The psychoneuroimmunology of depression

Mood, Anxiety, and Cognitive Alterations in Cancer Patients

BACKGROUND AND OBJECTIVE

To analyze the cytokine profile in cerebrospinal fluid (CSF), as well as mood, anxiety, and cognition profiles in patients with CC.

METHODS

One hundred and nine individuals were evaluated, 37 controls, 18 CWC, and 54 CC patients. Assessments included BDI, HADS, Digit Span, FAS-verbal, Animals/WMS-R, Matrix Reasoning and Vocabulary (WASI), and QLQ-C30.

RESULTS

The CC group exhibited 62.96% depression and probable anxiety/depression, with 75.92% showing attention deficits. The CC and CWC groups demonstrated significant cognitive impairment on the WASI-Vocabulary test (CWC: 13.4 ± 2.2; CC: 15.9 ± 1.1) compared to the control group (Ct: 22.8 ± 1.6; p = 0.0002). In the QLQ-C30 scores, the CC group reported a greater perceived loss of quality of life and health deterioration (score of 17.5 ± 2.6) and lower scores on the Functional Scale (49.8 ± 4.5). The CC group had 18.52% illiteracy, 18.52% incomplete higher education, and 22.22% complete elementary education. The CC group also had lower weight (Ct: 67.8 ± 1.4; CWC: 61.7 ± 3.1; CC: 59.6 ± 1.7; p = 0.0023) and BMI (CC: 21.5 [18.3; 24.8]; Ct: 24.9 [23; 25.8]; p = 0.0021) compared to controls. Cytokines detected in the CSF were MCP-1, VEGF, IL-8, IP-10, and MIP-1β. Higher concentrations of MCP-1 were found in cancer patients (CSC: 571.2 ± 105.8; CC: 399.5 ± 65.9; Ct: 1477 ± 0.1; p < 0.0001), along with lower levels of MIP-1β (CC: 4345 [3060; 7353]) and VEGF (CC: 48.3 ± 2.0; CWC: 49.8 ± 3.8; Ct: 64.8 ± 3.2; p < 0.0001).

CONCLUSIONS

The level of mental impairment (mood, anxiety, and cognitive deficits) correlated with cancer-associated and cachexia-associated inflammation, weight loss, low BMI, elevated C-reactive protein (CRP), leukocytosis, lymphopenia, anemia, hypoalbuminemia, and low scores on the QLQ-C30 questionnaire (Global Health Status, Functional Scale, Symptom Scale). The CC group exhibited a higher prevalence of depression/anxiety, a stronger correlation between depression and inflammation, and greater cognitive impairment in attention, reasoning, and language, alongside lower average educational attainment. The low concentration of certain cytokines in the CSF combined with elevated systemic CRP in cancer and cachexia, associated with mental disorders, presents a paradox that requires further investigation. Higher concentrations of the cytokine MCP-1 in cancer patient groups indicated a positive correlation with the preservation of language abilities in these patients.

Prolactin: A Mammalian Stress Hormone and Its Role in Cutaneous Pathophysiology

The hormone prolactin (PRL) is best recognised for its indispensable role in mammalian biology, specifically the regulation of lactation. Bearing in mind that the mammary gland is a modified sweat gland, it is perhaps unsurprising to discover that PRL also plays a significant role in cutaneous biology and is implicated in the pathogenesis of a range of skin diseases, often those reportedly triggered and/or exacerbated by psychological stress. Given that PRL has been implicated in over 300 biological processes, spanning reproduction and hair growth and thermo- to immunoregulation, a comprehensive understanding of the relationship between PRL and the skin remains frustratingly elusive. In an historical curiosity, the first hint that PRL could affect skin biology came from the observation of seborrhoea in patients with post-encephalitic Parkinsonism as a result of another global pandemic, encephalitis lethargica, at the beginning of the last century. As PRL is now being postulated as a potential immunomodulator for COVID-19 infection, it is perhaps timeous to re-examine this pluripotent hormone with cytokine-like properties in the cutaneous context, drawing together our understanding of the role of PRL in skin disease to illustrate how targeting PRL-mediated signalling may represent a novel strategy to treat a range of skin diseases and hair disorders.

Inter- and intrapopulation differences in the association between physical multimorbidity and depressive symptoms

BACKGROUND

The association between physical multimorbidity and depression differs by populations. However, no direct inter- or intrapopulation comparison of the association has been conducted. Thus, this study aims to estimate the association in China and the United States and reveal inter- and intrapopulation differences in the association.

METHODS

Middle-aged and older adults from the China Health and Retirement Longitudinal Study and the Health and Retirement Study were included. Physical multimorbidity was defined as the simultaneous presence of two or more chronic physical conditions and depressive symptoms was measured by the Center for Epidemiologic Studies Depression Scale. Generalized estimating equation model and stratification multilevel method were the main statistical models.

RESULTS

The presence of physical multimorbidity was associated with a higher risk of depression in both China (RR = 1.360 [95 % CI: 1.325-1.395]) and the US (RR = 1.613 [95 % CI: 1.529-1.701]). For individuals at a low risk of multimorbidity, multimorbidity was associated with 47.4 % (95 % CI: 1.377-1.579) and 71.1 % (95 % CI: 1.412-2.074) increases in the likelihood of depression in China and the US. The effect size was smaller for individuals at a moderate or high risk. However, the cross-national differences were greater for those with a high risk of multimorbidity.

LIMITATIONS

The self-report measures, attribution bias.

CONCLUSIONS

Compared to Chinese adults, the presence of physical multimorbidity led to an additional increase in depressive symptoms for American counterparts. The association was stronger for individuals at a low risk of multimorbidity, but cross-national differences were observed mostly among individuals at a high risk.

Increased regional body fat is associated with depressive symptoms: a cross-sectional analysis of NHANES data obtained during 2011-2018

AIMS

The findings from previous epidemiological studies of the association between regional body fat and depressive symptoms have been unclear. We aimed to determine the association between the body fat in different regions and depressive symptoms based on data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

This study included 3393 participants aged ≥ 20 years from the NHANES performed during 2011-2018. Depressive symptoms were assessed using the Patient Health Questionnaire-9. The fat mass (FM) was measured in different regions using dual-energy X-ray absorptiometry to determine the total FM, trunk FM, arm FM, and leg FM. The FM index (FMI) was obtained by dividing the FM in kilograms by the square of the body height in meters. Weighted data were calculated in accordance with analytical guidelines. Linear logistic regression models were used to quantify the association between regional FMI and depressive symptoms. Univariate and stratified analyses were also performed.

RESULTS

The participants in this study comprised 2066 males and 1327 females. There were 404 (11.91%) participants with depressive symptoms, who were aged 40.89 ± 11.74 years and had a body mass index of 30.07 ± 7.82 kg/m². A significant association was found between total FMI and depressive symptoms. In the fully adjusted multivariate regression model, a higher total FMI (odds ratio = 2.18, 95% confidence interval [CI] = 1.08-4.39) was related to a higher risk of depressive symptoms, while increased total FMI (β = 1.55, 95% CI = 0.65-2.44, p = 0.001), trunk FMI (β = 0.57, 95% CI = 0.04-1.10, p = 0.036), and arm FMI (β = 0.96, 95% CI = 0.33-1.59, p = 0.004) were significantly associated with PHQ-9 (Patient Health Questionnaire-9) scores, whereas the leg FMI was not (p = 0.102). The weighted association between total FMI and depressive symptoms did not differ significantly between most of the subpopulations (all p values for interaction > 0.05). The risk of having depression was higher in individuals who were non-Hispanic Whites, smokers, drinkers, obese, and had diabetes and thyroid problems (p < 0.05).

CONCLUSION

These findings suggest that the population with a higher regional FMI is more likely to have depressive symptoms, especially in those who also have an increased total FMI. The association is more pronounced in individuals who are smokers, drinkers, obese, and have diabetes and thyroid problems.

P2X7 receptor: a potential target for treating comorbid anxiety and depression

In clinical practice, depression and anxiety frequently coexist, and they are both comorbid with somatic diseases. The P2X7R is an adenosine 5'-triphosphate (ATP)-gated non-selective cation channel that is widely expressed in immune-related cells. Under conditions of stress, chronic pain, and comorbid chronic physical illness, P2X7R activation in glial cells leads to neuroinflammation. This could contribute to the development of anxiety and depression-related emotional disturbances. Previous studies have shown that the P2X7 receptor (P2X7R) plays an important role in the pathogenesis of both anxiety and depression. Thus, the P2X7R may play a role in the comorbidity of anxiety and depression. Positron emission tomography can be used to assess the degree and location of neuroinflammation by monitoring functional and expression-related changes in P2X7R, which can facilitate clinical diagnoses and guide the treatment of patients with anxiety and depression. Moreover, single nucleotide polymorphisms (SNPs) in the P2X7R gene are associated with susceptibility to different types of psychiatric disorders. Thus, evaluating the SNPs of the P2X7R gene could enable personalized mood disorder diagnoses and treatments. If the P2X7R were set as a therapeutic target, selective P2X7R antagonists may modulate P2X7R function, thereby altering the balance of intra- and extra-cellular ATP. This could have therapeutic implications for treating anxiety and depression, as well as for pain management. According to in vitro and in vivo studies, the P2X7R plays an important role in anxiety and depression. In this review, we consider the potential of the P2X7R as a therapeutic target for comorbid anxiety and depression, and discuss the potential diagnostic and therapeutic value of this receptor.

