Hormone responses to fenfluramine and placebo challenge in endogenous depression

NEUROBIOLOGICAL ASPECTS OF SUICIDE AND SUICIDE ATTEMPTS IN BIPOLAR DISORDER

Suicide and bipolar disorder (BD) are challenging, complex, and intertwined areas of study in contemporary psychiatry. Indeed, BD is associated with the highest lifetime risk for suicide attempt and completion of all the psychiatric conditions. Given that several clinical risk factors for both suicide and BD have been well noted in the literature, exploring the neurobiological aspects of suicide in BD may provide insights into both preventive measures and future novel treatments. This review synthesizes findings regarding the neurobiological aspects of suicide and, when applicable, their link to BD. Neurochemical findings, genes/epigenetics, and potential molecular targets for current or future treatments are discussed. The role of endophenotypes and related proximal and distal risk factors underlying suicidal behavior are also explored. Lastly, we discuss the manner in which preclinical work on aggression and impulsivity may provide additional insights for the future development of novel treatments.

The 5-HT deficiency theory of depression: perspectives from a naturalistic 5-HT deficiency model, the tryptophan hydroxylase 2Arg439His knockin mouse

A decreased level of brain 5-hydroxytryptamine (5-HT) has been theorized to be a core pathogenic factor in depression for half a century. The theory arose from clinical observations that drugs enhancing extracellular levels of 5-HT (5-HT(Ext)) have antidepressant effects in many patients. However, whether such drugs indeed correct a primary deficit remains unresolved. Still, a number of anomalies in putative biomarkers of central 5-HT function have been repeatedly reported in depression patients over the past 40 years, collectively indicating that 5-HT deficiency could be present in depression, particularly in severely ill and/or suicidal patients. This body of literature on putative 5-HT biomarker anomalies and depression has recently been corroborated by data demonstrating that such anomalies indeed occur consequent to severely reduced 5-HT(Ext) levels in a mouse model of naturalistic 5-HT deficiency, the tryptophan hydroxylase 2 His(439) knockin (Tph2KI) mouse. In this review, we will critically assess the evidence for 5-HT deficiency in depression and the possible role of polymorphisms in the Tph2 gene as a causal factor in 5-HT deficiency, the latter investigated from a clinical as well as preclinical angle.

What can post-mortem studies tell us about the pathoetiology of suicide?

Suicide is a major public health concern; however, its neurobiology is unclear. Post-mortem brain tissue obtained from suicide victims and normal controls offers a useful method for studying the neurobiology of suicide. Despite several limitations, these studies have offered important leads in the neurobiology of suicide. In this article, we discuss some important findings resulting from these studies, focusing on serotonergic mechanisms, signal transduction systems, neuroendocrine studies and immune function abnormalities in suicide. These studies suggest that abnormalities of certain receptor subtypes, components of signaling systems such as protein kinase C and protein kinase A, transcription factors such as cyclic AMP response element-binding protein and neurotrophins may play an important role in the pathophysiology of suicide. These studies also suggest abnormalities of hypothalamic-pituitary-adrenal axis system components, feedback mechanisms and cytokines, which are chemical mediators of the immune functions. Post-mortem brain tissue offers an opportunity for future studies, such as genetic and epigenetic studies.

Abnormal neuroendocrine response to clomipramine in hereditary affective psychosis

BACKGROUND

Blunting of prolactin response after serotonergic stimulation during a major depressive episode has been described by several investigators. In this study, the neuroendocrine responses to clomipramine were assessed in remitted patients suffering from hereditary depression.

METHODS

Twenty remitted patients from 11 large families with multigenerational, multiple cases of major affective disorder (bipolar disorder n=15, recurrent depression n=5, according DSM-IV) and 12 healthy relatives were investigated. After intravenous application of 12.5 mg of the serotonin re-uptake inhibitor clomipramine, serum prolactin and cortisol levels were analysed.

RESULTS

Patients and comparison group did not differ significantly with respect to age, baseline prolactin and cortisol concentrations. A gender effect was found in an exploratory analysis for prolactin but not for cortisol and therefore the data for prolactin were analysed separately. After clomipramine infusion, the increase of cortisol was significantly lower in patients than in the comparison group (P=.046). For prolactin, this effect could be found in the male (P=.012) as well as in the female (P=.007) subsample.

CONCLUSIONS

These results suggest that blunted prolactin and cortisol responses to serotonergic stimulation are characteristic for remitted depressive patients with previous episodes of major affective disorders.

