Relation between lymphocyte beta-adrenergic responsivity and the severity of depressive disorders

Association between the Ile164 β2 Adrenergic Receptor Polymorphism and Fatigue in Patients with Rheumatoid Arthritis

INTRODUCTION

In the present work, the frequency of inherited polymorphisms of the beta 2 adrenergic receptor (β2AR) gene and their association with fatigue in patients with rheumatoid arthritis (RA) was examined.

METHODS

An allele-specific polymerase chain reaction was used to determine the common variants of the β2AR at position 16, 27, and 164 in 92 German RA outpatients. Health Assessment Questionnaire (HAQ-DI), Beck Depression Inventory (BDI), Perceived Stress Questionnaire (PSQ-30), Multidimensional Fatigue Inventory (MFI-20) were utilized.

RESULTS

34.7% of German RA patients were diagnosed with associated fatigue. Fatigued patients were more likely to carry the Ile allele at position 164 (OR 7.33, 95% CI 1.09-59.8, p = 0.049). Comparing these risk factors' contribution to different fatigue dimensions revealed that Ile164 carriers only had significantly higher MFI-20 mean values for general fatigue (p = 0.014) while the clinical difference among other MFI subscales was the largest for mental fatigue (carrier: 8.23, SD: 4.22, noncarrier: 5.67, SD: 1.56, p = 0.089, Cohen's d = 0.629). Disease activity, perceived stress, and depression were also associated with fatigue with higher mean values for DAS28CRP (p = 0.038), PSQ (p < 0.001), and BDI-II (p < 0.001) in fatigued patients. Physical fatigue was correlated with disease activity (p = 0.009) and depression (p = 0.001) while mental fatigue showed associations with depression (p = 0.001) and perceived stress (p = 0.028).

CONCLUSION

The discovery study indicates that the Ile164 polymorphism might in contrast to other β2AR polymorphisms affect fatigue levels in RA patients. This association was observed especially with mental fatigue. Further replication studies are warranted to determine further role of β2AR polymorphisms in RA patients.

The Role of Beta-Adrenergic Receptors in Depression and Resilience

Norepinephrine is a catecholamine neurotransmitter that has been extensively implicated in the neurobiology of major depressive disorder (MDD). An accumulating body of evidence indicates that investigations into the action of norepinephrine at the synaptic/receptor level hold high potential for a better understanding of MDD neuropathology and introduce possibilities for developing novel treatments for depression. In this review article, we discuss recent advances in depression neuropathology and the effects of antidepressant medications based on preclinical and clinical studies related to beta-adrenergic receptor subtypes. We also highlight a beta-3 adrenergic receptor-involved mechanism that promotes stress resilience, through which antidepressant efficacy is achieved in both rodent models for depression and patients with major depression-an alternative therapeutic strategy that is conceptually different from the typical therapeutic approach in which treatment efficacy is achieved by reversing pathological alterations rather than by enhancing a good mechanism such as natural resilience. Altogether, in this review, we systematically describe the role of beta-adrenergic receptors in depression and stress resilience and provide a new avenue for developing a conceptually innovative treatment for depression.

A high-fat diet promotes depression-like behavior in mice by suppressing hypothalamic PKA signaling

Obesity is associated with an increased risk of depression. The aim of the present study was to investigate whether obesity is a causative factor for the development of depression and what is the molecular pathway(s) that link these two disorders. Using lipidomic and transcriptomic methods, we identified a mechanism that links exposure to a high-fat diet (HFD) in mice with alterations in hypothalamic function that lead to depression. Consumption of an HFD selectively induced accumulation of palmitic acid in the hypothalamus, suppressed the 3', 5'-cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway, and increased the concentration of free fatty acid receptor 1 (FFAR1). Deficiency of phosphodiesterase 4A (PDE4A), an enzyme that degrades cAMP and modulates stimulatory regulative G protein (Gs)-coupled G protein-coupled receptor signaling, protected animals either from genetic- or dietary-induced depression phenotype. These findings suggest that dietary intake of saturated fats disrupts hypothalamic functions by suppressing cAMP/PKA signaling through activation of PDE4A. FFAR1 inhibition and/or an increase of cAMP signaling in the hypothalamus could offer potential therapeutic targets to counteract the effects of dietary or genetically induced obesity on depression.

