Comparison of the effects of citalopram and escitalopram on 5-Ht-mediated neuroendocrine responses

Major depressive disorder and bistability in an HPA-CNS toggle switch

Major depressive disorder (MDD) is the most common psychiatric disorder. It has a complex and heterogeneous etiology. Most treatments take weeks to show effects and work well only for a fraction of the patients. Thus, new concepts are needed to understand MDD and its dynamics. One of the strong correlates of MDD is increased activity and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis which produces the stress hormone cortisol. Existing mathematical models of the HPA axis describe its operation on the scale of hours, and thus are unable to explore the dynamic on the scale of weeks that characterizes many aspects of MDD. Here, we propose a mathematical model of MDD on the scale of weeks, a timescale provided by the growth of the HPA hormone glands under control of HPA hormones. We add to this the mutual inhibition of the HPA axis and the hippocampus and other regions of the central nervous system (CNS) that forms a toggle switch. The model shows bistability between euthymic and depressed states, with a slow timescale of weeks in its dynamics. It explains why prolonged but not acute stress can trigger a self-sustaining depressive episode that persists even after the stress is removed. The model explains the weeks timescale for drugs to take effect, as well as the dysregulation of the HPA axis in MDD, based on gland mass changes. This understanding of MDD dynamics may help to guide strategies for treatment.

Behavioral, cortical and autonomic effects of single-dose escitalopram on the induction and regulation of fear and disgust: Comparison with single-session psychological emotion regulation with reappraisal

INTRODUCTION

Adaptive and successful emotion regulation, the ability to flexibly exert voluntary control over emotional experience and the ensuing behavior, is vital for optimal daily functioning and good mental health. In clinical settings, pharmacological and psychological interventions are widely employed to modify pathological emotion processing and ameliorate its deleterious consequences.

METHODS

In this study, we investigated the acute effects of single-dose escitalopram on the induction and regulation of fear and disgust in healthy subjects. Furthermore, we compared these pharmacological effects with psychological emotion regulation that utilized a cognitive strategy with reappraisal. Emotion induction and regulation tasks were performed before and 4 h after ingestion of placebo or 10 mg escitalopram in a randomized, double-blind design. The International Affective Picture System (IAPS) was used as a source of images, with threat-related pictures selected for fear and disease and contamination-related pictures for disgust. Behavioral data, electrodermal activity (EDA), and functional near-infrared spectroscopy (fNIRS) recordings were collected.

RESULTS

Escitalopram significantly reduced emotion intensity for both fear and disgust during emotion induction, albeit with differing electrodermal and hemodynamic activity patterns for the two negative emotions. At rest, i.e., in the absence of emotive stimuli, escitalopram increased sympathetic activity during the fear but not during the disgust experiments. For both fear and disgust, emotion regulation with reappraisal was more effective in reducing emotion intensity compared to pharmacological intervention with escitalopram or placebo.

DISCUSSION

We concluded that emotion regulation with reappraisal and acute administration of escitalopram, but not placebo, reduce emotion intensity for both fear and disgust, with cognitive regulation being significantly more efficient compared to pharmacological regulation under the conditions of this study. Results from the fNIRS and EDA recordings support the concept of differential mechanisms of emotion regulation that could be emotion-specific.

Sex differences in the ACTH and cortisol response to pharmacological probes are stressor-specific and occur regardless of alcohol dependence history

