Neuroendocrinological mechanisms of actions of antidepressant drugs

Higher levels of plasma Adrenocorticotropic hormone (ACTH) are associated with lower suicidal ideation in depressed patients compared to controls and suicide attempters, independently from depression severity

Introduction

Suicidal ideation, an important risk factor for suicide attempts, has an unclear neurobiological basis and is potentially linked to the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and immune-inflammatory systems. While inflammatory markers have been associated with suicide attempts and, to a lower extent suicidal ideation, the data on the role of a stress-response system is less robust, with most studies carried out with cortisol showing inconsistent results. The present study extends on the previous studies implicating stress-response and immune-inflammatory systems in suicidal thoughts and behaviours, focusing on the associations of several stress-response (adrenocorticotropic hormone (ACTH), cortisol, and dehydroepiandrosterone (DHEA)) and immune-inflammatory (C-reactive protein (CRP),interle ukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-alpha)) with suicidal ideation severity in recent suicide attempters, patients with major depressive disorder, and non-psychiatric controls.

Methods

This observational study included 156 adults from three Vilnius hospitals, recruited into one of the three groups in equal parts: recent suicide attempters, patients with major depressive disorder in current depressive episode, and non-psychiatric controls. Measures included the Hamilton Depression Rating Scale (HDRS-17) and the Beck Scale for Suicide Ideation/Suicide Severity Index (BSS/SSI), alongside sociodemographic data, alcohol, tobacco use, and morning blood samples, measuring plasma ACTH, cortisol, DHEA, CRP, and IL-6. Data were analysed with non-parametric tests, Kendall's tau correlation, and multivariate linear regression adjusted for confounders.

Results

We found a negative correlation between the plasma ACTH levels and suicidal ideation severity (tau = -0.130, p = 0.033), which was driven by the patients with major depressive disorder (tau = -0.237, p = 0.031). Suicidal ideation severity was also negatively correlated with TNF-alpha (tau = -0.231; p < 0.001), positively correlated with IL-6 (tau = 0.154, p = 0.015), and CRP levels (tau = 0.153, p = 0.015), but no differences were observed in group-stratified analyses. The association between plasma ACTH levels and suicidal ideation severity in patients with major depressive disorder remained robust to adjustment for major confounders (adjusted for age, sex, education years, body mass index, smoking status, plasma CRP and PEth concentration (measuring chronic alcohol exposure), and antidepressant use) in the linear regression model (t = -2.71, p = 0.011), as well as additionally adjusting for depression severity (t = -2.99, p = 0.006).

Discussion

The present study shows an association between plasma ACTH levels and suicidal ideation severity in patients with major depressive disorder, robust to adjustment for antidepressant use and depression severity. This finding highlights the potential role of ACTH, in elucidating the effects of stress and mental health disorders. Our findings underscore the importance of the HPA axis in the diagnosis and treatment of suicidal ideation in major depressive disorder and invite further research on interventions targeting this pathway.

Unraveling the molecular basis of cannabidiolic acid methyl Ester's anti-depressive effects in a rat model of treatment-resistant depression

Major depressive disorder (MDD) stands as a significant cause of disability globally. Cannabidiolic Acid-Methyl Ester (CBDA-ME) (EPM-301, HU-580), a derivative of Cannabidiol, demonstrates immediate antidepressant-like effects, yet it has undergone only minimal evaluation in psychopharmacology. Our goal was to investigate the behavioral and potential molecular mechanisms associated with the chronic oral administration of this compound in the Wistar Kyoto (WKY) genetic model of treatment-resistant depression. Male WKY rats were subjected to behavioral assessments before and after receiving chronic (14-day) oral doses of CBDA-ME (0.5 mg/kg), 15 mg/kg of imipramine or vehicle. At the end of the study, plasma corticosterone levels and mRNA expression of various genes in the medial Prefrontal Cortex and Hippocampus were measured. Behavioral outcomes from CBDA-ME treatment indicated an antidepressant-like effect similar to imipramine, as oral ingestion reduced immobility and increased swimming duration in the Forced Swim Test. Neither treatment influenced locomotion in the Open Field Test nor preference in the Saccharin Preference Test. The behavioral impact in WKY rats coincided with reduced corticosterone serum levels, upregulated mRNA expression of Cannabinoid receptor 1, Fatty Acid Amide Hydrolase, and Corticotropin-Releasing Hormone Receptor 1, alongside downregulation of the Serotonin Transporter in the hippocampus. Additionally, there was an upregulation of CB1 mRNA expression and downregulation of Brain-Derived Neurotrophic Factor in the mPFC. These findings contribute to our limited understanding of the antidepressant effects of CBDA-ME and shed light on its potential psychopharmacological mechanisms. This discovery opens up possibilities for utilizing cannabinoids in the treatment of major depressive disorder and related conditions.

Incident diabetes in adolescents using antidepressant: a systematic review and meta-analysis

BACKGROUND

The use of antidepressants has been on the rise among adolescents and young adults, populations also increasingly at risk for type 2 diabetes. However, the relationship between antidepressant uses and diabetes incidence in these age groups remains poorly understood.

METHODS

Adhering to PRISMA guidelines and the Cochrane Handbook, we conducted a comprehensive search in PubMed, Scopus, Embase, and Web of Science up to 21 February 2024, registering our protocol on PROSPERO (CRD42024516272).

RESULTS

Six studies, ranging from 16, 470 to 1, 582, 914 participants and spanning 2010 to 2023 across North America, Europe, and Asia, were included. The meta-analysis revealed a significant association between antidepressant use and diabetes onset, with 10 cases per 1, 000 observations (p < 0.01; I2 = 100%). Adolescents using high doses of antidepressants showed a 62% increased risk of developing diabetes compared to non-users or those on low doses (Risk ratio = 1.67; 95% CI 1.19-2.35; I2 = 87%; p < 0.01). The overall quality of the studies was high, with an average Newcastle-Ottawa Scale score of 7.66. Sensitivity analysis highlighted the robustness of these findings, except when removing specific studies, indicating potential sources of heterogeneity.

CONCLUSION

Antidepressant use in adolescents is associated with a significantly increased risk of diabetes onset, particularly at higher doses. This finding underscores the necessity for vigilant monitoring of glucose levels in this population and warrants further investigation into the underlying mechanisms and long-term outcomes.

Jnk1 and downstream signalling hubs regulate anxiety-like behaviours in a zebrafish larvae phenotypic screen

Current treatments for anxiety and depression show limited efficacy in many patients, indicating the need for further research into the underlying mechanisms. JNK1 has been shown to regulate anxiety- and depressive-like behaviours in mice, however the effectors downstream of JNK1 are not known. Here we compare the phosphoproteomes from wild-type and Jnk1-/- mouse brains and identify JNK1-regulated signalling hubs. We next employ a zebrafish (Danio rerio) larvae behavioural assay to identify an antidepressant- and anxiolytic-like (AA) phenotype based on 2759 measured stereotypic responses to clinically proven antidepressant and anxiolytic (AA) drugs. Employing machine learning, we classify an AA phenotype from extracted features measured during and after a startle battery in fish exposed to AA drugs. Using this classifier, we demonstrate that structurally independent JNK inhibitors replicate the AA phenotype with high accuracy, consistent with findings in mice. Furthermore, pharmacological targeting of JNK1-regulated signalling hubs identifies AKT, GSK-3, 14-3-3 ζ/ε and PKCε as downstream hubs that phenocopy clinically proven AA drugs. This study identifies AKT and related signalling molecules as mediators of JNK1-regulated antidepressant- and anxiolytic-like behaviours. Moreover, the assay shows promise for early phase screening of compounds with anti-stress-axis properties and for mode of action analysis.

Reduced urine pregnenolone concentration after clinical response in patients with depression: An open-label short-term prospective study

BACKGROUND

Identifying biological alterations in patients with depression, particularly those that differ between responders and non-responders, is of interest to clinical practice. Biomarker candidates involve neuroactive steroids, including pregnenolone (PREG) and allopregnanolone (ALLO). However, alterations in PREG and ALLO associated with treatment response are understudied. This study's main aim was to evaluate the effects of antidepressant treatment, clinical response, and treatment duration on PREG and ALLO in depression.

MATERIALS AND METHODS

In a 4-week, open-label trial, participants were allocated randomly to the venlafaxine (n = 27) or mirtazapine (n = 30) group. Urine concentrations of PREG and ALLO were assessed through gas chromatography-mass spectrometry. Participants collected night urine between 10:30 p.m. and 8:00 a.m. Two primary outcomes were analyzed. Firstly, the effect of treatment (mirtazapine or venlafaxine), clinical response (operationalized through the Hamilton Depression Rating Scale), and time (baseline compared to 28 days) on the urine concentrations of PREG or ALLO in depression. Finally, the effect of clinical response and time on the urine concentration of PREG or ALLO, independently of the antidepressant given (mirtazapine or venlafaxine). Linear mixed models were carried out.

