Reduced platelet serotonin in depression

Baseline platelet serotonin in a multi-site treatment study of depression in veterans administration patients: Distribution and effects of demographic variables and serotonin reuptake inhibitors

BACKGROUND

The objectives of the study were: (1) to examine the overall distribution of baseline platelet serotonin (5-hydroxytryptamine, 5-HT) values in patients seeking treatment for depression and to define subgroups based on the apparent presence or absence of drug exposure; (2) to assess the bioeffect of 5-HT reuptake inhibitors (SRIs) at the platelet 5-HT transporter; and (3) to examine the relationships of demographic variables including population (ancestry), sex, age, and season of sampling to platelet 5-HT concentration.

METHODS

Platelet 5-HT levels were measured in a cross-sectional study of 1433 Veterans Administration (VA) patients participating in a pragmatic multi-site pharmacogenomic treatment study of depression. Patients were characterized medically and demographically using VA health records and self-report.

RESULTS

A clearly bimodal distribution was observed for platelet 5-HT levels with the lower mode associated with patients exposed to SRIs at baseline. Median transporter blockade bioeffects were similar across the various selective 5-HT reuptake inhibitors (SSRIs) and 5-HT/norepinephrine reuptake inhibitors (SNRIs). In a subset of patients apparently not exposed to an SRI, significant effects of population and sex were observed with group mean platelet 5-HT levels being 25 % greater (p < 0.001) in African-American (AA) individuals compared to European-Americans (EAs). The female group mean was 14 % (p < 0.001) greater than male group mean. An effect of age was observed (r = -0.11, p < 0.001) and no effect of season or month of sampling was seen.

CONCLUSIONS

Further research is warranted to understand the bases and clinical implications of the population and sex differences. The apparent similarity in bioeffect at the 5-HT transporter across SSRIs and when comparing SSRIs and SNRIs informs discussions about initiating, dose adjustment and switching of 5-HT reuptake inhibitors.

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.

Relationship Between the Loudness Dependence of the Auditory Evoked Potential and the Severity of Suicidal Ideation in Patients with Major Depressive Disorder

Objective

The loudness dependence of the auditory evoked potential (LDAEP) is a reliable indicator that is inversely related to central serotonergic activity, and recent studies have suggested an association between LDAEP and suicidal ideation. This study investigated differences in LDAEP between patients with major depressive disorder and high suicidality and those with major depressive disorder and low suicidality compared to healthy controls.

Methods

This study included 67 participants: 23 patients with major depressive disorder with high suicidality (9 males, mean age 29.3 ± 15.7 years, total score of SSI-BECK ≥ 15), 22 patients with major depressive disorder with low suicidality (9 males, mean age 42.2 ± 14.4 years, total score of SSI-BECK ≤ 14), and 22 healthy controls (11 males, mean age 31.6 ± 8.7 years). Participants completed the following assessments: Patient Health Questionnaire-9, Beck Depression Inventory-II, Beck Scale for Suicidal ideation, State Anxiety Scale of the State-Trait Anxiety Inventory, Beck Anxiety Inventory, and LDAEP (measured at electrode Cz).

Results

There were no sex-related differences among groups (p = 0.821). The high-suicidality group exhibited significantly higher LDAEP compared to the low-suicidality group (0.82 ± 0.79 vs. 0.26 ± 0.36, p = 0.014). No significant differences were found between the control and high-suicidality (p = 0.281) or the control and low-suicidality groups (p = 0.236).

Conclusion

LDAEP was applied to demonstrate the association between serotonergic activity and suicidal ideation and suicide risk in major depression and may be a candidate of biological marker for preventing suicide in this study.

Poor sleep quality and associated factors among prisoners of the Diredawa correctional facility in eastern Ethiopia

BACKGROUND

Impaired sleep quality affects judgment, psychomotor skills, memory, decision-making, concentration, and attention. It might also contribute to the development of new physical health problems, as well as exacerbating already existing physical problems. Despite this, there is a scarcity of research done in Africa including Ethiopia that addressed this issue. So this study assessed the quality of sleep and related factors among prisoners of the Diredawa correctional facility, Diredawa, eastern Ethiopia.

METHODS

A cross-sectional study was done using a simple random sampling technique to recruit 421 participants from May 21 to June 21; 2017. A semi-structured questionnaire, Pittsburgh Sleeps Quality Index (PSFIG), Patient Health Questionnaire-9 (PQ-9), and Sleep Hygiene Index (SHI) were used to assess participants' socio-demographic data, sleep quality, depression, and sleep hygiene, respectively. The collected data were entered into EPA-data 3.1 and analyzed by using SPAS-20. Descriptive and analytical statistics were used. Bivariate and multivariable logistic regression with odds ratio and 95% CI were employed. The statistical significance was declared at p value < 0.05.

RESULTS

A total of 421 out of 423 prisoners were interviewed, resulting in a response rate of 99.5%. The prevalence of poor sleep quality was 227 (53.9%) with 95% CI (49.2, 58.7). Having co-morbidity of depression (adjusted odds ratio; OAR = 3.47, 95% CI 1.38,8.76), lifetime use of cigarette (OAR = 2.16, 95% CI 1.21,5.58), marijuana and hashish (OAR = 5.02, 95% CI 1.63,15.46), current use of coffee (OAR = 2.75, CI 1.37, 7.05), poor sleep hygiene (OAR = 3.19, CI 1.32,7.69), committing assault crime (OAR = 4.12, CI 1.29,10.63) and crime of rape (OAR = 5.57, CI (1.45, 13.89) were the associated factors for poor sleep quality in this study.

CONCLUSION

More than half of the participants (53.9%) have poor sleep quality. Depression, lifetime use of cigarettes, using cannabis and hashish, current use of coffee, poor sleep hygiene, and crime types were the associated factors that should be taken into consideration and evaluated early to minimize poor sleep quality.

Platelet Serotonin Level and Impulsivity in Human Self-destructive Behavior: A Biological and Psychological Study

Context:

Suicide is a disease and a global public health problem. Suicidology has come to become a topic of study for intervention and research. The serotonin (5-hydroxytryptamine [5HT]) system has remained a prime area of investigation. The neurons and platelets display structural and functional similarities. Ninety-nine percent of 5HT is contained in platelets, which shares similar 5HT uptake and release mechanisms with 5HT neurons.

Aims:

This study aims to study human self-destructive behavior (HSDB).

Objectives:

Exploring the biological (serotonin levels in platelets) and psychological aspects (impulsivity) of attempted suicide or HSDB.

Settings and Design:

Thirty-one patients, above the age of 18 years, with a recent history of HSDB, were studied and given an International Classification of Diseases-10 diagnosis, after a detailed interview.

Subjects and Methods:

For the platelet 5HT estimation, blood samples were collected, and enzyme immunometric assay carried out. Detailed assessment of the impulsivity was done by the 25-item structured diagnostic interview for borderlines by Zanarini et al.

Statistical Analysis Used:

We obtained both categorical and continuous data. Chi-square test, Fisher's test, Student's t-test, and Pearson's product moment correlation were used.

Results:

Female subjects outnumbered males by 2:1. Major depression, adjustment disorder, personality disorder were predominant diagnoses. The mean platelet serotonin concentration for males = 57.3 ng/ml, that of females = 56.05 ng/ml (P > 0.05). Platelet 5HT levels were found to be negatively correlated with impulsivity scores (P < 0.05).

Conclusions:

Platelet serotonin levels in our study sample were quite low when compared with those reported in published literature. Low serotonin levels were inversely related to impulsivity, but only in males.

