes in neuronal networks, neurotransmitters, and neuropeptides, which make the arousal- and stress-related brain systems more vulnerable to environmental stressful events in women. Certain brainstem nuclei, the amygdala, habenula, prefrontal cortex, and hypothalamus are important hubs in the stress-related neuronal network. Various hypothalamic nuclei play a central role in this sexually dimorphic network. This concerns not only the hypothalamus-pituitary-adrenal axis (HPA-axis), which integrates the neuro-endocrine-immune responses to stress, but also other hypothalamic nuclei and systems that play a key role in the symptoms of mood disorders, such as disordered day-night rhythm, lack of reward feelings, disturbed eating and sex, and disturbed cognitive functions. The present chapter focuses on the structural and functional sex differences that are present in the stress-related brain systems in mood disorders and PTSD, placing the HPA-axis in the center. The individual differences in the vulnerability of the discussed systems, caused by genetic and epigenetic developmental factors warrant further research to develop tailor-made therapeutic strategies.

The human hypothalamus in mood disorders: The HPA axis in the center

There are no specific structural neuropathological hallmarks found in the brain of mood disorders. Instead, there are molecular, functional and structural alterations reported in many brain areas. The neurodevelopmental underpinning indicated the presence of various genetic and developmental risk factors. The effect of genetic polymorphisms and developmental sequalae, some of which may start in the womb, result in functional changes in a network mediated by neurotransmitters and neuropeptides, which make the emotion- and stress-related brain systems more vulnerable to stressful events. This network of stress-related neurocircuits consists of, for instance, brainstem nuclei, the amygdala, habenula, prefrontal cortex and hypothalamus. Various nuclei of the hypothalamus form indeed one of the crucial hubs in this network. This structure concerns not only the hypothalamo-pituitary-adrenal (HPA) axis that integrate the neuro-endocrine-immune responses to stress, but also other hypothalamic nuclei and systems that play a key role in the symptoms of depression, such as disordered day-night rhythm, lack of reward feelings, disturbed eating, sex, and disturbed cognitive functions. The present review will focus on the changes in the human hypothalamus in depression, with the HPA axis in the center. We will discuss the inordinate network of neurotransmitters and neuropeptides involved, with the hope to find the most vulnerable neurobiological systems and the possible development of tailor-made treatments for mood disorders in the future.

Peripheral oxytocin and vasopressin: Biomarkers of psychiatric disorders? A comprehensive systematic review and preliminary meta-analysis

A large array of studies have investigated peripheral oxytocin (OT) and vasopressin (ADH) as potential biomarkers of psychiatric disorders, with highly conflicting and heterogenous findings. We searched Web of KnowledgeSM and Scopus® for English original articles investigating OT and/or ADH levels in different biological fluids (plasma/serum, saliva, urine and cerebrospinal fluid) across several psychiatric disorders. Sixty-four studies were included. We conducted 19 preliminary meta-analyses addressing OT alterations in plasma/serum, saliva, urine and cerebrospinal fluid of 7 psychiatric disorders and ADH alterations in plasma/serum, saliva, urine and cerebrospinal fluid of 6 psychiatric disorders compared to controls. Hedge's g was used as effect size measure, together with heterogeneity analyses, test of publication biases and quality control. None of them (except serum OT in anorexia nervosa) revealed significant differences. There is no convincing evidence that peripheral ADH or OT might be reliable biomarkers in psychiatric disorders. However, the lack of significant results was associated with high methodological heterogeneity, low quality of the studies, small sample size, and scarce reliability of the methods used in previous studies, which need to be validated and standardized.

Vasopressinergic control of stress-related behavior: studies in Brattleboro rats

Vasopressin, a nonapeptide, signaling both as hormone in the blood and neuromodulator/neurotransmitter in the brain is considered to be causally involved in the pathological changes underlying anxiety and depression. In the present review we summarize experimental data obtained with Brattleboro rats as a model of congenital vasopressin-deficiency to test the hypothesis that central vasopressin signaling contributes to anxiety- and depression-like behavior. Male, female and lactating rats were studied. We focused on the paraventricular nucleus of the hypothalamus (PVN) and the septum, two brain areas in which vasopressin is proposed to control the endocrine and behavioral stress response, respectively. The presented data support the hypothesis that the behavioral changes seen in these rats are brought about by an altered vasopressin signaling at the brain level. Whereas vasopressin synthesized and released within the hypothalamus is primarily involved in endocrine regulation, vasopressin signaling in other brain areas may contribute to anxiety- and depression-like behavioral parameters. Further studies in this context might focus particularly on the interplay between extra-hypothalamic brain areas such as the septum and the medial amygdala.

Cortisol levels and suicidal behavior: A meta-analysis

Suicide is a major cause of death worldwide, responsible for 1.5% of all mortality. The causes of suicidal behavior are not fully understood. Dysregulated hypothalamic-pituitary-adrenal (HPA) axis activity, as measured by cortisol levels, is one potential risk factor. This meta-analytic review aimed (i) to estimate the strength and variability of the association between naturally fluctuating cortisol levels and suicidal behavior and (ii) to identify moderators of this relationship. A systematic literature search identified 27 studies (N=2226; 779 suicide attempters and 1447 non-attempters) that met the study eligibility criteria from a total of 417 unique records initially examined. Estimates of effect sizes (r) obtained from these studies were analysed using Comprehensive Meta-Analysis. In these analyses, we compared participants identified as having a past history of suicide attempt(s) to those with no such history. Study quality, mean age of sample and percentage of male participants were examined as potential moderators. Overall, there was no significant effect of suicide group on cortisol. However, significant associations between cortisol and suicide attempts were observed as a function of age. In studies where the mean age of the sample was below 40 years the association was positive (i.e., higher cortisol was associated with suicide attempts; r=.234, p<.001), and where the mean age was 40 or above the association was negative (i.e., lower cortisol was associated with suicide attempts; r=-.129, p<.001). These findings confirm that HPA axis activity, as indicated by age-dependent variations in cortisol levels, is associated with suicidal behavior. The challenge for theory and clinical practice is to explain the complete reversal of the association with age and to identify its clinical implications.