The effect of inflammation markers on cortical thinning in major depressive disorder: A possible mediator of depression and cortical changes

BACKGROUND

Major depressive disorder (MDD) is a prevalent mental health condition with significant societal impact. Owing to the intricate biological diversity of MDD, treatment efficacy remains limited. Immune biomarkers have emerged as potential predictors of treatment response, underscoring the interaction between the immune system and the brain. This study investigated the relationship between cytokine levels and cortical thickness in patients with MDD, focusing on the corticolimbic circuit, to elucidate the influence of neuroinflammation on structural brain changes and contribute to a deeper understanding of the pathophysiology of MDD.

METHOD

A total of 114 patients with MDD and 101 healthy controls (HC) matched for age, sex, and body mass index (BMI) were recruited. All participants were assessed for depression severity using the Hamilton Depression Rating Scale (HDRS), and 3.0 T T1 weighted brain MRI data were acquired. Additionally, cytokine levels were measured using a highly sensitive bead-based multiplex immunosorbent assay.

RESULTS

Patients diagnosed with MDD exhibited notably elevated levels of interleukin-6 (p = 0.005) and interleukin-8 (p = 0.005), alongside significant cortical thinning in the left anterior cingulate gyrus and left superior frontal gyrus, with these findings maintaining significance even after applying Bonferroni correction. Furthermore, increased interleukin-6 and interleukin-8 levels in patients with MDD are associated with alterations in the left frontomarginal gyrus and right anterior cingulate cortex (ACC).

CONCLUSIONS

This suggests a potential influence of neuroinflammation on right ACC function in MDD patients, warranting longitudinal research to explore interleukin-6 and interleukin-8 mediated neurotoxicity in MDD vulnerability and brain morphology changes.

Gender-specific association of the accumulation of chronic conditions and disability in activities of daily living with depressive symptoms

BACKGROUND

In the era of rapid aging with a rising prevalence of multimorbidity, complex interactions between physical and psychological conditions have challenged the health care system. However, little is known about the association of the accumulation of chronic conditions and disability in activities of daily living with depressive symptoms, especially in developed countries.

METHODS

This population-based cohort study used data from the Health and Retirement Study. A total of 22,335 middle-aged and older adults participated in the 2014 (T1), 2016 (T2), and 2018 (T3) waves of the cohort were included. The accumulation of chronic conditions and disability were defined as the number of chronic diseases and the five activities of daily living. Depressive symptoms were measured by the Center for Epidemiologic Studies Depression Scale. A longitudinal mediation model with a cross-lagged panel model was run. As robust check, the models were applied with a longer follow-up period (from 2012 to 2018). Additionally, results were estimated in China.

RESULTS

Bidirectional associations have been found among the accumulation of chronic conditions, disability, and depressive symptoms, especially between disability and depression. Disability (T2) mediated 11.11 % and 16.87 % of the association between the accumulation of chronic conditions (T1) and depression (T3) for men and women in the United States. The results were consistent in robust analysis.

CONCLUSIONS

This study found that men and women routinely experienced disability and depressive symptoms because of the accumulation of chronic conditions. In terms of depressive symptoms, women were more sensitive to the accumulation of chronic conditions through disability.

Metabolic Syndrome: A Narrative Review from the Oxidative Stress to the Management of Related Diseases

Metabolic syndrome (MS) is a growing disorder affecting thousands of people worldwide, especially in industrialised countries, increasing mortality. Oxidative stress, hyperglycaemia, insulin resistance, inflammation, dysbiosis, abdominal obesity, atherogenic dyslipidaemia and hypertension are important factors linked to MS clusters of different pathologies, such as diabesity, cardiovascular diseases and neurological disorders. All biochemical changes observed in MS, such as dysregulation in the glucose and lipid metabolism, immune response, endothelial cell function and intestinal microbiota, promote pathological bridges between metabolic syndrome, diabesity and cardiovascular and neurodegenerative disorders. This review aims to summarise metabolic syndrome's involvement in diabesity and highlight the link between MS and cardiovascular and neurological diseases. A better understanding of MS could promote a novel strategic approach to reduce MS comorbidities.

Depressive symptoms and allostatic load have a bidirectional association among Puerto Rican older adults

BACKGROUND

Depression is strongly associated with chronic disease; yet, the direction of this relationship is poorly understood. Allostatic load (AL) provides a framework for elucidating depression-disease pathways. We aimed to investigate bidirectional, longitudinal associations of baseline depressive symptoms or AL with 5-year AL or depressive symptoms, respectively.

METHODS

Data were from baseline, 2-year, and 5-year visits of 620 adults (45-75 years) enrolled in the Boston Puerto Rican Health Study. The Center for Epidemiology Studies Depression (CES-D) scale (0-60) captured depressive symptoms, which were categorized at baseline as low (<8), subthreshold (8-15), or depression-likely (⩾16) symptoms. AL was calculated from 11 parameters of biological functioning, representing five physiological systems. Baseline AL scores were categorized by the number of dysregulated parameters: low (0-2), moderate (3-5), or high (⩾6) AL. Multivariable, multilevel random intercept and slope linear regression models were used to examine associations between 3-category baseline CES-D score and 5-year continuous AL score, and between baseline 3-category AL and 5-year continuous CES-D score.

RESULTS

Baseline subthreshold depressive symptoms [(mean (95% CI)): 4.8 (4.5-5.2)], but not depression-likely symptoms [4.5 (4.2-4.9)], was significantly associated with higher 5-year AL scores, compared to low depressive symptoms [4.3 (3.9-4.7)]. Baseline high AL [19.4 (17.6-21.2)], but not low AL [18.5 (16.5-20.6)], was significantly associated with higher 5-year CES-D score, compared to baseline moderate AL [16.9 (15.3-18.5)].

CONCLUSIONS

Depressive symptoms and AL had a bi-directional relationship over time, indicating a nuanced pathway linking depression with chronic diseases among a minority population.

Age as a moderator for the association between depression and self-rated health among cancer survivors: a U.S. based population study

BACKGROUND

Self-rated health (SRH) is a salient outcome for cancer survivors. Although depression is a well-studied correlate with SRH, few studies have focused on the role of cancer survivors' age on the association between depression and SRH. This study evaluates demographic and psychosocial factors associated with cancer survivors' SRH. We also assess the moderating role of age to the association between depression and SRH.

MATERIALS AND METHODS

This paper analyzed 2,470 U.S. cancer survivors from the 2019 National Health Interview Survey. Two ordered logistic regression models with complex survey weights were used for analyses. Missing data was addressed using multiple imputations by chained equations.

RESULTS

Being female, higher education and higher income were positively associated with better SRH. While the relationship between higher education and higher income was consistent with previous findings, the positive association between being female and SRH was different from previous studies. Age significantly moderated the association between depression and SRH, evidenced by results of the joint tests of all interaction term coefficients being statistically significant, F(2, 544.6) = 5.13, p < 0.01.

CONCLUSIONS

The findings of the study highlighted the significance of screening for social determinants of health and health disparity when supporting cancer survivors. Additionally, findings of this study emphasized the significance of adopting an age-specific approach when evaluating and addressing depression across different age groups of cancer survivors.

FKBP51 mediates resilience to inflammation-induced anxiety through regulation of glutamic acid decarboxylase 65 expression in mouse hippocampus

Background

Inflammation is a potential risk factor of mental disturbance. FKBP5 that encodes FK506-binding protein 51 (FKBP51), a negative cochaperone of glucocorticoid receptor (GR), is a stress-inducible gene and has been linked to psychiatric disorders. Yet, the role of FKBP51 in the inflammatory stress-associated mental disturbance remained unclear.

Methods

Fkbp5-deficient (Fkbp5-KO) mice were used to study inflammatory stress by a single intraperitoneal injection of lipopolysaccharide (LPS). The anxiety-like behaviors, neuroimaging, immunofluorescence staining, immunohistochemistry, protein and mRNA expression analysis of inflammation- and neurotransmission-related mediators were evaluated. A dexamethasone drinking model was also applied to examine the effect of Fkbp5-KO in glucocorticoid-induced stress.

Results

LPS administration induced FKBP51 elevation in the liver and hippocampus accompanied with transient sickness. Notably, Fkbp5-KO but not wild-type (WT) mice showed anxiety-like behaviors 7 days after LPS injection (LPS-D7). LPS challenge rapidly increased peripheral and central immune responses and hippocampal microglial activation followed by a delayed GR upregulation on LPS-D7, and these effects were attenuated in Fkbp5-KO mice. Whole-brain [¹⁸F]-FEPPA neuroimaging, which target translocator protein (TSPO) to indicate neuroinflammation, showed that Fkbp5-KO reduced LPS-induced neuroinflammation in various brain regions including hippocampus. Interestingly, LPS elevated glutamic acid decarboxylase 65 (GAD65), the membrane-associated GABA-synthesizing enzyme, in the hippocampus of WT but not Fkbp5-KO mice on LPS-D7. This FKBP51-dependent GAD65 upregulation was observed in the ventral hippocampal CA1 accompanied by the reduction of c-Fos-indicated neuronal activity, whereas both GAD65 and neuronal activity were reduced in dorsal CA1 in a FKBP51-independent manner. GC-induced anxiety was also examined, which was attenuated in Fkbp5-KO and hippocampal GAD65 expression was unaffected.

Conclusions

These results suggest that FKBP51/FKBP5 is involved in the systemic inflammation-induced neuroinflammation and hippocampal GR activation, which may contribute to the enhancement of GAD65 expression for GABA synthesis in the ventral hippocampus, thereby facilitating resilience to inflammation-induced anxiety.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02517-8.

