Serotonin but not norepinephrine-induced calcium mobilization of platelets is enhanced in affective disorders

Is there a relationship between morphological and functional platelet changes and depressive disorder?

BACKGROUND

Blood platelets, due to shared biochemical and functional properties with presynaptic serotonergic neurons, constituted, over the years, an attractive peripheral biomarker of neuronal activity. Therefore, the literature strongly focused on the investigation of eventual structural and functional platelet abnormalities in neuropsychiatric disorders, particularly in depressive disorder. Given their impact in biological psychiatry, the goal of the present paper was to review and critically analyze studies exploring platelet activity, functionality, and morpho-structure in subjects with depressive disorder.

METHODS

According to the PRISMA guidelines, we performed a systematic review through the PubMed database up to March 2020 with the search terms: (1) platelets in depression [Title/Abstract]"; (2) "(platelets[Title]) AND depressive disorder[Title/Abstract]"; (3) "(Platelet[Title]) AND major depressive disorder[Title]"; (4) (platelets[Title]) AND depressed[Title]"; (5) (platelets[Title]) AND depressive episode[Title]"; (6) (platelets[Title]) AND major depression[Title]"; (7) platelet activation in depression[All fields]"; and (8) platelet reactivity in depression[All fields]."

RESULTS

After a detailed screening analysis and the application of specific selection criteria, we included in our review a total of 106 for qualitative synthesis. The studies were classified into various subparagraphs according to platelet characteristics analyzed: serotonergic system (5-HT2A receptors, SERT activity, and 5-HT content), adrenergic system, MAO activity, biomarkers of activation, responsivity, morphological changes, and other molecular pathways.

CONCLUSIONS

Despite the large amount of the literature examined, nonunivocal and, occasionally, conflicting results emerged. However, the findings on structural and metabolic alterations, modifications in the expression of specific proteins, changes in the aggregability, or in the responsivity to different pro-activating stimuli, may be suggestive of potential platelet dysfunctions in depressed subjects, which would result in a kind of hyperreactive state. This condition could potentially lead to an increased cardiovascular risk. In line with this hypothesis, we speculated that antidepressant treatments would seem to reduce this hyperreactivity while representing a potential tool for reducing cardiovascular risk in depressed patients and, maybe, in other neuropsychiatric conditions. However, the problem of the specificity of platelet biomarkers is still at issue and would deserve to be deepened in future studies.

Outcome of patients with acute symptomatic pulmonary embolism and psychiatric disorders

OBJECTIVE

To address the association between psychiatric disorders and short-term outcomes after acute symptomatic pulmonary embolism (PE).

METHODS

We identified adults with PE enrolled in the RIETE registry between December 1, 2013, and January 31, 2019. Using multinomial regression, we assessed the association between a history of psychiatric disorders and the outcomes of all-cause mortality, PE-related mortality, and venous thromboembolism recurrence and bleeding rates through 30 days after initiation of treatment. We also examined the impact of depression on all-cause and PE-specific mortality.

RESULTS

Among 13,120 patients diagnosed with acute PE, 16.1% (2115) had psychiatric disorders and 4.2% died within the first 30-days of follow-up. Patients with psychiatric disorders had increased odds for all-cause (adjusted odds ratio [OR] 1.50; 95% CI, 1.21 to 1.86; P < 0.001) and PE-related mortality (adjusted OR 1.64; 95% CI, 1.09 to 2.48; P = 0.02) compared to those without psychiatric disorders. Multinomial logistic regression showed a non-significant trend toward lower risk of recurrences for patients with psychiatric disorders (adjusted OR 0.49; 95% CI, 0.21 to 1.15; P = 0.10). Psychiatric disorders were not significantly associated with increased odds for major bleeds during follow-up (adjusted OR 1.09; 95% CI, 0.85 to 1.40; P = 0.49). Results were consistent in a sensitivity analysis that only considered patients with a diagnosis of depression.

CONCLUSIONS

In patients with acute PE, history of psychiatric disorders might predict all-cause and PE-related death in the ensuing month after diagnosis.

Vascular depression: a new view of late-onset depression

We have suggested that cerebrovascular disease may predispose, precipitate, or perpetuate some late-life depressive syndromes. The mechanisms of "vascular depression" include disruption of cortico-striato-pallido-thalamo-cortical (CSPTC) pathways or their modulating systems. This view is supported by the presentation of vascular depression, which consists of depressive symptoms, cognitive abnormalities, as well as neuroimaging findings that may result from CSPTC impairment. Moreover, clinical and electrophysiological evidence of CSPTC impairment, an abnormality frequently found in patients with vascular depression, appears to be associated with poor response to antidepressant treatment and early relapse and recurrence. The vascular depression hypothesis provides the conceptual background for studies that may have clinical and theoretical impact. Agents influencing dopamine, acetylcholine, and opioid neurotransmitters may be studied in vascular depression, since these are essential neurotransmitters of the frontostriatal circuitry. Drugs used for prevention and treatment of cerebrovascular disease may be shown to reduce the risk for vascular depression or improve its outcomes. The choice of antidepressants in vascular depression may depend on their effect on neurological recovery from ischemic lesions. Finally, identification of specific relationships between specific symptoms, cognitive deficits, and disability may lead to interventions that target the patients' deficits as well as their interactions with psychosocial factors known to contribute to depression. Research can clarify the pathways to vascular depression by focusing on the site of lesion, the resultant brain dysfunction, the presentation of depression and time of onset, and the contribution of nonbiological factors.

Emergency department patients self-report higher patient inertia, hopelessness, and harmful lifestyle choices than community counterparts

Patient inertia is defined as an individual's failure to take responsibility for proactive lifestyle change and health conditions including hypertension. Generalized and hypertension-specific patient inertia factors were compared in 110 patients (48% women; 52% African American) from a Forsyth County, NC, emergency department (ED) and 104 community members (79% women; 70% African American) using the patient inertia-facilitated survey Patient Inertia-36. Statistically, more ED than community participants added salt to food at the table and consumed fast foods 5 to 7 days a week. ED patients agreed less often with health literacy questions about salt and BP. Hypertension associated Patient inertia questions asked of 45 ED and 40 community participants with a personal history of hypertension revealed a statistically higher sense of hopelessness surrounding blood pressure management in ED participants. Past BP control experiences of family members had statistically greater impact on community participants regarding their own BP control. Using a logistic regression model, advancing age and being surveyed in the ED were correlated with hopelessness towards BP control. ED patients make unhealthier diet choices and possess heightened generalized and hypertension-specific patient inertia including hopelessness towards controlling their BP that increases with age. These factors may contribute to this population's poor BP control, particularly self-efficacy barriers.