RESULTS

There was no significant difference in PREG and ALLO concentrations between baseline and 28 days in responders and non-responders when investigating the venlafaxine or the mirtazapine group. However, we found a significant reduction of urine PREG concentration after 28 days of treatment in responders who received either venlafaxine or mirtazapine (estimate = -0.56; p = 0.016; 95CI [-1.003; -0.115]; Cohen's d = -0.61).

CONCLUSIONS

Our main results indicate that responders in depression show reduced urinary PREG concentrations after 4-weeks of therapy, independently of the antidepressant used. More studies are needed to confirm these findings.

Antidepressant-like Effects of Representative Types of Food and Their Possible Mechanisms

Depression is a mental disorder characterized by low mood, lack of motivation, negative cognitive outlook, and sleep problems. Suicide may occur in severe cases, although suicidal thoughts are not seen in all cases. Globally, an estimated 350 million individuals grapple with depression, as reported by the World Health Organization. At present, drug and psychological treatments are the main treatments, but they produce insufficient responses in many patients and fail to work at all in many others. Consequently, treating depression has long been an important topic in society. Given the escalating prevalence of depression, a comprehensive strategy for managing its symptoms and impacts has garnered significant attention. In this context, nutritional psychiatry emerges as a promising avenue. Extensive research has underscored the potential benefits of a well-rounded diet rich in fruits, vegetables, fish, and meat in alleviating depressive symptoms. However, the intricate mechanisms linking dietary interventions to brain function alterations remain largely unexplored. This review delves into the intricate relationship between dietary patterns and depression, while exploring the plausible mechanisms underlying the impact of dietary interventions on depression management. As we endeavor to unveil the pathways through which nutrition influences mental well-being, a holistic perspective that encompasses multidisciplinary strategies gains prominence, potentially reshaping how we approach and address depression.

Stress Hormone Dynamics Are Coupled to Brain Serotonin 4 Receptor Availability in Unmedicated Patients With Major Depressive Disorder: A NeuroPharm Study

BACKGROUND

A prominent finding in major depressive disorder (MDD) is distorted stress hormone dynamics, which is regulated by serotonergic brain signaling. An interesting feature of the cerebral serotonin system is the serotonin 4 receptor (5-HT4R), which is lower in depressed relative to healthy individuals and also has been highlighted as a promising novel antidepressant target. Here, we test the novel hypothesis that brain 5-HT4R availability in untreated patients with MDD is correlated with cortisol dynamics, indexed by the cortisol awakening response (CAR). Further, we evaluate if CAR changes with antidepressant treatment, including a selective serotonin reuptake inhibitor, and if pretreatment CAR can predict treatment outcome.

METHODS

Sixty-six patients (76% women) with a moderate to severe depressive episode underwent positron emission tomography imaging with [11C]SB207145 for quantification of brain 5-HT4R binding using BPND as outcome. Serial home sampling of saliva in the first hour from awakening was performed to assess CAR before and after 8 weeks of antidepressant treatment. Treatment outcome was measured by change in Hamilton Depression Rating Scale 6 items.

RESULTS

In the unmedicated depressed state, prefrontal and anterior cingulate cortices 5-HT4R binding was positively associated with CAR. CAR remained unaltered after 8 weeks of antidepressant treatment, and pretreatment CAR did not significantly predict treatment outcome.

CONCLUSIONS

Our findings highlight a link between serotonergic disturbances in MDD and cortisol dynamics, which likely is involved in disease and treatment mechanisms. Further, our data support 5-HT4R agonism as a promising precision target in patients with MDD and disturbed stress hormone dynamics.

Psychedelics for treatment resistant depression: are they game changers?

INTRODUCTION

A new era of treatment for adults with treatment-resistant depression (TRD), which involves psychedelic substances, is dawning. Emerging evidence indicates that psychedelics can exert antidepressant effects through multiple neurobiological and psychological mechanisms. However, it remains to be seen if these new treatments will revolutionize the treatment of TRD.

AREAS COVERED

The present review focuses on the efficacy of serotoninergic psychedelics psilocybin, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine (DMT), ayahuasca, 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and mescaline (3,4,5-trimethoxyphenethylamine), as well as 3,4-methylenedioxymethamphetamine (MDMA), for TRD. A systematic search was conducted for psilocybin in TRD as emerging trials had not yet been subject to review. A narrative review summarized findings on other psychedelics.

EXPERT OPINION

Psychedelic therapy has created a paradigm shift in the treatment of TRD, as it can maximize therapeutic benefits and minimize potential risks. Psilocybin holds promise as a potential game-changer in the treatment of TRD, with initial evidence suggesting a rapid antidepressant effect sustained for some responders for at least 3 months. Nevertheless, further adequately powered, double-blind, comparator-controlled trials are required to explore and clarify the mechanisms of action and long-term effects of psychedelics in TRD. Psychedelics also hold promise for other psychiatric conditions, such as bipolar depression and post-traumatic stress disorder.

Effects of left anodal transcranial direct current stimulation on hypothalamic-pituitary-adrenal axis activity in depression: a randomized controlled pilot trial

The main objective of this study was to evaluate the effect of left anodal transcranial direct current stimulation (tDCS) on hypothalamic-pituitary-adrenal axis (HPAA) activity in individuals with depression. We conducted a 3-week, randomized, triple-blind pilot trial with 47 participants (dropout rate: 14.89%) randomly assigned to either the tDCS or control group (sham stimulation). Salivary cortisol was used as an HPAA activity marker since cortisol is the effector hormone of the HPAA. The primary outcome was the effect of tDCS on the diurnal cortisol pattern (DCP and area under the curve with respect to ground -AUCg-). Secondary outcomes included tDCS effects on cortisol awakening response (CAR) and cortisol decline (CD), as well as the variation of cortisol concentrations between the initiation of tDCS and 2 weeks later. Intention-to-treat and per-protocol analyses were conducted. Our primary outcome showed an absent effect of tDCS on DCP and AUCg. Additionally, tDCS had an absent effect on CAR, CD, and cortisol concentration variation before-after stimulation. Our pilot study suggests that anodal tDCS showed an absent effect on HPAA activity in individuals with depression. More studies are needed to confirm these findings.

Modulatory effect of long-term treatment with escitalopram and clonazepam on the expression of anxiety-related neuropeptides: neuromedin U, neuropeptide S and their receptors in the rat brain

BACKGROUND

Newly identified multifunctional peptidergic modulators of stress responses: neuromedin U (NMU) and neuropeptide S (NPS) are involved in the wide spectrum of brain functions. However, there are no reports dealing with potential molecular relationships between the action of diverse anxiolytic or antidepressant drugs and NMU and NPS signaling in the brain. The present work was therefore focused on local expression of the aforementioned stress-related neuropeptides in the rat brain after long-term treatment with escitalopram and clonazepam.

METHODS

Studies were carried out on adult, male Sprague-Dawley rats that were divided into 3 groups: animals injected with saline (control) and experimental individuals treated with escitalopram (at single dose 5 mg/kg daily), and clonazepam (at single dose 0.5 mg/kg). All individuals were sacrificed under anaesthesia and the whole brain excised. Total mRNA was isolated from homogenized samples of amygdala, hippocampus, hypothalamus, thalamus, cerebellum and brainstem. Real time-PCR method was used for estimation of related NPS, NPS receptor (NPSR), NMU, NMU and receptor 2 (NMUR2) mRNA expression. The whole brains were also sliced for general immunohistochemical assessment of the neuropeptides expression.

RESULTS

Chronic administration of clonazepam resulted in an increase of NMU mRNA expression and formation of NMU-expressing fibers in the amygdala, while escitalopram produced a significant decrease in NPSR mRNA level in hypothalamus. Long-term escitalopram administration affects the local expression of examined neuropeptides mRNA in a varied manner depending on the brain structure.

CONCLUSIONS

Pharmacological effects of escitalopram may be connected with local at least partially NPSR-related alterations in the NPS/NMU/NMUR2 gene expression at the level selected rat brain regions. A novel alternative mode of SSRI action can be therefore cautiously proposed.

Are Essential Trace Elements Effective in Modulation of Mental Disorders? Update and Perspectives

The emergence of mental disorders is associated with several risk factors including genetic and environmental susceptibility. A group of nutrients serves an especially important role in a number of essential neurodevelopmental processes through brain areas promoting the high degree of brain metabolism during early life, although almost all nutrients are needed. These include macronutrients and micronutrients (e.g., iron, magnesium, zinc, copper, selenium). Numerous nutritional psychiatry trials have been performed to examine the correlation of many individual nutrients with mental health, such as essential trace elements. The increased accumulation or lack of such components will facilitate an alternative metabolic pathway that can lead to many diseases and conditions of neurodevelopment. Mental functions have biochemical bases, so the impairment of such neurochemical mechanisms due to lack of trace elements can have mental effects. In psychological conditions such as depression, anxiety, schizophrenia, and autism, scientific studies demonstrate the putative role of trace element deficiency. Therefore, given the critical roles played by essential trace elements in the neurodevelopment and mental health, the effect of these elements' intake on the modulation of psychological functioning is reviewed.