Imaging serotonergic transmission with [11C]DASB-PET in depressed and non-depressed patients infected with HIV

INTRODUCTION

Site-selective imaging can provide significant insight into the mechanism of HIV-associated neurological disease. The goal of this study was to evaluate the involvement of serotonergic transmission in HIV-associated depression using [(11)C]DASB, a serotonin transporter (5-HTT)-specific radiopharmaceutical for positron emission tomography (PET).

METHODS

Nine depressed HIV+ subjects (HIV-D), 9 non-depressed HIV+ subjects (HIV-ND) and 7 healthy controls (HC) underwent an MRI scan and a [(11)C]DASB-PET scan. The outcome measure was 5-HTT binding potential normalized to non-displaceable tissue radioligand (BP(ND)).

RESULTS

HIV-ND subjects had lower mean regional 5-HTT BP(ND) estimates across regions compared to HC, while HIV-D subjects demonstrated higher mean regional binding values than HIV-ND subjects in most regions. Prior to correction for the false discovery rate, HIV-ND had significantly lower BP(ND) values compared to HC subjects in two regions (insula and anterior cingulate) and all HIV+ patients had significantly lower binding than HC in all regions except for the midbrain, thalamus and pons. After correction for the false discovery rate, only the insula showed significantly lower binding in HIV+ subjects compared to HC (P<0.0045). Despite a significant difference in the duration of illness between the HIV-D and HIV-ND groups, there was no definite correlation between the duration of illness and BP(ND).

CONCLUSION

Lower [(11)C]DASB binding in HIV+ patients compared to HC may reflect serotonergic neuronal loss as a component of generalized HIV-associated neurodegeneration. Higher mean regional BP(ND) values in HIV-D compared to HIV-ND subjects could reflect increased density of 5-HTT, leading to increased clearance of serotonin from the synapse, which could account, in part, for symptoms of depression. The lack of correlation between duration of illness and binding argues against these findings being the result of differential neurodegeneration only. Our findings suggest a possible role for dysregulated serotonergic transmission in HIV-associated depression.

Serotonergic function, two-mode models of self-regulation, and vulnerability to depression: what depression has in common with impulsive aggression

Evidence from diverse literatures supports the viewpoint that two modes of self-regulation exist, a lower-order system that responds quickly to associative cues of the moment and a higher-order system that responds more reflectively and planfully; that low serotonergic function is linked to relative dominance of the lower-order system; that how dominance of the lower-order system is manifested depends on additional variables; and that low serotonergic function therefore can promote behavioral patterns as divergent as impulsive aggression and lethargic depression. Literatures reviewed include work on two-mode models; studies of brain function supporting the biological plausibility of the two-mode view and the involvement of serotonergic pathways in functions pertaining to it; and studies relating low serotonergic function to impulsiveness, aggression (including extreme violence), aspects of personality, and depression vulnerability. Substantial differences between depression and other phenomena reviewed are interpreted by proposing that depression reflects both low serotonergic function and low reward sensitivity. The article closes with brief consideration of the idea that low serotonergic function relates to even more diverse phenomena, whose natures depend in part on sensitivities of other systems.

Serotonergic vulnerability and depression: assumptions, experimental evidence and implications

In recent years, the term serotonergic vulnerability (SV) has been used in scientific literature, but so far it has not been explicitly defined. This review article attempts to elucidate the SV concept. SV can be defined as increased sensitivity to natural or experimental alterations of the serotonergic (5-HTergic) system. Several factors that may disrupt the 5-HTergic system and hence contribute to SV are discussed, including genetic factors, female gender, personality characteristics, several types of stress and drug use. It is explained that SV can be demonstrated by means of manipulations of the 5-HTergic system, such as 5-HT challenges or acute tryptophan depletion (ATD). Results of 5-HT challenge studies and ATD studies are discussed in terms of their implications for the concept of SV. A model is proposed in which a combination of various factors that may compromise 5-HT functioning in one person can result in depression or other 5-HT-related pathology. By manipulating 5-HT levels, in particular with ATD, vulnerable subjects may be identified before pathology initiates, providing the opportunity to take preventive action. Although it is not likely that this model applies to all cases of depression, or is able to identify all vulnerable subjects, the strength of the model is that it may enable identification of vulnerable subjects before the 5-HT related pathology occurs.