Effects of chronic treatment with fluoxetine on receptor-stimulated increase of [Ca2+]i in astrocytes mimic those of acute inhibition of TRPC1 channel activity

Primary cultures of mouse astrocytes were used to investigate effects by chronic treatment (3-21 days) with fluoxetine (0.5-10 μM) on capacitative Ca(2+) influx after treatment with the SERCA inhibitor thapsigargin and on receptor agonist-induced increases in free cytosolic Ca(2+) concentration [Ca(2+)](i), determined with Fura-2. The agonists were the 5-HT(2B) agonist fluoxetine, the α(2)-adrenergic agonist dexmedetomidine, and ryanodine receptor (RyR) and IP(3) receptor (IP(3)R) agonists. In untreated sister cultures each agonist distinctly increased [Ca(2+)](i), but in cultures treated for sufficient length of time or with sufficiently high doses of fluoxetine, acute administration of fluoxetine, dexmedetomidine, or RyR or IP(3)R agonists elicited reduced, in some cases abolished, effects. Capacitative Ca(2+) entry, meditated by TRPC1 channels, was sufficiently inhibited to cause a depletion of Ca(2+) stores, which could explain the reduced agonist effects. All effects of chronic fluoxetine administration could be replicated by TRPC1 channel antibody or siRNA. Since increases in astrocytic [Ca(2+)](i) regulate release of gliotransmitters, these effects may have profound effects on brain function. They may be important for therapeutic effects of all 5 conventional 'serotonin-specific reuptake inhibitors' (SSRIs), which at concentrations used therapeutically (∼1 μM) share other of fluoxetine's chronic effects (Zhang et al., Neuron Glia Biol. 16 (2010) 1-13).

Serotonin-induced decrease of intracellular Ca(2+) release in platelets of bulimic patients normalizes during treatment

Numerous symptoms related to eating disorders have been shown to be influenced by serotonergic (5-HT) functioning, with the 5-HT(2A) receptor subtype being one of the most relevant involved in the pathophysiology of bulimia nervosa (BN). In line with this, Ca(2+) mobilization as mediated by 5-HT(2) receptors in platelets was shown to serve as a peripheral model for central nervous 5-HT functioning. Here, the 5-HT-induced intracellular Ca(2+) mobilization in platelets was measured in 13 female normal weight bulimic patients (14-18 years) upon admission and at the end of inpatient treatment. Findings were compared to 21 age-matched healthy female adolescents. 5-HT-induced Ca(2+) release was significantly decreased in bulimic patients upon admission and normalized during inpatient treatment. Antidepressive medication caused a significant improvement. The data provide further evidence that altered 5-HT(2) receptor functioning is involved in the pathophysiological underpinnings in BN.

Role of calcium metabolism in premenstrual syndrome

Premenstrual syndrome has been the subject of many myths and misconceptions over the centuries. It is a very common problem affecting millions of young women during their reproductive lives and is characterized by numerous recurrent, cyclical emotional and physical symptoms during the luteal phase of the menstrual cycle. The etiology of this disorder has remained poorly understood until only recently. Alterations in calcium homeostasis have long been associated with many affective disorders. Cyclical fluctuations of the ovarian steroid hormones across the menstrual cycle influence calcium metabolism, affect intestinal calcium absorption and modulate 1,25-dihydroxyvitamin D synthesis. Evidence now strongly suggests that abnormalities in calcium and vitamin D metabolism, specifically calcium and vitamin D deficiency, are responsible for these luteal-phase symptoms. Calcium and vitamin D supplementation may offer a simple solution to millions of women affected with premenstrual syndrome.

An antidepressant behaviour in mice carrying a gene-specific InsP3R1, InsP3R2 and InsP3R3 protein knockdown

Evidence has accumulated for the involvement of Ca(2+) in the pathophysiology of mood disorders. Elevations in both resting and stimulated intracellular Ca(2+) levels in patients with affective disorders have been reported. The role of inositol-1,4,5-trisphosphate receptors (InsP3Rs), which allow mobilization of intracellular Ca(2+) stores, was, then, investigated in the mouse forced swimming test. InsP3R antagonists (heparin, xestospongin C) as well as an inositol monophosphatase inhibitor (LiCl) showed an antidepressant activity of intensity comparable to clinically used antidepressants. InsP3Rl, InsP3R2 and InsP3R3 knockdown mice were obtained to investigate the role of InsP3R isoforms. We generated mice carrying a cerebral knockdown of InsP3Rl, InsP3R2 and InsP3R3 proteins by administering antisense oligonucleotides complementary to the sequence of InsP3Rl, InsP3R2 and InsP3R3. These antisense-treated mice showed a specific InsP3R protein level reduction in the mouse cerebral cortex and hippocampus, demonstrated by immunoblotting, immunoprecipitation and immunocytochemistry experiments. Knockdown mice for each InsP3R isoforms showed an antidepressant behaviour and the induced phenotype was reversible disappearing 7 days after the end of the treatment. The absence of impairment of locomotor activity and spontaneous mobility in InsP3R knockdown mice was revealed. These results indicate the involvement of the InsP3R-mediated pathway in the modulation of depressive conditions and may be useful for the development of new therapeutical strategies for the treatment of mood disorders.

Symptoms of depression and cardiovascular reactions to acute psychological stress: evidence from a population study

Depression and exaggerated cardiovascular reactivity are considered risk factors for cardiovascular disease, possibly as a result of common antecedents, such as altered autonomic nervous system function. We examined the association between depressive symptomatology and cardiovascular reactions to psychological stress in 1608 adults (875 women) comprising 3 distinct age cohorts: 24-, 44-, and 63-year olds. Depression was assessed using the Hospital Anxiety and Depression Scale. Blood pressure and heart rate were measured at baseline and during the paced auditory serial arithmetic test. Depression scores were negatively associated with systolic blood pressure and heart rate reactions, after adjustment for likely confounders such as sex, cohort, occupational status, body mass index, stress task performance score, baseline cardiovascular activity, antidepressant, and antihypertensive medication. The direction of association was opposite to that which would be expected if excessive reactivity were to mediate the association between depression and cardiovascular disease outcomes or if they shared common antecedents.