An overview of the neurobiology of suicidal behaviors as one meta-system

Suicidal behaviors (SB) may be regarded as the outmost consequence of mental illnesses, or as a distinct entity per se. Regardless, the consequences of SB are very large to both society and affected individuals. The path leading to SB is clearly a complex one involving interactions between the subject's biology and environmental influences throughout life. With the aim to generate a representative and diversified overview of the different neurobiological components hypothesized or shown implicated across the entire SB field up to date by any approach, we selected and compiled a list of 212 gene symbols from the literature. An increasing number of novel gene (products) have been introduced as candidates, with half being implicated in SB in only the last 4 years. These candidates represent different neuro systems and functions and might therefore be regarded as competing or redundant explanations. We then adopted a unifying approach by treating them all as parts of the same meta-system, using bioinformatic tools. We present a network of all components connected by physical protein-protein interactions (the SB interactome). We proceeded by exploring the differences between the highly connected core (~30% of the candidate genes) and its peripheral parts, observing more functional homogeneity at the core, with multiple signal transduction pathways and actin-interacting proteins connecting a subset of receptors in nerve cell compartments as well as development/morphology phenotypes and the stress-sensitive synaptic plasticity processes of long term potentiation/depression. We suggest that SB neurobiology might also be viewed as one meta-system and perhaps be explained as intrinsic unbalances acting within the core or as imbalances arising between core and specific peripheral components.

Restoration of peripheral V2 receptor vasopressin signaling fails to correct behavioral changes in Brattleboro rats

Beside its hormonal function in salt and water homeostasis, vasopressin released into distinct brain areas plays a crucial role in stress-related behavior resulting in the enhancement of an anxious/depressive-like state. We aimed to investigate whether correction of the peripheral symptoms of congenital absence of AVP also corrects the behavioral alterations in AVP-deficient Brattleboro rats. Wild type (WT) and vasopressin-deficient (KO) male Brattleboro rats were tested. Half of the KO animals were treated by desmopressin (V2-receptor agonist) via osmotic minipump (subcutaneous) to eliminate the peripheral symptoms of vasopressin-deficiency. Anxiety was studied by elevated plus maze (EPM), defensive withdrawal (DW) and marble burying (MB) tests, while depressive-like changes were monitored in forced swimming (FS) and anhedonia by sucrose preference test. Cell activity was examined in septum and amygdala by c-Fos immunohistochemistry after 10 min FS. KO rats spent more time in the open arm of the EPM, spent less time at the periphery of DW and showed less burying behavior in MB suggesting a reduced anxiety state. KO animals showed less floating behavior during FS revealing a less depressive phenotype. Desmopressin treatment compensated the peripheral effects of vasopressin-deficiency without a significant influence on the behavior. The FS-induced c-Fos immunoreactivity in the medial amygdala was different in WT and KO rats, with almost identical levels in KO and desmopressin treated animals. There were no differences in central and basolateral amygdala as well as in lateral septum. Our data confirmed the role of vasopressin in the development of affective disorders through central mechanisms. The involvement of the medial amygdala in the behavioral alterations of vasopressin deficient animals deserves further attention.

Disruption of fetal hormonal programming (prenatal stress) implicates shared risk for sex differences in depression and cardiovascular disease

Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics.

Copeptin during rest and exercise in major depression

BACKGROUND

High vasopressin levels and a correlation between vasopressin and cortisol has been observed in patients with depression. The aim was to assess copeptin, the c-terminal of provasopressin, and the association between cortisol, adrenocorticotropic hormone (ACTH) and copeptin in patients with depression. Secondly, to examine the copeptin response to acute exercise and aerobic training.

METHODS

Copeptin, ACTH, and cortisol were measured in 111 patients with depression and 57 controls at rest. Copeptin was also measured during exercise. The depressed patients were subsequently randomized to an aerobic training intervention or an exercise control intervention.

RESULTS

The plasma level of copeptin in depressed subjects was 5.14 pg/ml (IQR 3.4-8.4) and 4.82 pg/ml (IQR 2.8-7.5) in healthy controls (p=.66). The association between copeptin and cortisol was.02 (95% CI -.44 to.48; p=.93) and the association between copeptin and ACTH was -.06 (95% CI -.17 to.05; p=.27). All associations were independent of depression status (p=.15). Aerobic exercise training did not influence copeptin levels at rest (p=.09) or the response to acute exercise (p=.574). Copeptin decreased at rest in response to aerobic training in participants with high compliance to the exercise intervention (p=.04).

LIMITATIONS

We did not measure plasma osmolality, which is a possible confounder in this study.

CONCLUSIONS

Copeptin levels are not elevated or associated to ACTH or cortisol in depressed patients. Aerobic exercise training decreased copeptin levels in high attenders only. This study does not support a role of copeptin or vasopressin in depression.

The role of neuropeptides in suicidal behavior: a systematic review

There is a growing evidence that neuropeptides may be involved in the pathophysiology of suicidal behavior. A critical review of the literature was conducted to investigate the association between neuropeptides and suicidal behavior. Only articles from peer-reviewed journals were selected for the inclusion in the present review. Twenty-six articles were assessed for eligibility but only 22 studies were included. Most studies have documented an association between suicidality and some neuropeptides such as corticotropin-releasing factor (CRF), VGF, cholecystokinin, substance P, and neuropeptide Y (NPY), which have been demonstrated to act as key neuromodulators of emotional processing. Significant differences in neuropeptides levels have been found in those who have attempted or completed suicide compared with healthy controls or those dying from other causes. Despite cross-sectional associations between neuropeptides levels and suicidal behavior, causality may not be inferred. The implications of the mentioned studies were discussed in this review paper.