Platelet monoamine oxidase B (MAO-B) activity and its relationship to DL-fenfluramine-induced prolactin response in healthy men

Several techniques are used to assess central serotonergic neurotransmission in man, e.g. challenge tests (hormonal and physiological responses to serotonin active drugs), platelet MAO-B activity as well as brain imaging techniques. Little is known about how these tests relate to each other. The aim of the present study was therefore to investigate if platelet MAO-B activity could be related to hormonal and temperature responses to the serotonin active drug DL-fenfluramine in healthy men. Twelve male subjects without any history of psychiatric disorders or drug abuse/dependencies were recruited. Prior to the challenge with 60 mg DL-fenfluramine, which was given orally, blood for determination of platelet MAO-B activity was drawn. Blood samples for determination of serum prolactin and serum cortisol were drawn at baseline and thereafter every hour for the following six hours. In addition, body temperature was measured at the same time-points. Delta-values were calculated as the difference between the baseline values and the highest (prolactin and cortisol) or lowest value (temperature) thereafter. There was a strong positive correlation (r = 0.75, p < 0.02) between platelet MAO-B activity and Delta-prolactin. No correlations were found to Delta-cortisol, Delta-temperature or any of the baseline values. The results support the notion that the peripheral marker platelet MAO-B activity is related to the function of the central serotonergic neurotransmitter system as assessed by the prolactin response to 60 mg DL-fenfluramin.

Prolactin response to fenfluramine administration in patients with unipolar and bipolar depression and healthy controls

The hormonal response to the serotonin releasing agent/uptake inhibitor fenfluramine has been used as an indicator of central serotonin system function. The serotonergic system plays an important role in the etiology and pathogenesis of mood disorders. We compared the prolactin response to fenfluramine administration in unipolar depressed patients (major depressive disorder), depressed patients with bipolar disorder, and healthy controls. We found a trend towards a blunted prolactin response in depressed patients compared to healthy controls, after controlling for sex, family history, family history-by-gender interaction, and baseline levels. There was no significant difference between unipolar and bipolar patients in the baseline prolactin levels or the response to the fenfluramine administration. We also found a negative correlation between aggression and impulsivity scores and prolactin responses in subgroup with unipolar but not bipolar depression. Female patients with unipolar depression who had first-degree relatives with unipolar depression and normal controls had significantly higher prolactin responses than female patients with unipolar depression who did not have first-degree relatives with unipolar depression. The lack of difference in the response to fenfluramine administration between unipolar and bipolar depressed patients may indicate that overall serotonergic function in unipolar and bipolar depressed patients is similarly impaired.

The prolactin response to fenfluramine in depression: effects of melancholia and baseline cortisol

Depression may be associated with a hypofunction of central serotonergic systems. The prolactin response to fenfluramine, an indicator of serotonergic activity, has been reported to be blunted in depressed patients compared to controls. It has also been suggested that blunting is more likely in melancholic depression. Baseline cortisol, prolactin and tryptophan availability have also been suggested to affect this response. Forty-eight men and 61 women with a major depressive episode, and who were drug free, and 20 healthy control men underwent clinical evaluation and fenfluramine challenge with dl-fenfluramine 1 mg/kg. When baseline variables were covaried, there was no difference in prolactin response to fenfluramine between males with depression and age-matched controls. Amongst all the depressed patients, body mass index showed a significant association with prolactin response to fenfluramine. There was an interaction between baseline cortisol and DSM-III-R melancholic subtype of depression whereby non-melancholic patients appeared more likely to increase prolactin response to fenfluramine in response to higher cortisol levels. Prolactin response to fenfluramine was not blunted in major depression and there was no difference between melancholic and non-melancholic depression. However, the relationship between prolactin response to fenfluramine and baseline cortisol levels appeared to differ between these two subtypes of depression.

Interferon, tryptophan and depression

Depression is a frequent comorbid disorder of many inflammatory diseases and it is suggested that brain inflammatory processes have a pathogenic role in mood dysregulation. Several immunocompromised patients have been treated with cytokines and long-term treatments have resulted in a variety of neuropsychiatric side-effects. The objective of the study was to present evidence for an association between the induction of neuropsychiatric side-effects during treatment with interferon-α (IFN-α) and changes in serotonergic and immunological parameters. Moreover, the use of IFN-α-induced depression as a paradigm for research into the pathophysiology of depressive disorders in general will be discussed. This literature review focused on the relationships between tryptophan, serotonin, cytokines and depression associated with interferon treatment. Immunotherapy with IFN-α influences several immunological and serotonergic parameters, and induces in most patients neurovegetative, somatic and depressive symptoms. Literature findings indicate that the development of depressive symptoms in patients undergoing cytokine therapy are secondary to cytokine induction and could be mediated by a reduced availability of tryptophan to the brain, resulting ultimately in decreased serotonergic activity. Changes in the metabolism of tryptophan and consequently of serotonin may play a role in the pathophysiology of interferon-induced depression. Studies on interferon-induced neuropsychiatric side-effects may be a promising research paradigm and shed light on the role of immunological and serotonergic factors in the pathogenesis of depressive disorders in general. However, first the appropriate symptomatology of the interferon-induced depressive states has to be documented.