Differential Autonomic Nervous System Reactivity in Depression and Anxiety During Stress Depending on Type of Stressor

OBJECTIVES

It remains unclear whether depressive and anxiety disorders are associated with hyporeactivity or hyperreactivity of the autonomic nervous system (ANS) and whether deviant reactivity occurs in all types of stressors. This study compared ANS reactivity in people with current or remitted depression/anxiety with reactivity in healthy controls during two stress conditions.

METHODS

From the Netherlands Study of Depression and Anxiety, data of 804 individuals with current depression/anxiety, 913 individuals with remitted depression/anxiety, and 466 healthy controls (mean age = 44.1 years; 66.4% female) were available. Two conditions were used to evoke stress: a) an n-back task, a cognitively challenging stressor, and 2) a psychiatric interview, evoking personal-emotional stress related to the occurrence of symptoms of depression/anxiety. Indicators of ANS activity were heart rate (HR), root mean square of differences between successive interbeat intervals (RMSSD), respiratory sinus arrhythmia (RSA), and preejection period.

RESULTS

As compared with controls, participants with psychopathology had significant hyporeactivity of HR (controls = 4.1 ± 4.2 beats/min; remitted = 3.5 ± 3.5 beats/min; current psychopathology = 3.1 ± 3.4 beats/min), RMSSD (controls = -6.2 ± 14.5 milliseconds; remitted = -5.4 ± 17.8 milliseconds; current psychopathology = -3.5 ± 15.4 milliseconds), and RSA (controls = -9.3 ± 17.0 milliseconds; remitted = -7.4 ± 16.5 milliseconds; current psychopathology = -6.9 ± 15.0 milliseconds) during the n-back task. In contrast, during the psychiatric interview, they showed significant hyperreactivity of HR (controls = 2.7 ± 3.4 beats/min; remitted = 3.5 ± 3.4 beats/min; current psychopathology = 4.0 ± 3.3 beats/min), RMSSD (controls = -3.4 ± 12.2 milliseconds; remitted = -4.1 ± 12.1 milliseconds; current psychopathology = -5.6 ± 11.8 milliseconds), and RSA (controls = -3.8 ± 8.1 milliseconds; remitted = -4.3 ± 7.9 milliseconds; current psychopathology = -5.0 ± 7.9 milliseconds). The lack of group differences in preejection period reactivity suggests that the found effects were driven by altered cardiac vagal reactivity in depression/anxiety.

CONCLUSIONS

The direction of altered ANS reactivity in depressed/anxious patients is dependent on the type of stressor, and only the more ecologically valid stressors may evoke hyperreactivity in these patients.

In vivo β-adrenergic receptor responsiveness: ethnic differences in the relationship with symptoms of depression and fatigue

BACKGROUND

Depressive symptoms and fatigue frequently overlap in clinical samples and the general population. The link of depressive symptoms and fatigue with increased risk of cardiovascular disease has been partly explained by shared biological mechanisms including sympathetic overactivity. Prolonged sympathetic overactivity downregulates the responsiveness of the β-adrenergic receptor (β-AR), a receptor that mediates several end-organ sympathetic responses.

PURPOSE

The authors studied whether depression and fatigue are related to reduced β-AR responsiveness within the human body (in vivo) in an ethnically diverse sample of African and Caucasian Americans.

METHODS

The chronotropic25 dose (CD25) was used to determine in vivo β-AR responsiveness in 93 healthy participants. Psychometric measures included the Center of Epidemiological Studies-Depression Scale and the Multidimensional Fatigue Symptom Inventory.

RESULTS

Hierarchical regression analyses (adjusted for age, gender, body mass index, blood pressure, smoking, and ethnicity) revealed that mental fatigue was significantly related to reduced β-AR responsiveness (i.e., higher CD25 values) in the whole sample. Moderation analyses indicated significant ethnicity × depression/fatigue interactions. Depressive symptoms, total fatigue, emotional fatigue, mental fatigue, and physical fatigue were related to reduced β-AR responsiveness in Caucasian American but not in African Americans.

CONCLUSIONS

Our findings suggest that symptoms of depression and fatigue are related to decreased in vivo β-AR responsiveness in Caucasian Americans. The lack of this association in African Americans highlights the importance for considering ethnicity as a potential moderator in research focusing on associations between psychological variables and cardiovascular function.

