5-Hydroxytryptamine content of the whole blood in psychiatric illness and alcoholism

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.

The effect of some family characteristics on the relationship between mental symptoms and levels of serum serotonin and salivatory cortisol

Introduction: Psychological symptoms (PSs) are also seen in healthy individuals. The aim of this study is to examine some familial characteristics in the relationship between PSs and serum serotonin (5-HT) and salivary cortisol (sCTS) levels in healthy individuals. Materials and Method: A sociodemographic data form and a psychiatric symptom screening questionnaire (SCL-90-R) were given to 320 healthy individuals (156 males, 164 females) aged between 18-65 years and without any mental illness. Blood and saliva samples were duly taken and evaluated by ELISA method. The research protocol was approved by the Ankara Keçiören Training and Research Hospital Clinic Research Ethics Committee (study number KÖTRH-CREC_11.07.2012/103). Informed consent was obtained from the participants before participating in the study. Statistical analyzes were performed with the SPSS 15.0 program. Descriptive statistical data (number, percentage, mean, standard deviation, minimum and maximum), independent sample t test, One-way ANOVA test, Kruskal Wallis H test, Mann-Whitney U test, Pearson Correlation analysis were used in the analyzes. For statistical significance, p˂.05 was accepted as significant. Results: The highest PS levels of the participants were obsessive-compulsive symptoms (.92±.80), interpersonal sensitivity (.75±.55) and depressive symptoms (.72±.53), respectively. The general symptom index (GSI) was .61±.46. Psychotic (χ2(2)=7.021, p=.03) and phobic symptoms (χ2(2)=7.130, p=.03) in those living in a nuclear family, depression levels in those whose parents lived together (t=-2.114, p=.04) was lower. Somatization, anxiety, obsession, depression, interpersonal sensitivity, psychoticism, paranoid, thought, hostility and additional symptom levels were highest in illiterate parents. Phobic symptom levels were highest in those whose fathers were illiterate. In patients with a family history of psychiatric illness, somatization (t=2.108, p=.04), anxiety (t=2.103, p=.02), obsession (t=2.146, p=.03), depression (t=2.548, p=.01), anger-hostility (t=3.096, p=

Whole blood serotonin levels in healthy elderly are negatively associated with the functional activity of emotion-related brain regions

Understanding the role of neuromodulators of socio-affective processing is important to ensure psychological wellbeing during older years. Here, we investigated the link between blood serotonin levels and brain and behavioral responses to emotional information in healthy elderly. A priori regions of interest (ROI) were selected due to their role in emotion processing and their dense serotonergic innervation. Correlation analyses were performed between ROI-specific responses to emotional stimuli and whole blood serotonin levels. We found significant negative associations between serotonin and functional activity for the bilateral insula, dorsal anterior cingulate cortex and subgenual gyrus. No association with behavioral measures survived correction for multiple testing. Our results mirror prior pharmacological and genetic work on the link between serotonin and emotional brain reactivity in younger adults. Given the involvement of serotonin in several age-related changes, our study encourages future research to characterize the role of this neuromodulator in emotion processing across the lifespan.

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.

Lower levels of whole blood serotonin in obsessive-compulsive disorder and in schizophrenia with obsessive-compulsive symptoms

It has been reported that some schizophrenic patients suffer from obsessive-compulsive symptoms (OCS), and clozapine treatment is quite often associated with an occurrence/increase of OCS in schizophrenic patients. The aim of the study was to explore whether differences would exist in the clinical symptomatology and the whole blood serotonin (5-HT) concentrations in patients with obsessive-compulsive disorder (OCD), schizophrenic patients with and without OCS (S+OCS, S-OCS), and clozapine-treated schizophrenic patients with and without clozapine-induced OCS (CLZ+OCS, CLZ-OCS). We found that S+OCS patients (n=15) showed significantly lower scores on the Hamilton Anxiety Scale (HAMA), but similar levels of compulsions and obsessions using Yale-Brown Obsessive-Compulsive Scale (YBOCS) as compared to the patients (n=35) with OCD. S+OCS patients scored significantly lower on the Positive and Negative Syndrome Scale (PANSS) but higher on the Hamilton Depression Scale (HAMD) compared with S-OCS patients (n=19). However, CLZ+OCS patients (n=15) suffered from dominant compulsions but fewer obsessions compared with the OCD and S+OCS patients. OCD, S+OCS and CLZ+OCS groups had significantly lower levels of whole blood 5-HT than did the healthy volunteers (n=15), S-OCS and CLZ-OCS groups. It suggests that alterations in serotonin metabolism may be a common biological characteristic of OCS in OCD as well as in schizophrenia.