Serotonergic dysregulation in bipolar disorders: a literature review of serotonergic challenge studies

OBJECTIVES

Serotonin (5-hydroxytryptamine; 5-HT) and endocrine abnormalities have been repeatedly reported in bipolar disorders (BD). Useful methods to investigate 5-HT responsivity, and the interaction with neuroendocrine functioning, are provided by acute 5-HT challenge and depletion paradigms. In this review 5-HT challenges are limited to paradigms that stimulate 5-HT activity in BD.

METHODS

Literature was searched for in electronic libraries: MEDLINE and PSYCHLIT, period 1966-2001. Papers describing effects of an acute 5-HT challenge on neuroendocrine functioning in BD patients were selected.

RESULTS

Review of the literature revealed 15 studies: five papers described the effects of 5-HT challenges in manic BD patients, four papers in euthymic BD and seven in depressed BD patients. The reviewed 5-HT challenge paradigms are acute administration of oral and intravenous (i.v.) dosage of d,l-fenfluramine, tryptophan, 5-hydroxytryptophan, ipsapirone and buspirone. There were no papers which investigated neuroendocrine effects of m-chlorophenylpiperazine, clomipramine and citalopram in BD patients and were therefore not reviewed.

CONCLUSIONS

The literature on 5-HT challenge procedures in BD shows evidence for a blunted prolactin (PRL) in mania and depression as well as a blunted cortisol in euthymic BD patients. This suggests that in both mania and depression similar changes in the 5-HT system are involved. It is speculated that blunting of cortisol responses in euthymic BD patients may be a result of chronically altered 5-HT functioning, whereas changes in PRL release following 5-HT challenges reflect more state-dependent changes in 5-HT activity. The 5-HT responsivity in BD patients has also been associated with pharmacological treatment, suicidal behaviour, weight loss and age. Recommendations for future research are given.

Bio-social origins of depression in the community. Interactions between social adversity, cortisol and serotonin neurotransmission

BACKGROUND

Social adversity may be a risk factor for depression, by increasing cortisol secretion, which impairs serotonin (5-HT) neurotransmission.

AIMS

To examine this causal pathway in a community setting.

METHOD

Women who were currently ICD-10 depressed (n=94), vulnerable to depression but not depressed (n=166) and non-vulnerable controls (n=177) were recruited. We assessed social adversity and vulnerability (Life Events and Difficulties Schedule; Self Evaluation and Social Support Scales) and psychiatric state (Schedules for Clinical Assessment in Neuropsychiatry). Salivary cortisol concentrations were measured at 09.00 and 23.00 h. Serotonin function was assessed using prolactin responses to dexfenfluramine.

RESULTS

Cortisol concentrations were not increased in the depressed or vulnerable. Morning salivary and serum cortisol were reduced in depression. Evening cortisol was increased after recent life events. Life events and depression were associated with increased prolactin responses.

CONCLUSIONS

The hypothalamic-pituitary-adrenal axis is sensitive to social stress but does not mediate vulnerability to depression. Exaggerated 5-HT(2) receptor responsiveness to stress may play a role in the evolution of depression.

Serotonin and bipolar disorder

With the emergence of specific pharmacological probes for various serotonin (5-HT) receptors and radio-ligands for central 5-HT, it has now become possible to investigate its role in the pathogenesis of bipolar disorder more closely. This paper critically reviews the scientific literature regarding the relationship between bipolar disorder and serotonergic systems. The evidence suggests that central serotonergic activity is reduced in the depressive phase of bipolar disorder. Similar findings have been reported in bipolar patients when euthymic, indicating that that lower 5-HT activity could be a trait marker for bipolar disorder. Findings reported in the manic phase of this illness are inconsistent.