Effects of Celecoxib Adjunct to Selective Serotonin Reuptake Inhibitors on Obsessive-Compulsive Disorder

Introduction:

Inflammatory processes in the brain play an important role in the etiopathogenesis of Obsessive-Compulsive Disorder (OCD). Cyclooxygenase inhibitors, such as celecoxib reduce the production of proinflammatory cytokines. This double-blind study aimed to investigate the effects of adding celecoxib to Selective Serotonin Reuptake Inhibitors (SSRIs)on treating OCD.

Methods:

Sixty patients who met the diagnosis criteria for OCD based on the Diagnostic and Statistical Manual of Mental Disorders -Fourth Edition- Text Revision (DSM-IV-TR) were recruited in the present study. Two psychiatrists independently confirmed the diagnosis by performing structured interviews. The study participants included 23 patients who received SSRIs and celecoxib (400 mg twice daily) and 22 patients in the control group that received SSRIs and placebo. Moreover, at baseline, in weeks 4, 8, and 12, the explored patients were assessed by a psychiatrist using the Yale-Brown Obsessive-Compulsive Scale (Y-BCOS).

Results:

A significant difference was observed in the change of scores on the Y-BOCS in week 12, compared with the onset of the study between the study groups (t= −8.976, df=38, P=0.001). There was a significant difference between the study groups in obsession (F= 49.19, df= 1, P≤0.001), compulsion (F= 13.78, df= 1, P= 0.001), and OCD (F= 57.25, df= 1, P≤0.001), i.e., higher in the celecoxib group.

Conclusion:

This study showed that adjuvant treatment with celecoxib can further improve the symptoms of OCD in individuals receiving SSRIs.

Higher Perceived Stress and Poor Glycemic Changes in Prediabetics and Diabetics Among Indian Population

Diabetes mellitus (DM) is a chronic metabolic disorder with significant co-morbidities and healthcare burdens. Many large studies have investigated the association between perceived stress and DM; however, none investigated this in a larger Indian population. We hypothesized stress as one of the reasons for the progression of people with prediabetes into DM. The present study was, therefore, planned to report on associations between perceived stress and blood glucose markers stratified by diabetic status. The current descriptive study was a subset analysis of the nationwide cross-sectional survey, conducted in all Indian zones under the National Multicentric Diabetes Control Program. The study examined the perceived stress levels using a perceived stress scale (PSS-10) in people with prediabetes (n=649) and DM (n=485) and then segregated them into three categories (minimum, moderate, and severe). Blood glucose markers (fasting blood glucose, postprandial blood glucose, and HbA1c) were evaluated to report their association with the perceived stress. The study revealed a significantly higher HbA1c level in people with prediabetes, particularly those with severe perceived stress (6.12 ± 0.27) compared to other categories. Those with DM had a higher fasting blood glucose level, particularly with severe perceived stress (239.28 ± 99.52). An increased HbA1c level is noted in severely stressed people with prediabetes, requiring a comprehensive analysis with a longitudinal study of the role of perceived stress in the progression of prediabetes into DM. Additionally, higher fasting blood glucose levels in patients with DM and severe perceived stress suggests the need for establishing comprehensive diabetic care inclusive of stress management.

Do health behaviors mediate associations between personality traits and diabetes incidence?

PURPOSE

Personality traits have been reported to be associated with type 2 diabetes (T2DM) risk. The objective of this study was to examine whether and to what extent the associations between personality traits (dispositional optimism, hostility, and negative emotional expressiveness) and risk of T2DM were mediated by health behaviors and obesity.

METHODS

Postmenopausal women (n = 110,992) aged 50-79 years without diabetes at enrollment in the Women's Health Initiative study (1993-1998) were followed up to 25 years. Incident diabetes was assessed via a validated self-report of physician-diagnosed diabetes treated with insulin or other hypoglycemic medications. Mediation analyses were performed using approaches under a counterfactual framework.

RESULTS

An inverse association of optimism with diabetes was significantly mediated by a factor primarily extracted from physical activity, diet quality, and sleep quality with a mediated proportion of 28%. Positive associations for hostility and negative emotional expressiveness were substantially mediated by a factor primarily composed of body mass index and waist circumference with mediated proportions of 32% and 44%, respectively.

CONCLUSIONS

Our data revealed that less than half of the associations between personality traits and risk of T2DM were explained by indirect health behavior pathways. Women's personality traits should be considered in prevention of diabetes in addition to promoting health behaviors.

Real-Time Stress Assessment Using Sliding Window Based Convolutional Neural Network

Mental stress has been identified as a significant cause of several bodily disorders, such as depression, hypertension, neural and cardiovascular abnormalities. Conventional stress assessment methods are highly subjective and tedious and tend to lack accuracy. Machine-learning (ML)-based computer-aided diagnosis systems can be used to assess the mental state with reasonable accuracy, but they require offline processing and feature extraction, rendering them unsuitable for real-time applications. This paper presents a real-time mental stress assessment approach based on convolutional neural networks (CNNs). The CNN-based approach afforded real-time mental stress assessment with an accuracy as high as 96%, the sensitivity of 95%, and specificity of 97%. The proposed approach is compared with state-of-the-art ML techniques in terms of accuracy, time utilisation, and quality of features.

Sex-Specific Effects of Early Life Stress on Brain Mitochondrial Function, Monoamine Levels and Neuroinflammation

Sex differences have been reported in the susceptibility to early life stress and its neurobiological correlates in humans and experimental animals. However, most of the current research with animal models of early stress has been performed mainly in males. In the present study, prolonged maternal separation (MS) paradigm was applied as an animal model to resemble the effects of adverse early experiences in male and female rats. Regional brain mitochondrial function, monoaminergic activity, and neuroinflammation were evaluated as adults. Mitochondrial energy metabolism was greatly decreased in MS females as compared with MS males in the prefrontal cortex, dorsal hippocampus, and the nucleus accumbens shell. In addition, MS males had lower serotonin levels and increased serotonin turnover in the prefrontal cortex and the hippocampus. However, MS females showed increased dopamine turnover in the prefrontal cortex and increased norepinephrine turnover in the striatum, but decreased dopamine turnover in the hippocampus. Sex differences were also found for pro-inflammatory cytokine levels, with increased levels of TNF-α and IL-6 in the prefrontal cortex and hippocampus of MS males, and increased IL-6 levels in the striatum of MS females. These results evidence the complex sex- and brain region-specific long-term consequences of early life stress.

Personality traits and diabetes incidence among postmenopausal women

OBJECTIVE

We examined whether personality traits, including optimism, ambivalence over emotional expressiveness, negative emotional expressiveness, and hostility, were associated with risk of developing type 2 diabetes (hereafter diabetes) among postmenopausal women.

METHODS

A total of 139,924 postmenopausal women without diabetes at baseline (between 1993 and 1998) aged 50 to 79 years from the Women's Health Initiative were prospectively followed for a mean of 14 (range 0.1-23) years. Multivariable Cox proportional hazards regression models were used to assess associations between personality traits and diabetes incidence adjusting for common demographic factors, health behaviors, and depressive symptoms. Personality traits were gathered at baseline using questionnaires. Diabetes during follow-up was assessed via self-report of physician-diagnosed treated diabetes.

RESULTS

There were 19,240 cases of diabetes during follow-up. Compared with women in the lowest quartile of optimism (least optimistic), women in the highest quartile (most optimistic) had 12% (hazard ratio [HR], 0.88; 95% confidence interval [CI]: 0.84-0.92) lower risk of incident diabetes. Compared with women in the lowest quartile for negative emotional expressiveness or hostility, women in the highest quartile had 9% (HR, 1.09; 95% CI: 1.05-1.14) and 17% (HR, 1.17; 95% CI: 1.12-1.23) higher risk of diabetes, respectively. The association of hostility with risk of diabetes was stronger among nonobese than obese women.

CONCLUSIONS

Low optimism and high NEE and hostility were associated with increased risk of incident diabetes among postmenopausal women independent of major health behaviors and depressive symptoms. In addition to efforts to promote healthy behaviors, women's personality traits should be considered to guide clinical or programmatic intervention strategies in diabetes prevention.

Are neuropeptides relevant for the mechanism of action of SSRIs?

Selective serotonin reuptake inhibitors (SSRIs) are drugs of first choice in the therapy of moderate to severe depression and anxiety disorders. Their primary mechanism of action is via influence of the serotonergic (5-HT) system, but a growing amount of data provides evidence for other non-monoaminergic players in SSRI effects. It is assumed that neuropeptides, which play a role as neuromodulators in the CNS, are involved in their mechanism of action. In this review we focus on six neuropeptides: corticotropin-releasing factor - CRF, galanin - GAL, oxytocin - OT, vasopressin - AVP, neuropeptide Y - NPY, and orexins - OXs. First, information about their roles in depression and anxiety disorders are presented. Then, findings describing their interactions with the 5-HT system are summarized. These data provide background for analysis of the results of published preclinical and clinical studies related to SSRI effects on the neuropeptide systems. We also report findings showing how modulation of neuropeptide transmission influences behavioral and neurochemical effects of SSRIs. Finally, future research necessary for enriching our knowledge of SSRI mechanisms of action is proposed. Recognition of new molecular targets for antidepressants will have a significant effect on the development of novel therapeutic strategies for mood-related disorders.