Evaluation of peripheral serotonin content and α2-adrenergic receptor function as potential markers for life-long recurrent depressive disorder by using methodological improvements

OBJECTIVE

We aimed to evaluate the role and the relations between peripheral platelet serotonin content, blood plasma serotonin concentration and the function of platelet α₂-adrenergic receptors (α₂-AR) as potential state or trait biomarkers for recurrent depressive disorder (RDD).

METHODS

26 drug-free patients with life-long RDD and 31 healthy controls were included in the study. Several methodological improvements in blood collection and platelet isolation were implemented following the present standards in Haematology and Light transmission aggregometry.

RESULTS

Our results have shown lower platelet serotonin content, higher plasma serotonin concentration and desensitization of platelet α₂-AR in patients with RDD. The variables were found heterogeneous and mainly influenced by the clinical characteristics of the current episode. High amplitude of the α₂-AR correlated with severe anxious symptoms and high platelet serotonin content (as well as low plasma serotonin levels) were associated with psychotic symptoms.

CONCLUSIONS

The evaluated peripheral markers reflect only state (but not trait) abnormalities in patients with current severe episode of RDD. The observed peripheral α₂-AR and serotonin abnormalities are mutually not related and they are probably triggered by different mechanisms.

Evaluation of Alternative Euthanasia Methods of Neonatal Chickens

Simple Summary

Male layer chicks do not have economic value and are humanely killed after hatching. The layer industry is seeking alternative methods to humanely kill recently hatched male chicks. This study evaluated the use of gases or negative air pressure as a means of humane and viable alternatives to maceration. The treatments included carbon dioxide, nitrogen, reduced air pressure, and a negative control. The study showed that chicks exposed to treatments, gases or negative air pressure, did not differ significantly in terms of the physiological stress response. The use of carbon dioxide resulted in a faster onset of unconsciousness and ultimately death as compared to nitrogen or negative air pressure treatments.

Abstract

Hatched male layer chicks are currently euthanized by maceration in the United States. Public concerns on the use of maceration have led to the search for alternative methods. We hypothesized that gas inhalation and low atmospheric pressure stunning (LAPS) are viable and humane alternatives to instantaneous mechanical destruction. The objective of this study was to evaluate the physiological and behavioral responses of recently hatched male layer chicks when subjected to carbon dioxide, nitrogen inhalation, or LAPS. The study consisted of seven treatments: breathing air (NEG), 25% carbon dioxide (CO₂), 50% CO₂, 75% CO₂, 90% CO₂, 100% nitrogen (N₂), or LAPS. Ten day-of-hatch, male layer chicks were randomly assigned to each treatment, and each treatment was replicated on ten different days. A custom-made vacuum system was used to reduce air pressure inside the chamber from 100.12 kPa to 15.3 kPa for the LAPS treatment. Serum corticosterone and serotonin levels were measured using commercially available competitive enzyme linked immunosorbent assay (ELISA). Latencies to loss of posture and motionlessness were determined from video recordings. The 25% and 50% CO₂ treatments were discontinued after the first replication, as the majority of the chicks recovered. The chicks in the negative (NEG) group had significantly higher levels of corticosterone than the other four euthanasia treatments. On the other hand, the serotonin levels of chicks in the NEG group was significantly lower when compared to the other four euthanasia treatments. The latencies to loss of posture and motionlessness of chicks exposed to 75% and 90% CO₂ were significantly shorter than those in the LAPS and N₂ inhalation treatments. These data suggest that the stress responses of chicks to the CO₂, N₂, and LAPS treatments do not differ among each other. However, the CO₂ inhalation method was faster in inducing loss of posture and motionlessness in chicks than the LAPS and N₂ inhalation treatments.

Beneficial effects of trimetazidine on expression of serotonin and serotonin transporter in rats with myocardial infarction and depression

BACKGROUND

Trimetazidine is an anti-ischemic drug that can inhibit platelet aggregation and regulate serotonin (5-hydroxytryptamine [5-HT]) release. The purpose of this study was to investigate the therapeutic effects of trimetazidine on 5-HT and serotonin transporter (SERT) expression in experimentally induced myocardial infarction (MI), depression, and MI + depression.

MATERIALS AND METHODS

Eighty Sprague Dawley (SD) rats were randomly divided into a trimetazidine group and a saline group of 40 rats each. The trimetazidine group was given trimetazidine pretreatment for 4 weeks, while the saline group received saline for 4 weeks. Both groups were then subdivided into four subgroups (n=10), which were each subjected to a unique disease condition: sham surgery, MI, depression, or MI + depression. All rats were sacrificed 3 days thereafter, and serum and platelet levels of 5-HT and SERT were assessed. In addition, we experimented with trimetazidine posttreatment. Twenty SD rats underwent MI surgery, and were then randomly divided into a treatment and a saline group (n=10 each). For 4 weeks post-surgery, the trimetazidine group was given trimetazidine, while the saline group received saline. Serum and platelet levels of 5-HT and SERT were assessed.

RESULTS

Pretreatment with trimetazidine: in the nontreatment saline group, MI, depression, and MI + depression showed significant declines (P<0.05) in both serum and platelet 5-HT levels compared to sham. Trimetazidine treatment significantly increased serum and platelet 5-HT levels in the MI, depression, and MI + depression (P<0.05) subgroups compared to their counterparts in the saline group. Results for SERT were heterogeneous between serum and platelets. Trimetazidine treatment significantly decreased serum levels of SERT in the sham surgery subgroup (P<0.05), while significantly increasing levels in depression rats, compared to control (P<0.05). In platelets, trimetazidine significantly decreased SERT in sham surgery, MI, depression, and MI + depression rats, compared to control (P<0.05). This contrast suggests that trimetazidine has opposite effects in serum and platelet SERT levels for the three disease models. Post-surgery trimetazidine: increased serum 5-HT (P<0.05) and serum SERT (P<0.05) were observed, compared to control. In platelets, trimetazidine decreased both 5-HT and SERT compared to control, significantly (P<0.05) for 5-HT, but not significantly for SERT (P>0.05).

CONCLUSION

Trimetazidine has a regulatory effect on 5-HT and SERT in the serum and platelets. Because of the downstream effects of this regulation on blood vessel function and myocardial protection, trimetazidine may be a therapeutic or preventive agent in several disease processes, including MI, depression, and the comorbidity between these two diseases. Further investigation, aimed at exploring the clinical potential of trimetazidine, is therefore warranted.

The effects of maternal antidepressant use on offspring behaviour and brain development: Implications for risk of neurodevelopmental disorders

Approximately 10% of pregnant women are prescribed antidepressant drugs (ADDs), with selective serotonin reuptake inhibitors (SSRIs) the most widely prescribed. SSRIs bind to the serotonin transporter (SERT), blocking the reabsorption of serotonin by the presynaptic neuron and increasing serotonin levels in the synaptic cleft. The serotonergic system regulates a range of brain development processes including neuronal proliferation, migration, differentiation and synaptogenesis. Given the presence of SERT in early brain development, coupled with the ability of SSRIs to cross the placenta and also enter breast milk, concerns have been raised regarding the effects of SSRI exposure on the developing foetus and newborns. In this review, we evaluate preclinical and clinical studies that have examined the effects of maternal SSRI exposure and the risk for altered neurodevelopment and associated behaviours in offspring. While the current body of evidence suggests that maternal SSRI treatment may cause perturbations to the neurobiology, behaviour and ultimately risk for neurodevelopmental disorders in exposed offspring, conflicting findings do exist and the evidence is not conclusive. However, given the increasing incidence of depression and number of women prescribed ADDs during pregnancy, further investigation into this area is warranted.