Regulation of sexual behaviour in male macaques by sex steroid modulation of the serotonergic system

The view that androgen action is the primary impetus underlying male-typical behaviour has been irrevocably altered by the profound perturbations in social and sexual behaviour observed in recent models of oestrogen insufficiency in male mice. Evidence is also accumulating for an involvement of oestrogens in the modulation of neural systems that are thought to play important roles in male reproductive functioning. Specifically, the serotonergic system is implicated in diverse autonomic functions, most or all of which are sensitive to oestradiol as well. Although their interaction domains have yet to be examined in male primates, roles have been established for both oestrogen and serotonin in the regulation of male sexual behaviour. We used a blinded, sham-treated and self-controlled, randomized, multitreatment cross-over design to test the hypothesis that male sexual behaviour is regulated by oestrogen modulation of the serotonergic system in intact male Japanese macaques. Regression analysis revealed that oestradiol and whole blood tryptophan, but not testosterone or 5alpha-dihydrotestosterone, had additive, independent effects on male potentia over a range of hormone concentrations, whereas androgens were confirmed to be the primary determinants of sexual motivation. We suggest that modulation of the serotonergic system by 'female hormones' may be fundamental to the regulation of male mating success in higher primates. This might also explain, at least in part, why significant correlations between steroid hormones and male copulatory behaviour have traditionally proven so elusive in this order, thereby warranting a re-evaluation of the current notion that male sexual behaviour has been emancipated from activational hormonal control in higher primates.

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.

Peripheral serotonin measures in prepubertal psychiatric inpatients and normal children: associations with suicidal behavior and its risk factors

BACKGROUND

This study reports relationships between suicidal behavior and its risk factors in prepubertal children and whole blood and platelet serotonin-related measures.

METHODS

Seventy-five prepubertal psychiatric inpatients including 23 (30.7%) nonsuicidal, 32 (42.7%) with suicidal ideation, and 20 (26.6%) with a suicide attempt were compared to 35 normal prepubertal controls with regard to platelet serotonin content, serotonin-amplified platelet aggregation, and whole blood tryptophan.

RESULTS

Mean whole blood tryptophan content was significantly lower among inpatient children with a recent suicide attempt than among normal controls or inpatients with suicidal ideation (F = 3.94, df = 3.54, p < or = .01). Inpatient children with a mood disorder had significantly higher platelet serotonin content than inpatients without a mood disorder (F = 3.86, df = 2.80, p < or = .03). Racial/ethnic differences were also observed for inpatients and normal controls, with whites having significantly lower levels of platelet serotonin (expressed as ng/mL blood or ng/10(9) platelets) than blacks or Latinos. Blacks had significantly higher levels of whole blood tryptophan than other racial/ethnic groups.

CONCLUSIONS

The results suggest that whole blood tryptophan and platelet serotonin content should be studied for their predictive validity as risk factors for suicidal behavior in youth while controlling for racial/ethnic differences.