Corticostriatal circuit defects in Hoxb8 mutant mice

Hoxb8 mutant mice exhibit compulsive grooming and hair removal dysfunction similar to humans with the obsessive-compulsive disorder (OCD)-spectrum disorder, trichotillomania. As, in the mouse brain, the only detectable cells that label with Hoxb8 cell lineage appear to be microglia, we suggested that defective microglia cause the neuropsychiatric disorder. Does the Hoxb8 mutation in microglia lead to neural circuit dysfunctions? We demonstrate that Hoxb8 mutants contain corticostriatal circuit defects. Golgi staining, ultra-structural and electrophysiological studies of mutants reveal excess dendritic spines, pre- and postsynaptic structural defects, long-term potentiation and miniature postsynaptic current defects. Hoxb8 mutants also exhibit hyperanxiety and social behavioral deficits similar to mice with neuronal mutations in Sapap3, Slitrk5 and Shank3, reported models of OCD and autism spectrum disorders (ASDs). Long-term treatment of Hoxb8 mutants with fluoxetine, a serotonin reuptake inhibitor, reduces excessive grooming, hyperanxiety and social behavioral impairments. These studies provide linkage between the neuronal defects induced by defective Hoxb8-microglia and neuronal dysfunctions directly generated by mutations in synaptic components that result in mice, which display similar pathological grooming, hyperanxiety and social impairment deficits. Our results shed light on Hoxb8 microglia-driven circuit-specific defects and therapeutic approaches that will become essential to developing novel therapies for neuropsychiatric diseases such as OCD and ASDs with Hoxb8-microglia being the central target.

Two distinct ontogenies confer heterogeneity to mouse brain microglia

Hoxb8 mutant mice show compulsive behavior similar to trichotillomania, a human obsessive-compulsive-spectrum disorder. The only Hoxb8 lineage-labeled cells in the brains of mice are microglia, suggesting that defective Hoxb8 microglia caused the disorder. What is the source of the Hoxb8 microglia? It has been posited that all microglia progenitors arise at embryonic day (E) 7.5 during yolk sac hematopoiesis, and colonize the brain at E9.5. In contrast, we show the presence of two microglia subpopulations: canonical, non-Hoxb8 microglia and Hoxb8 microglia. Unlike non-Hoxb8 microglia, Hoxb8 microglia progenitors appear to be generated during the second wave of yolk sac hematopoiesis, then detected in the aorto-gonad-mesonephros (AGM) and fetal liver, where they are greatly expanded, prior to infiltrating the E12.5 brain. Further, we demonstrate that Hoxb8 hematopoietic progenitor cells taken from fetal liver are competent to give rise to microglia in vivo Although the two microglial subpopulations are very similar molecularly, and in their response to brain injury and participation in synaptic pruning, they show distinct brain distributions which might contribute to pathological specificity. Non-Hoxb8 microglia significantly outnumber Hoxb8 microglia, but they cannot compensate for the loss of Hoxb8 function in Hoxb8 microglia, suggesting further crucial differences between the two subpopulations.

Classical Risk Factors and Inflammatory Biomarkers: One of the Missing Biological Links between Cardiovascular Disease and Major Depressive Disorder

BACKGROUND

Cardiovascular disorders (CVD) and major depressive disorder (MDD) are the most frequent diseases worldwide responsible for premature death and disability. Behavioral and immunological variables influence the pathophysiology of both disorders. We therefore determined frequency and severity of MDD in CVD and studied whether MDD without CVD or other somatic diseases influences classical and inflammatory biomarkers of cardiovascular risk. In addition, we investigated the influence of proinflammatory cytokines on antidepressant treatment outcome.

METHODS

In a case-control design, 310 adults (MDD patients without CVD, CVD patients, and cardiologically and psychiatrically healthy matched controls) were investigated. MDD patients were recruited after admission in a psychiatric university hospital. Primary outcome criteria were clinical depression ratings (HAM-D scale), vital signs, classical cardiovascular risk factors and inflammatory biomarkers which were compared between MDD patients and healthy controls.

RESULTS

We detected an enhanced cardiovascular risk in MDD. Untreated prehypertension and signs directing to a metabolic syndrome were detected in MDD. Significantly higher inflammatory biomarkers such as the high sensitivity C-reaktive protein (hsCRP) and proinflammatory acute phase cytokines interleukine-1β (IL-1β) and interleukine-6 (IL-6) underlined the higher cardiovascular risk in physically healthy MDD patients. Surprisingly, high inflammation markers before treatment were associated with better clinical outcome and faster remission. The rate of MDD in CVD patients was high.

CONCLUSIONS

Patients suffering from MDD are at specific risk for CVD. Precise detection of cardiovascular risks in MDD beyond classical risk factors is warranted to allow effective prophylaxis and treatment of both conditions. Future studies of prophylactic interventions may help to provide a basis for prophylactic treatment of both MDD and CVD. In addition, the high risk for MDD in CVD patients was confirmed and underlines the requirement for clinical attention.

The role of anxious distress in immune dysregulation in patients with major depressive disorder

Although depression with anxious distress appears to be a clinically relevant subtype of major depressive disorder (MDD), whether it involves specific pathophysiology remains unclear. Inflammation has been implicated, but not comprehensively studied. We examined within a large MDD sample whether anxious distress and related anxiety features are associated with differential basal inflammation and innate cytokine production capacity. Data are from 1078 MDD patients from the Netherlands Study of Depression and Anxiety. In addition to the DSM-5 anxious distress specifier, we studied various dimensional anxiety scales (e.g. Inventory of Depressive Symptomatology anxiety arousal subscale [IDS-AA], Beck Anxiety Inventory [BAI], Mood and Anxiety Symptoms Questionnaire Anxious Arousal scale [MASQ-AA]). The specifier was constructed using five self-report items from the IDS and BAI. Basal inflammatory markers included C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α. Innate production capacity was assessed by 13 lipopolysaccharide (LPS)-stimulated inflammatory markers. Basal and LPS-stimulated inflammation index scores were created. Basal inflammation was not associated with anxious distress (prevalence = 54.3%) in MDD patients, except for a modest positive association for BAI score. However, anxious distress was associated with higher LPS-stimulated levels (interferon-γ, IL-6, monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, matrix metalloproteinase (MMP)-2, TNF-α, LPS-stimulated index). Other anxiety indicators (anxious distress specifier score, BAI, MASQ-AA) were also associated with increased innate production capacity. Within a large MDD sample, the anxious distress specifier was associated with increased innate cytokine production capacity but not with basal inflammation. Results from dimensional anxiety indicators largely confirm these results. These findings provide new insight into the pathophysiology of anxious depression.

Cortical thickness and subcortical structure volume abnormalities in patients with major depression with and without anxious symptoms

BACKGROUND

Anxious depression is one of the common subtypes of major depressive disorder (MDD). Clinically, patients with anxious depression exhibit more severe depressive symptoms than patients with nonanxious depression. The aim of the present study was to explore the common and differing cortical and subcortical structural changes between patients with anxious and nonanxious depression.

METHODS

Patients were placed into one of three groups: the anxious depression group (MDD patients with high levels of anxiety symptoms, n = 23), the nonanxious depression group (n = 22), and healthy controls (n = 43) that were matched for age, sex, and education level. All participants underwent T1-weighted MRI. The Freesurfer, which uses a set of automated sequences to analyze the abnormal changes of cortical thickness, cortical and subcortical structures, was used to process the T1 images.

RESULTS

Compared to controls, MDD patients showed thinner cortical thickness in the left inferior temporal, the right superior temporal, and the right parsorbitalis, and a smaller volume of the left hippocampus. Compared to nonanxious depression, anxious depressive patients showed a cortical thinning of the left superior frontal and right superior temporal, as well as the right lingual, and significantly increased subcortical volume of the bilateral caudate nuclei. Correlation analysis showed that the volumes of the bilateral caudate nuclei were directly proportional to the anxiety/somatization factor score.

CONCLUSIONS

These findings suggest that smaller hippocampal volume and atrophic prefrontal and temporal cortices might be a common pattern of cortical and subcortical alterations in patients with depression and/or anxiety. However, the change in the caudate nucleus volume may be indicative of anxious depression and may potentially be used to distinguish anxious from nonanxious depression.

Peripheral inflammatory cytokines and immune balance in Generalised Anxiety Disorder: Case-controlled study

INTRODUCTION

Previous investigations have demonstrated that major depression is associated with particular patterns of cytokine signalling. The primary aim of this study was to examine peripheral pro-inflammatory and anti-inflammatory cytokines and immune balance in Generalised Anxiety Disorder (GAD).

METHODS

A case-controlled cross-sectional study design was employed: 54 patients with GAD and 64 healthy controls were recruited. Participants completed self-report measures of anxiety and depression. Two pro-inflammatory and two anti-inflammatory cytokines were measured using multiplex technology.

RESULTS

Case-control logistic regression analyses revealed significant differences in serum levels of IL-10, TNF-α, and IFN-γ between GAD and control groups after adjusting for age, gender, body mass index, smoking and alcohol consumption: these group differences were independent of the presence or degree of depression. Comparison of pro-inflammatory to anti-inflammatory cytokine ratios indicated that there were significantly higher ratios of TNF-α/IL10, TNF-α/IL4, IFN-γ/IL10, and IFN-γ/IL4 in the GAD group compared to the control group.

CONCLUSIONS

This study is the first to investigate both pro- and anti-inflammatory cytokines and their balance in patients with GAD in comparison to healthy controls. The findings indicate a relatively increased pro-inflammatory response and decreased anti-inflammatory response and provide the first demonstration of an altered cytokine balance in GAD. Serum cytokine levels in GAD were independent of the presence of depression.