Differential changes in platelet reactivity induced by acute physical compared to persistent mental stress

Platelets are important in hemostasis, but also contain adhesion molecules, pro-inflammatory and immune-modulatory compounds, as well as most of the serotonin outside the central nervous system. Dysbalance in the serotonin pathways is involved in the pathogenesis of depressive symptoms. Thus, changes in platelet aggregation and content of bioactive compounds are of interest when investigating physiological stress-related mental processes as well as stress-related psychiatric diseases such as depression. In the present study, a characterization of platelet reactivity in acute physical and persistent mental stress was performed (aggregation, serotonin and serotonin 2A-receptor, P-selectin, CD40 ligand, matrix metalloproteinase-2 and -9 (MMP-2 and -9), platelet/endothelial adhesion molecule-1 (PECAM-1), intercellular adhesion molecule-1 (ICAM-1), β-thromboglobulin (β-TG) and platelet factor 4 (PF-4). Acute physical stress increased platelet aggregability while leaving platelet content of bioactive compounds unchanged. Persistent mental stress led to changes in platelet content of bioactive compounds and serotonin 2A-receptor only. The values of most bioactive compounds correlated with each other. Acute physical and persistent mental stress influences platelets through distinct pathways, leading to differential changes in aggregability and content of bioactive compounds.

Bioprofiling of platelets in medicated patients with depression

BACKGROUND

Changes in platelet bioactivity and aggregation are of interest when studying patients with depression as this could help to explain the statistically observed association of depression and chronic somatic, especially cardiovascular disease. This link could potentially be mediated through serotonergic signaling or immunological changes.

METHODS

38 medicated patients with major depressive disorder (MDD) and 30 mentally healthy controls, both without a diagnosis of cardiovascular disease, were included in this naturalistic study. Demographic and psychometric data were obtained. Platelet aggregability was measured by PFA-100 and bioactive compounds and serotonin levels were quantified in platelet sonicate.

RESULTS

The comparison of patients with controls revealed no changes in platelet aggregability, but significant differences in platelet content of several bioactive compounds. In a second analysis, patients were grouped according to the receptors and transporters influenced by their medication and again compared to controls. A significant effect of MDD was found for platelet content of serotonin, CD40L, interleukin-1β, and platelet factor-4, independent of medication. These markers can thus be classified as sensitive to MDD. The effect of medication on platelet parameters was also evaluated. Platelet content of matrix metalloproteinase-2 and β-thromboglobulin was normalized in MDD patients by medication acting on the serotonin transporter.

LIMITATIONS

Owing to the naturalistic study design, patients were on a variety of different medications and combination therapies. This was accounted for by a novel analysis method.

CONCLUSION

Platelet serotonin levels and content of immunomodulatory compounds are significantly altered in patients with MDD, even if treatment effects are taken into account.

Decreased Basal and postprandial plasma serotonin levels in patients with functional dyspepsia

BACKGROUND & AIMS

Patients with diarrhea-predominant irritable bowel syndrome (IBS) have been found to have increased postprandial levels of serotonin (5-HT). Functional dyspepsia (FD) and IBS have been proposed to have common methods of pathogenesis, but little is known about the role of 5-HT in FD.

METHODS

We measured postprandial levels of 5-HT in 54 patients with FD (based on Rome III criteria) and 28 asymptomatic healthy individuals (controls). Patients with gastroesophageal reflux disease and IBS as their predominant symptom were excluded. After an overnight fast, the subjects drank a liquid meal (Ensure; 1.06 kcal/mL at 30 mL/min) and underwent a (13)C-octanoic acid breath test to measure gastric emptying times. Blood samples were collected at 0, 30, 60, 90, and 120 minutes after the liquid meal for the 5-HT assay.

RESULTS

Thirty-five patients with FD (65%) had postprandial distress syndrome, and 6 (11%) had a combination of postprandial distress syndrome and epigastric pain syndrome. There were no differences in rates of gastric emptying between patients with FD (103.6 ± 19.4 minutes) and controls (83.1 ± 4.0 minutes; P = .30). However, patients with FD had lower caloric intake (823.40 ± 44.1 kcal) than controls (1021 ± 68.2 kcal; P = .026). Patients with FD also had lower basal (P = .03) and postprandial plasma levels of serotonin at 30 minutes (P = .04), 60 minutes (P = .01), 90 minutes (P = .02), and 120 minutes (P = .002) than controls, as well as area under the curve values over the 120-minute time period (P = .005). Repeated-measures analysis of variance correlated 5-HT level with FD (P < .001).

CONCLUSIONS

In contrast to patients with diarrhea-predominant IBS, those with FD have decreased basal and postprandial plasma levels of 5-HT. These findings indicate that the pathogenic mechanism of FD differs from that of diarrhea-predominant IBS, and that strategies to alter 5-HT levels or activity might be developed to treat patients with FD.

Evaluation of a novel ELISA for serotonin: urinary serotonin as a potential biomarker for depression

Depression is a common disorder with physical and psychological manifestations often associated with low serotonin. Since noninvasive diagnostic tools for depression are sparse, we evaluated the clinical utility of a novel ELISA for the measurement of serotonin in urine from depressed subjects and from subjects under antidepressant therapy. We developed a competitive ELISA for direct measurement of serotonin in derivatized urine samples. Assay performance was evaluated and applied to clinical samples. The analytical range of the assay was from 6.7 to 425 μg serotonin/g creatinine (Cr). The limit of quantification was 4.7 μg/g Cr. The average recovery for spiked urine samples was 104.4%. Average intra-assay variation was 4.4%, and inter-assay variation was <20%. The serotonin analysis was very specific. No significant interferences were observed for 44 structurally and nonstructurally related urinary substances. Very good correlation was observed between urinary serotonin levels measured by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS; ELISA = 1.16 × LC-MS/MS - 53.8; r = 0.965; mean % bias = 11%; n = 18). Serotonin was stable in acidified urine for 30 days at room temperature and at -20 °C. The established reference range for serotonin was 54-366 μg/g Cr (n = 64). Serotonin levels detected in depressed patients (87.53 ± 4.89 μg/g Cr; n = 60) were significantly lower (p < 0.001) than in nondepressed subjects (153.38 ± 7.99 μg/g Cr). Urinary excretion of serotonin in depressed individuals significantly increased after antidepressant treatment by 5-hydroxy-tryptophane and/or selective serotonin re-uptake inhibitor (p < 0.01). The present ELISA provides a convenient and robust method for monitoring urinary serotonin. It is suitable to monitor serotonin imbalances and may be particularly helpful in evaluating antidepressant therapies.

Depressant-like effects of parthenolide in a rodent behavioural antidepressant test battery

The anti-serotonergic effects of parthenolide (PTL) demonstrated in platelets inspired the present psychopharmacological investigation, which employs a battery of rodent behavioural assays of depression. In mice, PTL (0.5-2 mg kg−1) exhibited dose-dependent depressant-like effects in a forced swim test and a tail suspension test, without affecting the baseline locomotor status. The doses (1 and 2 mg kg−1) that induced depressant-like effects were found to significantly reduce 5-hydroxytrypto-phan-induced head twitch response. Interaction studies revealed that the depressant-like effects of PTL (1 mg kg−1) were reversed more efficiently by serotonergic antidepressants (venlafaxine, escitalopram, citalopram, fluoxetine) than by others (desipramine, bupropion) tested. Chronic treatment of PTL (1 and 2 mg kg−1) augmented the hyper-emotionality of olfactory bulbectomized rats, when compared with sham rats, as observed in modified open field, elevated plus maze and social interaction paradigms. This study depicts the severe depressogenic potential of PTL (in its pure form) plausibly mediated by platelet/neuronal hypo-serotonergic effects.