D-fenfluramine-induced prolactin responses in postwithdrawal alcoholics and controls

Serum prolactin response to the serotonin agonist D-fenfluramine were measured in 19 DSM-111-R male alcoholics, 2.5 or more weeks postalcohol withdrawal. Prolactin responses were compared with nine healthy nonalcoholic male controls. After an overnight fast, each subject received 30 mg of D-fenfluramine orally, and serial samples of serum prolactin were taken over a 4-hr period. D-fenfluramine caused a significantly attenuated peak delta-prolactin response in the alcoholics relative to the controls (p = 0.05). A repeated-measures ANOVA of delta-prolactin yielded a significant within-subjects effect of time (p < 0.05), a within-subjects effect of group that reached significance (p = 0.05), and a nonsignificant group by time interaction. The delta-prolactin value at time points 60 and 240 min postadministration of the probe was significantly attenuated in the alcoholic group, with p < 0.05. There was also some evidence for a diminished serotonergic response in those alcoholics with a negative family history. The delta-prolactin response did not correlate with subjects' age, duration of alcohol use, duration of abstinence from alcohol, severity of alcohol dependence, or age of onset. Results imply a relative subsensitivity of the serotonin system in postwithdrawal alcoholics, and this may be primarily of the 5-HT2 receptor.

Selective serotonin reuptake inhibitors: effects of chronic treatment on ethanol-reinforced behavior in mice

Several lines of evidence suggest that aspects of ethanol drinking are mediated, at least in part, by serotonergic (5-HT) neurotransmitter systems. Ethanol-preferring animals show decreases in serotonin function and receptor densities. In addition, serotonin uptake inhibitors have been shown to decrease ethanol consumption in animal models and in humans. However, the time course of these effects and their duration remain undetermined. In the present studies, C57BL/6J male mice were treated with one of three selective 5-HT reuptake inhibitors (SSRIs): fluoxetine, sertraline, or paroxetine. All three drugs produced initial decreases in operant lever pressing behavior for ethanol followed by a return to baseline on subsequent days. Immediately following 14 days of this initial treatment, subsequent treatment with higher SSRI doses was ineffective in decreasing ethanol-reinforced behavior. However, after a several week "washout period," SSRI pretreatment again produced an initial decrease in responding for ethanol, again followed by a return to baseline. Thus, suppression of ethanol drinking may be related to immediate changes in 5-HT function following treatment with SSRIs, and tolerance to this effect appears to develop rapidly.

Ethanol, monoamines, and affect

Evidence suggests that ethanol self-administration is directly related to central norepinephrine (NE) activity and inversely related to central serotonin (5-HT) activity. Normal male volunteers participated in a placebo controlled crossover design to assess the effects of 1-tyrosine (TY) and 1-tryptophan (TP) (precursors of catecholamines and 5-HT, respectively) in combination with ethanol, on several neurobehavioral measures. Ethanol by itself produced negative effects on several dimensions of mood. Dysphoria was potentiated by TP in combination with ethanol and either unchanged or attenuated by the combination of TY and ethanol. Ethanol impaired verbal recall, and neither TP nor TY in combination with ethanol altered that impairment. The results are consistent with the hypothesis that 5-HT mediates some of the negative mood effects produced by ethanol or antagonizes some of its positive effects, while NE at least partly mediates ethanol's positive effects on mood. Ethanol's impairment of verbal memory appears to be mediated by mechanisms outside the monoamine systems.

Serotonin and alcohol intake, abuse, and dependence: clinical evidence

A large body of literature has emerged concerning the role of the neurotransmitter serotonin (5-hydroxytryptamine, or 5-HT) in the regulation of alcohol intake and the development of alcoholism. Despite the wealth of information, the functional significance of this neurotransmitter remains to be fully elucidated. This paper, part one of a two-part review, summarizes the available clinical research along two lines: the effects of alcohol on serotonergic functioning and the effects of pharmacological manipulation of serotonergic functioning on alcohol intake in normal (nonalcohol dependent) and alcohol-dependent individuals. It is concluded that considerable evidence exists to support the notion that some alcoholic individuals may have lowered central serotonin neurotransmission.