Remediation of pharmaceuticals from contaminated water by molecularly imprinted polymers: a review

The release of pharmaceuticals into the environment induces adverse effects on the metabolism of humans and other living species, calling for advanced remediation methods. Conventional removal methods are often non-selective and cause secondary contamination. These issues may be partly solved by the use of recently-developped adsorbents such as molecularly imprinted polymers. Here we review the synthesis and application of molecularly imprinted polymers for removing pharmaceuticals in water. Molecularly imprinted polymers are synthesized via several multiple-step polymerization methods. Molecularly imprinted polymers are potent adsorbents at the laboratory scale, yet their efficiency is limited by template leakage and polymer quality. Adsorption performance of multi-templated molecularly imprinted polymers depends on the design of wastewater treatment plants, pharmaceutical consumption patterns and the population serviced by these wastewater treatment plants.

Potential biomarkers of major depression diagnosis and chronicity

BACKGROUND

Molecular biomarkers are promising tools to be routinely used in clinical psychiatry. Among psychiatric diseases, major depression disorder (MDD) has gotten attention due to its growing prevalence and morbidity.

METHODS

We tested some peripheral molecular parameters such as serum mature Brain-Derived Neurotrophic Factor (mBDNF), plasma C-Reactive Protein (CRP), serum cortisol (SC), and the salivary Cortisol Awakening Response (CAR), as well as the Pittsburgh sleep quality inventory (PSQI), as part of a multibiomarker panel for potential use in MDD diagnosis and evaluation of disease's chronicity using regression models, and ROC curve.

RESULTS

For diagnosis model, two groups were analyzed: patients in the first episode of major depression (MD: n = 30) and a healthy control (CG: n = 32). None of those diagnosis models tested had greater power than Hamilton Depression Rating Scale-6. For MDD chronicity, a group of patients with treatment-resistant major depression (TRD: n = 28) was tested across the MD group. The best chronicity model (p < 0.05) that discriminated between MD and TRD included four parameters, namely PSQI, CAR, SC, and mBDNF (AUC ROC = 0.99), with 96% of sensitivity and 93% of specificity.

CONCLUSION

These results indicate that changes in specific biomarkers (CAR, SC, mBDNF and PSQI) have potential on the evaluation of MDD chronicity, but not for its diagnosis. Therefore, these findings can contribute for further studies aiming the development of a stronger model to be commercially available and used in psychiatry clinical practice.

Pathophysiology of Major Depression by Clinical Stages

The comprehension of the pathophysiology of the major depressive disorder (MDD) is essential to the strengthening of precision psychiatry. In order to determine the relationship between the pathophysiology of the MDD and its clinical progression, analyzed by severity of the depressive symptoms and sleep quality, we conducted a study assessing different peripheral molecular biomarkers, including the levels of plasma C-reactive protein (CRP), serum mature brain-derived neurotrophic factor (mBDNF), serum cortisol (SC), and salivary cortisol awakening response (CAR), of patients with MDD (n = 58) and a control group of healthy volunteers (n = 62). Patients with the first episode of MDD (n = 30) had significantly higher levels of CAR and SC than controls (n = 32) and similar levels of mBDNF of controls. Patients with treatment-resistant depression (TRD, n = 28) presented significantly lower levels of SC and CAR, and higher levels of mBDNF and CRP than controls (n = 30). An increased severity of depressive symptoms and worse sleep quality were correlated with levels low of SC and CAR, and with high levels of mBDNF. These results point out a strong relationship between the stages clinical of MDD and changes in a range of relevant biological markers. This can assist in the development of precision psychiatry and future research on the biological tests for depression.

Serum proteomic analysis of major depressive disorder patients and their remission status: Novel biomarker set of zinc-alpha-2-glycoprotein and keratin type II cytoskeletal 1

Major depressive disorder (MDD) is the most common mood disorder, and causes various mental, physical and cognitive symptoms. Clinicians diagnose MDD using multiple interviews and overall impression during the interviews, which makes MDD diagnosis highly subjective. To overcome this, we investigated novel protein biomarker for MDD. Serum from each subject were analyzed using nano liquid chromatography-triple time-of-flight mass spectrometry. We identified two proteins, zinc-alpha-2-glycoprotein (ZA2G) and keratin type II cytoskeletal 1 (K2C1), as final biomarkers. These biomarkers were downregulated during depression (p < 0.05, AUC of ROC >0.7). ZA2G is related to tryptophan metabolism, which is a main serotonin synthesis pathway. K2C1 is involved in the kinin-kallikrein system, which produces bradykinin, an anti-inflammatory mediator in the brain. Our results suggest that the two protein candidates are related to inflammation and that MDD is highly associated with inflammation. Finally, since all subjects in the two groups were taking antidepressants, our results suggest that the identified biomarkers could determine the presence or absence of illness and could be used to monitor therapeutic effects.

Antidepressants on Multiple Sclerosis: A Review of In Vitro and In Vivo Models

Background

Increased prevalence of depression has been observed among patients with multiple sclerosis (MS) and correlated with the elevated levels of proinflammatory cytokines and the overall deregulation of monoaminergic neurotransmitters that these patients exhibit. Antidepressants have proved effective not only in treating depression comorbid to MS, but also in alleviating numerous MS symptoms and even minimizing stress-related relapses. Therefore, these agents could prospectively prove beneficial as a complementary MS therapy.

Objective

This review aims at illustrating the underlying mechanisms involved in the beneficial clinical effects of antidepressants observed in MS patients.

Methods

Through a literature search we screened and comparatively assessed papers on the effects of antidepressant use both in vitro and in vivo MS models, taking into account a number of inclusion and exclusion criteria.

Results

In vitro studies indicated that antidepressants promote neural and glial cell viability and differentiation, reduce proinflammatory cytokines and exert neuroprotective activity by eliminating axonal loss. In vivo studies confirmed that antidepressants delayed disease onset and alleviated symptoms in Experimental Autoimmune Encephalomyelitis (EAE), the most prevalent animal model of MS. Further, antidepressant agents suppressed inflammation and restrained demyelination by decreasing immune cell infiltration of the CNS.

Conclusion

Antidepressants were efficient in tackling numerous aspects of disease pathophysiology both in vitro and in vivo models. Given that several antidepressants have already proved effective in clinical trials on MS patients, the inclusion of such agents in the therapeutic arsenal of MS should be seriously considered, following an individualized approach to minimize the adverse events of antidepressants in MS patients.

Investigating the basis for the antidepressant effects of Gleditsiae spina using an integrated metabolomic strategy

OBJECTIVES

Gleditsiae spina (GS) is a natural antidepressant but its mechanisms of action remain unclear. In the present study, taxifolin (Tax) was selected to determine the role of flavonoids in the antidepressant effects of GS.

MATERIALS AND METHODS

Urine samples from C57BL/6 mice were analyzed based on ultra performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-Q/TOF-MS). Then, we investigated the therapeutic effects of GS and Tax in depression models in vivo. An integrated metabolomic approach was used to examine the metabolic profiles of GS/Tax groups and corticosterone model groups (Cor). Metabolic networks in response to GS/Tax treatment were established for the comparison of antidepressant activities.

RESULTS

Corticosterone exposure significantly increased serum levels of corticosterone but decreased serum levels of 5-hydroxytryptamine and sucrose consumption (P<0.01). Treatment with GS and Tax improved all measured variables compared to those of the corticosterone-exposed group (P< 0.01). The antidepressant effects of GS and Tax involved the regulation of pentose and glucuronate interconversions, arginine and proline metabolism, phenylalanine metabolism, taurine and hypotaurine metabolism, and the citrate cycle.

CONCLUSION

These findings indicate that flavonoids form the pharmacodynamic basis of the antidepressant effects of GS. Moreover, our findings highlight that integrated metabolomics provides a powerful tool to study the mechanisms and material basis of Chinese herbs.

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 Wistar-Kyoto rat model of endogenous depression: A tool for exploring treatment resistance with an urgent need to focus on sex differences

Major depressive disorder (MDD) is one of the leading causes of years lived with disability and contributor to the burden of disease worldwide. The incidence of MDD has increased by ~20% in the last decade. Currently antidepressant drugs such as the popular selective serotonin reuptake inhibitors (SSRIs) are the leading form of pharmaceutical intervention for the treatment of MDD. SSRIs however, are inefficient in ameliorating depressive symptoms in ~50% of patients and exhibit a prolonged latency of efficacy. Due to the burden of disease, there is an increasing need to understand the neurobiology underpinning MDD and to discover effective treatment strategies. Endogenous models of MDD, such as the Wistar-Kyoto (WKY) rat provide a valuable tool for investigating the pathophysiology of MDD. The WKY rat displays behavioural and neurobiological phenotypes similar to that observed in clinical cases of MDD, as well as resistance to common antidepressants. Specifically, the WKY strain exhibits increased anxiety- and depressive-like behaviours, as well as alterations in Hypothalamic Pituitary Adrenal (HPA) axis, serotonergic, dopaminergic and neurotrophic systems with emerging studies suggesting an involvement of neuroinflammation. More recent investigations have shown evidence for reduced cortical and hippocampal volumes and altered glutamatergic signalling in the WKY strain. Given the growing interest in therapeutics targeting the glutamatergic system, the WKY strain presents itself as a potentially useful tool for screening novel antidepressant drugs and their efficacy against treatment resistant depression. However, despite the sexual dimorphism present in the pathophysiology and aetiology of MDD, sex differences in the WKY model are rarely investigated, with most studies focusing on males. Accordingly, this review highlights what is known regarding sex differences and where further research is needed. Whilst acknowledging that investigation into a range of depression models is required to fully elucidate the underlying mechanisms of MDD, here we review the WKY strain, and its relevance to the clinic.