Depression and whole blood serotonin in patients with coronary heart disease from the Heart and Soul Study

OBJECTIVE

To evaluate whether depression is associated with whole blood serotonin in outpatients with stable coronary heart disease (CHD). Depression is associated with incident CHD and with adverse cardiovascular outcomes. Dysregulation of peripheral serotonin, common to both depression and CHD, may contribute to this association.

METHODS

We performed a cross-sectional study of 791 participants with stable CHD enrolled in the Heart and Soul Study and not taking antidepressant medication. We assessed major depression using the Computerized Diagnostic Interview Schedule (CDIS-IV) and measured whole blood serotonin (WBS) from fasting venous samples.

RESULTS

Of the 791 participants, 114 (14%) had current (past month) major depression, 186 (24%) had past (but not current) major depression, and 491 (62%) had no history of depression. Age-adjusted mean WBS was higher in participants with current major depression (139 +/- 6.5 ng/ml) than in those with past depression (120 +/- 5.0 ng/ml) or no history of depression (119 +/- 3.1 ng/ml) (p = .02). This association was unchanged after adjustment for demographic characteristics, medical comorbidities, medication use, and cardiac disease severity (p = .02). When serotonin was analyzed as a dichotomous variable, current depression was associated with a 70% greater odds of having WBS in the highest quartile (adjusted odds ratio = 1.71; 95% Confidence Interval = 1.03-2.83; p = .04).

CONCLUSIONS

In this sample of patients with stable CHD, current major depression was independently associated with higher mean WBS levels. Future studies should examine whether elevated WBS may contribute to adverse outcomes in patients with depression and CHD.

Dehydroepiandrosterone and monoamines in the limbic system of a genetic animal model of childhood depression

Monoamines and dehydroepiandrosterone (DHEA) levels were measured in a genetic animal model for childhood depression in four subcortical structures: nucleus accumbens (Nac), ventral tegmental area (VTA), amygdala and hypothalamus. The "depressive-like" strain was the Flinders Sensitive Line (FSL), compared to their controls, Sprague-Dawley (SD) rats. Prepubertal FSL rats showed abnormal levels of only a few monoamines and their metabolites in these brain regions. This is in contrast to former studies, in which adult FSL rats exhibited significantly higher levels of all the monoamines and their metabolites measured. These different abnormal monoamine patterns between the "depressed" prepubertal rats and their adults, may help to explain why depressed children and adolescents fail to respond to antidepressant treatment as well as adults do. On the other hand, FSL prepubertal rats exhibited the same pattern of abnormal DHEA basal levels as was found in adults in previous experiments. The results from the current study may imply that treatment with DHEA could be a promising novel therapeutic option for depressed children and adolescents that fail to respond to common (monoaminergic) antidepressant treatments.

Folate status and mood: is there a relationship?

Objective

To explore the relationship between subjective mood, folate status and homocysteine in healthy individuals.

Design

Subjective mood assessments were completed twice daily over the course of one week using the Positive and Negative Affect Scale (PANAS). The PANAS is a validated scale which considers mood state on two distinct continua, one reflecting positive mood and the other negative mood, each requiring response to 10 adjectives on a Likert scale. A blood sample was taken on one occasion at the start of the week during which subjective mood was assessed and analysed for red-blood-cell (RBC) folate, serum folate and plasma homocysteine concentrations.

Subjects

Male volunteers aged 19–47 years (n= 58) were recruited from local industries.

Results

High concentrations of RBC folate were associated with less variability (lower standard deviation) in negative mood (P= 0.023). Subjective mood, however, was not related to serum folate or homocysteine.

Conclusions

This study appears to be the first to uncover an association between long-term folate status and subjective mood (employing the PANAS) in healthy males. More research is needed to further explore the relationship between nutritional status and mood.

Role of paroxetine in interferon-alpha-induced immune and behavioural changes in male Wistar rats

Treatment with pro-inflammatory cytokine, IFNalpha was documented to result in neuropsychiatric complications including depression and treatment with antidepressant, paroxetine could improve the depressive symptoms. Therefore, the effects of IFNalpha on behaviour and cytokine changes in the whole blood culture and in the prefrontal cortex, hypothalamus and hippocampus areas of the brain in wistar rats were investigated with emphasis on the role of paroxetine in the prevention of depressive behaviour induced by pro-inflammatory cytokines. The group of rats treated with IFNalpha (s.c. 50,000 IU/kg for 3 days/week for 5 weeks) was compared with three other groups; 1) saline control group (s.c. normal saline 0.2 ml/kg/day for 7 weeks), 2) paroxetine control group (paroxetine suspension orally 10 mg/kg/day for 7 weeks) and 3) group treated with paroxetine for 2 weeks followed by IFNalpha for 5 weeks. In open filed, the IFNalpha treated rats showed anxiety behaviour compared to the rats from the other groups. There was no significant difference in home cage emergence test, Morris water maze and object recognition test. There is no significant difference in plasma corticosterone between groups. The pro-inflammatory cytokines (TNFalpha, IL1beta and IFNgamma), were significantly higher whereas the anti-inflammatory cytokine, IL10 was lower in the stimulated whole blood culture of IFNalpha treated rats. In the brain, both pro-inflammatory cytokine IL1beta and anti-inflammatory cytokine IL10 were higher in hypothalamus of the IFNalpha treated rats; by contrast the concentration of IL10 was lowest in hippocampus region of this group compared to the other groups. The paroxetine pretreated rats did not show these cytokine changes following IFNalpha treatment. Thus it appears that paroxetine pretreatment prevents the pro-inflammatory changes in blood and brain following IFNalpha treatment in turn prevents the anxiety behaviour.

The influence of daylight exposure on platelet 5-HT levels in patients with major depression and schizophrenia

Platelet serotonin (5-HT) can be used as a limited, peripheral model for the central 5-HT synaptosomes. Altered platelet 5-HT concentrations have been associated with psychiatric disorders like depression and schizophrenia. The aim of the present study was to compare platelet 5-HT concentrations during long, medium and short period of natural daylight exposure in a large number of medication-free male and female schizophrenic and depressed patients and sex-matched healthy controls. Platelet 5-HT concentration was determined spectrofluorimetrically in 240 (97 female, 143 male) schizophrenic and 258 (153 female, 105 male) nonpsychotic, nonsuicidal depressed medication-free patients and 328 (149 women, 179 men) healthy subjects during periods with short (<12), long (>12) and medium (average 12) hours of the natural daylight. Platelet 5-HT concentration was significantly lower in women compared to men in all groups. Healthy male subjects had significantly higher (p=0.011) platelet 5-HT concentrations during long compared to medium period. There were no significant differences (p>0.05) in platelet 5-HT concentration between different periods in healthy women. The significant increase in platelet 5-HT values were found in female (p=0.01) and male (p=0.029) depressed patients during long compared to short period. There were no significant associations between platelet 5-HT concentrations and different periods in both male and female schizophrenic patients. The results indicate the sex-related differences in the serotonergic system. The alterations of platelet 5-HT concentrations, observed across period with different durations of daylight exposure, point to a direct or indirect effect of light on peripheral 5-HT system that could be related to different sensitivity of the pineal gland to light and/or melatonin influence on 5-HT metabolism.