Circuits Regulating Pleasure and Happiness-Mechanisms of Depression

According to our model of the regulation of appetitive-searching vs. distress-avoiding behaviors, the motivation to display these essential conducts is regulated by two parallel cortico-striato-thalamo-cortical, re-entry circuits, including the core and the shell parts of the nucleus accumbens, respectively. An entire series of basal ganglia, running from the caudate nucleus on one side, to the centromedial amygdala on the other side, controls the intensity of these reward-seeking and misery-fleeing behaviors by stimulating the activity of the (pre)frontal and limbic cortices. Hyperactive motivation to display behavior that potentially results in reward induces feelings of hankering (relief leads to pleasure). Hyperactive motivation to exhibit behavior related to avoidance of misery results in dysphoria (relief leads to happiness). These two systems collaborate in a reciprocal fashion. In clinical depression, a mismatch exists between the activities of these two circuits: the balance is shifted to the misery-avoiding side. Five theories have been developed to explain the mechanism of depressive mood disorders, including the monoamine, biorhythm, neuro-endocrine, neuro-immune, and kindling/neuroplasticity theories. This paper describes these theories in relationship to the model (described above) of the regulation of reward-seeking vs. misery-avoiding behaviors. Chronic stress that leads to structural changes may induce the mismatch between the two systems. This mismatch leads to lack of pleasure, low energy, and indecisiveness, on one hand, and dysphoria, continuous worrying, and negative expectations on the other hand. The neuroplastic effects of monoamines, cortisol, and cytokines may mediate the induction of these structural alterations. Long-term exposure to stressful situations (particularly experienced during childhood) may lead to increased susceptibility for developing this condition. This hypothesis opens up the possibility of treating depression with psychotherapy. Genetic and other biological factors (toxic, infectious, or traumatic) may increase sensitivity to the induction of relevant neuroplastic changes. Reversal or compensation of these neuroplastic adjustments may explain the effects of biological therapies in treating depression.

Genetic Deletion of Neuronal PPARγ Enhances the Emotional Response to Acute Stress and Exacerbates Anxiety: An Effect Reversed by Rescue of Amygdala PPARγ Function

PPARγ is one of the three isoforms of the Peroxisome Proliferator-Activated Receptors (PPARs). PPARγ is activated by thiazolidinediones such as pioglitazone and is targeted to treat insulin resistance. PPARγ is densely expressed in brain areas involved in regulation of motivational and emotional processes. Here, we investigated the role of PPARγ in the brain and explored its role in anxiety and stress responses in mice. The results show that stimulation of PPARγ by pioglitazone did not affect basal anxiety, but fully prevented the anxiogenic effect of acute stress. Using mice with genetic ablation of neuronal PPARγ (PPARγ^NestinCre), we demonstrated that a lack of receptors, specifically in neurons, exacerbated basal anxiety and enhanced stress sensitivity. The administration of GW9662, a selective PPARγ antagonist, elicited a marked anxiogenic response in PPARγ wild-type (WT), but not in PPARγ^NestinCre knock-out (KO) mice. Using c-Fos immunohistochemistry, we observed that acute stress exposure resulted in a different pattern of neuronal activation in the amygdala (AMY) and the hippocampus (HIPP) of PPARγ^NestinCre KO mice compared with WT mice. No differences were found between WT and KO mice in hypothalamic regions responsible for hormonal response to stress or in blood corticosterone levels. Microinjection of pioglitazone into the AMY, but not into the HIPP, abolished the anxiogenic response elicited by acute stress. Results also showed that, in both regions, PPARγ colocalizes with GABAergic cells. These findings demonstrate that neuronal PPARγ is involved the regulation of the stress response and that the AMY is a key substrate for the anxiolytic effect of PPARγ.

SIGNIFICANCE STATEMENT

Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) is a classical target for antidiabetic therapies with thiazolidinedione compounds. PPARγ agonists such as rosiglitazone and pioglitazone are in clinical use for the treatment of insulin resistance. PPARγ has recently attracted attention for its involvement in the regulation of CNS immune response and functions. Here, we demonstrate that neuronal PPARγ activation prevented the negative emotional effects of stress and exerted anxiolytic actions without influencing hypothalamic-pituitary-adrenal axis function. Conversely, pharmacological blockade or genetic deletion of PPARγ enhanced anxiogenic responses and increased vulnerability to stress. These effects appear to be controlled by PPARγ neuronal-mediated mechanisms in the amygdala.

Abnormal gene expression of proinflammatory cytokines and their membrane-bound receptors in the lymphocytes of depressed patients

Abnormalities of protein levels of proinflammatory cytokines and their soluble receptors have been reported in plasma of depressed patients. In this study, we examined the role of cytokines and their membrane-bound receptors in major depressive disorder (MDD). We determined the protein and mRNA expression of proinflammatory cytokines, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and mRNA expression of their membrane-bound receptors in the lymphocytes from 31 hospitalized MDD patients and 30 non-hospitalized normal control (NC) subjects. The subjects were diagnosed according to DSM-IV criteria. Protein levels of cytokines were determined by ELISA, and mRNA levels in lymphocytes were determined by the qPCR method. We found that the mean mRNA levels of the proinflammatory cytokines IL-1β, IL-6, TNF-α, their receptors, TNFR1, TNFR2, IL-1R1 and the antagonist IL-1RA were significantly increased in the lymphocytes of MDD patients compared with NC. No significant differences in the lymphocyte mRNA levels of IL-1R2, IL-6R, and Gp130 were observed between MDD patients and NC. These studies suggest abnormal gene expression of these cytokines and their membrane-bound receptors in the lymphocytes of MDD patients, and that their mRNA expression levels in the lymphocytes could be a useful biomarker for depression.

Association Between Serum Levels of Vitamin D and the Risk of Post-Stroke Anxiety

Low levels of serum vitamin D are common in patients with mood disorders and stroke. It has been shown that low levels of serum vitamin D indicate a risk of depression in post-stroke subjects. Our aim was to determine the relationship between vitamin D and post-stroke anxiety (PSA).A consecutive series of 226 first acute ischemic stroke patients were recruited and followed up for 1 month. Serum levels of vitamin D were measured within 24 hours of admission. Patients with significant clinical symptoms of anxiety and a Hamilton anxiety scale score >7 were diagnosed as having PSA. In addition, 100 healthy subjects were recruited as controls and underwent measurements of serum vitamin D.A total of 60 patients (26.55%) showed anxiety at 1 month. Both PSA patients and non-PSA patients had lower serum levels of vitamin D than healthy subjects. A significant relationship was found between PSA and serum levels of vitamin D. Low serum levels of vitamin D (≤38.48 nmol/L) were independently associated with the development of PSA (OR: 2.49, 95% CI: 1.21-5.13, P = 0.01).Serum vitamin D status is related to the occurrence of anxiety in post-stroke patients and may be an independent risk factor of PSA after 1 month.

Persons Living With HIV/AIDS: Employment as a Social Determinant of Health

Purpose: For persons living with HIV/AIDS (PLWHA), the advent of highly active antiretroviral therapy has increased their longevity and quality of life. As HIV progresses, many PLWHA present declined domains of functioning that impede their ability to work. The authors explore employment as a social determinant of health to identify issues impacting employment outcomes for PLWHA.

Methods: The authors reviewed the literature addressing HIV across the domains of mental health functioning, neurocognitive functioning, and physical function and employment.

Results: When providing employment services to PLWHA, considerations for rehabilitation practitioners and educators include HIV/AIDS education, functional assessment, social support, considerations for women with HIV, highly active antiretroviral therapy (HAART), HIV/AIDS stigma, and employment resources for PLWHA.

Conclusion: With more than 1.2 million PLWHA in the United States, and most of new infections among persons 25–44 years of age, the prevalence of PLWHA seeking employment and inclusive of the U.S. workforce will continue to increase. Proving employment services for PLWHA is a complex process that is best served by an integrative service approach.

Care Partners and Multiple Sclerosis: Differential Effect on Men and Women

BACKGROUND

Caring for someone with multiple sclerosis (MS) can be a stressful experience that requires clinical attention. We investigated the impact of caregiver stress on the emotional well-being and physical health of the MS care partner using the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry.

METHODS

Care partners of NARCOMS participants were invited to complete an online questionnaire that captured demographic characteristics, health status, caregiver burden as measured by the Zarit Caregiver Burden Interview, and impact of caregiving on employment.

RESULTS

Of 1446 care partners who agreed to participate, 1333 had complete data. Most were men (n = 825, 61.9%), with a mean (SD) age of 51.1 (11.2) years. The mean (SD) Zarit total score was 24.6 (15.1), placing the overall group in the mild caregiver burden range. Compared with male care partners, female care partners reported higher levels of burden and stress and more medication use for stress/anxiety and mood disorders. Male care partners were more likely to report physical concerns. Care partners of people with primary progressive MS reported greater perceived burden than did partners of people with secondary progressive MS and relapsing-remitting MS. More than 40% of care partners (559 of 1288) had missed work during the past year owing to caregiving responsibilities.

CONCLUSIONS

Care partners of people with MS have substantial physical and psychological health concerns and experience an adverse impact on employment. Future research should evaluate how to mitigate the adverse effects of caregiving and evaluate positive aspects of the role.

Epidemiological support for genetic variability at hypothalamic-pituitary-adrenal axis and serotonergic system as risk factors for major depression

BACKGROUND

Major depressive disorder (MDD) is a serious, and common psychiatric disorder worldwide. By the year 2020, MDD will be the second cause of disability in the world. The GranadΣp study is the first, to the best of our knowledge, epidemiological study of mental disorders carried out in Andalusia (South Spain), being one of its main objectives to identify genetic and environmental risk factors for MDD and other major psychiatric disorders. In this study, we focused on the possible association of 91 candidate single nucleotide polymorphisms (SNPs) with MDD.

METHODS

A total of 711 community-based individuals participated in the GranadΣp study. All individuals were extensively assessed for clinical, psychological, sociodemographic, life style, and other environmental variables. A biological sample was also collected for subsequent genetic analyses in 91 candidate SNPs for MDD. DSM-IV diagnosis of MDD was used as the outcome variable. Logistic regression analysis assuming an additive genetic model was performed to test the association between MDD and the genetic data. The experiment-wide significance threshold adjusted with the SNP spectral decomposition method provided a maximum P-value (8×10(-3)) required to identify an association. Haplotype analyses were also performed.