Oxytocin plasma levels in psychiatric patients with and without recent suicide attempt

Easily available biomarkers for suicidality would be valuable for the identification of individuals at risk. Oxytocin has been shown to be associated with mental illness. We assessed basal oxytocin plasma levels of patients with (SA, n=41) and without (NSA, n=40) a 1-year history of attempted suicide. SA and NSA groups did not differ with respect to oxytocin levels. Plasma oxytocin may not be a biological suicide marker candidate.

Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems

The neurohypophysial hormone arginine vasopressin (AVP) is essential for a wide range of physiological functions, including water reabsorption, cardiovascular homeostasis, hormone secretion, and social behavior. These and other actions of AVP are mediated by at least three distinct receptor subtypes: V1a, V1b, and V2. Although the antidiuretic action of AVP and V2 receptor in renal distal tubules and collecting ducts is relatively well understood, recent years have seen an increasing understanding of the physiological roles of V1a and V1b receptors. The V1a receptor is originally found in the vascular smooth muscle and the V1b receptor in the anterior pituitary. Deletion of V1a or V1b receptor genes in mice revealed that the contributions of these receptors extend far beyond cardiovascular or hormone-secreting functions. Together with extensively developed pharmacological tools, genetically altered rodent models have advanced the understanding of a variety of AVP systems. Our report reviews the findings in this important field by covering a wide range of research, from the molecular physiology of V1a and V1b receptors to studies on whole animals, including gene knockout/knockdown studies.

Support for two increased vasopressinergic activities in depression at large and the differential effect of antidepressant treatment

Animal models of depression support a pathogenetic role for vasopressinergic activation involving increased arginine vasopressin (AVP) release and AVP receptor (V1b) synthesis. Evidence of this has been found particularly in patients with highly anxious-retarded (HAR) and above-normal AVP (ANA) depression. A general pathogenetic theory however predicts vasopressinergic activities to play a role in at least all major depressive disorders, and antidepressant (AD) treatment to be mediated by vasopressinergic reduction. We tested these hypotheses by re-analysing the data of 66 depressed patients; 27 with and 39 without AD treatment. The plasma AVP concentration and the AVP-cortisol correlation were used as presumed parameters of AVP release and pituitary V1b receptor function. A high AVP-cortisol correlation (r = 0.72; p < 0.001) was found in the non-AD group, and no correlation in the AD treatment group. AD treatment did not relate to plasma AVP concentration. The AVP-cortisol correlation in HAR and ANA depression was not explained by a low rate of AD treatment. These human data support the hypothesis of increased AVP release and receptor function as pathogenetic characteristics of major depression, and show selective normalization of the AVP-cortisol correlation, which is supposed to reflect the receptor function, by AD treatment.

Biomarkers for major depression and its delineation from neurodegenerative disorders

Major depressive disorders (MDD) are among the most debilitating diseases worldwide and occur with a high prevalence in elderly individuals. Neurodegenerative diseases (in particular Alzheimer's disease, AD) do also show a strong age-dependent increase in incidence and prevalence among the elderly population. A high number of geriatric patients with MDD show cognitive deficits and a very high proportion of AD patients present co-morbid MDD, which poses difficult diagnostic and prognostic questions. Especially in prodromal and in very early stages of AD, it is almost impossible to differentiate between pure MDD and MDD with underlying AD. Here, we give a comprehensive review of the literature on the current state of candidate biomarkers for MDD ("positive MDD markers") and briefly refer to established and validated diagnostic AD biomarkers in order to rule out underlying AD pathophysiology in elderly MDD subjects with cognitive impairments ("negative MDD biomarkers"). In summary, to date there is no evidence for positive diagnostic MDD biomarkers and the only way to delineate MDD from AD is to use "negative MDD" biomarkers. Because of this highly unsatisfactory current state of MDD biomarker research, we propose a research strategy targeting to detect and validate positive MDD biomarkers, which is based on a complex (genetic, molecular and neurophysiological) biological model that incorporates current state of the art knowledge on the pathobiology of MDD. This model delineates common pathways and the intersection between AD and MDD. Applying these concepts to MDD gives hope that positive MDD biomarkers can be successfully identified in the near future.

Association of FKBP5 gene haplotypes with completed suicide in the Japanese population

BACKGROUND

The hypothalamus-pituitary-adrenal (HPA) axis is known to have a role in suicidal behaviors in patients with affective disorders. However, the incomplete overlapping of the genetic factors of suicidal behaviors and the genetic factors of affective disorders suggest that the genes associated with predisposition to suicidal behaviors and affective disorders are different. There is increasing evidence that genes regulating the HPA axis have effects on suicidal behaviors. To test this idea, we examined the association of three HPA axis-related genes (glucocorticoid receptor (NR3C1), mineralocorticoid receptors (NR3C2), and FK506 binding protein 5 (FKBP5)) with suicide.

METHODS

We selected 3 SNPs of the FKBP5 (rs3800373, rs1360780, and rs2395635), 2 SNPs of the NR3C1 (rs6196 and rs10052957), and 3 SNPs of the NR3C2 genes (rs5525, rs5522, and rs2070951) based on their frequency in the Japanese population. Using TaqMan probe assays, we determined these SNPs in 219 completed suicide victims and 228 age- and gender-matched healthy control subjects.

RESULTS

No significant differences in genotypic distribution or allelic frequency of any single SNPs between the completed suicide and control groups were observed. The distributions of TT, TC, and GT haplotypes of the FKBP5 gene (comprised of rs3800373 and rs1360780) between the completed suicide and control groups were significantly different (p<0.05 for each haplotype). The TC haplotype withstood correction for multiple comparisons (corrected p = 0.034).

CONCLUSION

Our results suggest that haplotypes in FKBP5 gene are associated with completed suicide. This finding needs to be confirmed using rigorous SNPs selection in a larger sample.