Effect of folic acid supplementation on mood and serotonin response in healthy males

Evidence suggests that low folate status may be detrimental to mood and associated with depleted cerebrospinal fluid levels of the neurotransmitter serotonin (5-hydroxytryptamine; 5-HT). A placebo-controlled trial was carried out to determine the effect of folic acid supplementation (100 μg for 6 weeks followed by 200 μg for a further 6 weeks) upon subjective mood (Positive and Negative Affect Schedule) and biochemical markers of mood (5-HT) in healthy males (n23). Blood samples were obtained at baseline (week 0) and during the intervention at week 6 and week 12. Subjective mood assessments were obtained at week 0 and week 12. The results showed an increase in serum and erythrocyte folate concentrations (P=0·02 andP=0·003, respectively) and a corresponding decrease in plasma homocysteine (P=0·015) in response to the folic acid intervention. Neither subjective mood nor 5-HT levels, however, were significantly altered in response to the change in folate status. Folic acid given at physiological doses did not appear to improve the mood of healthy folate-replete individuals over a 12-week period. Further research is needed to address the effect of folic acid supplementation or of longer duration or increased dose, particularly in the face of sub-optimal folate status.

Peripheral serotonergic markers in acutely suicidal patients. 1. Comparison of serotonergic platelet measures between suicidal individuals, nonsuicidal patients with major depression and healthy subjects

BACKGROUND

A robust association between "suicidality" and deficits of the serotoninergic neurotransmission has been claimed in the past. However, many studies having investigated the relationship between suicidality and peripheral indicators of serotoninergic neurotransmission suffer from considering only one or a very small number of potentially useful serotoninergic parameters, whereas a synoptic multidimensional approach appears to be more appropriate. Furthermore, the psychiatric context within which suicidal behaviour occurs should be considered when interpreting biochemical findings of patients with suicidal ideation and suicide attempts.

METHODS

In the present study 5 peripheral serotonergic markers, (platelet 5HT concentration, 5HT uptake activity, 5HT(2A) receptor binding characteristics, MAO-B activity and tryptophan concentration in plasma) were assessed simultaneously. Of the 60 acutely suicidal inpatients (ICD-10: F43.xx, n = 52; F31/32/33, n = 8), 45 were suicide attempters. Data of 28 nonsuicidal patients with major depression (F31, n = 4; F32, n = 14; F33, n = 10) and 123 healthy volunteers represented the control groups.

RESULTS

Mean platelet 5HT concentration was significantly lower in suicidal inpatients when compared to nonsuicidal depressed patients, but did not differ from the figure in healthy subjects. Nonsuicidal depressed patients showed significantly higher mean platelet-5HT concentration than healthy controls. Mean V(max) of 5HT uptake in washed platelets, but not in platelet-rich plasma, was significantly higher in suicidal patients than in healthy controls, not, however, when compared to nonsuicidal depressed patients. Mean K(D) for the platelet 5HT(2A) receptor and MAO-B activity were significantly lower in suicidal patients as compared to nonsuicidal depressed patients and healthy controls. The observed differences in peripheral serotonergic markers between groups are partially due to a significant gender effect. A lower MAO-B activity was observed only in suicidal females, while the higher V(max) of 5HT uptake in washed platelets of suicidal patients was due to suicidal males.

CONCLUSIONS

In view of conflicting observations made by other authors and the present findings on suicidal patients with adjustment disorder it remains doubtful whether and if so to which extent platelet studies can provide valid information on serotonergic mechanisms related to suicidal behaviour.

Associations between whole-blood serotonin and subjective mood in healthy male volunteers

Little is known regarding the relationship between how mood is experienced and biochemical factors. This research has explored potential relationships between whole-blood serotonin (5-HT) and subjective mood, measured using the Positive and Negative Affect Schedule (PANAS), in healthy males (n=23). Univariate linear regression analysis indicated that 5-HT levels were positively related to positive affect (P=0.002) but not negative affect. Whole-blood 5-HT concentrations therefore appear to predict mood in healthy males. More research using larger samples and including females is needed to explore further associations between biomarkers and subjective measures of mood.

Whole blood serotonin and platelet activation in depressed post-myocardial infarction patients

Depression is an independent risk factor for post myocardial infarction (MI) mortality. Abnormalities in platelet function have been proposed as one of the mechanisms involved in increased cardiovascular risk among patients with depression post-MI. Depression in somatically healthy patients has been associated with increased platelet activation. Some but not all studies showed changes in blood serotonin level. Increased platelet activation and blood serotonin level have been associated with increased risk of cardiac events in patients with MI. The goal of this study was to investigate whether 1) depressed post-MI patients have higher markers of platelet activation as measured by plasma levels of beta-thromboglobulin (betaTG), platelet factor 4 (PF4) and soluble CD40 ligand (sCD40L) and higher serotonin (5-HT) levels than non-depressed post-MI patients and 2) treatment with the antidepressant mirtazapine decreases platelet activation. In this study, 25 depressed post-MI patients were asked for blood collection before start as well as after 8 weeks treatment with mirtazapine or placebo. The control group (n=22) consisted of non-depressed post-MI patients, matched for age, gender and time elapsed since MI. Plasma levels of betaTG, PF4 and sCD40L were not statistically different between the groups, but 5-HT levels were significantly higher in depressed patients. Treatment with mirtazapine resulted in a non-significant decrease in betaTG and PF4 and platelet 5-HT levels. Platelet and whole blood 5-HT, but not platelet activation was significantly increased in depressed post-MI patients. Treatment with mirtazapine showed a non-significant decrease in platelet activation and platelet 5-HT.

Platelet serotonin and plasma prolactin and cortisol in healthy, depressed and schizophrenic women

Serotonin (5-hydroxytryptamine, 5-HT) is involved in the regulation of hypothalamic-pituitary-adrenal axis (HPA) activity and prolactin (PRL) secretion. The present study examined the relationship between platelet 5-HT and plasma cortisol and PRL concentrations in 20 schizophrenic, 25 depressed, and 25 healthy women. At the time of blood sampling, the schizophrenic and depressed patients had been drug-free for at least 7 days. Platelet 5-HT, plasma cortisol and PRL concentrations were determined by spectrofluorimetric, radioimmunoassay and immunoradiometric methods, respectively. Platelet 5-HT concentration was significantly higher in schizophrenic patients than in depressed patients or in healthy controls, while it was significantly lower in depressed patients than in healthy controls or in schizophrenic patients. Plasma cortisol levels were significantly increased both in schizophrenic and in depressed patients compared with values in healthy controls. Values of plasma PRL were similar across groups. A significant correlation was found between platelet 5-HT and plasma cortisol, and platelet 5-HT and plasma PRL concentrations in healthy controls, but not in schizophrenic or depressed patients. There was no significant relationship between plasma PRL and cortisol levels in any of the groups. Our data, although obtained on peripheral biochemical markers, indicate that depression and schizophrenia are characterized by disturbed 5-HT transmission and dysregulated HPA axis activity.

Simultaneous Determination of Serotonin and 5-Hydroxyindole-3-acetic Acid in Human Urine by Automated Precolumn Derivatization and Semi-microbore Column Liquid Chromatography with Fluorescence Detection

An improved high-performance liquid-chromatographic (HPLC) assay for the simultaneous determination of serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in human urine is reported. Following the automated precolumn derivatization of urinary 5-HT and 5-HIAA with benzylamine, the derivatives are separated by isocratic elution on a reversed-phase C18 semi-microbore column, and are fluorometrically detected at an excitation wavelength of 345 nm and an emission wavelength of 480 nm. The detection limits of 5-HT and 5-HIAA are 7 and 5 nmol/l in urine (0.7 and 0.5 fmol/20-microl injection). The proposed automatic method permits a highly selective and sensitive determination of 5-HT and 5-HIAA in human urine without any sample purification.