Role of serotonergic and noradrenergic systems in the pathophysiology of depression and anxiety disorders

There is abundant evidence for abnormalities of the norepinephrine (NE) and serotonin (5HT) neurotransmitter systems in depression and anxiety disorders. The majority of evidence supports underactivation of serotonergic function and complex dysregulation of noradrenergic function, most consistent with overactivation of this system. Treatment for these disorders requires perturbation of these systems. Reproducible increases in serotonergic function and decreases in noradrenergic function accompany treatment with antidepressants, and these alterations may be necessary for antidepressant efficacy. Dysregulation of these systems clearly mediates many symptoms of depression and anxiety. The underlying causes of these disorders, however, are less likely to be found within the NE and 5HT systems, per se. Rather their dysfunction is likely due to their role in modulating, and being modulated by, other neurobiologic systems that together mediate the symptoms of affective illness. Clarification of noradrenergic and serotonergic modulation of various brain regions may yield a greater understanding of specific symptomatology, as well as the underlying circuitry involved in euthymic and abnormal mood and anxiety states. Disrupted cortical regulation may mediate impaired concentration and memory, together with uncontrollable worry. Hypothalamic abnormalities likely contribute to altered appetite, libido, and autonomic symptoms. Thalamic and brainstem dysregulation contributes to altered sleep and arousal states. Finally, abnormal modulation of cortical-hippocampal-amygdala pathways may contribute to chronically hypersensitive stress and fear responses, possibly mediating features of anxiety, anhedonia, aggression, and affective dyscontrol. The continued appreciation of the neural circuitry mediating affective states and their modulation by neurotransmitter systems should further the understanding of the pathophysiology of affective and anxiety disorders.

PET neuroimaging of clomipramine challenge in humans: focus on the thalamus

PET neuroimaging of serotonin responsivity relied previously mainly on fenfluramine, but that drug has been withdrawn from the market. Therefore, we determined whether clomipramine, which stimulates serotonergic mechanisms by inhibiting serotonin reuptake, has reliable effects in the healthy human brain as measured by [15O]H2O PET. The clomipramine challenge markedly reduced the relative rate of blood flow in the selected region of interest, namely the dorsomedial nucleus of the thalamus, a limbic region rich in serotonin uptake sites. These findings show similarities between effects of fenfluramine and clomipramine in the healthy human brain, and support the use of the clomipramine challenge in conjunction with PET for studying cerebral serotonergic mechanisms.

Prolactin response to D-fenfluramine and suicidal behavior in depressed patients

Previous studies of the prolactin response to D-fenfluramine in depressed patients have yielded inconsistent results. This may be because they did not address the question of suicidality. We carried out this study to test the hypothesis that lower prolactin response to D-fenfluramine is more closely associated with suicidal behavior than with depression itself. A D-fenfluramine test was performed in a sample of 18 healthy control subjects and in 85 drug-free inpatients with a DSM-III-R diagnosis of major depressive episode (49 with a history of suicide attempt, 36 without). Depressed inpatients with a history of suicide attempt showed a significantly lower prolactin response to D-fenfluramine compared to depressed inpatients without such a history and compared to control subjects. Healthy control subjects and depressed inpatients without a history of suicide attempt showed comparable levels of prolactin after D-fenfluramine. Time elapsed since suicide attempt did not influence prolactin level (baseline or post-stimulation). Results show that in our depressed drug-free inpatient sample, prolactin response to D-fenfluramine seems to be a marker of suicidality, but not of depression itself. We suggest that it is a trait marker of suicidality.

The citalopram challenge test in patients with major depression and in healthy controls

Neuroendocrine challenge tests in depressed patients have revealed a blunted hormonal reaction to serotonergic stimuli. In the present study, citalopram was chosen as the serotonergic agent for neuroendocrine stimulation. Compared to earlier challenge agents, citalopram has the advantage of serotonergic selectivity, its application is well tolerated and the possibility of intravenous application reduces pharmacokinetic interference. Sixteen patients suffering from an acute episode of major depression and 16 healthy controls underwent the stimulation procedure with 20 mg of citalopram and placebo. Whereas significant differences in the secretion of prolactin and cortisol between citalopram and placebo challenge were observed in the control group, no differences were found in the group of depressed patients. Comparison of depressed patients and controls showed a significantly blunted prolactin secretion in patients. Differences in cortisol secretion following serotonergic stimulation with citalopram did not become significant. The stimulation procedure was well tolerated in all subjects, although a higher number of side effects was observed in the control group. The amount of side effects did not correlate with the hormone responses. These results are in line with the hypothesis of serotonergic hypofunction in depressed patients. In conclusion, the 20-mg citalopram challenge test is thought to be a promising tool for further investigation of serotonergic function in psychiatric illness.

Serotonergic dysfunction in women with pure premenstrual dysphoric disorder: is the fenfluramine challenge test still relevant?