Women and men differ in their risk for developing stress-related conditions such as alcohol use and anxiety disorders and there are gender differences in the typical sequence in which these disorders co-occur. However, the neural systems underlying these gender-biased psychopathologies and clinical course modifiers in humans are poorly understood and may involve both central and peripheral mechanisms regulating the limbic-hypothalamic-pituitary-adrenal axis. In the present randomized, double blind, placebo-controlled, triple-dummy crossover study, we juxtaposed a centrally-acting, citalopram (2 mg/unit BMI) neuroendocrine stimulation test with a peripherally-acting, dexamethasone (Dex) (1.5 mg)/corticotropin-releasing factor (CRF) (1 μg/kg) test in euthymic women (N = 38) and men (N = 44) with (54%) and without histories of alcohol dependence to determine whether sex, alcohol dependence or both influenced the adrenocorticotropic hormone (ACTH) and cortisol responses to the pharmacological challenges and to identify the loci of these effects. We found that central serotonergic mechanisms, along with differences in pituitary and adrenal sensitivity, mediated sexually-diergic ACTH and cortisol responses in a stressor-specific manner regardless of a personal history of alcohol dependence. Specifically, women exhibited a greater response to the Dex/CRF test than they did the citalopram test while men exhibited the opposite pattern of results. Women also had more robust ACTH, cortisol and body temperature responses to Dex/CRF than men, and exhibited a shift in their adrenal glands' sensitivity to ACTH as measured by the cortisol/log (ACTH) ratio during that session in contrast to the other test days. Our findings indicate that central serotonergic and peripheral mechanisms both play roles in mediating sexually dimorphic, stressor-specific endocrine responses in humans regardless of alcohol dependence history.

Serum Prolactin Levels in Patients with Major Depressive Disorder Receiving Selective Serotonin-Reuptake Inhibitor Monotherapy for 3 Months: A Prospective Study

OBJECTIVE

It is unclear whether selective serotonin-reuptake inhibitors (SSRIs) can significantly increase the prolactin level. The purpose of this study was to identify the relationship between the prolactin level and the administration of SSRIs such as escitalopram and sertraline. An additional purpose was to determine whether the elevation of prolactin differs between escitalopram and sertraline treatment.

METHODS

Serum prolactin levels were measured at baseline and after 3 months in 23 patients who received SSRI monotherapy with escitalopram (n=18) (ESC group) or sertraline (n=5) (SERT group) for 3 months.

RESULTS

The prevalence of hyperprolactinemia at posttreatment was 34.8% (8/23). The overall pretreatment and posttreatment prolactin levels were 21.86±20.21 and 19.89±12.03 ng/mL (mean±SD), respectively, with ranges of 6.85-86.20 and 5.19-47.61 ng/mL. The pretreatment and posttreatment prolactin levels were 20.66±15.92 and 21.97±12.33 ng/mL, respectively, in the ESC group, and 26.18±33.75 and 12.43±7.76 ng/mL in the SERT group.

CONCLUSION

Clinicians should be aware that hyperprolactinemia can appear in patients receiving escitalopram or sertraline, even though they do not need routine monitoring for prolactin levels.

Acute Effects of Lysergic Acid Diethylamide on Circulating Steroid Levels in Healthy Subjects

Lysergic acid diethylamide (LSD) is a serotonin 5-hydroxytryptamine-2A (5-HT2A ) receptor agonist that is used recreationally worldwide. Interest in LSD research in humans waned after the 1970s, although the use of LSD in psychiatric research and practice has recently gained increasing attention. LSD produces pronounced acute psychedelic effects, although its influence on plasma steroid levels over time has not yet been characterised in humans. The effects of LSD (200 μg) or placebo on plasma steroid levels were investigated in 16 healthy subjects using a randomised, double-blind, placebo-controlled, cross-over study design. Plasma concentration-time profiles were determined for 15 steroids using liquid-chromatography tandem mass-spectrometry. LSD increased plasma concentrations of the glucocorticoids cortisol, cortisone, corticosterone and 11-dehydrocorticosterone compared to placebo. The mean maximum concentration of LSD was reached at 1.7 h. Mean peak psychedelic effects were reached at 2.4 h, with significant alterations in mental state from 0.5 h to > 10 h. Mean maximal concentrations of cortisol and corticosterone were reached at 2.5 h and 1.9 h, and significant elevations were observed 1.5-6 h and 1-3 h after drug administration, respectively. LSD also significantly increased plasma concentrations of the androgen dehydroepiandrosterone but not other androgens, progestogens or mineralocorticoids compared to placebo. A close relationship was found between plasma LSD concentrations and changes in plasma cortisol and corticosterone and the psychotropic response to LSD, and no clockwise hysteresis was observed. In conclusion, LSD produces significant acute effects on circulating steroids, especially glucocorticoids. LSD-induced changes in circulating glucocorticoids were associated with plasma LSD concentrations over time and showed no acute pharmacological tolerance.