Effects of Aerobic Exercise on Cortisol Stress Reactivity in Response to the Trier Social Stress Test in Inpatients with Major Depressive Disorders: A Randomized Controlled Trial

Physical activity is associated with a favourable (blunted) cortisol stress reactivity in healthy people. However, evidence from experimental study and with psychiatric patients is missing. This study examines whether exercise training impacts on cortisol stress reactivity in inpatients with major depressive disorder (MDD). These new insights are important because the stress reactivity of healthy people and patients with severe symptoms of depression might differ. Methods: The study was designed as a randomized controlled trial (trial registration number: NCT02679053). In total, 25 patients (13 women, 12 men, mean age: 38.1 12.0 years) completed a laboratory stressor task before and after a six-week intervention period. Nine samples of salivary free cortisol were taken before and after the Trier social stress test (TSST). Fourteen participants took part in six weeks of aerobic exercise training, while 11 patients were allocated to the control condition. While the primary outcome of the study was depressive symptom severity, the focus of this paper is on one of the secondary outcomes (cortisol reactivity during the TSST). The impact of aerobic exercise training was examined with a repeated-measures analysis of variance. We also examined the association between change in depression and cortisol response via correlational analysis. Cortisol reactivity did not change from baseline to post-intervention, either in the intervention or the control group. Participation in six weeks of aerobic exercise training was not associated with participants' cortisol reactivity. Moreover, depressive symptom change was not associated with change in cortisol response. Aerobic exercise training was not associated with patients' stress reactivity in this study. Because many patients initially showed a relatively flat/blunted cortisol response curve, efforts might be needed to find out which treatments are most efficient to promote a normalization of HPA axis reactivity.

Changes in Cortisol but Not in Brain-Derived Neurotrophic Factor Modulate the Association Between Sleep Disturbances and Major Depression

Sleep disturbance is a symptom consistently found in major depression and is associated with a longer course of illness, reduced response to treatment, increased risk of relapse and recurrence. Chronic insomnia has been associated with changes in cortisol and serum brain-derived neurotrophic factor (BDNF) levels, which in turn are also changed in major depression. Here, we evaluated the relationship between sleep quality, salivary cortisol awakening response (CAR), and serum BDNF levels in patients with sleep disturbance and treatment-resistant major depression (n = 18), and in a control group of healthy subjects with good (n = 21) and poor (n = 18) sleep quality. We observed that the patients had the lowest CAR and sleep duration of all three groups and a higher latency to sleep than the healthy volunteers with a good sleep profile. Besides, low CAR was correlated with more severe depressive symptoms and worse sleep quality. There was no difference in serum BDNF levels between groups with distinct sleep quality. Taken together, our results showed a relationship between changes in CAR and in sleep quality in patients with treatment-resistant depression, which were correlated with the severity of disease, suggesting that cortisol could be a physiological link between sleep disturbance and major depression.

An initial exploration of hair cortisol responses to antidepressants in unmedicated patients with depression

OBJECTIVE

Major depressive disorder is associated with abnormal functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Studies using hair cortisol to measure the effect of antidepressants on the HPA axis are lacking. The aim of this study was to explore the long-term effects of antidepressants on hair cortisol concentration (HCC).

METHODS

Participants were 42 patients and 36 healthy individuals. The patients took antidepressants for 4 weeks. Patient HCC was measured pre-treatment and post-treatment. The HCC of healthy controls was also measured.

RESULTS

Patient post-treatment HCC (mean ± standard deviation: 34.40 ± 32.57 pmol/mg) was significantly higher than patient pre-treatment HCC (17.42 ± 12.40 pmol/mg) and healthy control HCC (10.22 ± 7.99 pmol/mg). No significant correlation was found between Hamilton Depression Rating Scale scores and HCC at pre-treatment or post-treatment.

CONCLUSIONS

Hair cortisol concentration analysis could be used to monitor the dynamics of the effects of antidepressants on the HPA axis.

Sex differences in the hypothalamic-pituitary-adrenal axis: An obstacle to antidepressant drug development?

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has long been implicated in the pathophysiology of depression, and HPA axis-based compounds have served as potential new therapeutic targets, but with no success. This review details sex differences from animal and human studies in the function of HPA axis elements (glucocorticoids, corticotropin releasing factor, and vasopressin) and related compounds tested as candidate antidepressants. We propose that sex differences contribute to the failure of novel HPA axis-based drugs in clinical trials. Compounds studied preclinically in males were tested in clinical trials that recruited more, if not exclusively, women, and did not control, but rather adjusted, for potential sex differences. Indeed, clinical trials of antidepressants are usually not stratified by sex or other important factors, although preclinical and epidemiological data support such stratification. In conclusion, we suggest that clinical testing of HPA axis-related compounds creates an opportunity for targeted, personalized antidepressant treatments based on sex. LINKED ARTICLES: This article is part of a themed section on The Importance of Sex Differences in Pharmacology Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.21/issuetoc.

Perinatal exposure to venlafaxine leads to lower anxiety and depression-like behavior in the adult rat offspring

Depression during pregnancy and in the post-partum period is a growing health issue. Venlafaxine, a representative of serotonin and noradrenaline reuptake inhibitors, is used to treat a wide spectrum of mood disorders. However, the limited number of prenatal and perinatal studies raises the question about the long-term consequences of venlafaxine therapy. The aim of this study was to investigate the effect of venlafaxine exposure during pregnancy and lactation on anxiety-like and depression-like behaviors, as well as adrenocortical hormone concentrations in the adult rat offspring. For this purpose, rat dams were treated orally with venlafaxine from day 15 of gestation to postnatal day 20 at doses of 7.5, 37.5, and 75 mg/kg. Administration of venlafaxine during gestation and lactation affected anxiety-like and depression-like behaviors in adult rat offspring of both sexes. The animals exposed through their mothers to venlafaxine, particularly at the lowest and middle doses, were less anxious and less depressive in several relevant behavioral tests, which can be considered a deviation from the normal state. At clinically relevant doses, venlafaxine did not alter circulating level of corticosterone and aldosterone in the adult offspring. In general, the consequences of venlafaxine were dose dependent and more apparent in females. Together, these results suggest that prenatal and early postnatal exposure to venlafaxine may interfere with functional development of the brain, though not necessarily in a negative way.

Trick or treat? Evaluating contributing factors and sex-differences for developmental effects of maternal depression and its treatment

Maternal depression and treatment with selective serotonin reuptake inhibitors (SSRIs), the most common form of pharmaceutical intervention, can both have an impact on infant development. As such, it is difficult for healthcare providers to recommend a course of treatment to expectant mothers suffering from depression, or to women on antidepressant medication prior to pregnancy. This review will discuss the existing research on the developmental impacts of maternal depression and its treatment with SSRIs, with a particular focus on contributing factors that complicate our attempt to disentangle the consequences of maternal depression and its treatment such as the timing or severity of the depression. We will explore avenues for translational animal models to help address the question of "Trick or Treat", i.e.: which is worse for offspring development: exposure to maternal depression, or the SSRI treatment? Further, we will explore sex-dependent outcomes for the offspring in human and animal studies as male and female offspring may react differently to the presence of maternal depression or antidepressant treatment. Without more clinical and preclinical data, it remains difficult for women to make an informed decision regarding their depression treatment before, during, and after their pregnancy.

PTSD psychotherapy improves blood pressure but leaves HPA axis feedback sensitivity stable and unaffected: First evidence from a pre-post treatment study

Although key to development of tailored drugs for augmentation treatment of psychotherapy for posttraumatic stress disorder (PTSD), the biological correlates of PTSD remission are still unknown, probably because pre-post treatment studies searching for them are rare. Not even the feedback sensitivity of the otherwise well-studied hypothalamic-pituitary-adrenal (HPA) axis nor arterial blood pressure (BP), which was previously reported to be elevated in PTSD patients, have so far been analyzed during PTSD treatment. To narrow this knowledge gap, we first performed an overnight dexamethasone suppression test (DST) in a mixed-sex cohort of 25 patients with severe PTSD vs. 20 non-traumatized healthy controls (nt-HC). In addition to hormones, BP and heart rate (HR) were measured at each of the four assessment points (APs). Second, the same parameters were assessed again in 16 of these patients after 12 sessions of integrative trauma-focused cognitive behavioral therapy (iTF-CBT). In relation to nt-HC, PTSD patients showed a significant elevation in HR and diastolic BP while their systolic BP, DST outcomes and basal serum cortisol levels (BSCL) were not significantly altered. In response to iTF-CBT, PTSD symptoms and dysfunctional stress coping strategies improved significantly in PTSD patients. Most important, also their systolic and diastolic BP levels ameliorated at distinct APs while their DST outcomes and BSCL remained unchanged. To our knowledge, this is the first pre-post treatment study assessing the stability of the DST outcome and BP levels during PTSD treatment. Our results provide first evidence for a non-involvement of HPA axis feedback sensitivity in PTSD symptom improvement and, furthermore, suggest a possible role for BP-regulating pathways such as the sympathetic nervous system in PTSD remission. Limitations arise from the small sample size, the lack of an untreated patient group and drug treatment of patients.