Neural plasticity and proliferation in the generation of antidepressant effects: hippocampal implication

It is widely accepted that changes underlying depression and antidepressant-like effects involve not only alterations in the levels of neurotransmitters as monoamines and their receptors in the brain, but also structural and functional changes far beyond. During the last two decades, emerging theories are providing new explanations about the neurobiology of depression and the mechanism of action of antidepressant strategies based on cellular changes at the CNS level. The neurotrophic/plasticity hypothesis of depression, proposed more than a decade ago, is now supported by multiple basic and clinical studies focused on the role of intracellular-signalling cascades that govern neural proliferation and plasticity. Herein, we review the state-of-the-art of the changes in these signalling pathways which appear to underlie both depressive disorders and antidepressant actions. We will especially focus on the hippocampal cellularity and plasticity modulation by serotonin, trophic factors as brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) through intracellular signalling pathways—cAMP, Wnt/β-catenin, and mTOR. Connecting the classic monoaminergic hypothesis with proliferation/neuroplasticity-related evidence is an appealing and comprehensive attempt for improving our knowledge about the neurobiological events leading to depression and associated to antidepressant therapies.

Genetic heterogeneity according to age at onset in bipolar disorder: a combined positional cloning and candidate gene approach

This study is the first that formally tests for genetic heterogeneity of bipolar disorder (BD) according to age at onset (AAO) sub-groups by combining positional cloning and candidate gene approaches. Our previous genome-wide linkage-scan identified five genomic regions linked to early-onset form of BD. The present study uses association analysis to test genetic heterogeneity of candidate genes located in these five regions in a sample of 443 unrelated bipolar patients and 1,731 controls. The study involved the following steps: (1) test of heterogeneity by comparing early-onset BD patients versus later-onset BD patients; and (2) for significant results in step 1, comparison of early-onset BD patients and later-onset BD patients separately to controls. Two types of analyses were used: the single SNP test and the gene-based association test. We provide evidence for genetic heterogeneity within the ADRB2 (beta-2adrenoreceptor) gene region that is specifically associated with the early onset form of BD with an OR of 1.8. Unfortunately, the genotyping coverage of ADRB2 in the Wellcome Trust Case Control Consortium sample meant undermined our efforts to undertake a replication. However, as the ADRB2 gene product directly interacts with the CACNA1C gene product, and is known to be implicated in BD susceptibility, we conclude that further exploration of the relationships between ADRB2 and BD needs to be undertaken.

Association of in vivo β-adrenergic receptor sensitivity with inflammatory markers in healthy subjects

OBJECTIVE

Several stress-related states and conditions that are considered to involve sympathetic overactivation are accompanied by increased circulating levels of inflammatory immune markers. Prolonged sympathetic overactivity involves increased stimulation of the β-adrenergic receptor (β-AR). Although prior research suggests that one mechanism by which sympathetic stimulation may facilitate inflammation is via β-AR activation, little work has focused on the relationship between circulating inflammatory immune markers and β-AR function within the human body (in vivo). We examined whether decreased β-AR sensitivity, an indicator of prolonged β-adrenergic overactivation and a physiological component of chronic stress, is related to elevated levels of inflammatory immune markers.

METHODS

Ninety-three healthy participants aged 19 to 51 years underwent the chronotropic 25 dose isoproterenol test to determine in vivo β-AR function. Circulating levels of C-reactive protein, interleukin 6, and soluble tumor necrosis factor receptor 1 were determined.

RESULTS

β-AR sensitivity was lower in people with higher C-reactive protein concentrations (r = 0.326, p = .003). That relationship remained significant after controlling for sociodemographic and health variables such as age, sex, ethnicity, body mass index, mean arterial blood pressure, heart rate, leisure-time exercise, and smoking status. No significant relationship was found between chronotropic 25 dose and interleukin 6 or soluble tumor necrosis factor receptor 1.

CONCLUSIONS

This study demonstrates a link between in vivo β-adrenergic receptor function and selected circulating inflammatory markers (CRP) in humans. Future studies in specific disease states may be promising.