The influence of Hatha yoga as an add-on treatment in major depression on hypothalamic-pituitary-adrenal-axis activity: a randomized trial

OBJECTIVES

The impact of Hatha yoga as add-on treatment to quetiapine fumarate extended release (QXR) or escitalopram (ESC) in depressed patients on hypothalamic-pituitary-adrenal (HPA) axis activity was assessed.

METHODS

60 inpatients suffering from major depressive disorder (MDD) according to DSM-IV were randomized for a 5 week treatment with Yoga or not (control group) and with either QXR (300 mg/day) or ESC (10 mg/day). Serial dexamethasone/corticotropin releasing hormone (DEX/CRH) tests were performed to assess HPA axis function. The Hamilton Depression Rating Scale (21-HAMD) was used weekly.

RESULTS

A more pronounced down regulation of the HPA axis activity due to yoga could not be detected. The stepwise long term cortisol reduction was seen in both medication groups, irrespectively of yoga add-on treatment. In addition, cortisol improvers in week 1 of therapy (reduction in cortisol peak value within the DEX/CRH test) reached significant greater amelioration of depressive symptoms after 5 weeks.

CONCLUSIONS

Our results suggest that antidepressant agents down regulate HPA axis function to a greater extent than additional Hatha yoga treatment. Moreover, an early reduction of HPA system hyperactivity after one week of pharmacological treatment seems to raise the possibility of a favorable treatment response.

Impact on cortisol and antidepressant efficacy of quetiapine and escitalopram in depression

BACKGROUND

In this study, the impact of quetiapine fumarate extended release (QXR) and escitalopram (ESC) on HPA axis activity was investigated in depressed patients in relationship to antidepressant efficacy.

METHODS

In a randomized, open-label 5-week trial 60 inpatients suffering from major depression (DSM-IV criteria) were treated for 5 weeks with either QXR (300 mg/day) or ESC (10mg/day). The dexamethasone/CRH (DEX/CRH) test was performed before treatment, after 1, and after 5 weeks of treatment. Cortisol (COR) AUC values were used to assess HPA axis function. The Hamilton Depression Rating Scale was used weekly to estimate antidepressant efficacy.

RESULTS

QXR and ESC showed comparable antidepressant effects but strongly differed in their impact on HPA axis activity. In the QXR group, a marked inhibition of COR AUC levels was observed which was most pronounced after one week of treatment but showed a partial re-increase after 5 weeks of treatment. In contrast, ESC transiently stimulated COR AUC values (week 1) whereas COR AUC levels at week 0 and week 5 were comparable. COR improvement at week 1 (defined as COR peak value reduction between DEX/CRH test 1 and 2) was significantly associated with better clinical outcome.

CONCLUSION

Apparently, different effects on HPA axis activity reflect distinct pharmacoendocrinological properties of psychotropic drugs.

'It's the way that you look at it'--a cognitive neuropsychological account of SSRI action in depression

The fact that selective serotonin reuptake inhibitors (SSRIs) have antidepressant effects in some patients supports the notion that serotonin plays a role in the mode of action of antidepressant drugs. However, neither the way in which serotonin may alleviate depressed mood  nor the reason why several weeks needs to elapse before the full antidepressant effect of treatment is expressed  is known. Here, we propose a neuropsychological theory of SSRI antidepressant action based on the ability of SSRIs to produce positive biases in the processing of emotional information. Both behavioural and neuroimaging studies show that SSRI administration produces positive biases in attention, appraisal and memory from the earliest stages of treatment, well before the time that clinical improvement in mood becomes apparent. We suggest that the delay in the clinical effect of SSRIs can be explained by the time needed for this positive bias in implicit emotional processing to become apparent at a subjective, conscious level. This process is likely to involve the re-learning of emotional associations in a new, more positive emotional environment. This suggests intriguing links between the effect of SSRIs to promote synaptic plasticity and neurogenesis, and their ability to remediate negative emotional biases in depressed patients.