The fenfluramine (FEN) neuroendocrine challenge paradigm, which involves measuring the response of prolactin (PRL) release to an oral challenge dose of FEN, provides a means of assessing serotonin (5-HT) function. The purpose of this study was to ascertain the role of 5-HT in premenstrual dysphoric disorder (PMDD) by measuring: (1) PRL and cortisol (CORT) responses to FEN; and (2) platelet 3H-imipramine binding levels, in females with pure PMDD (without a past or present comorbid mood disorder) in comparison to healthy controls. FEN challenge tests were administered to nine female patients with pure PMDD and nine healthy female controls during the follicular and late luteal phases of a menstrual cycle. There were no differences in the PRL response to FEN for women with PMDD compared to healthy controls. However, the trend toward a delayed response to FEN and a significant negative correlation between delta(max) PRL and basal CORT in patients but not in controls during both phases of the menstrual cycle suggest an underlying 5-HT dysfunction in patients as compared to controls. This is further supported by the finding of significantly lower Bmax 3H-imipramine binding levels in the patients during the late luteal phase.

Prolactin response to D-fenfluramine in outpatients with major depression

There is much indirect evidence of serotonin abnormalities in patients with major depression. Unfortunately, previous reports of serotonin challenge studies in depressed patients have yielded conflicting results. In order to test the serotonin hypothesis of depression, the authors compared 20 outpatients with major depressive disorder to 20 normal control subjects using prolactin response to D-fenfluramine as a measure of central serotonergic (5-HT) functioning. Patients were free of histories of suicidal behavior and had no Axis II disorders. There were no significant differences in prolactin responses between depressed patients and control subjects to challenge with D-fenfluramine at a dose of 0.5 mg/kg. The possible implications of these findings are discussed with respect to theories regarding biological vulnerabilities to major depression.

Psychoneuroendocrinology of depression. Prolactin

Prolactin provides us with a window to the brain in our quest for understanding the psychobiology of depression, since the regulation of its release involves some of the monamine neurotransmitter systems that have been implicated in the pathophysiology of depression. Investigation examining basal prolactin plasma concentrations in depressed patients, including assessments of the rhythm of prolactin release, have not provided clear, consistent findings. Further exploration of the precise mechanisms involved in serotonin-stimulated prolactin release should shed light on the pathophysiology of abnormal prolactin responsivity in depression, and by extension, the psychobiologic basis of depression.

Recovery from major depression is not associated with normalization of serotonergic function

BACKGROUND

Plasma prolactin response to fenfluramine, a serotonergic agent, is typically blunted in moderately to severely depressed adults when compared to healthy controls. It is not clear, however, whether this dysregulation represents an acute change during symptomatic depression or a chronic disturbance.

METHODS

In the current study, the prolactin responses to D,L-fenfluramine (weight-adjusted oral dose) of 29 adults who had a history of at least one major depressive episode (DSM-III-R criteria), but not during the past year, were compared to the prolactin responses of 58 age-, sex-, and socioeconomic status-matched adults without a lifetime history of major depression.

RESULTS

Individuals with a positive history of major depression had significantly lower peak prolactin responses than controls. This finding was not attributable to weight, fenfluramine bioavailability, or baseline prolactin levels.

CONCLUSIONS

This is the first investigation to compare men and women with a history of depression but not depressed at the time of the fenfluramine challenge to a similar group of healthy controls. The results are consistent with the hypothesis that central serotonergic activity is persistently disturbed in adults who experience depressive episodes.

5-HT brain function in affective disorder: d,l-fenfluramine-induced hormone release and clinical outcome in long-term lithium/carbamazepine prophylaxis

Prolactin (PRL) and Cortisol (CORT) responses to d,l-fenfluramine (FEN) challenge (60 mg) were examined in patients with affective disorders on two occasions under euthymic conditions: drug-free before admission to prophylactic treatment and after about 9 months of medication with lithium or carbamazepine. Response to treatment was assessed by a complex algorithm using continuous ratings in outpatient clinic over a period of 2 years. In general, treatment resulted in a delayed and diminished CORT release (n.s.); subgroup analysis revealed an attenuated CORT response (P < 0.05) in responders, whereas nonresponders showed no change in CORT secretion pattern except an enhanced CORT baseline value (P < 0.05). Cross-sectional comparison of responders with nonresponders under medication yielded a trend for greater CORT stimulation in nonresponders. This result was not affected by FEN/NorFEN or lithium/carbamazepine serum levels, baseline CORT values, age, sex, diagnostic distribution, number of appointments to the outpatient clinic or duration of medication at the time of FEN test session. Before onset of prophylactic medication responders and nonresponders could not be discriminated significantly regarding stimulated hormone release, probably due to the small sample size (n = 17). CORT response to FEN was increased in drugfree unipolar patients compared to bipolar (P < 0.05) and to schizoaffective patients (P < 0.1). In accordance with its well-documented presynaptic 5-HT-agonistic action lithium medication resulted in a significantly greater increase in CORT release than carbamazepine (P < 0.05). Evaluation of PRL stimulation showed patterns of secretion quite similar to those of CORT, without reaching statistical significance in most cases. Perhaps due to methodological differences in assessing treatment response, these data do not confirm former results, which supposed an enhanced 5-HT net activity in long-term prophylactic lithium treatment. Because of high interindividual variances of hormone parameters, the FEN-test procedure is not a useful tool for the prediction of therapeutical outcome in terms of clinical routine use. Relations of stimulated hormone response as a marker of central serotoninergic activity and clinical outcome are discussed.