Inter-relationships of intermediate phenotypes for serotonin function, impulsivity, and a 5-HT2A candidate allele: His452Tyr

Central serotonin (5-hydroxytryptamine, 5-HT) function has a role in a range of genetically influenced psychiatric diagnoses and behaviors. Several human 5-HT receptor polymorphisms are 'candidate alleles', altering in vitro function, and potentially affecting behavior and drug response. The 5-HT(2A) His452Tyr polymorphism alters signal transduction, and has been associated with diminished efficacy of clozapine in schizophrenia. Another 5-HT(2A) receptor polymorphism consists of the silent thymidine-cytosine substitution (102T>C), which has been controversially associated with schizophrenia. We investigated the role of His452Tyr and the 102T>C in behavior and in vivo intermediate biochemical phenotypes. Intracellular 5-HT-induced Ca(2+) release by platelets and fenfluramine-induced prolactin release by pituitary were evaluated in 27 psychiatrically interviewed subjects (including both impulsive patients and controls) stratified by His452Tyr genotype and also genotyped for a second 5-HT(2A) polymorphism, 102T>C. Subjects with increased measures of impulsivity showed decreased postreceptor 5-HT function, as indicated by reduced 5-HT-induced Ca(2+) release, but no alteration in net 5-HT function, as measured by fenfluramine response. No significant effects of either polymorphism were associated with altered 5-HT-induced calcium response or fenfluramine-stimulated prolactin release. One available Tyr452/Tyr452 homozygote had diminished Ca(2+) release and one of the highest levels of fenfluramine response. Although not statistically significant, the effect of the T102C, but not the His452Tyr, genotype on prolactin level change over time was associated with a medium to large strength of association (treatment magnitude of T(2)=0.10), suggesting that further study is warranted.

Corticosteroids, depression and the role of serotonin

Patients frequently use medications simultaneously for different complaints, without being aware of the interactions these products may have. An example of this is the simultaneous use of corticosteroids and medications for depression, defiant or aggressive behaviour. Research has also indicated that corticosteroids lower serotonin levels. However, lowered serotonin levels may result in depression, aggression and other psychological conditions. These secondary complaints, caused by the corticosteroids and other products that lower serotonin levels, may then be treated with selective serotonin reuptake inhibitors (SSRIs) or psycho-stimulants (that are known to indirectly increase serotonin levels). The current research takes a look at lowered serotonin levels when using corticosteroids, as well as the interactions with SSRIs and psycho-stimulants. Furthermore, evidence is presented to prove the hypothesis that some individuals with asthma (e.g. children using systemic corticosteroids that lower serotonin levels) might present with symptoms of depression, attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder and even conduct disorder; and that treating these secondary complaints with SSRIs and psycho-stimulants will result in the upregulating of serotonin levels, and that, in turn, will trigger asthma.

The platelet window: examining receptor regulated second messenger processes in psychosis and depression

Peripheral markers of psychiatric illness provide a potentially important window into the pathophysiology of a number of psychiatric illnesses. Direct access to pathophysiological processes is fraught with difficulty. However, receptor-regulated second messenger-mediated calcium shifts are an accessible and practical method by which to examine changes in a clinical population. This is possible because platelets and neurons share some physiological features. The platelet intracellular calcium response to receptor stimulation has previously been used as a peripheral marker of psychiatric illness across a range of neurotransmitters, including serotonin, dopamine and glutamate. This review considers the specificity and selectivity of this response and its use in psychotic and mood disorders.

Increased coronary events in depressed cardiovascular patients: 5-HT2A receptor as missing link?

OBJECTIVE

Major depressive disorder and depressive symptoms have been identified as independent risk factors for cardiac morbidity and mortality in patients with ischemic heart disease. Increased susceptibility to platelet activation has been proposed as one of the mechanisms by which depression acts as a significant risk factor for thrombotic events. In this review, data on platelet activation and platelet aggregation measures in depressed patients with or without concomitant cardiovascular disease are given. Data on the influence of antidepressants on parameters of platelet activation are summarized.

METHODS

A literature search was done by checking MEDLINE Advanced and PsycInfo from 1990 to 2003 and through checking the bibliographies of these sources. The following key words were used for this search: platelet activation, platelet aggregation, depression, depressive disorder, ischemic heart disease, calcium, and serotonin.

RESULTS

There is an indication of enhanced platelet activation and aggregation in depressed patients. Next, patients with a depressive disorder show signs of a hyperactive platelet 5-HT2A receptor signal transduction system as measured by increased platelet calcium mobilization after stimulation of platelets with serotonin.

CONCLUSIONS

Depression appears to be associated with an increased susceptibility for serotonin-mediated platelet activation. Upregulation and/or increased sensitivity of 5-HT2A/1B receptors and downregulated 5-HT transporter receptors in the periphery may contribute to increased risk of thromboembolic events in patients with depression and cardiovascular disease. Increased platelet reactivity based on a hyperreactive 5-HT2A receptor signaling system might be influenced by antidepressive medication that antagonizes platelet 5-HT2A receptors.

Altered 5-HT-induced calcium response in the presence of staurosporine in blood platelets from bipolar disorder patients

We have reported that the platelet intracellular calcium (Ca) mobilization after stimulation by serotonin (5-HT) is specifically enhanced in bipolar disorder among various psychiatric disorders, compared with that in normal control. To explore the mechanisms of enhanced Ca response to 5-HT in the platelets, we first examined the relation between the 5HT-elicited Ca mobilization and 5-HT(2A) receptor density using the platelets from 13 normal subjects. From this study, we found no significant correlation between two measures. Then, we investigated the effects of staurosporine, a protein kinase C (PKC) inhibitor, on Ca response to 5-HT in platelets from patients with major depressive disorder (unipolar), bipolar disorder, and normal controls. While 5-HT-induced Ca mobilization, in the presence of 100 nM staurosporine, was significantly attenuated in normal controls and patients with major depressive disorder, the inhibitory effect of staurosporine was not observed in bipolar disorder. These results suggest that the failure in inhibiting the platelet intracellular Ca response to 5-HT in bipolar disorder may be related to increased activity of PKC rather than increased 5-HT(2A) receptor number. Moreover, the trend of the Ca response towards staurosporine may become a specific biological marker for unipolar-bipolar dichotomy.