Regional brain serotonin synthesis is increased in the olfactory bulbectomy rat model of depression: an autoradiographic study

Serotonin synthesis rates were evaluated using alpha-[14C]methyl-l-tryptophan (alpha-MTrp) autoradiographic methods in olfactory bulbectomized (OBX) rats. They were significantly (p < 0.05) increased in the frontal (50%) and parietal (40%) cortices, superior olive (over 30%), and the substantia nigra (30%) in the OBX rats as compared to the sham operated animals. There were also increases in 5-hydroxytryptamine (5-HT) synthesis in some limbic areas: the cingulate (32%), the medial forebrain bundle (58%), the hippocampus (13-25%) and the thalamus (22-40%). The largest increase in 5-HT synthesis after OBX was observed in the sensory-motor cortex (67%). 5-HT synthesis rates were significantly decreased in the dorsal and medial raphe nuclei, but there was no significant change the ventral tegmental area and the locus coeruleus following OBX. These results indicate that olfactory bulbectomy causes an imbalance in 5-HT synthesis in some projection areas by disproportionally increasing 5-HT synthesis rates in specific brain regions and making more 5-HT available for neurotransmission. This imbalance in 5-HT synthesis and the subsequent elevation of tissue 5-HT may be responsible for the creation of non-physiological circuitry which may, in part, be reflected in the symptoms resembling human depression.

Evidence that serotonin affects female sexual functioning via peripheral mechanisms

A review of the literature indicates that serotonin is active in several peripheral mechanisms that are likely to affect female sexual functioning. Serotonin has been found in several regions of the female genital tract in both animals and humans. In the central nervous system (CNS), serotonin acts primarily as a neurotransmitter, but in the periphery, serotonin acts primarily as a vasoconstrictor and vasodilator. Since, in the periphery, the principal component of sexual arousal is vasocongestion of the genital tissue, it is likely that serotonin participates in producing normal sexual arousal. In addition, serotonin administration produces contraction of the smooth muscles of the genito-urinary system and is found in nerves innervating the sexual organs. Taken together, this evidence suggests that peripheral serotonergic activity may be involved in the normal sexual response cycle. In addition, exogenous substances that alter serotonin activity, such as selective serotonin uptake inhibitors (SSRIs) and the atypical antipsychotics, can produce sexual dysfunction. It is possible that sexual side effects seen with these drugs may result, at least in part, from their action on peripheral mechanisms.

Upregulation of the platelet Serotonin2A receptor and low blood serotonin in suicidal psychiatric patients

Suicidality has been found to be associated with low pre- and postsynaptic serotonin functioning. The purpose of this study was to examine whether in acutely suicidal psychiatric inpatients, the blood serotonin concentration was related to the underlying psychiatric disorder and whether it was associated with changes in the affinity (dissociation constant, KD) or in the maximal binding capacity (Bmax) of the platelet serotonin2A receptor. We therefore determined the blood serotonin concentrations and the platelet serotonin2A receptor activities of 45 suicidal psychiatric patients and 20 healthy subjects. We found that the blood serotonin concentrations were significantly lower in suicidal patients compared to healthy subjects. In all diagnostic categories (affective disorder, schizophrenia and adjustment disorder) we noted a significantly higher maximal binding capacity of the platelet serotonin2A receptor. These findings support the notion that a reduction in the availability of serotonin and an upregulation of the serotonin2A receptors in psychiatric patients are associated with a loss of control over suicidal impulses.

Physiological characteristics of platelet/circulatory serotonin: study on a large human population

The aim of this work was the study of platelet/circulatory serotonin (5-hydroxytryptamine, 5-HT), specifically alternative ways of its measurement and main physiological characteristics. The study was performed on a large human population (N=500) of blood donors of both sexes over the course of a longer time period (17 months). Owing to the heterogeneity in measurement of circulatory serotonin encountered in the literature, three ways of expression were comparatively studied: per unit number of platelets, per unit mass of platelet protein and per unit volume of whole blood. Results demonstrated unimodal distribution of individual frequencies of platelet/circulatory serotonin in the human population with the mean values of 579+/-169 ng 5-HT/10(9) platelets; 332+/-89.9 ng 5-HT/mg protein and 130+/-42.3 ng 5-HT/ml blood (mean+/-S.D.). A progressive decrease of serotonin level with age (18-65 years) was demonstrated, reaching statistical significance between the extreme age groups. No significant differences in the serotonin level between the sexes were observed. No seasonal oscillations in platelet/circulatory serotonin were found. Platelet serotonin demonstrated intra-individual stability over time. Finally, regarding the methodology of measurement, our results demonstrated a good correlation among the above-mentioned ways of expression of platelet/circulatory serotonin. This indicates the possibility of intercomparison of the literature reports expressing this physiological parameter either as 5-HT concentration in platelets or as 5-HT level in the circulation.

Platelets and psychiatry: lessons learned from old and new studies

Platelets play an important role not only in hemostasis but also in the pathophysiology of coronary artery disease. The complex interactions among the vascular endothelium, platelets, and blood components are one of the most exciting research areas today. This review addresses some fundamentals of platelet physiology and examines why platelets are interesting probes for neurophysiology. Results of current studies suggest that platelets are affected by diverse stressors, including psychological ones, and that platelets offer an interesting vantage point for understanding the neurophysiology of various psychiatric disorders. We also describe how platelets have been used for various types of research, including studies of stress associated with cardiovascular disease and studies of platelets in psychopharmacological research. Finally, we examine some of the psychiatric literature related to platelets; these studies range from case studies from the 1920s to contemporary experimental studies.

Relationship between impulsivity and platelet serotonin content in adolescents

The relationship between impulsivity and serotonin function was explored in impulsive and non-depressed adolescents. Platelet serotonin content was chosen as a peripheral indicator of central serotonin function. Impulsivity was assessed with a questionnaire. All measures were performed once a week over a 6-week period for all subjects. Subjects comprised eight adolescent inpatients who were hospitalized as a result of their impulsive acts and eight healthy age- and sex-matched control subjects. Mean platelet serotonin concentration was significantly higher in the impulsive group than in the control group. Platelet serotonin concentration was positively correlated with the intensity of impulsivity in the patient group.

Platelet 5-HT and plasma MHPG levels in patients with bipolar I and bipolar II depressions and normal controls

BACKGROUND

It has been suggested that platelet serotonin (5-HT) content may reflect aspects of the presynaptic reuptake of 5-HT, while plasma 3-methoxy-4-hydroxy-phenylglycol (MHPG) levels may provide an index of central noradrenergic function.

METHODS

In order to determine if there is a biological distinction in 5-HT or noradrenergic function within bipolar I and bipolar II depressions, we measured levels of platelet 5-HT and plasma MHPG in 12 patients with bipolar I depression, 12 patients with bipolar II depression, and 20 normal healthy controls. All subjects were medication free for at least 4 weeks prior to the study.

RESULTS

There was a trend towards higher platelet 5-HT in bipolar I or II depressions when compared to normal controls, whereas there was no difference in platelet 5-HT levels between bipolar I and II depressed patients. When bipolar I and II patients were pooled, there was a significant increase in platelet 5-HT levels in bipolar depressives compared to normal controls, and there was a trend towards a weak positive correlation between platelet 5-HT and 21-item HAMD scores in the patient group. In contrast, there was no difference in plasma MHPG levels between the three groups.

LIMITATIONS

This study was limited to a small sample size, single point sampling and did not match seasons.

CONCLUSIONS

Our findings did not provide supportive evidence for a distinctive 5-HT or noradrenergic function within bipolar I and bipolar II depressions. However, the finding of increased platelet 5-HT levels in bipolar depressed patients compared to normal controls is consistent with the results of previous studies, and may suggest an increase in presynaptic 5-HT reuptake, presumably resulting from diminished synaptic 5-HT availability in this condition.