Escitalopram and neuroendocrine response in healthy first-degree relatives to depressed patients--a randomized placebo-controlled trial

INTRODUCTION

The mechanisms by which selective serotonin re-uptake inhibitors (SSRI) act in depressed patients remain unknown. The serotonergic neurotransmitter system and the hypothalamic-pituitary-adrenal (HPA) system may interact. The aim of the AGENDA trial was to investigate whether long-term intervention with SSRI versus placebo affects the cortisol response in the dexamethasone corticotropin-releasing hormone (DEX-CRH) test in healthy first-degree relatives to patients with major depressive disorder (MDD).

METHODS

Eighty healthy first-degree relatives to patients with MDD were randomized to escitalopram 10 mg versus matching placebo daily for four weeks. The primary outcome measure was the intervention difference in the change of the total area under the curve (CorAUC(total)) for plasma cortisol in the DEX-CRH test at entry to after four weeks of intervention.

RESULTS

Change in CorAUC(total) showed no statistically significant difference between the escitalopram and the placebo group, p = 0.47. There were large intra- and inter-individual differences in the results of the DEX-CRH test. There was statistically significant negative correlation between the plasma escitalopram concentration and change in CorAUC(total), rho = -0.41, p = 0.01. Post-hoc analyses showed a statistically significant interaction between age and intervention group and change in log CorAUC(total).

CONCLUSION

The present trial does not support an effect of escitalopram 10 mg daily compared with placebo on the HPA-axis in healthy first-degree relatives to patients with MDD. Increasing levels of escitalopram tended to decrease the HPA-response in the DEX-CRH test and this effect increased with age.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00386841.

Influence of citalopram and environmental temperature on exercise-induced changes in BDNF

PURPOSE

Serum brain-derived neurotrophic factor (BDNF) is known to increase with exercise. This increase is believed to originate from the brain and it is suggested that monoamines are involved in BDNF regulation. Heat exposure could influence the supposed BDNF output from the brain. Therefore, we hypothesized that administration of a selective serotonin reuptake inhibitor could influence the exercise-induced increase in BDNF, and that peripheral BDNF will be higher when exercise is performed in the heat.

METHODS

Eleven well-trained males performed 4 experimental trials on a cycle ergometer with citalopram or placebo treatment (20 mg in 12 h) in an environmental temperature of 18°C or 30°C. Blood samples (BDNF and cortisol) were taken at 4 time points: at rest, after 60 min at 55% W(max), after a time trial of 30 min at 75% W(max) and following 15 min of recovery. Heart rate and core temperature were measured.

RESULTS

Performance on the time trial was 20% worse in 30°C compared to 18°C (p<0.01), without influence of citalopram. Serum BDNF was found to be lower under citalopram treatment, while basal cortisol levels were increased (p<0.05). Exercise triggered an increase in both BDNF and cortisol (p<0.001). BDNF followed the same pattern as core temperature during exercise, with higher levels of both variables in 30°C. Cortisol was also increased in 30°C compared to temperate conditions (p<0.01).

CONCLUSION

Exercise caused a rise in serum BDNF and cortisol. This increase was enhanced with exercise in the heat. Since permeability of the blood-brain barrier increases with exercise in the heat, the hypothesis was raised that this causes a higher cerebral output of BDNF. Serotonergic stimulation did not increase peripheral BDNF, which was even lower with citalopram administration. Future research should focus on mechanisms behind BDNF increase with exercise.

Quantification of cerebral blood flow as biomarker of drug effect: arterial spin labeling phMRI after a single dose of oral citalopram

Arterial spin labeling (ASL) allows noninvasive quantification of cerebral blood flow (CBF), which can be used as a biomarker of drug effects in pharmacological magnetic resonance imaging (phMRI). In a double-blind, placebo-controlled crossover study, we investigated the effects of a single oral dose of citalopram (20 mg) on resting CBF in 12 healthy subjects, using ASL phMRI. Support-vector machine (SVM) analysis detected significant drug-induced reduction in CBF in brain regions including the amygdala, fusiform gyrus, insula, and orbitofrontal cortex. These regions have been shown to have abnormally elevated CBF in patients with major depression, as well as in subjects genetically prone to depression. Mixed-effects analysis on data extracted from selected regions of interest (ROIs) revealed significant drug effect only in serotonergic areas of the brain (z = -4.45, P < 0.005). These results demonstrate the utility of ASL phMRI as a biomarker of pharmacological activity of orally administered drugs in the brain.