Subjective social status predicts in vivo responsiveness of β-adrenergic receptors

OBJECTIVE

Several poor health outcomes, including cardiovascular risk, have been associated with both subjective social status (SSS) and sympathetic overactivity. Because prolonged sympathetic overactivation down regulates beta adrenergic receptor (β-AR) function, reduced β-AR responsiveness is considered an indicator of sympathetic overactivity and a cardiovascular risk factor. Though prior research has focused on objective social status and β-AR function, no studies have examined the association between SSS and β-AR function. We aimed to learn whether SSS predicts the in vivo responsiveness of β-ARs.

METHODS

We assessed the chronotropic 25 dose (CD25), an in vivo marker of β-AR responsiveness, in 94 healthy participants. The MacArthur scales of subjective social status were used to assess SSS in the U.S.A. (SSS-USA) and in the local community (SSS-C). Objective social status was analyzed by calculating the Hollingshead two-factor index.

RESULTS

β-AR responsiveness was reduced (as indicated by higher CD25 values) in participants with lower SSS-USA (p = .007) and lower SSS-C (p < .001). The relationship between CD25 and SSS was particularly robust with respect to SSS-C. Hierarchical regression analyses revealed that SSS-C remained a significant predictor of CD25 (p < .001) and accounted for 14% of the total variance (32%) in CD25 after adjusting for sociodemographic variables (age, ethnicity, gender), health factors (exercise, smoking status, body mass index) and objective social status.

CONCLUSION

Our results indicate that β-AR function may be an important component of the link between SSS and health.

Combined effect of depressive symptoms and hostility on autonomic nervous system function

Depression and hostility have been separately related to indicators of sympathetic hyperactivation and parasympathetic hypoactivation. We examined the associations of depressive symptoms, hostility, and their interaction with pre-ejection period (PEP) and high frequency heart rate variability (HRV), specific indices of sympathetic and parasympathetic cardiac control, respectively. Healthy, young adults (N=120) completed questionnaires assessing depressive symptoms and hostility and underwent autonomic testing. Although main effects were not observed, a depressive symptoms×hostility interaction was detected for PEP (β=.25, p=.01). Simple slope analyses revealed that hostility was negatively related to PEP among individuals with low depressive symptoms but was not associated with PEP among those with mild-to-moderate depressive symptoms. No interaction effect was detected for high frequency HRV. Our findings suggest that depressive symptoms may moderate the link between hostility and sympathetic activation such that hostility is accompanied by sympathetic hyperactivation only when depressive symptoms are minimal.

Mood states, sympathetic activity, and in vivo beta-adrenergic receptor function in a normal population

The purpose of this study was to examine the relationship between mood states and beta-adrenergic receptor function in a normal population. We also examined if sympathetic nervous system activity is related to mood states or beta-adrenergic receptor function. Sixty-two participants aged 25-50 years were enrolled in this study. Mood states were assessed using the Profile of Mood States (POMS). Beta-adrenergic receptor function was determined using the chronotropic 25 dose isoproterenol infusion test. Level of sympathetic nervous system activity was estimated from 24-hr urine norepinephrine excretion. Higher tension-anxiety, depression-dejection, and anger-hostility were related to decreased beta-adrenergic receptor sensitivity (i.e., higher chronotropic 25 dose values), but tension-anxiety was the only remaining independent predictor of beta-adrenergic receptor function after controlling for age, gender, ethnicity, and body mass index (BMI). Urinary norepinephrine excretion was unrelated to either mood states or beta-adrenergic receptor function. These findings replicate previous reports that anxiety is related to decreased (i.e., desensitized) beta-adrenergic receptor sensitivity, even after controlling for age, gender, ethnicity, and body mass index.

Allelic isoforms and decrease in serotonin transporter mRNA in lymphocytes of patients with major depression