Biological parameters in major depression: effects of paroxetine, viloxazine, moclobemide, and electroconvulsive therapy. Relation to early clinical outcome

BACKGROUND

Clinical and pharmacologic studies report a relative or absolute serotonergic deficiency in major depression; however, the variability of clinical characteristics of illness has led to controversial results. In the present work, we looked for a possible relationship between i) biochemical values that indirectly reflect aminergic neurons activity and clinical characteristics and ii) their evolution and the early clinical outcome under antidepressive therapies (ATs).

METHODS

Platelet serotonin content, platelet monoamine oxydase activity, and urinary biopterins were measured in 27 depressed patients before and during four different ATs (paroxetine, viloxazine, moclobemide, or electroconvulsive therapy). Depressive symptomatology and its evolution under ATs were quantified using three clinical rating scales.

RESULTS

A severe symptomatology, high serotonin (5-HT) platelet content, and high or low urinary B could represent risk factors leading to a smaller or delayed response to an AT. Furthermore, the early improvement under ATs was negatively correlated to pretreatment 5-HT platelet content.

CONCLUSIONS

Determination of 5-HT level could be useful in the choice of an AT.

Hypothalamic-pituitary-adrenal axis function and platelet serotonin concentrations in depressed patients

Plasma cortisol and platelet serotonin (5-hydroxytryptamine, 5-HT) concentrations were determined in 39 male psychotic and 39 male non-psychotic depressed inpatients, and in 69 male healthy control subjects. Psychotic or non-psychotic depressed patients had higher predexamethasone plasma cortisol levels than found in the control group. After the dexamethasone suppression test (DST), psychotic and non-psychotic depressed patients were subdivided into suppressors and non-suppressors. Psychotic and non-psychotic patients had significantly different platelet 5-HT concentrations among themselves and compared with the control group. However, there was no significant correlation between plasma cortisol levels and platelet 5-HT concentrations. Dexamethasone administration did not affect platelet 5-HT concentrations within subtypes of depressed patients. Abnormal cortisol suppression after the DST occurred more frequently in psychotic than in non-psychotic patients. Platelet 5-HT and plasma cortisol concentrations were decreased in patients with pronounced suicidal behaviour. Our results suggest that plasma cortisol and platelet 5-HT concentrations might serve as independent biological markers for different subtypes of depression.

Seasonal influence on platelet 5-HT levels in patients with recurrent major depression and schizophrenia

The influence of seasons on platelet serotonin (5-HT) concentration was determined in 88 unipolar depressed and 117 schizophrenic male inpatients, and 90 normal male controls. Platelet 5-HT concentrations showed moderate, but insignificant intragroup seasonal variations in healthy controls and in the groups of depressed (psychotic and nonpsychotic) and schizophrenic (positive and negative) patients. In spring, platelet 5-HT concentrations were higher in schizophrenic patients than in normal controls or in depressed patients, while in other seasons platelet 5-HT concentrations were not significantly different between the groups. Higher platelet 5-HT concentrations were detected in psychotic when compared to nonpsychotic depressed patients in summer, fall, and winter. Increased platelet 5-HT concentrations observed in schizophrenic patients with positive symptoms clearly separated these patients from patients with negative schizophrenia, especially in spring, summer, and fall. Our results indicate the necessity to match patients with regard to the season of the sampling, and to divide depressed and schizophrenic patients into subtypes.

3,4-Dimethoxybenzylamine as a sensitive pre-column fluorescence derivatization reagent for the determination of serotonin in human platelet-poor plasma

3,4-Dimethoxybenzylamine is shown to be a highly sensitive pre-column fluorescence derivatization reagent for the determination of serotonin in plasma by high-performance liquid chromatography. The reagent reacts selectively with 5-hydroxyindoles including serotonin in slightly alkaline media in the presence of potassium hexacyanoferrate(III) to give highly fluorescent derivatives. The derivatives of six standard 5-hydroxyindoles (5-hydroxytryptophan, 5-hydroxyindole-3-acetic acid, serotonin, 5-hydroxyindole-3-acetamide, N-acetyl-5-hydroxytryptamine and 5-hydroxytryptophol) are separated within 18 min by isocratic elution using acetonitrile-10 mM phosphate buffer (pH 6.0)-50 mM 1-hexanesulfonic acid on a Wakosil II 5C18RS reversed-phase column. The detection limits (signal-to-noise ratio=3) for the indoles were 1.0-5.7 fmol in a 100-microl injection volume. The method was applied to the measurement of serotonin in human platelet-poor plasma.

Whole-blood serotonin in children and adolescents with mood and behavior disorders

Whole-blood serotonin (5-hydroxytryptamine, 5-HT) levels were measured in 118 children and adolescents with DSM-III-R mood disorders (n = 30) or behavior disorders (n = 27), a mixed group who met criteria for both mood and behavior disorders (n = 47), and a small sample of normal control subjects (n = 14). The patients were selected from consecutive admissions to an inpatient state hospital setting and the control subjects were recruited from a local high school. Levels of whole-blood 5-HT were significantly higher in the behavior disorder group (193 +/- 120) than in the mood disorder (122 +/- 83) or mixed mood and behavior (137 +/- 95) patient groups, but did not differ from control levels (170 +/- 48). A subsample of patients irrespective of diagnostic classification who had been on a selective serotonin reuptake inhibitor (SSRI) before admission had significantly lower whole-blood 5-HT concentrations (97.8 +/- 78.4) than those in patients who had been receiving some other type of psychotropic medication at admission (159.8 +/- 109.2) and from those in unmedicated patients (161.9 +/- 101.4). The 5-HT concentrations for patients receiving non-SSRI psychotropic medications did not differ from those of unmedicated patients. The frequency analysis of 5-HT concentration by psychiatric disorder group suggests that patients with mood disorders have the lowest values (below 100 ng/ml) and patients with behavior disorders have the highest values (above 300 ng/ml). Levels in the limited sample of normal subjects were all between 100 and 300 ng/ml. These findings were not accounted for by age, sex, gender, race, or season and lend support to accumulating research on simple neurobiological indicators in blood that help to distinguish these child/adolescent psychiatric disorders from each other and from individuals without these disorders.

Estrogen augments serotonergic activity in postmenopausal women

To investigate the influence of estrogen replacement on serotonergic activity in postmenopausal women, the serotonin agonist meta-chlorophenylpiperazine (m-CPP) (0.5 mg/kg) was given orally to 18 normal postmenopausal women, 11 of whom were also tested following 30 days' treatment with estrogen transdermal patches (estraderm 0.1 mg). Fifteen normal, healthy women of reproductive status served as a control group. Cortisol and prolactin responses to m-CPP were measured. Without estrogen, the prolactin and cortisol responses of postmenopausal women to m-CPP were blunted compared to those of reproductive women. Estrogen replacement increased the hormonal responses. It is suggested that decreased serotonergic activity in postmenopausal women might contribute to their vulnerability to affective disorders. Estrogen replacement therapy might decrease this vulnerability and might add to the efficacy of serotonergic antidepressants when warranted.