Central noradrenaline transporter availability is linked with HPA axis responsiveness and copeptin in human obesity and non-obese controls

The central noradrenaline (NA) stress-response network co-mediates hypothalamic-pituitary-adrenal (HPA) axis activation and arginine-vasopressin (AVP) release. Dysregulation of these systems contributes to stress-related diseases such as human obesity, but their interrelation remains unclear. The study was aimed to test for the first time in vivo whether central noradrenergic activity quantitatively indexed by the availability of the presynaptic NA transporter (NAT) is associated with HPA axis responsiveness as measured with the combined dexamethasone suppression/corticotropin releasing hormone stimulation (dex/CRH) test and copeptin as a surrogate marker of the serum AVP tone in highly obese, otherwise, healthy individuals compared to age- and sex-matched non-obese, healthy controls. In order to assess central NAT availability, positron emission tomography (PET) was applied using the NAT-selective radiotracer S,S-[¹¹C]O-methylreboxetine (MRB) and correlated with curve indicators derived from the dex/CRH test (maximum, MAX, and area under the curve, AUC, for cortisol and adrenocorticotropic hormone, ACTH) as well as with copeptin. In non-obese controls, positive correlations were found between the NAT distribution volume ratios (DVR) of the orbitofrontal cortex (OFC) and the amygdala with the HPA response (OFC: ACTH_MAX r = 0.87, p = .001; cortisol_MAX r = 0.86, p = .002; amygdala: ACTH_MAX r = 0.86, p = .002; cortisol_MAX r = 0.79, p = .006), while in obesity, the hypothalamic DVR correlated inversely with the HPA axis response (cortisol_MAX, r = -0.66, p = .04) and with copeptin (r = -0.71, p = .02). This association of central NAT availability with HPA axis responsiveness and copeptin suggests a mechanistic interaction between noradrenergic transmission with HPA axis activity and the serum AVP system that differs between non-obese individuals with prefrontal-limbic involvement and obesity with a hypothalamic-centered relationship. Whether the latter finding contributes to obesogenic behavior needs to be further explored.

Different Endocrine Effects of an Evening Dose of Amitriptyline, Escitalopram, and Placebo in Healthy Participants

Objective

The primary aim of this study was to further characterize the acute effects of amitriptyline (AMI) and escitalopram (ESC) on serum levels of ghrelin, leptin, cortisol and prolactin in healthy humans.

Methods

Eleven healthy male participants received a single dose of AMI 75 mg, ESC 10 mg, or placebo (PLA) at 9:00 PM in a double blind, randomized, controlled, repeated measures study separated by one week. Fasting morning serum levels (7:00 AM) of ghrelin, leptin, cortisol and prolactin were assessed.

Results

A repeated measures multivariate analysis of variance revealed a significant main effect for the factor condition (AMI, ESC, PLA). Subsequent univariate analyses demonstrated significant condition effects for ghrelin and cortisol. Post-hoc analyses demonstrated a significant reduction of ghrelin levels after AMI in comparison to PLA, and a significant reduction of cortisol levels after AMI in comparison to both ESC and PLA. Other contrasts did not reach statistical significance.

Conclusion

Administration of a single dose of AMI, but not of ESC, leads to a significant reduction in morning serum ghrelin and cortisol levels. No effects on leptin and prolactin levels were observed. The differential impact of AMI and ESC on hormones might contribute to different adverse effect profiles of both substances.

Animal models of maternal depression for monitoring neurodevelopmental changes occurring in dams and offspring

Depression is one of the most prevalent and life-threatening forms of mental illness affecting about 20% of the population. Depressive disorder as a biochemical phenomenon, was first recognized in the mid-20^th century of research, however the etiology of this disease is still not well understood. Although the need to investigate depressive disorders has emerged from the needs of clinical practice, there are many preclinical studies, which brought new insights into this field of research. During experimental work it was crucial to develop appropriate animal models, where the neurohumoral mechanism was similar to humans. In the past decades, several animal models of maternal depression have been developed. We describe the three most popular rodent models of maternal depression which are based on 1. stress prior to gestation, 2. prenatal stress and 3. early life stress. The above-mentioned animal models appear to fulfill many criteria for a relevant animal model of depression; they alter the regulation of the HPA, induce signs of depression-like behavior and several antidepressant treatments can reverse the state induced by maternal stress. Although, they are not able to model all aspects of maternal depression, they are useful models for monitoring neurodevelopmental changes occurring in dams and offspring.

Antidepressant-like actions by silencing of neuronal ELAV-like RNA-binding proteins HuB and HuC in a model of depression in male mice

Currently available antidepressant drugs often fail to achieve full remission and patients might evolve to treatment resistance, showing the need to achieve a better therapy of depressive disorders. Increasing evidence supports that post-transcriptional regulation of gene expression is important in neuronal development and survival and a relevant role is played by RNA binding proteins (RBP). To explore new therapeutic strategies, we investigated the role of the neuron-specific ELAV-like RBP (HuB, HuC, HuD) in a mouse model of depression. In this study, a 4-week unpredictable chronic mild stress (UCMS) protocol was applied to mice to induce a depressive-like phenotype. In the last 2 weeks of the UCMS regimen, silencing of HuB, HuC or HuD was performed by using specific antisense oligonucleotides (aODN). Treatment of UCMS-exposed mice with anti-HuB and anti-HuC aODN improved both anhedonia and behavioural despair, used as measures of depressive-like behaviour, without modifying the response of stressed mice to an anxiety-inducing environment. On the contrary, HuD silencing promoted an anxiolytic-like behaviour in UCMS-exposed mice without improving depressive-like behaviours. The antidepressant-like phenotype of anti-HuB and anti-HuC mice was not shown concurrently with the promotion of adult hippocampal neurogenesis in the dentate gyrus, and no increase in the BDNF and CREB content was detected. Conversely, in the CA3 hippocampal region, projection area of newly born neurons, HuB and HuC silencing increased the number of BrdU/NeuN positive cells. These results give the first indication of a role of nELAV in the modulation of emotional states in a mouse model of depression.

Parallels between Postpartum Disorders in Humans and Preweaning Piglet Mortality in Sows

Simple Summary

Humans and sows are both highly social species that exhibit a wide variety of maternal behaviors and responsivity to pregnancy and parturition. Piglet crushing is a production and welfare concern for the swine industry. Similar to rates of postpartum depression in humans, the performance of piglet crushing is more likely in first-time mothers. Furthermore, hormonal profiles and social factors that influence the development of this disease in humans mirror those observed in sows surrounding parturition. This article reviews the biological, social, and management factors that may be contributing to this problem of piglet crushing through the lens of how postpartum depression develops in humans. Utilizing knowledge from human psychology and animal welfare science may provide producers with management tools to mitigate piglet crushing and provide new insight into the factors that contribute to human postpartum disorders.

Abstract

Pregnancy and parturition in all mammals is accompanied with physical, psychological, social, and hormonal shifts that impact the mother physically and psychologically. Pre-weaning piglet mortality continues to be a major welfare and economic issue in U.S. swine production, running at 12–15% with crushing by the sow the major cause. Much research has focused on farrowing environment design, yet the fact that little progress has been made emphasizes that psychosocial factors may impact rates of postpartum disorders (PPD). There is a mismatch between evolved adaptations and contemporary psychosocial and management practices. Many factors associated with the development of PPD in humans are mirrored in sows that perform piglet crushing. These factors include poor mental welfare (anxiety, difficulty coping with stress), a lack of experience, a lack of social support, and individual differences in their sensitivity to hormone concentrations. Understanding what strategies are effective in preventing PPD in humans may have welfare and production benefits for sows—and sows may be a possible model for better understanding PPD in humans.

Cortisol Modulation by Ayahuasca in Patients With Treatment Resistant Depression and Healthy Controls

Major depression is a highly prevalent mood disorder, affecting about 350 million people, and around 30% of the patients are resistant to currently available antidepressant medications. Recent evidence from a randomized controlled trial (RCT) supports the rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression. The aim of this study was to explore the effect of ayahuasca on plasma cortisol and awakening salivary cortisol response, in the same group of treatment-resistant patients (MD) and in healthy volunteers (C). Subjects received a single dose of ayahuasca or placebo (dosing session), and both plasma and awakening salivary cortisol response were measured at baseline (before dosing session) and 48 h after the dosing session. Baseline assessment (D0) showed blunted awakening salivary cortisol response and hypocortisolemia in patients, with respect to healthy controls. Salivary cortisol was also measured during dosing session, and we observed higher increases for both C and MD that ingested ayahuasca than placebo. After 48 h from the dosing session with ayahuasca, patients' awakening salivary cortisol response is similar to the ones detected in controls. No significant changes in plasma cortisol levels were observed 48 h after the sessions. Therefore, these findings point to new evidence on the modulation of salivary cortisol levels as a result of an ayahuasca session, both in healthy and depressive volunteers. Considering that cortisol acts in regulation of distinct physiological pathways, emotional and cognitive processes, it is assumed to be critically involved to the etiology of depression and its regulation seems to be important for the treatment and remission of major depression, ayahuasca use as antidepressant should be further investigated. Moreover, this study highlights the importance of psychedelics in the treatment of human mental disorders.