RESULTS

One SNP (rs623580) located in the tryptophan hydroxylase 1 gene (TPH1; chromosome 11), one intergenic variant (rs9526236) upstream of the 5-hydroxytryptamine receptor 2A gene (HTR2A; chromosome 13), and five polymorphisms (rs17689966, rs173365, rs7209436, rs110402, and rs242924) located in the corticotropin-releasing hormone receptor 1 gene (CRHR1; chromosome 17), all showed suggestive trends for association with MDD (P<0.05). Within CRHR1 gene, the TATGA haplotype combination was found to increase significantly the risk for MDD with an odds ratio =1.68 (95% CI: 1.16-2.42, P=0.006).

CONCLUSION

Although limited, perhaps due to insufficient sample size power, our results seem to support the notion that the hypothalamic-pituitary-adrenal and serotonergic systems are likely to be involved in the genetic susceptibility for MDD. Future studies, including larger samples, should be addressed for further validation and replication of the present findings.

Depressive symptoms post hip fracture in older adults are associated with phenotypic and functional alterations in T cells

Background

Ageing is accompanied by reduced immunity, termed immunesenescence. The immune system does not act in isolation and is sensitive to both psychological and physical stress. Hip fracture is a common physical stressor in older adults with a high incidence of new onset depression, which relates to poorer prognosis. We therefore set out to examine the possible synergistic effects of physical stress (hip fracture) and psychological stress (depressive symptoms) on the aged immune system.

Results

T cell phenotype and function was assessed in 101 hip fracture patients (81 female) 6 weeks after hip fracture and 43 healthy age-matched controls (26 female). 38 fracture patients had depressive symptoms at 6 weeks. T cell frequency (p = .01) and numbers (p = .003) were both lower in depressed hip fracture patients compared to healthy controls. The frequency of senescent CD28^-ve (p = .001), CD57^+ve (p = .001), KLRG1^+ve (p = .03) CD8 T cells, as well as senescent CD28^-ve CD4^+ve (p = .01) and CD57^+ve CD4^+ve (p = .003) T cells were higher in depressed hip fracture patients compared with healthy controls and the frequency of CD28^-ve CD8 T cells was also higher when compared to patients with hip fracture alone (p = .01). Additionally, activated CD69^+ve (p = .005) and HLADR^+ve (p < .001) CD8 T cells, were also higher in depressed hip fracture patients compared to healthy controls. On examining cytokine production by activated T cells, a significant increase in TNFα (p = .03) and IL6 (p = .04) production was observed in CD4 T cells from hip fracture patients with depressive symptoms compared to healthy controls.

Conclusions

As none of the patients in the study had a prior history of depression, our data suggest that the development of depressive symptoms in hip fracture patients is associated with altered T cell phenotype and increased pro-inflammatory function which is not seen in patients who do not develop depression after hip fracture. Treating depressive symptoms promptly in hip fracture patients may therefore improve immunity and outcomes in these patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-014-0025-5) contains supplementary material, which is available to authorized users.

Relevance of the anti-inflammatory properties of curcumin in neurodegenerative diseases and depression

This review is an attempt to summarize our current understanding of curcumin's potential as a neuroprotectant and an antidepressant. This dual property confers a unique advantage to this herbal medication, believed to be devoid of any major side effects, to combat commonly observed co-morbid conditions of a neurodegenerative and a neuropsychiatric disorder. Moreover, in line with the theme of this series, the role of inflammation and stress in these diseases and possible anti-inflammatory effects of curcumin, as well as its interaction with signal transduction proteins as a common denominator in its varied mechanisms of action, are also discussed. Thus, following a brief introduction of curcumin's pharmacology, we present research suggesting how its anti-inflammatory properties have therapeutic potential in treating a devastating neurological disorder (Parkinson's disease = PD) and a debilitating neuropsychiatric disorder (major depressive disorder = MDD). It is concluded that curcumin, or better yet, an analog with better and longer bioavailability could be of important therapeutic potential in PD and/or major depression.

Anxiety, depression, coronary artery disease and diabetes mellitus; an association study in ghaem hospital, iran

BACKGROUND

There is an increasing trend in the prevalence of coronary artery disease (CAD) in Iran.

OBJECTIVES

The present study aimed to investigate the relationship of anxiety, depression, diabetes and coronary artery disease among patients undergoing angiography in Ghaem Hospital, Mashhad, Iran.

PATIENTS AND METHODS

This case-control study was conducted between September 2011 and August 2012 among 200 patients undergoing coronary angiography for symptoms of coronary disease at Ghaem Hospital, Mashhad, Iran. The control group consisted of 697 healthy adults recruited from the individuals who attended the clinic for routine medical checkups or pre-employment examinations. The Beck anxiety and depression inventory scores and fasting blood glucose results were assessed in all the subjects. Data were analyzed using SPSS version 16. P < 0.05 was regarded as statistically significant.

RESULTS

The mean age of patients was 57.52 ± 9.33 years old and for the control group it was 55.35 ± 8.45 years; there was no significant difference between the subjects (P = 0.647) regarding age. There was also no significant difference in gender distribution between the patients and control groups (P = 0.205). There was however a significant difference in anxiety and depression scores between the patients and healthy controls (P < 0.001). There was a significant positive correlation between anxiety score and depression score in both groups when data were analyzed by Pearson test. (P < 0.001, r = 0.604 and r = 0.521). Moreover, there was a significant positive linear correlation between the depression/anxiety scores and fasting blood glucose concentrations in the patients group (r = 0.3, P < 0.001) and a weak negative correlation in the healthy controls (r = -0.096, P < 0.05).

CONCLUSIONS

Depression and anxiety are potentially important factors among patients with angiographically-defined CAD. There appear to be significant associations between glucose tolerance and anxiety and depression in these patients.

Emotional regulatory function of receptor interacting protein 140 revealed in the ventromedial hypothalamus

Receptor-interacting protein (RIP140) is a transcription co-regulator highly expressed in macrophages to regulate inflammatory and metabolic processes. However, its implication in neurological, cognitive and emotional conditions, and the cellular systems relevant to its biological activity within the central nervous system are currently less clear. A transgenic mouse line with macrophage-specific knockdown of RIP140 was generated (MΦRIPKD mice) and brain-region specific RIP140 knockdown efficiency evaluated. Mice were subjected to a battery of tests, designed to evaluate multiple behavioral domains at naïve or following site-specific RIP140 re-expression. Gene expression analysis assessed TNF-α, IL-1β, TGF-1β, IL1-RA and neuropeptide Y (NPY) expression, and in vitro studies examined the effects of macrophage's RIP140 on astrocytes' NPY production. We found that RIP140 expression was dramatically reduced in macrophages within the ventromedial hypothalamus (VMH) and the cingulate cortex of MΦRIPKD mice. These animals exhibited increased anxiety- and depressive-like behaviors. VMH-targeted RIP140 re-expression in MΦRIPKD mice reversed its depressive- but not its anxiety-like phenotype. Analysis of specific neurochemical changes revealed reduced astrocytic-NPY expression within the hypothalamus of MΦRIPKD mice, and in vitro analysis confirmed that conditioned medium of RIP140-silnenced macrophage culture could no longer stimulate NPY production from astrocytes. The current study revealed an emotional regulatory function of macrophage-derived RIP140 in the VMH, and secondary dysregulation of NPY within hypothalamic astrocyte population, which might be associated with the observed behavioral phenotype of MΦRIPKD mice. This study highlights RIP140 as a novel target for the development of potential therapeutic and intervention strategies for emotional regulation disorders.

Oxidative imbalance and anxiety disorders

The oxidative imbalance appears to have an important role in anxiety development. Studies in both humans and animals have shown a strong correlation between anxiety and oxidative stress. In humans, for example, the increased malondialdehyde levels and discrepancies in antioxidant enzymes in erythrocytes have been observed. In animals, several studies also show that anxiety-like behavior is related to the oxidative imbalance. Moreover, anxiety-like behavior can be caused by pharmacological-induced oxidative stress. Studies using knockout or overexpression of antioxidant enzymes have shown a relationship between anxiety-like behavior and oxidative stress. Related factors of oxidative stress that could influence anxious behavior are revised, including impaired function of different mitochondrial proteins, inflammatory cytokines, and neurotrophic factors. It has been suggested that a therapy specifically focus in reducing reactive species production may have a beneficial effect in reducing anxiety. However, the neurobiological pathways underlying the effect of oxidative stress on anxiety symptoms are not fully comprehended. The challenge now is to identify the oxidative stress mechanisms likely to be involved in the induction of anxiety symptoms. Understanding these pathways could help to clarify the neurobiology of the anxiety disorder and provide tools for new discovery in therapies and preventive strategies.