Serotonin transporter, measured by the specific binding of [(3)H]paroxetine, has been reported to be reduced in circulating lymphocytes of patients with major depression. Due to this observation, the objective of the present report was to determine the levels of serotonin transporter mRNA in lymphocytes obtained from 29 major depression patients (4 men, age 33.10+/-1.63 years) and from 30 subjects included as a control group (4 men, age 37.54+/-2.18 years) using RT-PCR. The patients were diagnosed according to the criteria of the American Psychiatric Association, and had a severity of depression of 32.68+/-1.55 determined by the Hamilton Rating Scale for Depression. The DNA was submitted to polymerase chain reaction with primers for the 5' regulatory region of human serotonin transporter, which could show the long and the short allelic forms of the transporter gene for the 5 HTTLPR polymorphism. Semiquantitative analysis was performed using beta-actin as internal and external standard. Control subjects presented the two allelic forms in 9.09% and depressed patients in 8.69%. The long variant was present in 73% of controls and in 60% of patients, without significant differences. There was a significant reduction in mRNA in depressed patients expressing the long allele. The number of immunofluorescent lymphocytes, labeled with a specific antibody against serotonin transporter, was reduced in the patients, as well as CD3+ lymphocytes. Serotonin and 5-hydroxyindoleacetic acid in platelet-poor plasma or lymphocytes did not differ between depressed patients and controls. The reduction in lymphocyte serotonin transporter described in major depression might be due to a decrease in the level of its mRNA and in the number of cells expressing it. These observations might implicate that functional modifications are associated with nervous-immune interactions in depression.

Adenylate cyclase activity in postmortem brain of suicide subjects: reduced response to beta-adrenergic stimulation

BACKGROUND

Biochemical research on the etiopathogenesis of affective disorders has focused on transduction mechanisms beyond receptors, such as adenylate cyclase activity.

METHODS

Adenylate cyclase activity (AC) was measured in postmortem frontal cortex samples from 11 suicide victims with a firm antemortem diagnosis of major depressive disorder and 11 matched control cases. We analyzed the basal activity of the enzyme and that following stimulation with forskolin, guanine nucleotides, and the beta(1)-adrenoceptor agonist xamoterol.

RESULTS

A significant negative correlation between the period of tissue storage and the response of AC to the different stimuli assayed was observed. No difference was found in the levels of basal, forskolin-, and GTPgammaS-stimulated activity between control and major depressive disorder cases, both in the drug-free and the drug-treated subgroups. In contrast, we found a significant lower response to beta(1)-adrenoceptors agonist-stimulated AC activity in the major depressive disorder group (p <.01). This pattern of reduced response was also found in the subgroup of patients with negative toxicology for antidepressants.

CONCLUSIONS

These results, directly obtained from the brain of depressed patients, reinforce the involvement of noradrenergic neurotransmission in depressive illness. They also support the relevance of cyclic adenosine monophosphate signaling pathways in the etiopathogenesis of affective disorders.

The Association of Forskolin-Stimulated Cyclic AMP Levels in Peripheral Blood Mononuclear Cells of Healthy People with Depressive Mood and Sense of Coherence

Abstract: Background: Depressive mood exerts a suppressive effect on immune functions, mediated through neuro-immune processes. Research suggests a protective effect of sense of coherence (SOC) on psychological and physical health in face of stressful life events. Cyclic adenosine monophosphate (cAMP) is a cellular second messenger that is coupled to certain receptors expressed on peripheral blood mononuclear cells (PBMC). By interfering with the neuro-endocrine-immune axis, depressive mood may induce changes in intracellular cAMP levels in PBMC. Aims of study: To examine a possible association of SOC, stressful life events during the previous year, depressive mood, and cAMP levels. Methods: Fifteen male volunteers participated in the study. They completed the SOC and Zung's depression questionnaires and stressful life events inventory. Basic cAMP level and forskolin-stimulated cAMP production were measured in PBMC. Results: Forskolin-stimulated cAMP production was significantly higher in individuals who reported higher depressive mood, more stressful life events, or lower SOC scores. SOC scores explained 40% of forskolin-stimulated cAMP production. Basal cAMP levels could not be correlated with psychological scores. Age or education level did not affect forskolin-stimulated or basal cAMP levels. Conclusions: Our data suggest that high forskolin-stimulated cAMP production in PBMC is associated with low SOC, which points to availability of personal resources for coping with stressful life events. Further examination of the possible mediating role of SOC in relation to depressive mood and neuroimmune functions is needed.

A study on nitric oxide, beta-adrenergic receptors and antioxidant status in the polymorphonuclear leukocytes from the patients of depression

BACKGROUND

alterations in the polymorphonuclear leukocyte (PMNs) receptors, second messenger system and in their responses have been found associated with depression. Recently role of tetrahydrobiopterin and nitric oxide has also been reported in the depressive disorders. It was therefore considered worthwhile to investigate the NOS activity in the PMNs, which like neurons, also express neuronal NOS (nNOS), antioxidant enzyme levels [superoxide dismutase (SOD), catalase and glutathione peroxidase (Gpx)] and beta-adrenergic receptors in the patients of depression.