HPA axis reactivity to pharmacologic and psychological stressors in euthymic women with histories of postpartum versus major depression

It is unclear whether women with a history of postpartum depression (PPD) have residual, abnormal hypothalamic-pituitary-adrenal (HPA) axis reactivity, as has been reported in major depression (MDD). Further unclear is whether the abnormalities in HPA axis reactivity associated with MDD represent a stable, underlying predisposition or a state-dependent phenomenon. This study sought the following: (1) to determine if euthymic postpartum women with a history of depression have an abnormal HPA axis reactivity to pharmacologic and psychological challenges and (2) to compare HPA reactivity in women with histories of PPD versus MDD. As a secondary objective, we wanted to determine the influence of trauma history on HPA axis function. Forty-five parous (12-24 months postpartum), euthymic women with history of MDD (n = 15), PPD (n = 15), and controls (n = 15) completed pharmacologic (dexamethasone/corticotropin-releasing hormone (CRH) test [DEX/CRH]) and psychological (Trier social stress test [TSST]) challenges during the luteal phase. Outcome measures were cortisol and adrenocorticotropic hormone (ACTH) response after DEX/CRH, and blood pressure, heart rate, epinephrine, norepinephrine, and cortisol response during the TSST. All groups had robust cortisol and ACTH response to DEX/CRH and cortisol response to TSST. Groups did not differ significantly in cortisol or ACTH response to DEX/CRH or in blood pressure, heart rate, epinephrine, norepinephrine, or cortisol response to TSST. Cortisol/ACTH ratio did not differ significantly between groups. Trauma history was associated with decreased cortisol response to DEX/CRH in women with histories of MDD, which was not significant after correction (F _8,125, p = 0.02, Greenhouse-Geisser corrected p = 0.11). Currently euthymic women with histories of MDD or PPD did not demonstrate residual abnormal stress responsivity following administration of either a pharmacologic or psychological stressor.

Escitalopram affects spexin expression in the rat hypothalamus, hippocampus and striatum

BACKGROUND

Spexin (SPX) is a recently discovered neuropeptide that exhibits a large spectrum of central and peripheral regulatory activity, especially when considered as a potent anorexigenic factor. It has already been proven that antidepressants, including selective serotonin reuptake inhibitors (SSRI), can modulate peptidergic signaling in various brain structures. Despite these findings, there is so far no information regarding the influence of treatment with the SSRI antidepressant escitalopram on brain SPX expression.

METHODS

In this current study we measured SPX mRNA and protein expression in the selected brain structures (hypothalamus, hippocampus and striatum) of rats chronically treated with a 10mg/kg dose of escitalopram using quantitative Real-Time PCR and immunohistochemistry.

RESULTS

Strikingly, long-term (4 week) drug treatment led to the downregulation of SPX expression in the rat hypothalamus. This supports the hypothesis that SPX may be involved in the hypothalamic serotonin-dependent actions of SSRI antidepressants and possibly also in the central mechanism of body mass increase. Conversely, SPX expression increased in the hippocampus and striatum.

CONCLUSIONS

This is the first report of the effects of a neuropsychiatric medication on SPX expression in animal brain. Our findings shed a new light on the pharmacology of antidepressants and may contribute to a better understanding of the alternative mechanisms responsible for antidepressant action.

Brain serotonin 4 receptor binding is associated with the cortisol awakening response

Serotonin signalling is considered critical for an appropriate and dynamic adaptation to stress. Previously, we have shown that prefrontal serotonin transporter (SERT) binding is positively associated with the cortisol awakening response (CAR) (Frokjaer et al., 2013), which is an index of hypothalamic-pituitary-adrenal (HPA)-axis output dynamics. Here, we investigated in healthy individuals if cerebral serotonin 4 receptor (5-HT4r) binding, reported to be a proxy for serotonin levels, is associated with CAR. Thirty healthy volunteers (25 males, age range 20-56 years) underwent 5-HT4r PET imaging with [(11)C]-SB207145, genotyping of the SERT-linked polymorphic region (5-HTTLPR), and performed serial home sampling of saliva (5 time points from 0 to 60min from awakening) to assess CAR. The association between 5-HT4r binding in 4 regions of interest (prefrontal cortex, anterior cingulate cortex, pallidostriatum, and hippocampus) and CAR was tested using multiple linear regression with adjustment for age and 5-HTTLPR genotype. Finally, an exploratory voxel-based analysis of the association was performed. CAR was negatively associated with 5-HT4r binding in pallidostriatum (p=0.01), prefrontal cortex (p=0.03), and anterior cingulate cortex (p=0.002), respectively, but showed no association in hippocampus. The results remained significant when taking into account other potentially relevant covariates. In conclusion, our finding reinforces an association between HPA-axis function and serotonin signaling in vivo in humans. We suggest that higher synaptic serotonin concentration, here indexed by lower 5-HT4r binding, supports HPA-axis dynamics, which in healthy volunteers is reflected by a robust CAR.

Altered monoamine system activities after prenatal and adult stress: A role for stress resilience?

INTRODUCTION

Prenatal stress (PNS) and stress in adulthood are risk factors for development of major depressive disorder. The present study aimed to 1) confirm previous neuroendocrine and behavioral changes induced by PNS, and 2) to characterize the effect of early- and late life stress on the in vivo activity of monoamine systems.

METHODS

Gestational dams were restrained thrice daily under bright illumination from gestational day (GD)11-20. Behavior and neuroendocrine responses to the forced swim test (FST) were determined in adult (50-80 days) offspring, and electrophysiological single unit recordings of dorsal raphe nucleus serotonin (5-HT), ventral tegmental area dopamine (DA) and locus coeruleus norepinephrine (NE) neurons were obtained at baseline and 24h after the FST.

RESULTS

Gestational dams did not habituate to chronic restraint stress, and PNS reduced the birth weight of offspring. In adulthood, swim stress elevated CORT levels longer in PNS animals, while it had no effect on swim behaviors. Baseline firing activity of 5-HT neurons was decreased in PNS animals, while the firing activity of NE and DA neurons was increased. Swim stress had no effect on the firing on 5-HT neurons, but normalized the firing activity of catecholamine neurons in PNS animals.

CONCLUSION

The present data confirm previously established effects on neuroendocrine and physiological measures, and demonstrate an altering effect of PNS and stress on monoamine system activities in adulthood. Since PNS did not result in a depressive-like phenotype, these central changes following PNS might play reflect adaptive changes contributing to stress resilience in adulthood.

Is increased antidepressant exposure a contributory factor to the obesity pandemic?

Major depressive disorder (MDD) and obesity are both common heterogeneous disorders with complex aetiology, with a major impact on public health. Antidepressant prescribing has risen nearly 400% since 1988, according to data from the Centers for Disease Control and Prevention (CDC). In parallel, adult obesity rates have doubled since 1980, from 15 to 30 percent, while childhood obesity rates have more than tripled. Rising obesity rates have significant health consequences, contributing to increased rates of more than thirty serious diseases. Despite the concomitant rise of antidepressant use and of the obesity rates in Western societies, the association between the two, as well as the mechanisms underlying antidepressant-induced weight gain, remain under explored. In this review, we highlight the complex relationship between antidepressant use, MDD and weight gain. Clinical findings have suggested that obesity may increase the risk of developing MDD, and vice versa. Hypothalamic-pituitary-adrenal (HPA) axis activation occurs in the state of stress; concurrently, the HPA axis is also dysregulated in obesity and metabolic syndrome, making it the most well-understood shared common pathophysiological pathway with MDD. Numerous studies have investigated the effects of different classes of antidepressants on body weight. Previous clinical studies suggest that the tricyclics amitriptyline, nortriptyline and imipramine, and the serotonin norepinephrine reuptake inhibitor mirtazapine are associated with weight gain. Despite the fact that selective serotonin reuptake inhibitor (SSRI) use has been associated with weight loss during acute treatment, a number of studies have shown that SSRIs may be associated with long-term risk of weight gain; however, because of high variability and multiple confounds in clinical studies, the long-term effect of SSRI treatment and SSRI exposure on body weight remains unclear. A recently developed animal paradigm shows that the combination of stress and antidepressants followed by long-term high-fat diet results, long after discontinuation of antidepressant treatment, in markedly increased weight, in excess of what is caused by high-fat diet alone. On the basis of existing epidemiological, clinical and preclinical data, we have generated the testable hypothesis that escalating use of antidepressants, resulting in high rates of antidepressant exposure, might be a contributory factor to the obesity epidemic.