5-HT1A/1B receptors as targets for optimizing pigmentary responses in C57BL/6 mouse skin to stress

Stress has been reported to induce alterations of skin pigmentary response. Acute stress is associated with increased turnover of serotonin (5-hydroxytryptamine; 5-HT) whereas chronic stress causes a decrease. 5-HT receptors have been detected in pigment cells, indicating their role in skin pigmentation. To ascertain the precise role of 5-HT in stress-induced pigmentary responses, C57BL/6 mice were subjected to chronic restraint stress and chronic unpredictable mild stress (CRS and CUMS, two models of chronic stress) for 21 days, finally resulting in abnormal pigmentary responses. Subsequently, stressed mice were characterized by the absence of a black pigment in dorsal coat. The down-regulation of tyrosinase (TYR) and tyrosinase-related proteins (TRP1 and TRP2) expression in stressed skin was accompanied by reduced levels of 5-HT and decreased expression of 5-HT receptor (5-HTR) system. In both murine B16F10 melanoma cells and normal human melanocytes (NHMCs), 5-HT had a stimulatory effect on melanin production, dendricity and migration. When treated with 5-HT in cultured hair follicles (HFs), the increased expression of melanogenesis-related genes and the activation of 5-HT1A, 1B and 7 receptors also occurred. The serum obtained from stressed mice showed significantly decreased tyrosinase activity in NHMCs compared to that from nonstressed mice. The decrease in tyrosinase activity was further augmented in the presence of 5-HTR1A, 1B and 7 antagonists, WAY100635, SB216641 and SB269970. In vivo, stressed mice received 5-HT precursor 5-hydroxy-l-tryptophan (5-HTP), a member of the class of selective serotonin reuptake inhibitors (fluoxetine; FX) and 5-HTR1A/1B agonists (8-OH-DPAT/CP94253), finally contributing to the normalization of pigmentary responses. Taken together, these data strongly suggest that the serotoninergic system plays an important role in the regulation of stress-induced depigmentation, which can be mediated by 5-HT1A/1B receptors. 5-HT and 5-HTR1A/1B may constitute novel targets for therapy of skin hypopigmentation disorders, especially those worsened with stress.

HPA axis genetic variation, cortisol and psychosis in major depression

Genetic variation underlying hypothalamic pituitary adrenal (HPA) axis overactivity in healthy controls (HCs) and patients with severe forms of major depression has not been well explored, but could explain risk for cortisol dysregulation. In total, 95 participants were studied: 40 patients with psychotic major depression (PMD); 26 patients with non-psychotic major depression (NPMD); and 29 HCs. Collection of genetic material was added one third of the way into a larger study on cortisol, cognition and psychosis in major depression. Subjects were assessed using the Brief Psychiatric Rating Scale, the Hamilton Depression Rating Scale and the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders. Blood was collected hourly for determination of cortisol from 1800 to 0900 h and for the assessment of alleles for six genes involved in HPA axis regulation. Two of the six genes contributed significantly to cortisol levels, psychosis measures or depression severity. After accounting for age, depression and psychosis, and medication status, only allelic variation for the glucocorticoid receptor (GR) gene accounted for a significant variance for mean cortisol levels from 1800 to 0100 h (r(2)=0.288) and from 0100 to 0900 h (r(2)=0.171). In addition, GR and corticotropin-releasing hormone receptor 1 (CRHR1) genotypes contributed significantly to psychosis measures and CRHR1 contributed significantly to depression severity rating.

Elevated brain glucose and glycogen concentrations in an animal model of depression

INTRODUCTION

Recent data indicate that there is a link between depression and diabetes and that excess glucocorticoids may play an underlying role in the pathogenesis of both of these diseases. The aim of the present study was to determine whether there are any alterations in glucose, glycogen, glucose transporters, insulin, insulin receptors or corticosterone concentrations in the hippocampus and frontal cortex in a prenatal stress rat model of depression.

METHODS

Male rats whose mothers had been subjected to stress and control animals were subjected to the Porsolt test to verify the experimental model. Next, some of the rats were subjected to acute stress and/or were administered glucose. Glucose, glycogen, corticosterone, insulin, insulin receptor, phospho-insulin receptor and glucose transporter (GLUT1, GLUT3 and GLUT4) concentrations were assayed.

RESULTS

Prenatally stressed rats exhibited glucose and glycogen concentrations in both investigated brain structures that exceeded those of the control animals. Prenatal stress also increased the levels of glucose transporters - GLUT1 in both tissues and GLUT4 in the frontal cortex. The changes in the prenatally stressed rats were more prominent in the animals that were subjected to stress or glucose loading in adulthood.

CONCLUSION

The increase in carbohydrate brain concentrations evoked by prenatal stress may result from changes in the amounts of glucose transporters, especially GLUT1. Moreover, the obtained results support the hypothesis that stress during the perinatal period permanently increases the sensitivity of brain tissue to factors that act in adulthood. © 2014 S. Karger AG, Basel.

Integrated expression profiles of mRNA and miRNA in polarized primary murine microglia

Neuroinflammation contributes to many neurologic disorders including Alzheimer’s disease, multiple sclerosis, and stroke. Microglia is brain resident myeloid cells and have emerged as a key driver of the neuroinflammatory responses. MicroRNAs (miRNAs) provide a novel layer of gene regulation and play a critical role in regulating the inflammatory response of peripheral macrophages. However, little is known about the miRNA in inflammatory activation of microglia. To elucidate the role that miRNAs have on microglial phenotypes under classical (M1) or alternative (M2) activation under lipopolysaccharide (‘M1’-skewing) and interleukin-4 (‘M2a’-skewing) stimulation conditions, we performed microarray expression profiling and bioinformatics analysis of both mRNA and miRNA using primary cultured murine microglia. miR-689, miR-124, and miR-155 were the most strongly associated miRNAs predicted to mediate pro-inflammatory pathways and M1-like activation phenotype. miR-155, the most strongly up-regulated miRNA, regulates the signal transducer and activator of transcription 3 signaling pathway enabling the late phase response to M1-skewing stimulation. Reduced expression in miR-689 and miR-124 are associated with dis-inhibition of many canonical inflammatory pathways. miR-124, miR-711, miR-145 are the strongly associated miRNAs predicted to mediate anti-inflammatory pathways and M2-like activation phenotype. Reductions in miR-711 and miR-124 may regulate inflammatory signaling pathways and peroxisome proliferator-activated receptor-gamma pathway. miR-145 potentially regulate peripheral monocyte/macrophage differentiation and faciliate the M2-skewing phenotype. Overall, through combined miRNA and mRNA expression profiling and bioinformatics analysis we have identified six miRNAs and their putative roles in M1 and M2-skewing of microglial activation through different signaling pathways.

Insulin resistance and dysregulation of tryptophan-kynurenine and kynurenine-nicotinamide adenine dinucleotide metabolic pathways

Insulin resistance (IR) underlines aging and aging-associated medical (diabetes, obesity, dyslipidemia, hypertension) and psychiatric (depression, cognitive decline) disorders. Molecular mechanisms of IR in genetically or metabolically predisposed individuals remain uncertain. Current review of the literature and our data presents the evidences that dysregulation of tryptophan (TRP)-kynurenine (KYN) and KYN-nicotinamide adenine dinucleotide (NAD) metabolic pathways is one of the mechanisms of IR. The first and rate-limiting step of TRP-KYN pathway is regulated by enzymes inducible by pro-inflammatory factors and/or stress hormones. The key enzymes of KYN-NAD pathway require pyridoxal-5-phosphate (P5P), an active form of vitamin B6, as a cofactor. Deficiency of P5P diverts KYN-NAD metabolism from production of NAD to the excessive formation of xanthurenic acid (XA). Human and experimental studies suggested that XA and some other KYN metabolites might impair production, release, and biological activity of insulin. We propose that one of the mechanisms of IR is inflammation- and/or stress-induced upregulation of TRP-KYN metabolism in combination with P5P deficiency-induced diversion of KYN-NAD metabolism towards formation of XA and other KYN derivatives affecting insulin activity. Monitoring of KYN/P5P status and formation of XA might help to identify subjects at risk for IR. Pharmacological regulation of the TRP-KYN and KYN-NAD pathways and maintaining of adequate vitamin B6 status might contribute to prevention and treatment of IR in conditions associated with inflammation/stress-induced excessive production of KYN and deficiency of vitamin B6, e.g., type 2 diabetes, obesity, cardiovascular diseases, aging, menopause, pregnancy, and hepatitis C virus infection.

Chronic depression as a model disease for cerebral aging

Conceptualizations of the underlying neurobiology of major depression have changed their focus from dysfunctions of neurotransmission to dysfunctions of neurogenesis and neuroprotection. The “neurogenesis hypothesis of depression” posits that changes in the rate of neurogenesis are the underlying mechanism in the pathology and treatment of major depression. Stress, neuroinflammation, dysfunctional insulin regulation, oxidative stress, and alterations in neurotrophic factors possibly contribute to the development of depression. The influence of antidepressant therapies, namely pharmacotherapy and neuroprotectants, on cellular plasticity are summarized. A dysfunction of complex neuronal networks as a consequence of neural degeneration in neuropsychiatric diseases has led to the application of deep brain stimulation. We discuss the way depression seen in the light of the neurogenesis hypothesis can be used as a model disease for cerebral aging. A common pathological mechanism in depression and cerebral aging—a dysfunction of neuroprotection and neurogenesis—is discussed. This has implications for new treatment methods.

Anxiety disorders and inflammation in a large adult cohort

Although anxiety disorders, like depression, are increasingly being associated with metabolic and cardiovascular burden, in contrast with depression, the role of inflammation in anxiety has sparsely been examined. This large cohort study examines the association between anxiety disorders and anxiety characteristics with several inflammatory markers. For this purpose, persons (18-65 years) with a current (N=1273) or remitted (N=459) anxiety disorder (generalized anxiety disorder, social phobia, panic disorder, agoraphobia) according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria and healthy controls (N=556) were selected from the Netherlands Study of Depression and Anxiety. In addition, severity, duration, age of onset, anxiety subtype and co-morbid depression were assessed. Inflammatory markers included C-reactive protein (CRP), interleukin (IL)-6 and tumor-necrosis factor (TNF)-α. Results show that after adjustment for sociodemographics, lifestyle and disease, elevated levels of CRP were found in men, but not in women, with a current anxiety disorder compared with controls (1.18 (s.e.=1.05) versus 0.98 (s.e.=1.07) mg l(-1), P=0.04, Cohen's d=0.18). No associations were found with IL-6 or TNF-α. Among persons with a current anxiety disorder, those with social phobia, in particular women, had lower levels of CRP and IL-6, whereas highest CRP levels were found in those with an older age of anxiety disorder onset. Especially in persons with an age of onset after 50 years, CRP levels were increased compared with controls (1.95 (s.e.=1.18) versus 1.27 (s.e.=1.05) mg l(-1), P=0.01, Cohen's d=0.37). In conclusion, elevated inflammation is present in men with current anxiety disorders. Immune dysregulation is especially found in persons with a late-onset anxiety disorder, suggesting the existence of a specific late-onset anxiety subtype with a distinct etiology, which could possibly benefit from alternative treatments.