METHODS

patients were diagnosed according to the DSM-IV and were medication free, while healthy age-matched controls were also included in the study to estimate nitrite content, beta-adrenergic receptors and antioxidant enzymes in the PMNs according to the standard methodologies.

RESULTS

an analysis of 66 cases of depression and 114 controls revealed 73% decrease in nitrite content and 71% decrease in beta-adrenergic receptor binding in the patients as compared to the healthy controls. However, activities of SOD, catalase and Gpx were not significantly altered in the patients.

CONCLUSION

the results of the present study for the first time indicate alterations the NOS activity in PMNs obtained form the patients of affective disorders.

Depression as a spreading adjustment disorder of monoaminergic neurons: a case for primary implication of the locus coeruleus

A model for the pathophysiology of depression is discussed in the context of other existing theories. The classic monoamine theory of depression suggests that a deficit in monoamine neurotransmitters in the synaptic cleft is the primary cause of depression. More recent elaborations of the classic theory also implicitly include this postulate, other theories of depression frequently prefer to depart from the monoamine-based model altogether. We suggest that the primary defect emerges in the regulation of firing rates in brainstem monoaminergic neurons, which brings about a decrease in the tonic release of neurotransmitters in their projection areas, an increase in postsynaptic sensitivity, and concomitantly, exaggerated responses to acute increases in the presynaptic firing rate and transmitter release. It is proposed that the initial defect involves, in particular, the noradrenergic innervation from the locus coeruleus (LC). Dysregulation of the LC projection activities may lead in turn to dysregulation of serotonergic and dopaminergic neurotransmission. Failure of the LC function could explain the basic impairments in the processing of novel information, intensive processing of irrational beliefs, and anxiety. Concomitant impairments in the serotonergic neurotransmission may contribute to the mood changes and reduction in the mesotelencephalic dopaminergic activity to loss of motivation, and anhedonia. Dysregulation of CRF and other neuropeptides such as neuropeptide Y, galanin and substance P may reinforce the LC dysfunction and thus further weaken the adaptivity to stressful stimuli.

Decreases in dilated pupil size in depressed patients with age may reflect adrenergic changes

Some studies have suggested that noradrenergic activity may decrease with age in depressed patients. Pupil size is regulated by a balance between norepinephrine and acetylcholine. The present study compares pupil size in 10 unmedicated patients with unipolar depression (296. 3) and in 16 normal controls. Pupil size after dilation with tropicamide, a cholinergic antagonist, was inversely related to age in the patients (r=-0.87), but did not diminish with age in controls. The results suggest that pupil size may provide an index of diminished noradrenergic function with age in patients with major depression.

[3H]Paroxetine binding to human peripheral lymphocyte membranes of patients with major depression before and after treatment with fluoxetine

Serotonin has been involved in major depression and is also related to central and peripheral mechanisms of neuroimmunomodulation. Recently, the uptake of [3H]serotonin into human peripheral blood lymphocytes has been reported. We determined the density of serotonin uptake sites by the binding of [3H]paroxetine to blood peripheral lymphocyte membrane preparations of controls and of patients with major depression before and after treatment with fluoxetine for six weeks. The severity of depression was assessed by the use of Hamilton Rating Scale for Depression and of Beck Depression Inventory. There was a reduction in the number of sites for [3H]paroxetine in patients before administration of the antidepressant respecting controls, and a recovery after the treatment. Affinity was unchanged. No correlation was obtained between the severity of symptoms determined by Hamilton Rating Scale for Depression or by Beck Depression Inventory, and the number of binding sites for [3H]paroxetine. The levels of the plasma serotonin metabolite, 5-hydroxyindoleacetic acid, did not differ between the three groups of subjects, but serotonin was lower in patients after treatment respecting controls and in patients before treatment. The significant correlation between specific binding of [3H]paroxetine and plasma serotonin levels in controls was not present in the patients. Lymphocyte serotonin transporter is decreased in major depressed patients and is modulated by antidepressant treatment. In addition of counting with a peripheral marker in depression, the study of serotonin system in lymphocytes might contribute to understand the bi-directional interaction between the nervous and the immune systems.