Serotonergic function and self-injurious behavior in personality disorder patients

Self-directed aggression, whether in the form of non-suicidal self-mutilation or suicidal behavior, is a prominent feature of personality disorders. We hypothesized that self-injurious behavior, like suicidal behavior, represents a form of self-directed aggression, and may, like suicidal behavior and impulsive aggression, be associated with a decrease in central serotonin function in personality disorder patients. Ninety-seven patients with DSM-III personality disorder underwent D,L-fenfluramine challenge as an assessment of serotonergic activity. Patients with a history of self-mutilation or suicide had blunted prolactin and cortisol responses to D,L-fenfluramine compared to those with neither, and those with both had the most blunted responses to fenfluramine. These data raise the possibility that the central 5-HT abnormality, previously associated with suicidal behavior, may be associated with self-directed violence and not necessarily specifically with suicidal intent.

5-HT neuroendocrine function in major depression: prolactin and cortisol responses to D-fenfluramine

We studied the prolactin and cortisol responses to the 5-HT releasing agent, D-fenfluramine in 31 drug-free depressed patients and 29 healthy controls, using a double-blind, placebo-controlled design. There was no difference in either endocrine response between depressives and controls. Examining the sexes separately, or restricting comparisons to patients with melancholic depression, did not lead to any differences between the groups. Our findings suggest that in contrast to other 5-HT neuroendocrine probes such as L-tryptophan and clomipramine, the prolactin response to fenfluramine are not consistently blunted in depressed patients.

Brain serotonin (5-HT) neuroendocrine function in patients taking cholesterol-lowering drugs

Brain serotonin (5-HT) neuroendocrine function, plasma tryptophan, and platelet 5-HT content were examined in 20 patients treated in a lipid clinic for hypercholesterolaemia with combined drug and diet therapy and in 20 healthy matched controls. Treatment had produced a substantial decrease in total cholesterol concentrations in the patients, but they still had higher cholesterol and triglyceride levels than control subjects. The patients were somewhat more depressed than controls but did not differ from them in degree of hostility, free or total plasma tryptophan, or prolactin response to 30 mg of d-fenfluramine. This study does not reveal evidence of abnormal brain 5-HT neuroendocrine function in hypercholesterolaemic patients receiving cholesterol-lowering medications and diet.

The neuroendocrine response to d-fenfluramine in women with premenstrual depression

An oral d-fenfluramine neuroendocrine challenge test was carried out in 17 women with premenstrual depression and 14 controls, twice in each subject, once in the late luteal phase when mood change was likely to be at its worst (i.e. premenstrual) and once postmenstrually. Women weighing < 65 kg received 15 mg, the remainder 30 mg of d-fenfluramine. Although there was considerable individual variability, a substantial average prolactin response was observed in both groups but no phase, group or group x phase interaction effects were found. Oestradiol levels were significantly higher during the postmenstrual test but showed no relationship to prolactin response. Cortisol showed a more modest response to the drug and a phase effect was found, with cortisol increase being greater during the postmenstrual test in both groups. In contrast to earlier findings with i.v. L-tryptophan challenge, the present study failed to show any difference in neuroendocrine response between women with premenstrual depression and controls. These results suggest that 5-hydroxy-tryptophan2 receptor function is unaltered in perimenstrual mood disorder although other interpretations of the negative findings are discussed.