Testosterone has antidepressant-like efficacy and facilitates imipramine-induced neuroplasticity in male rats exposed to chronic unpredictable stress

Hypogonadal men are more likely to develop depression, while testosterone supplementation shows antidepressant-like effects in hypogonadal men and facilitates antidepressant efficacy. Depression is associated with hypothalamic-pituitary-adrenal (HPA) axis hyperactivity and testosterone exerts suppressive effects on the HPA axis. The hippocampus also plays a role in the feedback regulation of the HPA axis, and depressed patients show reduced hippocampal neuroplasticity. We assessed the antidepressant-like effects of testosterone with, or without, imipramine on behavioral and neural endophenotypes of depression in a chronic unpredictable stress (CUS) model of depression. A 21-day CUS protocol was used on gonadectomized male Sprague-Dawley rats treated with vehicle, 1mg of testosterone propionate, 10mg/kg of imipramine, or testosterone and imipramine in tandem. Testosterone treatment reduced novelty-induced hypophagia following CUS exposure, but not under non-stress conditions, representing state-dependent effects. Further, testosterone increased the latency to immobility in the forced swim test (FST), reduced basal corticosterone, and reduced adrenal mass in CUS-exposed rats. Testosterone also facilitated the effects of imipramine by reducing the latency to immobility in the FST and increasing sucrose preference. Testosterone treatment had no significant effect on neurogenesis, though the combination of testosterone and imipramine increased PSA-NCAM expression in the ventral dentate gyrus. These findings demonstrate the antidepressant- and anxiolytic-like effects of testosterone within a CUS model of depression, and provide insight into the mechanism of action, which appears to be independent of enhanced hippocampal neurogenesis.

Contrasting regional Fos expression in adolescent and young adult rats following acute administration of the antidepressant paroxetine

Adolescents and adults may respond differently to antidepressants, with poorer efficacy and greater probability of adverse effects in adolescents. The mechanisms underlying this differential response are largely unknown, but likely relate to an interaction between the neural effects of antidepressants and brain development. We used Fos immunohistochemistry to examine regional differences in adolescent (postnatal day (PND) 28) and young adult (PND 56) male, Wistar rats given a single injection of the selective serotonin reuptake inhibitor paroxetine (10mg/kg). Paroxetine induced widespread Fos expression in both adolescent and young adult rats. Commonly affected areas include the bed nucleus of the stria terminalis (dorsolateral), medial preoptic area, paraventricular hypothalamic and thalamic nuclei and central nucleus of the amygdala. Fos expression was generally lower in adolescents with significantly greater Fos expression observed in young adults in the prelimbic cortex, supraoptic nucleus, basolateral amygdala, lateral parabrachial and Kölliker-Fuse nuclei. However, a small subset of regions showed greater adolescent Fos expression including the nucleus accumbens shell, lateral habenula and dorsal raphe. Paroxetine increased plasma corticosterone concentrations in young adults, but not adolescents. Plasma paroxetine levels were not significantly different between the age groups. These results indicate a different c-Fos signature of acute paroxetine in adolescent rats, with greater activation in key mesolimbic and serotonergic regions, but a more subdued cortical, brainstem and hypothalamic response. This suggests that the atypical response of adolescents to paroxetine may be related to a blunted neuroendocrine response, combined with insufficient top-down regulation of limbic regions involved in reward and impulsivity.

Corticosterone exposure augments sensitivity to the behavioral and neuroplastic effects of fluoxetine in C57BL/6 mice

Both genetic background and pre-existing stress play critical roles in the effects of antidepressant drugs. The current studies showed this principal by demonstrating that exposure to the stress hormone corticosterone (CORT) allowed behavioral and neurogenic effects to emerge following chronic treatment with fluoxetine of C57BL/6 mice, a strain ordinarily resistant to these effects. Adult male mice were implanted subcutaneously with 21-day slow-release CORT pellets (10 mg) or placebo and then co-treated with 5 mg/kg fluoxetine (b.i.d., i.p.) or saline for 14 days. Animals were then assessed for approach behavior in the novelty-induced hypophagia (NIH) test, hippocampal cell proliferation, corticosteroid receptor expression, and CORT plasma levels. Co-treatment of CORT with fluoxetine significantly reduced approach behavior in the novel environment of the NIH test and increased hippocampal cell proliferation whereas fluoxetine given alone was ineffective. CORT given alone did not alter approach behavior in the novel environment and caused a smaller increase of cell proliferation. The CORT effect was blocked by adrenalectomy and was likely due to increased adrenal feedback. Cell proliferation in CORT-treated animals was associated with reduced mineralocorticoid, but not glucocorticoid, receptor mRNA expression. Although the pellets were advertised to release CORT for 21 days, plasma CORT levels were increased at 1 day after implantation but were not sustained when measured at 7 days or longer intervals. Nevertheless, the transient CORT increase was sufficient to induce long-lasting behavioral and molecular changes when followed by fluoxetine treatment. These studies warrant further investigation into the role of glucocorticoids and environmental stress as adjunctive facilitators of the response to antidepressants, especially for treatment-resistant patients.

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C57BL/6J mice are not responsive to behavioral and neurogenic effects of chronic fluoxetine.

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CORT reduced anxiogenic behavior, increased hippocampal neurogenesis in response to fluoxetine.

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CORT pellets are not effective in sustaining elevated plasma CORT levels.

The HPA axis in bipolar disorder: Systematic review and meta-analysis

OBJECTIVES

To provide a quantitative and qualitative synthesis of the available evidence on the role of Hypothalamic-Pituitary-Adrenal (HPA) axis in the pathophysiology of Bipolar Disorder (BD).

METHODS

Meta-analysis and meta-regression of case-control studies examining the levels of cortisol, ACTH, CRH levels. Systematic review of stress reactivity, genetic, molecular and neuroimaging studies related to HPA axis activity in BD.

RESULTS

Forty-one studies were included in the meta-analyses. BD was associated with significantly increased levels of cortisol (basal and post-dexamethasone) and ACTH, but not of CRH. In the meta-regression, case-control differences in cortisol levels were positively associated with the manic phase (p=0.005) and participants' age (p=0.08), and negatively with antipsychotics use (p=0.001). Reviewed studies suggest that BD is associated with abnormalities of stress-related molecular pathways in several brain areas. Variants of HPA axis-related genes seem not associated with a direct risk of developing BD, but with different clinical presentations. Also, studies on unaffected relatives suggest that HPA axis dysregulation is not an endophenotype of BD, but seems related to environmental risk factors, such as childhood trauma. Progressive HPA axis dysfunction is a putative mechanism that might underlie the clinical and cognitive deterioration of patients with BD.

CONCLUSIONS

BD is associated with dysfunction of HPA axis activity, with important pathophysiological implications. Targeting HPA axis dysfunctions might be a novel strategy to improve the outcomes of BD.

Neurobiological effects of exercise on major depressive disorder: A systematic review

Exercise displays promise as an efficacious treatment for people with depression. However, no systematic review has evaluated the neurobiological effects of exercise among people with major depressive disorder (MDD). The aim of this article was to systematically review the acute and chronic biological responses to exercise in people with MDD. Two authors conducted searches using Medline (PubMed), EMBASE and PsycINFO. From the searches, twenty studies were included within the review, representing 1353 people with MDD. The results demonstrate that a single bout of exercise increases atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), copepetin and growth hormone among people with MDD. Exercise also potentially promotes long-term adaptations of copeptin, thiobarbituric acid reactive species (TBARS) and total mean frequency (TMF). However, there is limited evidence that exercise promotes adaptations on neurogenesis, inflammation biomarkers and brain structure. Associations between depressive symptoms improvement and hippocampus volume and IL-1β were found. Nevertheless, the paucity of studies and limitations presented within, precludes a more definitive conclusion of the underlying neurobiological explanation for the antidepressant effect of exercise in people with MDD. Further trials should utilize appropriate assessments of neurobiological markers in order to build upon the results of our review and further clarify the potential mechanisms associated with the antidepressant effects of exercise.

Paracrine control of steroidogenesis by serotonin in adrenocortical neoplasms

Serotonin (5-hydroxytryptamine; 5-HT) is able to activate the hypothalamo-pituitary-adrenal axis via multiple actions at different levels. In the human adrenal gland, 5-HT, released by subcapsular mast cells, stimulates corticosteroid production through a paracrine mode of communication which involves 5-HT receptor type 4 (5-HT4) primarily located in zona glomerulosa. As a result, 5-HT is much more efficient to stimulate aldosterone secretion than cortisol release in vitro and administration of 5-HT4 receptor agonists to healthy individuals is followed by an increase in plasma aldosterone levels without any change in plasma cortisol concentrations. Interestingly, adrenocortical hyperplasias and tumors responsible for corticosteroid hypersecretion exhibit various cellular and molecular defects which tend to reinforce the intraadrenal serotonergic tone. These pathophysiological mechanisms, which are summarized in the present review, include an increase in adrenal 5-HT production and overexpression of 5-HT receptors in adrenal neoplastic tissues. Altogether, these data support the concept of adrenal serotonergic paracrinopathy and suggest that 5-HT and its receptors may constitute valuable targets for pharmacological treatments of primary adrenal diseases.