Adrenergic receptors in premenstrual dysphoric disorder. II. Neutrophil beta2-adrenergic receptors: Gs protein coupling, phase of menstrual cycle and prediction of luteal phase symptom severity

Abnormal beta2-adrenergic receptor coupling to Gs protein is implicated in depressive disorders. Steroid hormones and antidepressants modulate beta-adrenergic receptor coupling, which may relate to the therapeutic efficacy of antidepressants. We examined beta2-adrenergic receptors in 18 patients with premenstrual dysphoric disorder (PMDD), in 15 control subjects during the follicular phase and in 12 patients during late luteal phase. Antagonist-measured receptor density, agonist-measured receptor density in the high- and low-conformational states and agonist affinity to both states were measured. Coupling indices to Gs protein were determined from agonist-displacement experiments. Follicular beta2-adrenergic receptor density was higher in patients than in control subjects, with a trend for higher receptor density in the high-conformational state. The phase of menstrual cycle had no effect on beta2-adrenergic receptor regulation in PMDD. Exploratory correlations showed that the K(L)/K(H) ratio was related to anxiety ratings in control subjects and %R(H) was correlated with symptom severity in patients. In patients, follicular beta2-adrenergic receptor binding measures were correlated with luteal symptom severity. These findings suggest abnormal beta2-adrenergic receptor regulation in PMDD. Further exploration of the role of beta-adrenergic receptor kinase, sex steroid hormones and antidepressants on beta-adrenergic receptor regulation in PMDD is warranted.

Differential G protein measures in mononuclear leukocytes of patients with bipolar mood disorder are state dependent

Quantitative and functional measurements of G proteins were undertaken in mononuclear leukocytes of bipolar disordered patients comparing bipolar depressed with manic patients groups in order to verify whether any alterations observed in G protein functional or immunoreactive measures in bipolar mood disorder are state- or trait-dependent characteristics. Compared with the control group of 30 subjects, isoproterenol- and carbamylcholine-enhanced Gpp(NH)p binding capacities were highly significantly increased in the group of 20 manic patients, while highly significantly reduced in the group of 11 bipolar depressed patients. While manic patients showed highly significant elevations in mononuclear leukocytes levels of G alpha s and G alpha i, evaluated through immunoblot analysis using specific polyclonal antibodies against the subunit proteins, mononuclear leukocytes of bipolar depressed patients show significant reductions in G alpha s and G alpha i immunoreactive levels. G beta subunit levels were found to be similar in all three groups. The changes in G protein measures observed in mononuclear leukocytes of mood disordered patients thus represent state characteristics of the disorder.

Reduced beta-adrenergic receptor-coupled Gs protein function and Gs alpha immunoreactivity in mononuclear leukocytes of patients with depression

beta-Adrenergic receptor-coupled Gs protein function was measured in 26 depressed patients through cholera toxin-sensitive, isoproterenol-induced increases in 3H-Gpp(NH)p binding capacity to mononuclear leukocytes (MNL). Highly significant reductions in receptor-coupled Gs protein function were observed in the depressed patients: 2.0 +/- 1.3% increases in guanine nucleotide-binding capacity, in comparison with the control group values of 28.3 +/- 6.9%. Similar reductions in Gs protein function were detected in both uni- and bipolar depressed patients. A significant negative correlation was found between receptor-coupled Gs protein measures and the severity of depression. Adding semiquantitative measures of MNL Gs alpha through immunoblot analysis by use of polyclonal antibodies against Gs alpha subunit, it was found that Gs alpha relative immunoreactivity was reduced from 100 +/- 2.0% in the control group of subjects to 75.9 +/- 2.3% in the depressed patients. We have previously described hyperfunctional Gs proteins in leukocytes of patients with mania. The present findings of reduced function of Gs in depressed patients suggests receptor-coupled Gs protein activity as a biochemical parameter indicatory of the affective state. Reduced receptor-coupled Gs protein function may reflect reduced levels of the beta-adrenergic receptor previously shown in leukocytes of depressed patients; however, our complementary immunoblot studies suggest a direct, postreceptor, quantitative, and functional reduction in Gs protein in MNL of depressed patients.