Hostility in heroin abusers subtypes: fluoxetine and naltrexone treatment

1. Substance abusers subtypes have been identified considering underlying psychobiological disorder, familial factors, age of onset, legal problems and drug of choice. 2. In the present study the authors submitted 98 male heroin addicted individuals (age 19-28 y) to the Buss Durkee Hostility Inventory (Italian version) and a structured interview concerning social and clinical history; legal problems, age of onset of drug abuse, drug of choice. 3. Serotonergic system sensitivity was evaluated with fenfluramine challenge for PRL assay. 4. Thirty two patients (group A) showed high score for resentment and guilt at BDHI (hostility in), low rate of legal problems, late age of onset, preference for heroin and alcohol. Twenty nine patients (group B) showed high score for assault and irritability at BDHI (hostility out), high rate of legal problems, early age of onset, preference for heroin and cocaine. The other 37 patients (group C) showed aggression score in the normal range at BDHI, no legal problems, late onset of substance abuse, preference for heroin only. 5. PRL responses was blunted in group A (p < 0.001) and significantly decreased in group B (p < 0.05). PRL plasma levels were inversely correlated with HRSD scores. 6. All the patients were included in a treatment protocol with fluoxetine and naltrexone or placebo and naltrexone for 6 months. 7. The treatment was effective in group A with a significant improvement of BDHI results and decrease of craving score, lower level of drop out, lower level of positive urine controls. No significant differences between fluoxetine and placebo effects have been evidenced in patients of group B and C. The present findings suggest that psychopharmacological approach to addiction needs a diagnostic screening for specific subtypes.

Serotonin function in detoxified heroin abusers: prolactin and cortisol responses to fenfluramine challenge

The function of the central serotonergic system was examined indirectly through the measurement of prolactin (PRL) and cortisol responses to fenfluramine challenges in 27 heroin addicts 2 months after detoxification and in nine healthy volunteers. Heroin abusers included nine addicts with comorbid depressive disorders (Group A), nine with aggressive behavior and antisocial personality (Group B), and nine with heroin addiction uncomplicated by other Axis I and II psychiatric disorders (Group C). PRL and cortisol responses of patients in Group A were blunted, while those of patients in Groups B and C did not differ from those of the healthy volunteers. Cortisol responses in Group A differed significantly from those in the other patient groups and in the normal comparison group for AUC analyses, but the diagnosis x time interaction showed a significant difference only between Group A and the normal group. Our data suggest that the function of the serotonergic system is impaired in heroin addicts with comorbid depression but not in heroin addicts who are not clinically depressed. Thus, the serotonergic system does not appear to be impaired by prolonged opioid exposure, per se.

Dieting decreases plasma tryptophan and increases the prolactin response to d-fenfluramine in women but not men

We studied the effect of 3 weeks of moderate calorie restriction on 5-HT-mediated prolactin (PRL) release in healthy volunteers using the 5-HT-releasing agent d-fenfluramine. In women, dieting significantly lowered plasma total and free tryptophan (TRP) and increased the PRL response to d-fenfluramine. None of these measures were altered in men who dieted. These findings add to the data indicating that dieting alters brain 5-HT function in women, perhaps as a consequence of reducing the availability of plasma TRP.

Neuroendocrine evidence for reduced serotonergic neurotransmission during heavy drinking

A fenfluramine (60-mg oral dose) challenge test was performed in 19 male heavy drinkers (mean daily consumption 88 g of pure alcohol). Twelve healthy males served as controls. The prolactin and temperature responses to fenfluramine were significantly reduced in the group of heavy drinkers. The results suggest impaired central serotonergic neurotransmission in alcoholism, possibly involving subsensitivity in various serotonin receptor subtypes.

Oral D-fenfluramine and neuroendocrine challenge: problems with the 30 mg dose in men

Ten healthy male volunteers of normal weight received 30 mg of D-fenfluramine, a putative selective releaser of 5-hydroxytryptamine (5-HT), and placebo by mouth in balanced order at a 1 week interval after a light breakfast. Blood was taken for estimation of plasma cortisol and prolactin, and the patients completed self rating scales for stress and arousal and rated themselves on visual analogue scales for mood, hunger and alertness at appropriate time points from 30 min before to 300 min after drug/placebo ingestion. There were no statistically discernible effects of D-fenfluramine on either hormone measures or subjective ratings. The failure to find effects may be due to a too low dose of D-fenfluramine and/or a lower sensitivity to the drug in men compared with women. More information is required on the dose/response relationship and drug absorption especially after food. However, the findings cast doubt on results already obtained employing this dose of the drug in studies that have included male subjects. Furthermore, the interpretation of earlier studies with D,L-fenfluramine at a dose of 60 mg is also made more uncertain by the failure to confirm that the more selective D-isomer produces equivalent effects.