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 serotonin levels in alcoholic patients: changes related to physiological and pathological factors

This study investigated platelet serotonin (5-hydroxytryptamine; 5-HT) levels and the effects of different physiological and pathological factors in 108 alcoholic patients (alcohol abuse, n = 49; alcohol dependence, n = 59) and 32 healthy control subjects. Platelet 5-HT levels were determined by a fluorescent-ortho-phthalaldehyde assay. In patients, platelet 5-HT levels during withdrawal from alcohol and after 2 weeks of abstinence were significantly lower than in control subjects. Among patients, this decrease was enhanced both in alcohol-dependent patients and in patients who were depressed during the withdrawal phase, whereas lifetime impulse control disorders (mostly found in alcohol abusers) were associated with comparatively high platelet 5-HT levels (i.e., close to control subjects' values). These results, which reflect the likely biphasic effect of alcohol ingestion upon 5-HT functioning, are consistent with the dimensional 5-HT hypothesis in psychiatric disorders.

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.

Platelet serotonin decrease in alcoholic patients

This study investigated the platelet 5-HT levels and their changes according to different physiological and pathological factors in 30 young alcoholic patients (16 alcohol abusers and 14 alcohol-dependent subjects) and 26 healthy controls. Platelet 5-HT levels were determined by a fluorescent-ortho-phthalaldehyde assay. The mean platelet 5-HT levels obtained in patients during withdrawal and after 2 weeks of abstinence were significantly lower than in controls. Presence of positive history of impulse control disorders (ICD) influenced the mean platelet 5-HT levels in patients. These preliminary results suggest that the platelet 5-HT level decrease observed in alcohol-dependent patients mostly free from ICD and in alcohol abusers mostly affected by ICD might result from comparable neurobiological mechanisms. However, the age of onset of alcohol dependence might depend on psychological functioning features.

Ethanol potentiates serotonin stimulated inositol lipid metabolism in primary astroglial cell cultures

Serotonin-stimulated activation of phospholipase C in primary astroglial cell cultures was studied as a mean of evaluating the effect of acute ethanol exposition on this signal transduction system. The addition of 50-150 mM ethanol prior to stimulation with 10(-5) M serotonin led to a potentiation of the serotonin-induced [3H]-inositol phosphate formation and an increased incorporation of [3H]-inositol into the three phosphoinositides studied. This potentiating effect of ethanol was observed only when ethanol was added together with serotonin. No stimulatory effect of ethanol per se was found. Furthermore, ethanol had no effect on arginine-vasopressin, bradykinin or phenylephrine stimulated inositol lipid metabolism.

Increased serotonin2 (5-HT2) receptor binding as measured by 3H-lysergic acid diethylamide (3H-LSD) in the blood platelets of depressed patients

3H-Lysergic acid diethylamide (3H-LSD) binding, a putative measure of 5-HT2 receptor binding, was studied in the blood platelets of 29 depressed patients and 24 normal controls. The Bmax (maximum number of 3H-LSD binding sites) in the blood platelets of depressed patients was significantly greater than that of normal volunteers. This increase in Bmax was due to an increase in female depressed patients only. Bmax was significantly lower in female compared to male normal controls but there was no difference between male and female depressed patients. There was also no difference in Kd (an inverse measure of affinity of 3H-LSD binding to its sites) between normal controls and depressed patients. The correlations between Bmax of 3H-LSD binding and the Bmax of the 3H-imipramine binding site or the Vmax of 5-HT uptake sites were not significant. The role of serotonergic processes in the psychobiology of depression is discussed.

Effects of fluoxetine on the intragastric self-administration of ethanol in the alcohol preferring P line of rats

Rats of the alcohol-preferring P line (n = 7) were trained to self-administer ethanol (20% v/v) and water via an intragastric IG catheter. Food was available ad lib. Ethanol intakes averaged approximately 5-6 g/kg body wt./day. Treatment with the serotonin (5-HT) uptake inhibitor fluoxetine (10 mg/kg/day; IG) for seven consecutive days produced a marked decrease in ethanol self-administration on the first day, which was sustained throughout the seven days of treatment to values as low as 1 g/kg/day. Concomitant with the decrease in ethanol intake, the self-infusion of water gradually increased during the period of fluoxetine treatment. Total caloric intake (ethanol plus food) was moderately reduced during fluoxetine treatment; the decrease in food consumption was consistent but not statistically significant. When fluoxetine treatment was terminated, ethanol self-administration quickly returned to the prefluoxetine levels, while water intake began to decrease. Since no ethanol was consumed orally, the IG ethanol was not self-administered for its taste or smell, but apparently for its postingestive pharmacological effects. The robust reduction of ethanol self-infusion that occurred with fluoxetine treatment suggests that the 5-HT systems are involved in the reinforcing effects of ethanol in the P line of rats.