Epinephrine- and thrombin-stimulated high-affinity GTPase activity in platelet membranes from patients with psychiatric disorders

Although heterotrimeric guanine nucleotide-binding regulatory (G) proteins have been implicated in the pathophysiology of mental illnesses (especially mood disorders), direct evidence has been scarce. This study was designed to reveal possible abnormalities of receptor-coupled G protein function in platelets in patients with psychiatric disorders such as depression and schizophrenia. The functional status of alpha(2A)-adrenergic receptor-coupled G(i2) and thrombin receptor-coupled G proteins (G(i2)+G(q)) was determined by the increase in high-affinity GTPase activity in response to epinephrine and thrombin, respectively, in platelet membranes from 18 patients with mood disorders (15 unipolar and three bipolar subtype), 13 schizophrenic patients, four neurotic patients and 29 healthy control subjects. Neither alpha(2A)-adrenergic receptor-coupled G(i2) nor thrombin receptor-coupled G(q) was functionally altered in platelets from psychiatric patients compared with control subjects. No significant correlation was observed between these biochemical measures in platelets and severity of psychopathological symptoms. The functional coupling efficiency of G proteins with receptors appears intact, at least between alpha(2A)-adrenergic receptors and G(i2), and between thrombin receptors and G(q), in platelets from patients with psychiatric disorders.

Serotonin 5-HT(2A) receptor gene polymorphism, 5-HT(2A) receptor function and personality traits in healthy subjects: a negative study

BACKGROUND

Central serotonin-2A (5-HT(2A)) receptor dysfunction is regarded as an important factor in the etiology of affective disorders. The relations between some personality traits and the vulnerability of affective disorders are also implicated. Moreover, there are several reports which describe the association between 5-HT(2A) receptor gene polymorphisms and mental disorders. We therefore examined the relationship between personality traits, the 5-HT(2A) receptor function, and 5-HT(2A) receptor gene polymorphisms.

METHODS

5-HT-induced intraplatelet calcium (Ca) mobilization, 5-HT(2A) receptor gene polymorphisms (A-1438G, T102C, T516C, C1340T, C1354T), and Temperament and Character Inventory (TCI) scores were examined in 133 healthy subjects.

RESULTS

Neither 5-HT-induced Ca mobilization nor 5-HT(2A) receptor gene polymorphisms (A-1438G, T102C) appear to be associated with seven personality dimensions including Harm Avoidance. There was no significant difference in the Ca response among the subjects with -1438A/A, A/G and G/G genotypes. Since the appearance of the other types of the 5-HT(2A) receptor gene polymorphisms (T516C, C1340T and C1354T) was quite rare in our sample, we were unable to examine the relationship between these polymorphisms, and the TCI score or the Ca response.

LIMITATIONS

Our failure to find a significant association may reflect the false negative results due to the small sample size and low statistical power. Further studies in depressed patients may clarify the complicated relationship between personality traits and the vulnerability of affective disorders.

CONCLUSIONS

Personality traits detected by TCI may not be directly related to the 5-HT(2A) receptor function or 5-HT(2A) receptor gene polymorphism which may be involved in the vulnerability of affective disorders.

Effect of antidepressants on ATP-dependent calcium uptake by neuronal endoplasmic reticulum

This study investigated the effect of tricyclic and atypical antidepressants on adenosine triphosphate (ATP) dependent calcium uptake by the endoplasmic reticulum of lysed synaptosomes from rat brain cortex. Tricyclic antidepressants (imipramine, desipramine, clomipramine, amitriptyline) exhibited no effect in the lower range (0.06 to 2 µM) of drug concentrations, and a concentration-dependent inhibition of calcium uptake in the upper range (6 to 200 µM). A concentration-dependent inhibition was observed for atypical antidepressants (mianserin, desmethylmianserin, venlafaxine, desmethylvenlafaxine, fluoxetine) in both the lower and the upper range of drug concentrations. Since no stimulation of calcium uptake was observed in either concentration range, it appears that the tricyclic and atypical antidepressants tested are not capable of normalizing, through their effect on the endoplasmic reticulum, an overactive calcium signal, which is possibly implicated in the etiology of affective disorders. Also, although only marginal inhibition of calcium uptake is expected at brain concentrations of tricyclics and mianserin–desmethylmianserin that are likely to be encountered during clinical use, a more substantial inhibition could occur with fluoxetine.Key words: adenosine triphosphate-dependent calcium uptake, neuronal endoplasmic reticulum, lysed brain synaptosomes, tricyclic antidepressants, atypical antidepressants.

Modulation of serotonin2A receptor function in rats after repeated treatment with dexamethasone and L-type calcium channel antagonist nimodipine

1. It has been conceivable that the hypothalamic-pituitary-adrenal (HPA) axis hyperactivity plays an important role in the pathophysiology of depression. In the present study, we have investigated the effect of repeated treatment with dexamethasone on serotonin (5-HT) 1A, 5-HT2A and alpha1-adrenergic receptors in the rat frontal cortex. Moreover, several studies have suggested the effectiveness of L-type calcium channel antagonist nimodipine for the treatment of depression. We also investigated the effect of repeated treatment with nimodipine on 5-HT2A receptor in rats with repeated dexamethasone treatment. 2. Repeated treatment with dexamethasone (1 mg/kg/day for 14 days) increased the density of 5-HT2A receptor, but not 5-HT1A and alpha1-adrenergic receptors in the rat frontal cortex. 3. The density of 5-HT2A receptor in the rat frontal cortex was significantly increased 1 day after repeated treatment with dexamethasone, but was not increased 7 or 14 days after repeated treatment. Wet dog shakes (WDS) induced by (+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI), a 5-HT2A receptor agonist, in rats were significantly enhanced 1, 7 and 14 days after repeated treatment with dexamethasone, although the frequency of WDS gradually decreased after repeated treatment. 4. Repeated treatment with nimodipine (5 mg/kg/day for 14 days) attenuated DOI-induced WDS enhanced by repeated treatment with dexamethasone (1 mg/kg/day for 14 days), however, it did not change the density of 5-HT2A receptor. Repeated treatment with dexamethasone decreased locomotor activity and body weight, but repeated treatment with nimodipine did not recover these parameters. 5. The results of the present study suggest that repeated treatment with dexamethasone may selectively increase the 5-HT2A receptor in the rat frontal cortex and affect 5-HT2A receptor-mediated signal transduction. In addition, the intracellular calcium homeostasis by blocking calcium influx through L-type calcium channel may play an important role in the regulation of the 5-HT2A receptor function by dexamethasone.

Serotonin-induced platelet intracellular calcium mobilization in various psychiatric disorders: is it specific to bipolar disorder?