Neuropeptide and sigma receptors as novel therapeutic targets for the pharmacotherapy of depression

Among the most prevalent of mental illnesses, depression is increasing in incidence in the Western world. It presents with a wide variety of symptoms that involve both the CNS and the periphery. Multiple pharmacological observations led to the development of the monoamine theory as a biological basis for depression, according to which diminished neurotransmission within the CNS, including that of the dopamine, noradrenaline (norepinephrine) and serotonin systems, is the leading cause of the disorder. Current conventional pharmacological antidepressant therapies, using selective monoamine reuptake inhibitors, tricyclic antidepressants and monoamine oxidase inhibitors, aim to enhance monoaminergic neurotransmission. However, the use of these agents presents severe disadvantages, including a delay in the alleviation of depressive symptoms, significant adverse effects and high frequencies of non-responding patients. Neuroendocrinological data of recent decades reveal that depression and anxiety disorders may occur simultaneously due to hypothalamus-pituitary-adrenal (HPA) axis hyperactivity. As a result, the stress-diathesis model was developed, which attempts to associate genetic and environmental influences in the aetiology of depression. The amygdala and the hippocampus control the activity of the HPA axis in a counter-balancing way, and a plethora of regulatory neuropeptide signalling pathways are involved. Intervention at these molecular targets may lead to alternative antidepressant therapeutic solutions that are expected to overcome the limitations of existing antidepressants. This prospect is based on preclinical evidence from pharmacological and genetic modifications of the action of neuropeptides such as corticotropin-releasing factor, substance P, galanin, vasopressin and neuropeptide Y. The recent synthesis of orally potent non-peptide micromolecules that can selectively bind to various neuropeptide receptors permits the onset of clinical trials to evaluate their efficacy against depression.

Hypothalamic vasopressin and oxytocin mRNA expression in relation to depressive state in Alzheimer's disease: a difference with major depressive disorder

Arginine vasopressin (AVP) and oxytocin (OXT), produced in the hypothalamic paraventricular (PVN) and supraoptic nucleus (SON), are considered to be involved in the pathophysiology of major depressive disorder (MDD). The objective of this study was to determine, for the first time, the relationship between AVP and OXT gene expression and depressive state in Alzheimer's disease (AD). Post-mortem brain tissue was obtained from six control subjects, and from a prospectively studied cohort of 23 AD patients, using the DSM-IIIR and the Cornell Scale for Depression in Dementia to determine depression diagnosis and severity. The amount of AVP and OXT mRNA was determined by in situ hybridisation. AD patients did not differ from controls with respect to the amount of AVP or OXT mRNA in the PVN or SON. Also, no differences were found between depressed and nondepressed AD patients and no relationship was found between the depression severity and AVP or OXT mRNA expression. The results indicate that AVP and OXT gene expression in the PVN and SON is unchanged in depressed AD patients compared to nondepressed AD patients. This is in contrast with the enhanced AVP gene expression in MDD, suggesting a difference in pathophysiology between MDD and depression in AD.

New topics in vasopressin receptors and approach to novel drugs: role of the vasopressin receptor in psychological and cognitive functions

Arginine vasopressin (AVP) is a neurohypophyseal peptide best known as an antidiuretic hormone. AVP receptors have been classified into three subtypes: V1a, V1b, and V2 receptors. V1a receptor (V1aR) and V1b receptor (V1bR) are widely distributed in the central nervous system, including the septum, cortex, hippocampus, and hypothalamus. Clinical studies have demonstrated an involvement of AVP in psychiatric disorders. In the present study, we examined the performance of V1aR or V1bR knockout (KO) mice compared to wild-type (WT) mice in behavioral tests. V1aR and V1bR KO mice exhibited deficits of social behavior and prepulse inhibition in comparison to WT mice. Moreover, V1aR KO mice exhibited reduced anxiety-like behavior and impairment of spatial learning. These results suggest that V1aR and V1bR play an important role in psychological and cognitive functions.

Vasopressin-neurophysin and DST in major depression: relationship with suicidal behavior

The purpose of the present study was to assess if AVP-neurophysin is associated with hypercortisolemia and suicidal behaviour in depressed patients. The study included 28 patients subgrouped into suicide attempters (n=13) and nonattempters (n=15). We assessed basal AVP-neurophysins concentrations and post-dexamethasone (DST) cortisol levels. Concentrations of AVP-neurophysins did not differ between DST suppressors and nonsuppressors: 0.29+/-0.13 ng/ml vs 0.36+/-0.21 ng/ml, (F=1.1, df=1, 27, p=0.30). Suicide attempters did not differ from nonattempters for AVP-neurophysins levels. Our results fail to support a role of AVP in the early cortisol escape.

Vasopressin: behavioral roles of an "original" neuropeptide

Vasopressin (Avp) is mainly synthesized in the magnocellular cells of the hypothalamic supraoptic (SON) and paraventricular nuclei (PVN) whose axons project to the posterior pituitary. Avp is then released into the blood stream upon appropriate stimulation (e.g., hemorrhage or dehydration) to act at the kidneys and blood vessels. The brain also contains several populations of smaller, parvocellular neurons whose projections remain within the brain. These populations are located within the PVN, bed nucleus of the stria terminalis (BNST), medial amygdala (MeA) and suprachiasmatic nucleus (SCN). Since the 1950s, research examining the roles of Avp in the brain and periphery has intensified. The development of specific agonists and antagonists for Avp receptors has allowed for a better elucidation of its contributions to physiology and behavior. Anatomical, pharmacological and transgenic, including "knockout," animal studies have implicated Avp in the regulation of various social behaviors across species. Avp plays a prominent role in the regulation of aggression, generally of facilitating or promoting it. Affiliation and certain aspects of pair-bonding are also influenced by Avp. Memory, one of the first brain functions of Avp that was investigated, has been implicated especially strongly in social recognition. The roles of Avp in stress, anxiety, and depressive states are areas of active exploration. In this review, we concentrate on the scientific progress that has been made in understanding the role of Avp in regulating these and other behaviors across species. We also discuss the implications for human behavior.