Curcumin for the treatment of major depression: a randomised, double-blind, placebo controlled study

BACKGROUND

Curcumin, the principal curcuminoid derived from the spice turmeric, influences several biological mechanisms associated with major depression, namely those associated with monoaminergic activity, immune-inflammatory and oxidative and nitrosative stress pathways, hypothalamus-pituitary-adrenal (HPA) axis activity and neuroprogression. We hypothesised that curcumin would be effective for the treatment of depressive symptoms in individuals with major depressive disorder.

METHODS

In a randomised, double-blind, placebo-controlled study, 56 individuals with major depressive disorder were treated with curcumin (500 mg twice daily) or placebo for 8 weeks. The primary measure was the Inventory of Depressive Symptomatology self-rated version (IDS-SR30). Secondary outcomes included IDS-SR30 factor scores and the Spielberger State-Trait Anxiety Inventory (STAI).

RESULTS

From baseline to week 4, both curcumin and placebo were associated with improvements in IDS-SR30 total score and most secondary outcome measures. From weeks 4 to 8, curcumin was significantly more effective than placebo in improving several mood-related symptoms, demonstrated by a significant group x time interaction for IDS-SR30 total score (F1, 53=4.22, p=.045) and IDS-SR30 mood score (F1, 53=6.51, p=.014), and a non-significant trend for STAI trait score (F1, 48=2.86, p=.097). Greater efficacy from curcumin treatment was identified in a subgroup of individuals with atypical depression.

CONCLUSIONS

Partial support is provided for the antidepressant effects of curcumin in people with major depressive disorder, evidenced by benefits occurring 4 to 8 weeks after treatment.

LIMITATIONS

Investigations with larger sample sizes, over extended treatment periods, and with varying curcumin dosages are required.

Longitudinal effects of the SSRI paroxetine on salivary cortisol in Major Depressive Disorder

Hypothalamic-pituitary-adrenal (HPA)-axis dysregulation is a prominent finding in more severe Major Depressive Disorder (MDD), and is characterized by increased baseline cortisol levels at awakening (BCL), blunted cortisol awakening response (CAR) and increased area under the cortisol curve (AUC). Selective serotonin reuptake inhibitors (SSRIs) appear to normalize HPA-axis dysfunction, but this is hardly investigated longitudinally. We studied salivary BCL, CAR and AUC at awakening and 30min thereafter. We compared measurements in initially drug-free MDD-patients with healthy controls (HCs) at study-entry. In patients, we repeated measures after 6 and 12 weeks' treatment with the SSRI paroxetine. Non-responding patients received a randomized dose-escalation after six weeks' treatment. We found no significant study-entry differences in BLC, CAR or AUC between MDD-patients (n=70) and controls (n=51). In MDD-patients, we found general decreases of BCL and AUC during paroxetine treatment (p≤0.007), especially in late and non-responders. Importantly, while overall CAR did not change significantly over time, it robustly increased over 12 weeks especially when patients achieved remission (p≤0.041). The dose-escalation intervention did not significantly influence CAR or other cortisol parameters. In conclusion, paroxetine seems to interfere with HPA-axis dysregulation, reflected in significant overall decreases in BCL and AUC during treatment. Paroxetine appears to decrease HPA-axis set-point in MDD, which might result in increased HPA-axis activity over time, which is further improved when patients achieve remission (ISRCTN register nr. ISRCTN44111488).

Modulation of OCT3 expression by stress, and antidepressant-like activity of decynium-22 in an animal model of depression

The organic cation transporter-3 (OCT3) is a glucocorticoid-sensitive uptake mechanism that has been shown to regulate the bioavailability of monoamines in brain regions that are implicated in the pathophysiology of depression. In the present study, the relative impacts of acute stress alone and acute stress with a history of repeated stress (chronic+acute) were evaluated in two strains of rats: the stress-vulnerable Wistar-Kyoto (WKY) strain and the somewhat more stress-resilient Long-Evans (LE) strain. OCT3 mRNA was significantly upregulated in the hippocampus of LE rats 2h after exposure to acute restraint stress, but not in acutely-restrained rats with a history of repeated social defeat stress. WKY rats exhibited a very different pattern. OCT3 mRNA was unaffected by acute restraint stress alone but was robustly upregulated after repeated+acute stress. There was also a corresponding increase in cytosolic OCT3 protein following repeated+acute stress in WKY rats 3h after presentation of the acute stressor. These results are consistent with the hypothesis that altered expression of the OCT3 may play a role in stress coping, and strain differences in regulation of this expression may contribute to differences in physiological and behavioral responses to stress. Furthermore, the OCT3 inhibitor, decynium 22 (1 and 10μg/kg, i.p.) reduced immobility of WKY rats, but not that of LE rats, in the forced swim test, suggesting that blockade of the OCT3 has antidepressant-like effects. Since WKY rats also appear to be resistant to the behavioral effects of traditional antidepressants, this also suggests that OCT3 antagonism may be an alternative therapeutic strategy for the treatment of depression in individuals who do not respond to conventional antidepressants.

Influence of sex and stress exposure across the lifespan on endophenotypes of depression: focus on behavior, glucocorticoids, and hippocampus

Sex differences exist in vulnerability, symptoms, and treatment of many neuropsychiatric disorders. In this review, we discuss both preclinical and clinical research that investigates how sex influences depression endophenotypes at the behavioral, neuroendocrine, and neural levels across the lifespan. Chronic exposure to stress is a risk factor for depression and we discuss how stress during the prenatal, postnatal, and adolescent periods differentially affects males and females depending on the method of stress and metric examined. Given that the integrity of the hippocampus is compromised in depression, we specifically focus on sex differences in how hippocampal plasticity is affected by stress and depression across the lifespan. In addition, we examine how female physiology predisposes depression in adulthood, specifically in postpartum and perimenopausal periods. Finally, we discuss the underrepresentation of women in both preclinical and clinical research and how this limits our understanding of sex differences in vulnerability, presentation, and treatment of depression.

The association of proopiomelanocortin polymorphisms with the risk of major depressive disorder and the response to antidepressants via interactions with stressful life events

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis is among the most consistent neuroendocrine abnormalities in major depressive disorder (MDD). The peptide adrenocorticotropin hormone (ACTH) mediates HPA axis function during stress and is encoded by the proopiomelanocortin (POMC) gene polycistronically. After screening 39 POMC polymorphisms, we evaluated the association of polymorphisms with susceptibility to MDD in 145 MDD patients and 193 normal subjects; in patients, we also evaluated the response to treatment with antidepressants. Additionally, we investigated the role of gene-environment interaction between POMC haplotypes and stressful life events (SLE) in the treatment response. Although genotypes and haplotypes were not significantly associated with the risk of MDD, non-remitters were more likely to carry haplotype 1 (ht1) and to have no ht2 than were remitters (corrected P = 0.010-0.035). Although observations were limited in patients without SLE, a significant haplotype-SLE interaction was observed (P = 0.020). Additionally, at 1, 2, and 8 weeks of treatment, the 21-item Hamilton Depression Rating scores of MDD subjects with POMC ht2 were significantly (P = 0.003-0.044) lower than those of patients with ht1 in subjects those did not experience SLE. MDD subjects possessing POMC ht2 achieved remission significantly (P = 0.013; survival analysis) faster than patients with ht1. This study suggests that POMC haplotypes, via an interaction with SLE, are associated with antidepressant treatment outcomes in MDD patients. Regarding SLE, haplotypes of the POMC gene could be useful markers for predicting the response to antidepressant treatment in MDD patients.

Hypothalamic-pituitary-adrenocortical axis: neuropsychiatric aspects

Evidence of aberrant hypothalamic-pituitary-adrenocortical (HPA) activity in many psychiatric disorders, although not universal, has sparked long-standing interest in HPA hormones as biomarkers of disease or treatment response. HPA activity may be chronically elevated in melancholic depression, panic disorder, obsessive-compulsive disorder, and schizophrenia. The HPA axis may be more reactive to stress in social anxiety disorder and autism spectrum disorders. In contrast, HPA activity is more likely to be low in PTSD and atypical depression. Antidepressants are widely considered to inhibit HPA activity, although inhibition is not unanimously reported in the literature. There is evidence, also uneven, that the mood stabilizers lithium and carbamazepine have the potential to augment HPA measures, while benzodiazepines, atypical antipsychotics, and to some extent, typical antipsychotics have the potential to inhibit HPA activity. Currently, the most reliable use of HPA measures in most disorders is to predict the likelihood of relapse, although changes in HPA activity have also been proposed to play a role in the clinical benefits of psychiatric treatments. Greater attention to patient heterogeneity and more consistent approaches to assessing treatment effects on HPA function may solidify the value of HPA measures in predicting treatment response or developing novel strategies to manage psychiatric disease.