BACKGROUND

Serotonin (5-HT)-stimulated platelet intracellular calcium (Ca) mobilization has been reported to be enhanced in unmedicated depressive patients compared to those of normal healthy subjects, which suggests increased 5-HT2A receptor function in these patients. It has not been ascertained whether this enhanced response is specific to some type of affective disorders among various mental disorders.

METHODS

We examined 5-HT-induced platelet intracellular Ca response in 152 unmedicated outpatients with various psychiatric disorders including bipolar disorder (BD), major depressive disorder with melancholia (DM), major depressive disorder without melancholia (DN), schizophrenia (SCH), panic disorder (PD), obsessive-compulsive disorder (OCD), social phobia (SP) and bulimia nervosa (BN), and 30 normal controls.

RESULTS

We observed no significant differences in basal intracellular Ca concentration among all patient subgroups and normal controls. While the 5-HT-induced Ca response was significantly and specifically higher in patients with BD than in normal controls, no significant differences were found in the Ca response to 5-HT between patients with DM, DN, SCH, PD, OCD, SP and BN, and normal controls.

LIMITATIONS

The sample sizes of each group are still small. Therefore, they have to be enlarged in the continuation of the study so as to increase the power of the statistical tests.

CONCLUSION

These results indicate the possibility that enhanced signal transduction, mediated by the 5-HT2A receptor, may be specific to bipolar disorder.

Platelet glutamate receptor supersensitivity in major depressive disorder

Dysregulation of glutamate has been described in depression, and supersensitivity of platelet glutamate receptors has been found in both psychotic major depression and schizophrenia. The aim of this study was to examine the platelet glutamate receptor sensitivity in patients with nonpsychotic, unipolar major depression to assess whether this is a marker of depression or of psychosis. Glutamate receptor sensitivity was assessed using the platelet intracellular calcium response to glutamate (0-100 micromol) measured by spectrofluorometry. The depression group showed a significantly greater platelet intracellular calcium response to glutamate stimulation than the control group, both in terms of absolute values (p = 0.007) and percentage of response from baseline (p = 0.030). These data suggest that platelet glutamate receptors may be supersensitive in depression and that the platelet may be a possible peripheral marker of glutamate function in depression.

The platelet as a peripheral marker in psychiatric illness

The identification of peripheral markers of psychiatric illness is important if an improvement in the diagnosis and treatment of various diseases with overlapping symptomatology is desired. There are many disorders that not only have overlapping symptomatology, but also have similar biological disturbances. The functional capability of the neurons involved in the disease processes may be at the crux of the underlying pathology. The platelet intracellular calcium response to neurotransmitter stimulation has previously been used as a peripheral marker of psychiatric illness. This review discusses evidence in support of the extended use of the platelet as a peripheral marker. The use of the platelet intracellular calcium response to neurotransmitter stimulation as a state or trait marker in major depression, the specificity and selectivity of this response, and the possible use of the platelet as a peripheral marker in psychotic disorders such as schizophrenia, mania and psychotic depression are shown. Finally, a proposed mechanism for the association between certain psychiatric disorders and cardiovascular disease is discussed. Copyright 2001 John Wiley & Sons, Ltd.

Effect of acute lipopolysaccharide administration on (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2 aminopropane-induced wet dog shake behavior in rats: comparison with body weight change and locomotor activity

1. Several reports have shown that serotonin (5-HT)2A receptor density and its function are altered after physiological or pharmacological stress. To examine whether an acute administration of lipopolysaccharide (LPS), a bacterial endotoxin, affected 5-HT2A receptor function, wet dog shakes of male Wistar rats were observed after a subcutaneous injection of DOI, a 5-HT2A receptor agonist following LPS treatment. Body weight change and locomotor activity were also observed. 2. DOI (1 mg/kg)-induced WDS significantly decreased after 400 or 1000 microg/kg LPS treatment compared with that of control rats 1 and 3 hr after injection, and WDS completely recovered 8 hr after LPS treatment. Treatment with 10 mg/kg indomethacin (IND) or 1 mg/kg naltrexone (NLTX) canceled the effect of 400 microg/kg LPS on DOI-induced WDS. 3. Body weight decrease was significantly greater in LPS-treated rats compared with control rats 3, 5 and 8 hr after treatment. Treatment with IND (10 mg/kg) significantly recovered the reduction in body weight induced by 400 microg/kg LPS. Treatment with NLTX (1 mg/kg) also prevented the LPS effect on body weight decrease. 4. Eight hr after treatment with LPS (400 microg/kg), the rats showed significant attenuation of locomotor activity. IND (10 mg/kg) treatment abolished the inhibitory effect of LPS on locomotor activity, and NLTX (1 mg/kg) also improved the decrease in locomotion 8 hr after LPS treatment. 5. Plasma tumor necrosis factor (TNF)-alpha concentration dramatically increased 1 hr after the injection of 400 microg/kg LPS, and returned almost to the basal level 3 hr later. Next, rats were injected with 50 microg/kg TNF-alpha intraperitoneally, and body weight change and DOI-induced WDS was determined 3 hr after TNF-alpha injection. Body weight loss was significantly greater in rats treated with TNF-alpha. On the other hand, DOI-induced WDS was not altered when rats were treated with TNF-alpha. 6. These results suggest that acute treatment with LPS inhibited 5-HT2A receptor-mediated behavior via cyclooxygenase and opioid receptor activation, but that the inhibition of the WDS by LPS appears to be independent of TNF-alpha production.

Correlations for serotonin levels and measures of mood in a nonclinical sample

The Beck Depression Inventory is frequently used to detect depression and its severity because depression is a prevalent mood disorder and is commonly treated by prescription of selective serotonin-reuptake inhibitors such as Prozac. The importance of serotonin (5-HT) in the treatment of major depression is evident but the nature of this involvement is unclear. In this study, the characteristics of platelets are employed as a peripheral model of the neuron to estimate central serotonergic activity, which is a consequence of numerous factors including 5-HT2 receptor sensitivity. The greater the sensitivity of the platelet serotonin receptors, the lower the concentration of serotonin required to mobilise a particular amount of calcium from internal stores through serotonin stimulation. Hence, Platelet 5-HT2 receptor sensitivity is inferred from the concentration of serotonin that is required to produce half maximal intracellular calcium mobilisation (EC50). In the present study, the correlation of -.422 between scores on the Beck Depression Inventory and EC50 in a sample of 49 university students was significant, implying that mood is significantly related to 5-HT2 receptor sensitivity, such that increases in depressed mood are accompanied by increases in 5-HT2 receptor sensitivity.