The stress system in depression and neurodegeneration: focus on the human hypothalamus

The stress response is mediated by the hypothalamo-pituitary-adrenal (HPA) system. Activity of the corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) forms the basis of the activity of the HPA-axis. The CRH neurons induce adrenocorticotropin (ACTH) release from the pituitary, which subsequently causes cortisol release from the adrenal cortex. The CRH neurons co-express vasopressin (AVP) which potentiates the CRH effects. CRH neurons project not only to the median eminence but also into brain areas where they, e.g., regulate the adrenal innervation of the autonomic system and affect mood. The hypothalamo-neurohypophysial system is also involved in stress response. It releases AVP from the PVN and the supraoptic nucleus (SON) and oxytocin (OXT) from the PVN via the neurohypophysis into the bloodstream. The suprachiasmatic nucleus (SCN), the hypothalamic clock, is responsible for the rhythmic changes of the stress system. Both centrally released CRH and increased levels of cortisol contribute to the signs and symptoms of depression. Symptoms of depression can be induced in experimental animals by intracerebroventricular injection of CRH. Depression is also a frequent side effect of glucocorticoid treatment and of the symptoms of Cushing's syndrome. The AVP neurons in the hypothalamic PVN and SON are also activated in depression, which contributes to the increased release of ACTH from the pituitary. Increased levels of circulating AVP are also associated with the risk for suicide. The prevalence, incidence and morbidity risk for depression are higher in females than in males and fluctuations in sex hormone levels are considered to be involved in the etiology. About 40% of the activated CRH neurons in mood disorders co-express nuclear estrogen receptor (ER)-alpha in the PVN, while estrogen-responsive elements have been found in the CRH gene promoter region, and estrogens stimulate CRH production. An androgen-responsive element in the CRH gene promoter region initiates a suppressing effect on CRH expression. The decreased activity of the SCN is the basis for the disturbances of circadian and circannual fluctuations in mood, sleep and hormonal rhythms found in depression. Neuronal loss was also reported in the hippocampus of stressed or corticosteroid-treated rodents and primates. Because of the inhibitory control of the hippocampus on the HPA-axis, damage to this structure was expected to disinhibit the HPA-axis, and to cause a positive feedforward cascade of increasing glucocorticoid levels over time. This 'glucocorticoid cascade hypothesis' of stress and hippocampal damage was proposed to be causally involved in age-related accumulation of hippocampal damage in disorders like Alzheimer's disease and depression. However, in postmortem studies we could not find the presumed hippocampal damage of steroid overexposure in either depressed patients or in patients treated with synthetic steroids.

A review of prospective studies of biologic predictors of suicidal behavior in mood disorders

Predicting suicide is difficult due to the low base rate, even in high-risk groups, and the multi-causal nature of suicidal behavior. Clinical predictors have shown low specificity. Retrospective and cross-sectional studies have identified a number of biologic anomalies associated with suicide and suicide attempt. Prospective studies provide estimates of the predictive utility of biologic measures. Here we review prospective studies of suicidal behavior and serotonergic, noradrenergic, dopaminergic and hypothalamic-pituitary-adrenocortical axis function in mood disorders. The most promising biologic predictors are low CSF 5-HIAA and HPA axis dysfunction as demonstrated by dexamethasone non-suppression that are each associated with about 4.5 fold greater risk of suicide.

Increased arginine vasopressin mRNA expression in the human hypothalamus in depression: A preliminary report

BACKGROUND

Elevated arginine vasopressin (AVP) plasma levels have been observed in major depression, particularly in relation to the melancholic subtype. Two hypothalamic structures produce plasma vasopressin: the supraoptic nucleus (SON) and the paraventricular nucleus (PVN). The aim of this study was to establish which structure is responsible for the increased vasopressin plasma levels in depression.

METHODS

Using in situ hybridization, we determined the amount of vasopressin messenger ribonucleic acid (mRNA) in the PVN and SON in postmortem brain tissue of nine depressed subjects (six with the melancholic subtype) and eight control subjects.

RESULTS

In the SON, a 60% increase of vasopressin mRNA expression was found in depressed compared with control subjects. In the melancholic subgroup, AVP mRNA expression was significantly increased in both the SON and the PVN compared with control subjects.

CONCLUSIONS

We found increased AVP gene expression in the SON in depressed subjects. This might partly explain the observed increased vasopressin levels in depression.

Corticotropin-releasing hormone, arginine vasopressin, gastrin-releasing peptide, and neuromedin B alterations in stress-relevant brain regions of suicides and control subjects

BACKGROUND

Postmortem levels of several stress- and depression-relevant neuropeptides were assessed in brain regions of depressed suicides relative to control subjects that had died of other causes.

METHODS

Brains of suicides and those that died from other causes were collected soon after death (typically <6 hours). Immunoreactivity levels (ir) of corticotropin-releasing hormone (CRH-ir) and arginine vasopressin (AVP-ir), and the bombesin analogs, gastrin-releasing peptide (GRP-ir), and neuromedin B (NMB-ir), were assessed.

RESULTS

Levels of CRH-ir among suicides were elevated in the locus coeruleus (LC), frontopolar, dorsolateral prefrontal (DMPFC) and ventromedial prefrontal cortices, but were reduced at the dorsovagal complex (DVC). The concentration of AVP-ir was elevated at the paraventricluar hypothalamic nucleus, LC, and DMPFC, and reduced at the DVC. Finally, GRP and NMB variations, which might influence anxiety states, were limited, although GRP-ir within the LC of suicides was higher than in control subjects, while NMB-ir was reduced at the DVC of suicides.