Neurobiology of anxious depression: a review

Anxious depression is a common, distinct clinical subtype of major depressive disorder (MDD). This review summarizes current neurobiological knowledge regarding anxious depression. Peer-reviewed articles, published January 1970 through September 2012, were identified via PUBMED, EMBASE, and Cochrane Library, using the following key words: anxious depression electroencephalography (EEG), anxious depression functional magnetic resonance imaging (fMRI), anxious depression genetics, anxious depression neurobiology, and anxious melancholia neurobiology. Despite a general dearth of neurobiological research, the results suggest that anxious depression-when defined either syndromally or dimensionally-has distinct neurobiological findings that separate it from nonanxious depression. Structural neuroimaging, EEG, genetics, and neuropsychiatric studies revealed differences in subjects with anxious depression compared to other groups. Endocrine differences between individuals with anxious depression and those with nonanxious depression have also been noted, as evidenced by abnormal responses elicited by exogenous stimulation of the system. Despite these findings, heterogeneity in the definition of anxious depression complicates the results. Because exploring the neurobiology of this depressive subtype is important for improving diagnosis, prognosis, and treatment, enrichment strategies to decrease heterogeneity within the field should be employed for future research.

Dysregulated diurnal cortisol pattern is associated with glucocorticoid resistance in women with major depressive disorder

Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis is believed to play a role in the pathophysiology of depression. To investigate mechanisms that may underlie this effect, we examined several indices of HPA axis function - specifically, diurnal cortisol slope, cortisol awakening response, and suppression of cortisol release following dexamethasone administration - in 26 pre-menopausal depressed women and 23 never depressed women who were matched for age and body mass index. Salivary cortisol samples were collected at waking, 30 min after waking, and at bedtime over three consecutive days. On the third day, immediately after the bedtime sample, participants ingested a 0.5mg dexamethasone tablet; they then collected cortisol samples at waking and 30 min after waking the following morning. As predicted, depressed women exhibited flatter diurnal cortisol rhythms and more impaired suppression of cortisol following dexamethasone administration than non-depressed women over the three sampling days. In addition, flatter diurnal cortisol slopes were associated with reduced cortisol response to dexamethasone treatment, both for all women and for depressed women when considered separately. Finally, greater self-reported depression severity was associated with flatter diurnal cortisol slopes and with less dexamethasone-related cortisol suppression for depressed women. Depression in women thus appears to be characterized by altered HPA axis functioning, as indexed by flatter diurnal cortisol slopes and an associated impaired sensitivity of cortisol to dexamethasone. Given that altered HPA axis functioning has been implicated in several somatic conditions, the present findings may be relevant for understanding the pathophysiology of both depression and depression-related physical disease.

Neuroinflammation, neurodegeneration, and depression

Neurodegeneration and depression are two common co-morbid conditions, particularly within the aging population. Research has linked neuroinflammation as a major contributing factor to both of these diseases. The key to neuroinflammation effects on neurodegeneration and depression appears to lie within the dysregulation of the control and release of pro- and anti-inflammatory cytokines. This can come from an internal or external insult to the system, or from changes in the individual due to aging that culminate in immune dysregulation. The need to reduce neuroinflammation has led to extensive research into neuroprotectants. We discuss the efficacy found with nicotine, alcohol, resveratrol, curcumin, and ketamine. Our main focus will be on what research tells us about the connections between neuroinflammation, neurodegeneration, and depression, and the hope that neuroprotectants research gives people suffering from neurodegeneration and depression stemming from neuroinflammation. We will conclude by making suggestions for future research in this area.

Wiki-pi: a web-server of annotated human protein-protein interactions to aid in discovery of protein function

Protein-protein interactions (PPIs) are the basis of biological functions. Knowledge of the interactions of a protein can help understand its molecular function and its association with different biological processes and pathways. Several publicly available databases provide comprehensive information about individual proteins, such as their sequence, structure, and function. There also exist databases that are built exclusively to provide PPIs by curating them from published literature. The information provided in these web resources is protein-centric, and not PPI-centric. The PPIs are typically provided as lists of interactions of a given gene with links to interacting partners; they do not present a comprehensive view of the nature of both the proteins involved in the interactions. A web database that allows search and retrieval based on biomedical characteristics of PPIs is lacking, and is needed. We present Wiki-Pi (read Wiki-π), a web-based interface to a database of human PPIs, which allows users to retrieve interactions by their biomedical attributes such as their association to diseases, pathways, drugs and biological functions. Each retrieved PPI is shown with annotations of both of the participant proteins side-by-side, creating a basis to hypothesize the biological function facilitated by the interaction. Conceptually, it is a search engine for PPIs analogous to PubMed for scientific literature. Its usefulness in generating novel scientific hypotheses is demonstrated through the study of IGSF21, a little-known gene that was recently identified to be associated with diabetic retinopathy. Using Wiki-Pi, we infer that its association to diabetic retinopathy may be mediated through its interactions with the genes HSPB1, KRAS, TMSB4X and DGKD, and that it may be involved in cellular response to external stimuli, cytoskeletal organization and regulation of molecular activity. The website also provides a wiki-like capability allowing users to describe or discuss an interaction. Wiki-Pi is available publicly and freely at http://severus.dbmi.pitt.edu/wiki-pi/.

Analysis of region-specific changes in gene expression upon treatment with citalopram and desipramine reveals temporal dynamics in response to antidepressant drugs at the transcriptome level

RATIONALE

The notion that the onset of action of antidepressant drugs (ADs) takes weeks is widely accepted; however, the sequence of events necessary for therapeutic effects still remains obscure.

OBJECTIVE

We aimed to evaluate a time-course of ADs-induced alterations in the expression of 95 selected genes in 4 regions of the rat brain: the prefrontal and cingulate cortices, the dentate gyrus of the hippocampus, and the amygdala.

METHODS

We employed RT-PCR array to evaluate changes during a time-course (1, 3, 7, 14, and 21 days) of treatments with desipramine (DMI) and citalopram (CIT). In addition to repeated treatment, we also conducted acute treatment (a single dose of drug followed by the same time intervals as the repeated doses).

RESULTS

Time-dependent and structure-specific changes in gene expression patterns allowed us to identify spatiotemporal differences in the molecular action of two ADs. Singular value decomposition analysis revealed differences in the global gene expression profiles between treatment types. The numbers of characteristic modes were generally smaller after CIT treatment than after DMI treatment. Analysis of the dynamics of gene expression revealed that the most significant changes concerned immediate early genes, whose expression was also visualized by in situ hybridization. Transcription factor binding site analysis revealed an over-representation of serum response factor binding sites in the promoters of genes that changed upon treatment with both ADs.

CONCLUSIONS

The observed gene expression patterns were highly dynamic, with oscillations and peaks at various time points of treatment. Our study also revealed novel potential targets of antidepressant action, i.e., Dbp and Id1 genes.

Stress-induced sensitization of cortical adrenergic receptors following a history of cannabinoid exposure

The cannabinoid receptor agonist, WIN 55,212-2, increases extracellular norepinephrine levels in the rat frontal cortex under basal conditions, likely via desensitization of inhibitory α2-adrenergic receptors located on norepinephrine terminals. Here, the effect of WIN 55,212-2 on stress-induced norepinephrine release was assessed in the medial prefrontal cortex (mPFC), in adult male Sprague-Dawley rats using in vivo microdialysis. Systemic administration of WIN 55,212-2 30 min prior to stressor exposure prevented stress-induced cortical norepinephrine release induced by a single exposure to swim when compared to vehicle. To further probe cortical cannabinoid-adrenergic interactions, postsynaptic α2-adrenergic receptor (AR)-mediated responses were assessed in mPFC pyramidal neurons using electrophysiological analysis in an in vitro cortical slice preparation. We confirm prior studies showing that clonidine increases cortical pyramidal cell excitability and that this was unaffected by exposure to acute stress. WIN 55,212-2, via bath application, blocked postsynaptic α2-AR mediated responses in cortical neurons irrespective of exposure to stress. Interestingly, stress exposure prevented the desensitization of α2-AR mediated responses produced by a history of cannabinoid exposure. Together, these data indicate the stress-dependent nature of cannabinoid interactions via both pre- and postsynaptic ARs. In summary, microdialysis data indicate that cannabinoids restrain stress-induced cortical NE efflux. Electrophysiology data indicate that cannabinoids also restrain cortical cell excitability under basal conditions; however, stress interferes with these CB1-α2 AR interactions, potentially contributing to over-activation of pyramidal neurons in mPFC. Overall, cannabinoids are protective of the NE system and cortical excitability but stress can derail this protective effect, potentially contributing to stress-related psychopathology. These data add to the growing evidence of complex, stress-dependent modulation of monoaminergic systems by cannabinoids and support the potential use of cannabinoids in the treatment of stress-induced noradrenergic dysfunction.