The specificity of platelet glutamate receptor supersensitivity in psychotic disorders

Hypoglutamatergic function is implicated in the pathogenesis of schizophrenia, and supersensitivity of platelet NMDA receptors has been reported in schizophrenia. The aim of this study was to examine the platelet glutamate receptor sensitivity in patients with schizophrenia (n=12), mania with psychotic features (n=10) and depression with psychotic features (n=10) and matched controls (n=12) in order to assess if this is a marker of schizophrenia or occurs in other psychotic conditions. Glutamate receptor sensitivity was assessed using the intracellular calcium response to glutamate measured with spectrofluorometry. The percentage response of the schizophrenic and depressed psychotic subjects to glutamate stimulation was significantly greater than control subjects (p<0.005). The mania with psychotic features group was not significantly different to controls. This data suggests that platelet glutamate receptors may be supersensitive in schizophrenia and depression with psychotic features. Furthermore, the platelet may be a possible peripheral marker of glutamate function in schizophrenia and depression with psychotic features.

Platelet supersensitivity to thrombin stimulation in depression: a possible mechanism for the association with cardiovascular mortality

The mortality risk associated with cardiovascular disease is significantly increased in patients with major depression and panic disorder. The mechanism of this phenomenon is unclear. Thrombin is responsible for platelet aggregation and shape change, and it plays a significant role in the development of thromboembolic events. In this study, we examined the platelet second messenger intracellular calcium response to thrombin stimulation in patients with major depression (n = 13), major depression after response to electroconvulsive therapy (ECT; n = 13), subsyndromal depression (n = 16), schizophrenia (n = 15), and control subjects (n = 65). Patients with major depression had significantly higher intracellular calcium responses to thrombin stimulation than control subjects, patients with subsyndromal depression, and patients with schizophrenia (p < 0.05). Electroconvulsive therapy did not significantly change this supersensitivity. This suggests that the platelet response to activation in patients with major depression is supersensitive. This study suggests a possible mechanism for the increased risk of cardiovascular disease that is seen in these two psychiatric disorders. The lack of difference between the control and subsyndromal depression groups appears to validate current diagnostic thresholds in depression. The failure of nonpharmacologic treatment to alter this marker suggests that it may be a trait marker of depression.

Gender and psychosomatic aspects of ischemic heart disease

While women and their doctors have traditionally worried about mortality from breast and gynecological malignancies, over the past 5 years they have come to realize that ischemic cardiac disease (IHD) is the number one killer of women in most Western countries. This has led to public and professional education campaigns and a new emphasis on gender and gender-specific research in IHD. Unfortunately, this literature remains poorly developed and much work remains to be done. Even in samples in which there may be sufficient numbers to allow for the evaluation of gender and gender differences, these important analyses have often been overlooked. This article provides a review of what is known about gender and gender differences in psychosocial and behavioral issues in IHD.

Augmented platelet calcium uptake in response to serotonin stimulation in patients with major depression measured using Mn2+ influx and 45Ca2+ uptake

There is an augmented platelet intracellular calcium response to serotonin stimulation in major depression. The role that calcium influx has in this process is not known. The objective of this study was to determine platelet calcium influx in response to serotonin by two methods, Mn2+ influx and 45Ca2+ uptake, in order to observe if the uptake response to serotonin was augmented in major depression by comparing the response to normal controls. The use of the two methods of calcium influx showed that serotonin stimulates calcium uptake into platelets. Furthermore, patients with major depression have significantly augmented platelet calcium uptake in response to serotonin. The interesting finding was that calcium uptake into platelets is biphasic, occurring immediately and after five minutes. These results may support the two pool model for calcium oscillations within cells whereby extracellular calcium is needed for intracellular calcium release, and for replenishment of depleted stores once intracellular calcium is released.

The current status of the platelet 5-HT(2A) receptor in depression

The author reviews the current status of the platelet serotonin (5-HT)(2A) receptor in depression. Considered are studies of receptor binding, and 5-HT-induced platelet activation and aggregation. 5-HT(2A) receptor density tends to increase in depression, although this more clearly relates to suicidality than depression per se. Indeed, data are consistent with the hypothesis that increased density of platelet 5-HT(2A) receptors may be a marker for increased risk of suicide. 5-HT-induced calcium mobilization is enhanced in unipolar depression; however, unlike in bipolar depression, baseline calcium levels are not. Despite inconsistencies, 5-HT-induced aggregation appears inhibited in depression. This may manifest as a relative inhibition, i.e. no change in aggregation response despite a higher density of 5-HT(2A) receptors. The inhibited aggregation response is state dependent, and acute phase proteins or components of the stress response may be factors. It is unclear if differences between depressed and normal subjects in disposition of 5-HT(2A) receptors are generally indicative of traits or states. Nonetheless, there is little evidence that the degree of departure from normal density or activity of platelet of 5-HT(2A) receptors reflects severity of depression.

Relationship between serotonin and the temperament and character inventory

The unified biosocial theory of personality, proposed by Cloninger, conceptualises personality as a combination of heritable, neurobiologically based traits (temperament dimensions), and traits reflecting sociocultural learning (character dimensions). The temperament dimensions are thought to be related to activity in specific central neurotransmitter systems. The relationship of the dimensions of the Temperament and Character Inventory, particularly harm avoidance (HA), and platelet 5-HT2 receptor sensitivity was investigated in a sample of undergraduate student volunteers (N = 49). Serotonin-receptor binding results in Ca2+ release from intracellular stores. The concentration of serotonin required to produce half maximal Ca2+ response (EC50) is indicative of 5-HT2 receptor sensitivity such that the lower the EC50 serotonin concentration, the greater the 5-HT2 receptor sensitivity. A significant inverse correlation was found between HA and EC50 (r = -0.644, P < 0.001). Self-directedness was also significantly correlated with EC50 (r = 0.391, P = 0.005). Novelty seeking, a personality trait similar to sensation seeking, was not significantly correlated with serotonin.