CONCLUSIONS

The data show several neuropeptide changes in relation to suicide, although it is premature to ascribe these outcomes specifically to the suicide act versus depression. Likewise, it is uncertain whether the neuropeptide alterations were etiologically related to suicide/depression or secondary to the depressive state.

Depression with above-normal plasma vasopressin: validation by relations with family history of depression and mixed anxiety and retardation

An anxious-retarded subtype of depression has been derived from the DSM-IV category of melancholia. It is defined by combined high scores for anxiety and retardation, and is related to family history of depression and increased plasma vasopressin (AVP) levels. Central problems concerning this hypothesized subcategory are whether elevated plasma AVP is related to family history, whether it would be better operationalized by a cut-off level for plasma AVP than as continuous variable, and whether the anxious-retarded phenotype would be better described in terms that account for full variability of mixed anxiety and retardation. A previous study suggested that above-normal plasma AVP was a more useful endophenotypic parameter than plasma AVP as a continuous variable. To answer these and related questions, 81 patients were investigated. Receiver Operating Characteristic analyses yielded a cut-off value of 5.56 pg/ml for above-normal plasma AVP, log-transformed plasma AVP (ln (AVP)) was used as continuous variable, and the correlation between anxiety and retardation was used to account for full variability of the anxious-retarded phenotype. Family history was related to above-normal plasma AVP (n = 16) and non-significantly to ln (AVP). Depression with above-normal plasma AVP, as well as familial depression with above-normal plasma AVP, showed a high correlation between anxiety and retardation, and this correlation was significantly higher than that found in the depressed patient control groups. The data support the delimitation of a largely familial depression with above-normal plasma AVP, vasopressinergic activation of the hypothalamus-pituitary-adrenal axis and a variable anxious-retarded phenotype.

The stress system in the human brain in depression and neurodegeneration

Corticotropin-releasing hormone (CRH) plays a central role in the regulation of the hypothalamic-pituitary-adrenal (HPA)-axis, i.e., the final common pathway in the stress response. The action of CRH on ACTH release is strongly potentiated by vasopressin, that is co-produced in increasing amounts when the hypothalamic paraventricular neurons are chronically activated. Whereas vasopressin stimulates ACTH release in humans, oxytocin inhibits it. ACTH release results in the release of corticosteroids from the adrenal that, subsequently, through mineralocorticoid and glucocorticoid receptors, exert negative feedback on, among other things, the hippocampus, the pituitary and the hypothalamus. The most important glucocorticoid in humans is cortisol, present in higher levels in women than in men. During aging, the activation of the CRH neurons is modest compared to the extra activation observed in Alzheimer's disease (AD) and the even stronger increase in major depression. The HPA-axis is hyperactive in depression, due to genetic factors or due to aversive stimuli that may occur during early development or adult life. At least five interacting hypothalamic peptidergic systems are involved in the symptoms of major depression. Increased production of vasopressin in depression does not only occur in neurons that colocalize CRH, but also in neurons of the supraoptic nucleus (SON), which may lead to increased plasma levels of vasopressin, that have been related to an enhanced suicide risk. The increased activity of oxytocin neurons in the paraventricular nucleus (PVN) may be related to the eating disorders in depression. The suprachiasmatic nucleus (SCN), i.e., the biological clock of the brain, shows lower vasopressin production and a smaller circadian amplitude in depression, which may explain the sleeping problems in this disorder and may contribute to the strong CRH activation. The hypothalamo-pituitary thyroid (HPT)-axis is inhibited in depression. These hypothalamic peptidergic systems, i.e., the HPA-axis, the SCN, the SON and the HPT-axis, have many interactions with aminergic systems that are also implicated in depression. CRH neurons are strongly activated in depressed patients, and so is their HPA-axis, at all levels, but the individual variability is large. It is hypothesized that particularly a subgroup of CRH neurons that projects into the brain is activated in depression and induces the symptoms of this disorder. On the other hand, there is also a lot of evidence for a direct involvement of glucocorticoids in the etiology and symptoms of depression. Although there is a close association between cerebrospinal fluid (CSF) levels of CRH and alterations in the HPA-axis in depression, much of the CRH in CSF is likely to be derived from sources other than the PVN. Furthermore, a close interaction between the HPA-axis and the hypothalamic-pituitary-gonadal (HPG)-axis exists. Organizing effects during fetal life as well as activating effects of sex hormones on the HPA-axis have been reported. Such mechanisms may be a basis for the higher prevalence of mood disorders in women as compared to men. In addition, the stress system is affected by changing levels of sex hormones, as found, e.g., in the premenstrual period, ante- and postpartum, during the transition phase to the menopause and during the use of oral contraceptives. In depressed women, plasma levels of estrogen are usually lower and plasma levels of androgens are increased, while testosterone levels are decreased in depressed men. This is explained by the fact that both in depressed males and females the HPA-axis is increased in activity, parallel to a diminished HPG-axis, while the major source of androgens in women is the adrenal, whereas in men it is the testes. It is speculated, however, that in the etiology of depression the relative levels of sex hormones play a more important role than their absolute levels. Sex hormone replacement therapy indeed seems to improve mood in elderly people and AD patients. Studies of rats have shown that high levels of cumulative corticosteroid exposure and rather extreme chronic stress induce neuronal damage that selectively affects hippocampal structure. Studies performed under less extreme circumstances have so far provided conflicting data. The corticosteroid neurotoxicity hypothesis that evolved as a result of these initial observations is, however, not supported by clinical and experimental observations. In a few recent postmortem studies in patients treated with corticosteroids and patients who had been seriously and chronically depressed no indications for AD neuropathology, massive cell loss, or loss of plasticity could be found, while the incidence of apoptosis was extremely rare and only seen outside regions expected to be at risk for steroid overexposure. In addition, various recent experimental studies using good stereological methods failed to find massive cell loss in the hippocampus following exposure to stress or steroids, but rather showed adaptive and reversible changes in structural parameters after stress. Thus, the HPA-axis in AD is only moderately activated, possibly due to the initial (primary) hippocampal degeneration in this condition. There are no convincing arguments to presume a causal, primary role for cortisol in the pathogenesis of AD. Although cortisol and CRH may well be causally involved in the signs and symptoms of depression, there is so far no evidence for any major irreversible damage in the human hippocampus in this disorder.