Antidepressant-induced hyperprolactinaemia: incidence, mechanisms and management

Prolactin, a polypeptide hormone, is responsible, amongst other things, for milk production during lactation and breast enlargement during pregnancy. Numerous drugs can affect prolactin levels. Most commonly, conventional antipsychotics are associated with hyperprolactinaemia but there have also been reports of antidepressants causing hyperprolactinaemia. This review sets out to establish the incidence of antidepressant-induced hyperprolactinaemia, its possible mechanism and to determine appropriate remedial actions. Nearly all antidepressants are reported to be associated with hyperprolactinaemia. Incidence rates were not clearly established and symptoms were very rare. The mechanism by which antidepressants may cause hyperprolactinaemia is not fully understood, though several theories have been postulated, such as serotonin stimulation of GABAergic neurons and indirect modulation of prolactin release by serotonin. Patients taking antidepressants presenting to their clinician with symptoms potentially related to hyperprolactinaemia, such as galactorrhoea, should have their plasma prolactin level measured and their antidepressant changed if an increased prolactin level is confirmed. Routine monitoring of prolactin levels is otherwise not appropriate.

Escitalopram: in the treatment of major depressive disorder in adolescent patients

Escitalopram is a selective serotonin reuptake inhibitor (SSRI), and is the second antidepressant to be approved for use in treating major depressive disorder (MDD) in adolescent patients (aged 12-17 years) in the US. In a randomized, double-blind, flexible-dose, multicenter trial, once-daily escitalopram 10-20 mg (n = 154) for 8 weeks was significantly better than placebo (n = 157) in improving the severity of depressive symptoms (as assessed by the change in the Children's Depression Rating Scale-Revised [CDRS-R] total score) in adolescent patients with MDD. Preliminary data from a combined analysis of the double-blind data from this trial and double-blind data from a 16-week, fixed-dose, extension study suggest a significant difference between escitalopram and placebo recipients in the change in CDRS-R total scores after 24 weeks of treatment. In a similarly designed flexible-dose trial in pediatric patients (aged 6-17 years), a significant difference between once-daily escitalopram 10-20 mg (n = 77) and placebo (n = 80) for 8 weeks, as assessed by the change in CDRS-R total score, was not shown in the primary analysis (i.e. patients of all ages). In a pre-specified subgroup of adolescent patients, no significant difference was shown between the escitalopram and the placebo groups when analyzed using the last observation carried forward method, but was shown using the observed case method. Escitalopram 10-20 mg/day showed better efficacy than placebo for some secondary endpoints (e.g. the change in the Clinical Global Impression [CGI]-Severity score, the CGI-Improvement response rate) but not others (e.g. CDRS-R response rate, rate of remission) [corrected].Once-daily escitalopram 10-20 mg for 8 weeks was generally well tolerated in clinical trials in adolescent or pediatric patients with MDD. The incidence of suicidality-related adverse events was generally similar between escitalopram and placebo recipients.

Escitalopram prolonged fear induced by simulated public speaking and released hypothalamic-pituitary-adrenal axis activation

Simulated public speaking (SPS) test is sensitive to drugs that interfere with serotonin-mediated neurotransmission and is supposed to recruit neural systems involved in panic disorder. The study was aimed at evaluating the effects of escitalopram, the most selective serotonin-selective reuptake inhibitor available, in SPS. Healthy males received, in a double-blind, randomized design, placebo (n = 12), 10 (n = 17) or 20 (n = 14) mg of escitalopram 2 hours before the test. Behavioural, autonomic and neuroendocrine measures were assessed. Both doses of escitalopram did not produce any effect before or during the speech but prolonged the fear induced by SPS. The test itself did not significantly change cortisol and prolactin levels but under the higher dose of escitalopram, cortisol and prolactin increased immediately after SPS. This fear-enhancing effect of escitalopram agrees with previously reported results with less selective serotonin reuptake inhibitors and the receptor antagonist ritanserin, indicating that serotonin inhibits the fear of speaking in public.