Repeated administration of dexamethasone increases phosphoinositide-specific phospholipase C activity and mRNA and protein expression of the phospholipase C beta 1 isozyme in rat brain

Altered hypothalamic-pituitary-adrenal (HPA) function has been shown to be associated with changes in mood and behavior. The enzyme phosphoinositide-specific phospholipase C (PI-PLC), an important component of the PI signal transduction system, plays a major role in mediating various physiological functions. In the present study, we investigated the effects of a single dose and of repeated administration (0.5 or 1.0 mg/kg for 10 days) of dexamethasone (DEX), a synthetic glucocorticoid, on PI-PLC activity and on expression of PLC isozymes (beta1, delta1, and gamma1) in rat brain. Repeated administration of DEX (1.0 mg/kg) caused a significant increase in PI-PLC activity and in protein expression of the PLC beta1 isozyme in both membrane and cytosol fractions of cortex and hippocampus; however, the repeated administration of a smaller dose of DEX (0.5 mg/kg) caused these changes only in hippocampus but not in cortex. The increase in PLC beta1 protein was associated with an increase in its mRNA level, as measured by competitive RT-PCR. A single administration of DEX (0.5 or 1.0 mg/kg) to rats had no significant effects on PI-PLC activity or on the protein expression of PLC isozymes. These results suggest that DEX up-regulates PI-PLC in rat brain, which presumably is due to a selective increase in expression of the PLC beta1 isozyme, and that these changes in PI-PLC may be related to HPA axis-mediated changes in mood and behavior.

Elevated basal and thapsigargin-stimulated intracellular calcium of platelets and lymphocytes from bipolar affective disorder patients measured by a fluorometric microassay

BACKGROUND

A number of investigators have reported finding elevated basal and stimulated intracellular calcium levels in the platelets or lymphocytes of bipolar disorder patients.

METHODS

Intracellular calcium was measured by a micro fura-2 fluorometric method in the platelets and lymphocytes of 30 affective disorder patients and 14 control subjects.

RESULTS

We observed significantly elevated basal calcium concentrations in bipolar patient platelets and lymphocytes compared to control subjects. Bipolar patient platelet calcium responses to thrombin, serotonin, and thapsigargin were also significantly greater than control subjects. The peak calcium levels of lymphocytes of bipolar patients were greater than control subjects only when stimulated by thapsigargin. There were significant differences between bipolar and unipolar patients in basal and thapsigargin-stimulated calcium measures but not between bipolar I and bipolar II patients. Unmedicated versus medicated calcium measures were not significantly different. We also found little correlation between calcium measures and the severity of mood rating.

CONCLUSIONS

Using this method, we were able to confirm and extend the work of others, indicating altered intracellular calcium homeostasis in the blood cells of bipolar disorder patients. In addition, our data suggest that storage operated calcium channels may be the source of the elevated intracellular calcium in platelets and lymphocytes of bipolar patients.

Serotonin-induced platelet intracellular Ca2+ responses in untreated depressed patients and imipramine responders in remission

BACKGROUND

Intracellular Ca2+ metabolism in platelets has been investigated as a peripheral marker of affective disorders.

METHODS

We investigated the intracellular free Ca2+ concentration in platelets in both untreated depressed patients with no medications and patients in remission who were treated by imipramine (IMI) (IMI responders) using a Ca(2+)-sensitive fluorescent probe fura-2.

RESULTS

The increases in intracellular free Ca2+ concentration in platelets induced by stimulation with serotonin (5-HT) ([Ca2+] delta) were significantly higher in both the untreated patients and the IMI responders compared with healthy controls; however, there were no significant differences in the basal Ca2+ levels in the platelets ([Ca2+]B) among the three groups. On the other hand, in the IMI responders, we observed positive correlations between the duration of the remission and [Ca2+]B, but not [Ca2+] delta.

CONCLUSIONS

Our present data suggest that the enhancement of 5-HT2A-induced Ca2+ responses persisted after remission in depressed patients, and that the duration of the remission is a factor varying the intracellular basal Ca2+ levels.

Platelet cytosolic calcium hyperresponsivity to serotonin in patients with hypertension and depressive symptoms

BACKGROUND

Data from recent studies indicate that the presence of depression is an independent risk factor for cardiovascular and cerebrovascular events. The mechanism by which depression increases the morbidity and mortality risks in patients with comorbid vascular disease is currently the object of considerable research interest. Platelets may be involved in this pathological process. Although many investigators have extensively evaluated platelet biochemistry in depressed patients, there currently exists very little information regarding how the biochemical alterations might relate to an increased risk of cardiovascular events. In this study, we examined the responsivity of platelet cytosolic calcium concentrations ([Ca++]i) to serotonin stimulation in populations of hypertensive patients with or without comorbid depressive symptoms.

METHODS

We utilized Fura-2 loaded platelets to compare changes in intracellular calcium levels (delta [Ca++]i) following serotonin stimulation among 48 patients with hypertension and varying degrees of depressive symptomatology.

RESULTS

We found that those patients with higher scores on standardized depression rating scales showed significantly greater [Ca++]i (82.82 +/- 15.88 mmol/L) increase compared with [Ca++]i (60.10 +/- 22.65 mmol/L) patients with lower depression scores.

CONCLUSIONS

The results of this study support the hypothesis that the enhanced platelet reactivity seen in patients with depressive symptoms may mediate the deleterious effects of depression on cardiovascular disease.

The platelet intracellular calcium response to serotonin and thrombin in patients with panic disorder

Serotonin is implicated in both the biology of depression and anxiety. The aim of this study was to examine the platelet intracellular calcium response to serotonin and thrombin using spectrofluorometry in 14 patients with DSM-4 panic disorder compared to 14 matched controls. Patients did not show significantly higher baseline platelet intracellular calcium levels and serotonin stimulated levels of intracellular calcium than control subjects. There was a much smaller standard deviation in the control subjects than in the panic patients. The intracellular calcium response to thrombin activation was however greater in panic patients than in control subjects (P<0.001). The failure of this study to find enhanced sensitivity of 5-HT2 receptors in panic disorder is compatible with the findings of previous challenge studies that found no consistent dysregulation of serotonin in panic disorder. The enhanced thrombin sensitivity, nevertheless suggests some receptor mediated second messenger changes independent of serotonin in the disorder.

Effect of antidepressants on intracellular Ca++ mobilization in human frontal cortex

BACKGROUND

It is well documented that central serotonin (5-HT)2 receptor dysfunction is involved in the biochemistry and pathophysiology of depression and might be corrected by antidepressant drug treatment.

METHODS

The effect of imipramine (IMI) and fluoxetine (FLX) on 5-HT2A receptor-mediated intracellular calcium ([Ca++]i) mobilization in synaptosomes of human frontal cortex was studied. [Ca++]i was measured using Fura-2AM.