Arginine vasopressin and adrenocorticotropin secretion in response to psychosocial stress is attenuated by ethanol in sons of alcohol-dependent fathers

Familial risk and environmental stress promote the development of alcohol dependence. We investigated whether a positive family history of alcoholism affects the neuroendocrine response to a standardized laboratory stress test in healthy subjects without alcohol use disorders. Twenty-four high-risk subjects with a paternal history of alcoholism (PHA) and 16 family history negative (FHN) controls were evaluated. Psychosocial stress was induced by having subjects deliver a 5-min speech and mental arithmetics in front of an audience on separate days, after drinking either placebo or ethanol (0.6 g/kg) in a randomized sequence. Adrenocorticotropin (ACTH) was measured in 10 plasma samples covering up to 75 min after the stress test. Plasma arginine vasopressin (AVP) was determined before the stressor, at the time of maximum ACTH secretion, and at 75 min after stress onset. The stress test induced a phasic increase in ACTH secretion. At the time of maximum ACTH, AVP was significantly increased in relation to baseline. Compared to placebo, alcohol administration significantly attenuated maximum ACTH concentration in PHA but not FHN subjects, and decreased AVP measured in the same samples in PHA but not FHN subjects. We conclude that activation of the hypothalamic-pituitary-adrenal system by psychosocial stress is accompanied by an increase in peripheral plasma AVP levels. Secretion of both ACTH and AVP suggest that alcohol attenuates the stress response selectively in PHA but not FHN subjects. This might imply some short-term positive alcohol effect in sons of alcoholics, but also constitute a mechanism by which their risk to develop alcohol use disorders is increased.

The neurobiology of suicide and suicidality

OBJECTIVE

To investigate the current state of knowledge regarding the neurobiology of suicide and suicidality.

METHOD

The literature on the neurobiology of suicidality and suicide was reviewed.

RESULTS

There is clear evidence that the activity of 3 neurobiological systems has a role in the pathophysiology of suicidal behaviour. This includes hyperactivity of the hypothalamo-pituitary-adrenal axis, dysfunction of the serotonergic (5-HTergic) system, and excessive activity of the noradrenergic system. While the first and the last system appear to be involved in the response to stressful events, dysfunction of the serotonergic system is thought to be trait-dependent and associated with disturbances in the regulation of anxiety, impulsivity, and aggression. It can be hypothesized that neurobiological dysfunctions mediate the occurrence of suicidal behaviour through the disturbed modulation of basic neuropsychological functions.

CONCLUSION

Increasing insight into the neurobiological basis of suicidal behaviour suggests that serotonin (5-HT) agonists have an important role in the treatment and prevention of suicidal behaviour. Studies of the efficacy of such drugs have, however, been disappointing. Because suicidal behaviour continues to be a major public health problem, further study is clearly needed, including research on the effect of combined pharmacologic and psychotherapeutic approaches.

Lower cortisol levels in depressed patients with comorbid post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is often comorbid with major depressive episodes (MDEs) and both conditions carry a higher rate of suicidal behavior. Hypothalamic-pituitary-adrenal (HPA) axis and serotonin abnormalities are associated with both conditions and suicidal behavior, but their inter-relation is not known. We determined cortisol response to placebo or fenfluramine in MDE, MDE and PTSD (MDE+PTSD), and healthy volunteers (HVs) and examined the relation of cortisol responses to suicidal behavior. A total of 58 medication-free patients with MDE (13 had MDE+PTSD) and 24 HVs were studied. They received placebo on the first day and fenfluramine on the second day. Cortisol levels were drawn before challenge and for 5 h thereafter. The MDE+PTSD group had the lowest plasma cortisol, the MDE group had the highest, and HVs had intermediate levels. There were no group differences in cortisol response to fenfluramine. Suicidal behavior, sex, and childhood history of abuse were not predictors of baseline or postchallenge plasma cortisol. Cortisol levels increased with age. This study finds elevated cortisol levels in MDE and is the first report of lower cortisol levels in MDE+PTSD. The findings underscore the impact of comorbidity of PTSD with MDE and highlight the importance of considering comorbidity in psychobiology.

Anxious-retarded depression: relation with plasma vasopressin and cortisol

Dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis is related to melancholic or endogenous depression; however, the strength of this relationship depends on the definition of the specific depression subcategory. A two-dimensionally defined subcategory, anxious-retarded depression, is related to melancholic depression. Since arginine vasopressin (AVP) activates the HPA axis, and both major depression and the melancholic subcategory are associated with elevated plasma AVP levels, we investigated whether the plasma AVP level is also elevated in anxious-retarded depression, melancholic depression and anxious-retarded melancholic depression, and whether plasma AVP and cortisol levels are correlated in these subcategories. A total of 66 patients with major depression not using oral contraception were investigated. Patients with anxious-retarded depression had a highly significant AVP-cortisol correlation, while no such correlation was found in patients with nonanxious-retarded depression. Log-transformed mean plasma AVP values were higher in patients with anxious-retarded depression than in patients with nonanxious-retarded depression. Patients with anxious-retarded melancholic depression also had a significantly elevated level of plasma AVP and a highly significant correlation between plasma AVP and cortisol levels. The correlation was low in patients with melancholic depression. Anxious-retarded depression may be a useful refinement of the melancholic subcategory with regard to dysregulation of the HPA axis and plasma AVP release.