Platelet serotonin content and plasma tryptophan in peri- and postmenopausal women: variations with plasma oestrogen levels and depressive symptoms

Platelet serotonin content was measured by high pressure liquid chromatography in 56 peri- and postmenopausal women, in order to study variations of this parameter with hormonal status and depressive mood symptoms. Clinical symptoms were assessed by a self-report depression symptom scale (CES-D of NIMH). Thirty-eight women with a score of 16 or more were considered as presenting depressive symptoms (mean score +/- SD = 28.8 +/- 10.5), while the others formed the control group (n = 18, score = 4.4 +/- 4.2). Platelet serotonin contents were significantly lower in the 'depressed' group (0.302 +/- 0.010 vs. 0.366 +/- 0.020 nmol 10(-8) platelets, means + SEM, P less than 0.001 by Mann-Whitney U-test). In 'depressed' women who had been treated for one or more depressive episodes, platelet 5-HT contents (0.283 +/- 0.023, n = 18, P less than 0.01) were significantly lower with respect to controls. In patients without previous episodes of depression, serotonin expressed in nmol 10(-8) platelets did not differ significantly from controls but serotonin expressed in nmol ml-1 of blood was slightly lower than control values (0.890 +/- 0.085, n = 20 vs. 1.088 +/- 0.090 nmol ml-1, n = 18, P less than 0.02). Platelet serotonin content was positively correlated to plasma oestrone and oestradiol concentrations among the control group but not in the 'depressed' group.(ABSTRACT TRUNCATED AT 250 WORDS)

The 5-hydroxytryptamine stimulated formation of inositol phosphate is inhibited in platelets from alcoholics

The accumulation of inositol monophosphate (IP1) was measured after stimulation of 5-hydroxytryptamine2 (5-HT2) receptors on platelets from alcoholics and healthy controls. In controls, 5-HT induced a dose-dependent response with an EC50 = 2 x 10(-6) M and a maximal response at 10(-5) M. Ritanserin, a selective 5-HT2 antagonist, markedly reduced the accumulation. The IP1 formation after stimulation by 10(-5) M 5-HT was significantly impaired in platelets from alcoholics as compared to controls. This study indicates that the 5-HT2 receptor function is inhibited in alcoholics. It also illustrates the possibility of using IP1 formation in peripheral cells as a mean of studying receptor function in disease.

Serotonergic activity and disinhibitory psychopathy in alcoholism

Evidence exists of an increased risk for alcoholism in those individuals with some form of disinhibitory behavioral disturbance such as impulsivity, low frustration tolerance, attention span deficits, impersistance, sociopathy, hyperactivity and stimulus-seeking behavior. Studies have also linked alcohol abuse with aggression and criminality. Aggressive and impulsive individuals have been shown to have low levels of the major CSF metabolite of serotonin, 5-hydroxyindoleacetic acid. Interestingly, abstinent alcoholic men, and non-alcoholic first-degree relatives have been shown to have similar decrement. Alcoholism may therefore be part of a spectrum of disinhibitory psychopathy which is characterized by reduced central serotonergic activity, and has a familial or genetic component.

Monoamine transport in depression: kinetics and dynamics

There appears to be an abnormality in monoamine transport in major depressive disorders that may be specific to these disorders, although it may not be primarily an aminergic lesion. Kinetic factors alone are insufficient to explain the observed effects of antidepressants on transport mechanisms, or changes in uptake with therapeutic response, suggesting dynamic influences on uptake processes that deserve further exploration. The investigation of these influences may indicate that platelet 5-HT uptake offers diagnostic and theoretical possibilities not adverted to at present and another rationale for the use of platelets in research on mental disorders.