RESULTS

It was observed that in response to 5-HT (10 mumol/L) there was a significant increase (254%; p < .001) in [Ca++]i compared to basal level (140.00 +/- 31.77 nmol/L/mg protein). Both IMI and FLX (10-1000 nmol/L) induce mobilization of basal [Ca++]i in a dose-dependent manner. IMI and FLX antagonize the 5-HT-stimulated [Ca++]i mobilization in a dose-dependent manner. IMI showed higher antagonizing effect at lower concentration (10 nmol/L); however, FLX showed maximum antagonizing effect at higher concentration (1000 nmol/L).

CONCLUSIONS

It is observed that imipramine and fluoxetine have different effects on antagonizing the 5-HT response in frontal cortex. One mode of action of these antidepressants might be by decreasing the intracellular calcium.

Inhibition of platelet serotonin uptake by cytochrome P450 inhibitors miconazole and econazole

Serotonin uptake in human platelets was inhibited by cytochrome P450 inhibitors such as miconazole and econazole but not clotrimazole. There was a correlation between inhibition of serotonin uptake and inhibition of imipramine binding, suggesting that these P450 inhibitors may inhibit serotonin uptake via direct binding to the transporter. P450 inhibitor effects on serotonin uptake did not seem to be related to the effects of these compounds on intracellular calcium mobilization. Additionally, nitric oxide pathway stimulation does not appear to be involved.

The role of calcium in the etiology of the affective disorders

Calcium abnormalities are some of the more consistent findings in platelets of affective disorder patients. While medication status does not correlate with this finding, antidepressants do modulate intracellular calcium. This, in combination with reports that calcium channel inhibitors may have antidepressant potential, suggests that calcium may play an important role in this disorder. This paper reviews the specificity of calcium abnormalities for the affective disorders and also discusses possible mechanisms of action.

Intracellular calcium signaling systems in the pathophysiology of affective disorders

In this paper, we show the importance of intracellular calcium (Ca2+) signaling systems in the pathophysiology of mood disorders based on our recent work. Patients with affective disorders appear to have an enhanced intracellular Ca2+ rise in response to serotonin. We have observed effects of antidepressant drugs on intracellular Ca2+ signaling in rat cultured neuronal cells and glioma cells, and found that acute application of several classes of antidepressant drugs inhibited intracellular Ca2+ signaling and Ca2+-related signaling. It is important to investigate the role of intracellular Ca2+ signaling system for an understanding of the pathophysiology of affective disorders.

Calcium mobilization evoked by amyloid beta-protein involves inositol 1,4,5-triphosphate production in human platelets

We examined the effects of amyloid beta-protein (A beta) on Ca2+ mobilization in human platelets. The addition of A beta fragments 25-35 (A beta 25-35) gradually increased the cytoplasmic free Ca2+ concentration ([Ca2+]i). After the maximum response, [Ca2+]i decreased and then reached a sustained, higher level of [Ca2+]i. Similar effects were also observed with A beta 1-40, whereas 1-28 , 12-28 and 31-35 did not affect the Ca2+ response. In the absence of extracellular Ca2+, A beta 25-35 caused a transient increase in [Ca2+]i, which returned to the resting level. U73122, a phospholipase C inhibitor, completely abolished Ca2+ mobilization induced by thrombin and A beta 25-35. Furthermore, A beta enhanced the production of inositol 1,4,5-trisphosphate (IP3) in platelets. These findings suggest that Ca2+ mobilization induced by A beta 25-35 is due to phospholipase C activation and IP3 production.

Platelet cytosolic calcium responses to serotonin in depressed patients and controls: relationship to symptomatology and medication

BACKGROUND

Serotonin produces an exaggerated rise in platelet cytosolic calcium (delta [Ca++]i) in patients with mood disorders. Studies on patients with bipolar disorder consistently demonstrate calcium abnormalities. By comparison, data on patients with major depression are more variable.

METHODS

To determine causes of variability, we utilized Fura-2 loaded platelets to compare changes in platelet intracellular calcium levels (delta [Ca++]i) following serotonin stimulation in 24 patients with major depression and in 20 controls. We also sought relationships between the delta [Ca++]i responses and scores on clinical depression and anxiety scales.

RESULTS

We found positive correlations between delta [Ca++]i responses and the clinical scales across all subjects. Furthermore, depressed patients with high anxiety had significantly increased delta [Ca++]i responses compared to depressed patients with low anxiety. In addition, patients receiving selective-serotonin reuptake inhibitors (SSRIs) demonstrated reduced delta [Ca++]i responses compared to patients not on SSRIs.

CONCLUSIONS

Since elevations in [Ca++]i mediate platelet aggregation and secretion cascades, the enhanced responsivity observed in depressed, and in particular anxious, depressed patients may contribute to their increased risk for vascular disease.

Heart rate variability at rest and during mental stress in patients with coronary artery disease: differences in patients with high and low depression scores

This study tested the hypothesis that coronary artery disease (CAD) patients with high depressed mood scores differ in sympatho-vagal balance during mental stress compared to patients with low depressed mood scores. Using electrocardiographic monitoring, heart variability data from spectral analysis and hemodynamic parameters were obtained prior to and during mental stress from 34 men and 7 women. A public speaking task was used as the mental stressor. Patients were grouped by a median split of their Minnesota Multiphasic Personality Inventory-Depression score. During mental stress, patients with higher depression scores had greater changes in peak heart rate (p < .05) and low frequency to high frequency power ratio (p < 0.05) than patients with lower scores suggesting a shift toward more sympathetic activity during mental stress. These findings may be related to the reported relation between depression and survival risk in patients with CAD.

Heart rate variability in patients with coronary artery disease: differences in patients with higher and lower depression scores

OBJECTIVE

This study tested the hypothesis that coronary artery disease patients with higher depression scores have lower heart rate variability during daily life.

METHOD

Thirty-three men and nine women, ranging in age from 46 to 79, with coronary artery disease and exercise-induced ischemia were studied. The standard deviation of normal R-R intervals (SDNN) and average heart rate were obtained from 24-hour ambulatory electrocardiographic monitoring. Patients were grouped by a median split of the Minnesota Multiphasic Personality Inventory (MMPI-D) score.

RESULTS

SDNN was lower (p = .009) and average heart rate was higher (p = .003) in patients with higher depression scores. These relationships remained substantially unaltered after statistically adjusting for the only demographic/clinical factor that varied between the groups: gender.

CONCLUSIONS

In comparison to the lower depression score group, those with higher depression scores had lower heart rate variability during daily life. These findings may be related to the reported relationship between depression and survival risk in patients with coronary artery disease.