Vasopressin as a target for antidepressant development: an assessment of the available evidence

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis is one of the key biological abnormalities described in major depressive disorder, occurring in 30-50% of depressed subjects. Corticotropin-releasing hormone (CRH) and vasopressin (AVP) are the main regulators of this stress system, with the two neuropeptides acting synergistically in bringing about adrenocorticotropin (ACTH) release from the anterior pituitary and cortisol from the adrenal gland. Based on the demonstration of elevated cerebrospinal fluid levels of CRH in depressives, and other evidence, it has been postulated that excess CRH and the resultant increased HPA forward drive form the basis of neuroendocrine dysregulation in depression. However, there is an accumulating body of evidence to support a significant role for AVP in the regulation of pituitary-adrenal activity in health and also in depressive disorder. This review, based on a Medline search from 1980 to 2001, focuses on the functional neuroanatomy, receptor pharmacology, VP synergism with CRH, and the data from clinical and pre-clinical studies that support an important role for AVP in the pathophysiology of major depression. We suggest that future antidepressants may target the vasopressinergic system.

Neuropeptides involved in the pathophysiology of schizophrenia and major depression

The present review summarizes the findings on the role of neuropeptides in the pathophysiology of schizophrenia and major depression. Several neuropeptides as vasopressin and endorphins in particular, beta-endorphin and gamma-type endorphins, cholecystokinin (CCK), neurotensin, somatostatin and Neuropeptide Y have been implicated in schizophrenia. During the last decade, however, few attempts to explore the significance of most of these and other neuropeptides in the pathophysiology of the disease or their therapeutic potential are found in the literature. An exception is neurotensin, which exerts neuroleptic-like effects in animal studies, while CSF, brain and blood studies are inconclusive. Things are different in major depression. Here much attention is paid to the endocrine abnormalities found in this disorder in particular the increased activity of the hypothalamic-pituitary-adrenal (HPA) axis. Neuropeptides as corticotropin-releasing hormone (CRH), vasopressin and corticosteroids are implicated in the symptomatology of this disorder. As a consequence much work is going on investigating the influence of CRH and corticosteroid antagonists or inhibitors of the synthesis of corticosteroids as potential therapeutic agents. This review emphasizes the role of vasopressin in the increased activity of the HPA axis in major depression and suggests exploration of the influence of the now available non-peptidergic vasopressin orally active V1 antagonists.

Stress system alterations and mood disorders in suicidal patients. A review

Stress system alterations, in particular HPA axis hyperactivations, are fairly well documented in suicide victims and in depressed suicide attempters who subsequently complete suicide. In suicide attempters with no documented completed suicide, the results are more inconsistent. This may depend on differences in studies due to diagnostic heterogeneity among suicide attempters, and the time between the suicide attempt and the examination. Recent data suggests differences in the stress system between depressed patients with a recent suicide attempt and depressed patients in general. The field merits further examination, with thorough examinations of genotypes, actual suicide attempts and stress in combination with examinations of the stress system.

Hypothalamo-pituitary-adrenal cortical responses to low-dose physostigmine and arginine vasopressin administration: sex differences between major depressives and matched control subjects

Of heuristic value in understanding the neurochemistry of major depression is whether the hypothalamo-pituitary-adrenocortical (HPA) axis hyperactivity that occurs in this illness can be related to putative neurotransmitter dysfunction(s). Cholinergic neurotransmission stimulates hypothalamic corticotropin releasing hormone (CRH) and arginine vasopressin (AVP) secretion, both of which stimulate pituitary corticotropin (ACTH) secretion, but whether the HPA axis in humans is activated only by doses of cholinergic agonists that produce noxious side effects remains controversial. To test the hypothesis of increased cholinergic sensitivity in major depression, physostigmine (PHYSO), a reversible cholinesterase inhibitor, was administered to patients and control subjects at a dose that elevated plasma ACTH, cortisol, and AVP concentrations but produced few or no side effects. Exogenous AVP also was administered to determine if it would augment the effect of low-dose PHYSO on the HPA axis. Twelve premenopausal or estrogen-replaced female major depressives, 12 individually matched female control subjects, eight male major depressives, and eight matched male control subjects underwent four test sessions 5-7 days apart: PHYSO (8 microg/kg IV), AVP (0.08 U/kg IM), PHYSO + AVP, and saline control. Serial blood samples were taken before and after pharmacologic challenge and analyzed for ACTH1-39, cortisol, and AVP. Estradiol and testosterone were also measured at each test session. PHYSO (8 microg/kg) significantly increased plasma ACTH, cortisol, and AVP, while producing no side effects in approximately half the subjects and predominantly mild side effects in the other half. These hormone increases following PHYSO occurred primarily in the female depressives and the male control subjects and were not significantly related to the presence or absence of side effects. The greater the ACTH and AVP responses to PHYSO, the stronger their correlation, suggesting that AVP may have been acting as a secretagogue for ACTH. Administered AVP significantly increased the secretion of ACTH in the patients and control subjects to a similar degree, and AVP given after PHYSO did not augment the HPA axis response to a greater degree in the depressives than in the control subjects. Plasma estradiol and testosterone were within the normal range for all four groups of subjects and were not significantly related to their HPA axis hormone responses. The study results support the hypothesis of heightened cholinergic sensitivity in premenopausal female, but not in male, patients with major depression. The low dose of PHYSO used may represent a useful paradigm for central cholinergic stimulation of the HPA axis.

Hypothalamic Peptides in Human Brain Diseases

The human hypothalamus is subdivided into some 20 well-defined nuclei that have a multitude of specific functions from the time of birth to the moment we die. Hypothalamic nuclei show structural and functional differences not only in relation to classic neuroendocrine disorders, such as diabetes insipidus, climacteric flushes and Kallman's syndrome, but also in relation to gender and sexual orientation, to adaptive processes such as non-thyroidal illness and in psychiatric disorders such as depression.