Comparison of whole blood serotonin and platelet MAO in children with schizophrenia and major depressive disorder

Whole blood serotonin and platelet monoamine oxidase (MAO) activity in boys with schizophrenia, schizotypal personality disorder, or major depressive disorder was compared with that of boys serving as controls. Boys with schizophrenia and schizotypal personality disorder had significantly higher platelet MAO than boys with major depressive disorder or controls. Boys with major depressive disorder had lower whole blood serotonin than boys with schizophrenia or schizotypal personality disorder.

Maprotiline in the treatment of endogenous depression: comparison of therapeutic effect with serotonin level in blood platelets

In blood platelets of untreated patients with endogenous depression a significantly lower concentration of serotonin (5-HT) was found than in healthy persons (P less than 0.05). The patients were afterwards divided into two groups: group I with mild symptoms of depression (total scores by Hamilton Depression Rating Scale below 40) and group II with severe depression (total scores above 40). The gradual diminishing of symptoms in both groups was accompanied by no change in 5-HT level in the first group and by progressive and well marked increases in platelet 5-HT content in the second one, attaining average normal values at the end of week 3 of treatment with maprotiline. In in vitro experiments maprotiline inhibited the uptake of 5-HT into blood platelets of healthy persons less than doxepin. After injection of maprotiline in rats (50 mg/kg IP) the turnover rate of 5-HT in the brain was only marginally affected if measured by 5-HT rise and 5-hydroxyindoleacetic acid (5-HIAA) decline after administration of the MAO inhibitor pargyline, or by estimation of 5-HIAA increase after blocking active transport with probenecid. However, after treatment with maprotiline alone, the 5-HIAA level in the rat brain was significantly increased, although the concentration of 5-HT was not altered. These results suggest: a) the possibility of an action of maprotiline on serotoninergic neurons and b) the suitability of blood platelets as a model for such an investigation.

Factors influencing monoamine metabolites and tryptophan in patients with alcohol dependence

Cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA) and tryptophan (TRY) were measured in 36 female patients with alcohol dependence defined by strict operational criteria. Results were compared with a control group of 32 women hospitalized in a neurological unit for peripheral diseases. Several disorders presumably interfering with monoamine metabolism were excluded and diet, psychomotor activity, diurnal variation, nutritional state and similar nonspecific variables controlled in both groups. Only 5-HIAA was found to be decreased in development patients as compared to controls. Since 5-HIAA--but neither HVA nor TRY--correlated with body height in both groups, we eliminated its effect by analysis of covariance: as a result 5-HIAA difference became statistically significant but the other two biochemical measures remained unchanged. A multivariate regression analysis with five independent clinical variables (body height, age, weight, years of alcohol abuse and days of abstinence) yielded significant determination coefficient R2 only for 5-HIAA. Regarding its components only body height and days of abstinence proved to be significantly correlated with 5-HIAA. Severity of withdrawal symptoms assessed on a rating scale in 14 patients with 4 days or less of abstinence correlated marginally with HVA but not with 5-HIAA. This latter metabolite decreased only in patients with 5 days or more of abstinence; the difference between 5-HIAA levels of short-term and long-term abstinence subgroups was statistically highly significant.

Inhibitory effect of ethanol on 5-hydroxytryptamine (serotonin) uptake in human blood platelets in vitro

Ethanol in concentrations higher than 10(-2) M (or about 0.5% W/W) inhibited the uptake of 14C-5-hydroxytryptamine (serotonin) in human blood platelets in an artificial, protein-free medium, by a non-competitive mechanism. The inhibition was not influenced by the alcohol dehydrogenase inhibitor methylpyrazole (10(-3) M). In concentrations up to 0.1 M, ethanol had no effect on 5-HT efflux from the platelets. At higher concentrations, ethanol increased efflux. Inhibition of 5-HT uptake was found to increase progressively in the sequence methanol - ethanol - propanol - butanol.