Determination of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid and tryptophan in plasma and urine by HPLC with fluorimetric detection

Using native fluorescence detection, 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and tryptophan were resolved from themselves and other naturally occurring compounds using reversed-phase HPLC within 5 min. Deproteinated platelet-poor plasma (PPP) and crude diluted urine were injected directly into the chromatograph. Careful selection of the HPLC column is important and various octadecyl silica (ODS) and base deactivated silic (BDS) columns were evaluated. Pre-treatment of an ODS column with tetrabutylammonium ions gave good selectivity. Between pH 5 and 6 the compounds were well resolved from each other. The limit of quantitative detection of 5-HT and 5-HIAA was 3.5 nmol/L. The overall chromatogram obtained using native fluorescence is cleaner than that obtained with the more commonly employed electrochemical (EC) systems although the chromatography is effectively the same. For analysis of 5-HT in plasma, collection in EDTA was more efficient than lithium heparin. Plasma 5-HT in healthy volunteers was mean 61 (SD = +/- 73) nmol/L, n = 20; urine 5-HIAA gave mean 28.95 (SD = +/- 0.98) mumol/L, (n = 12). Whole blood 5-HT analysis is unreliable in comparison with platelet-poor plasma.

Acute tryptophan depletion in bulimia: effects on large neutral amino acids

Acute tryptophan depletion, which may reduce brain serotonin synthesis in humans, was evaluated in bulimic and normal subjects assessing its effects on the plasma ratio of tryptophan to the sum of the other large, neutral amino acids (TRP/sigma LNAA). Thirteen bulimic and 9 control women ingested an amino acid mixture containing either 2.3 g (control mixture) or 0 g of tryptophan (active mixture), in combination with 100 g of the other amino acids. Six healthy male volunteers were also studied, using a similar mixture containing 4.6 g of tryptophan. Bulimic and control women both experienced sizable reductions in the plasma TRP/sigma LNAA ratio, compared to baseline values, for both the active mixture (10% of baseline) or the control mixture (45% of baseline). For bulimic women, the active mixture produced a significant increase in fatigue and a trend toward increased anxiety and indecisiveness. The control mixture did not maintain baseline TRP/sigma LNAA ratios so we identified a control amino acid mixture that does not cause a drop in the plasma TRP/sigma LNAA ratio when ingested (4.6 g tryptophan in combination with 100 g of other amino acids). An oral, tryptophan-deficient amino acid mixture produced acute, substantial reductions in the plasma TRP/sigma LNAA ratio in all subjects, suggesting that the treatment should reduce brain tryptophan uptake and serotonin synthesis. A control mixture containing tryptophan was also identified that maintains the plasma TRP/sigma LNAA ratio at pretreatment values.

Circadian rhythm of tryptophan, serotonin, melatonin, and pituitary hormones in schizophrenia

Circadian rhythm abnormalities have been described mostly with respect to manic-depressive illness; little information is available concerning circadian rhythms and schizophrenia or their influence on neuroleptic drugs. We showed previously that the MESOR of dopamine is higher in schizophrenic patients than in healthy subjects and that women who are drug-free schizophrenic have lower prolactin MESORs and lower amplitudes than healthy women. We now report the data of a cosinor analysis of tryptophan, serotonin, melatonin, and pituitary hormones in the blood of 34 healthy subjects, 90 drug-free schizophrenics, and 25 neuroleptic-treated schizophrenic patients. This data indicated a significant phase advance of serum tryptophan, prolactin, and melatonin concentrations, a trend toward a phase advance in serotonin. Thyroid stimulating hormone (TSH), and growth hormone concentrations, and decreases in the TSH MESORs among patients compared to healthy subjects. These results suggest that circadian changes, such as phase advances and alterations in MESOR, are not only present in depression but also in schizophrenia. Although neuroleptic treatment raised the prolactin MESOR and amplitude, it did not elicit any change in circadian rhythmicity among the other parameters.

Determination of 5-hydroxytryptamine and tryptophan by liquid chromatography in whole blood. Its interest for the exploration of mental disorders

1. 5-Hydroxytryptamine (5-HT) is a well known neurotransmitter implicated in mental disorders, tryptophan (Trp) as amino acid precursor may be interesting. 2. A rapid and simple reversed-phase (mu Bondapac C18 as stationary phase) liquid chromatographic method with fluorimetric detection (excitation: 302 nm, emission: 340 nm) is described for the quantitation of 5-hydroxytryptamine (5-HT) and free tryptophan (Trp), in whole blood. 5-fluoro-dl-tryptophan (5-FdlT) was used as internal standard. The mobile phase was 0.01 M phosphate buffer (pH = 4.5) with 0.0025 M 1-heptane sulfonic acid and 15% methanol. 3. In blood of healthy subjects (n = 30), the concentrations were, for 5-HT: 258 +/- 68 ng/ml and for Trp: 5.7 +/- 1.02 micrograms/ml. 4. The assay was used to follow the effect of antidepressant drugs, as a 5-HT reuptake inhibitor (clomipramine) and a monoamine oxidase inhibitor (moclobemide). After 4 week treatments, we observed, with clomipramine by 7 patients (150 mg/day) a highly significant reduction (p < 0.01) in 5-HT levels (77% +/- 12) and with moclobemide by 8 patients (300 or 450 or 600 mg/day) a highly significant increase in 5-HT levels (from 16% to 300% according to the drug dosage). These two drugs did not influence blood Trp concentrations. 5. Assays on whole blood present various advantages: (i) the simplicity for clinical departments (ii) the absence of sample pretreatment and (iii) the assurance that the entire platelet population is assayed since all of the 5 HT in blood is bound to platelets.

Migraine and depression: biological aspects

There is a considerable overlap in migraine and depression incidence, and both conditions may be associated with low levels of 5-hydroxytryptamine (5-HT). During a migraine attack there is evidence for low levels of platelet 5-HT and possibly also low Vmax for 5-HT uptake; both these findings are also associated with the depressed state. Both conditions can be treated by tricyclic and monoamine oxidase inhibiting antidepressants. However, there are also clear differences: migraine attacks are brief and self limiting. Part of the migraine cascade occurs outside the blood brain barrier, presumably involving blood vessels and, unlike depression, migraine attacks can be ameliorated by drugs which only act peripherally. In addition, migraine patients, especially males, often have permanently low levels of platelet monoamine oxidase activity, whereas patients with unipolar depression tend to have raised levels of this marker. This low enzyme activity may reflect part of the vulnerability to migraine, often associated in the prodromal phase with agitation or hyperactivity. Migraine may form part of a family of brief recurrent self-limiting disorders, which involve disturbances of both mood and monoamines; during the headache phase of the attack, the links with depression are most apparent.

Platelet and whole blood serotonin content in depressed inpatients: correlations with acute and life-time psychopathology

Platelet or whole blood serotonin content did not differ significantly in patients with major depression compared to healthy controls, but within the patient group, platelet serotonin levels correlated negatively with severity of depression (r = -0.49, p = 0.007). Levels were 39% lower in patients who had made a suicide attempt compared to nonattempter patients (47.2 +/- 27.3 versus 77.6 +/- 41.7 ng/10(8) platelets, p = 0.04). Conversely, comorbid borderline personality disorder (85.3 +/- 41.5 ng/10(8) platelets) was associated with 31% greater platelet serotonin content than nonborderline patients (58.9 +/- 31.1 ng/10(8) platelets) and 27% greater than healthy controls (62.4 +/- 19.8 ng/10(8) platelets). A pronounced seasonal variation in whole blood and platelet serotonin content was found in both patients and controls, largely due to lower levels in summer. Excluding cases tested in the summer abolished the statistically significant differences in patients with and without comorbid borderline personality disorder (BPD). Nevertheless, BPD attempters had lower serotonin levels than BPD nonattempters but higher serotonin levels than non-BPD attempters. Current hostility and a life-time history of aggression were positively correlated with platelet serotonin content (r = 0.44, p = 0.04 and r = 0.41, p = 0.06). This study provides evidence for an association between lower platelet serotonin content and depression and suicidal behavior, and association of higher platelet serotonin content and comorbid borderline personality disorder and behavior traits such as aggressivity.