Antidepressant-Induced Sexual Dysfunction among Newer Antidepressants in a Naturalistic Setting

OBJECTIVE

Antidepressants used to treat depression are frequently associated with sexual dysfunction. Sexual side effects affect the patient's quality of life and, in long-term treatment, can lead to non-compliance and relapse. However, studies covering many antidepressants with differing mechanisms of action were scarce. The present study assessed and compared the incidence of sexual dysfunction among different antidepressants in a naturalistic setting.

METHODS

Participants were married patients diagnosed with depression, per DSM-IV diagnostic criteria, who had been taking antidepressants for more than 1 month. We assessed the participants via the Arizona Sexual Experiences Scale (ASEX), Beck Depression Inventory (BDI), and State-Trait Anxiety Inventory (STAI), and assessed their demographic variables, types and dosages of antidepressants, and duration of antidepressant use via their medical records.

RESULTS

One hundred and one patients (46 male, 55 female, age 42.2+/-7 years) completed the instruments. Thirteen were taking fluoxetine (mean dose 21.3+/-8.5 mg/day), 24 were taking paroxetine (mean dose 20.4+/-7.2 mg/day), 20 taking citalopram (mean dose 22.1+/-6.5 mg/day), 22, venlafaxine (mean dose 115.7+/-53.2 mg/day) and 22, mirtazapine (mean dose 18+/-8.7 mg/day). Mean ages, sex ratios, and BDI and STAI scores did not differ significantly across antidepressants. A substantial number of participants (46.5%, n=47) experienced sexual dysfunction. The prevalence of sexual dysfunction differed across drugs: citalopram 60% (n=12), venlafaxine 54.5% (n=12), paroxetine 54.2% (n=13), fluoxetine 46.2% (n=6), and mirtazapine 18.2% (n=4). Regression analyses revealed the significant factors for sexual dysfunction were being female, total scores on the BDI and SAI, and type of antidepressant (F=4.92, p<0.0001). Of the antidepressants, the mirtarzapine group's total ASEX score was significantly lower than the scores of the citalopram, fluoxetine, and paroxetine groups.

CONCLUSION

The incidence of sexual dysfunction was substantially high during antidepressant treatment. The incidence of sexual dysfunction differed among antidepressants having different mechanisms of action. Our study suggests the need for clinicians to consider the impact of pharmacotherapy on patients' sexual functioning in the course of treatment with antidepressants.

Specific effects of escitalopram on neuroendocrine response

PURPOSE

Citalopram, a selective serotonin reuptake inhibitor, is used as a neuroendocrine probe in human subjects to assess serotonin function as reflected in prolactin and plasma cortisol release. Citalopram is a racemic mixture of equal proportions of the S(+) and R(-) enantiomers. Inhibition of serotonin reuptake and, consequently, antidepressant activity is associated, almost exclusively, with the S(+) enantiomer ("escitalopram"). Studies in animal models indicate that the presence of the R(-) isomer may interfere with the serotonin reuptake activity of escitalopram. The current study compared the neuroendocrine effects of citalopram and escitalopram in healthy human volunteers.

METHODS

Plasma cortisol and prolactin levels following a single oral dose of citalopram (40 mg) or escitalopram (20 mg) were compared in samples taken every 15-30 min over a period of 240 min. Plasma citalopram concentration was determined at the same intervals.

RESULTS

Escitalopram and citalopram caused equivalent increases in plasma cortisol and prolactin. The administration of dexamethasone prior to the escitalopram challenge blocked the evoked increase in cortisol.

CONCLUSION

This is the first study to prove that a single dose of escitalopram acts centrally and not peripherally, providing further support of the use of oral escitalopram as a probe for brain serotonergic function.

Neuroendocrine and subjective responses to pharmacological challenge with citalopram: a controlled study in male and female ecstasy/MDMA users

Despite evidence that +/-3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') causes persistent alterations to the serotonergic system of animals, evidence for long-term neurological effects of ecstasy/MDMA in humans remains equivocal. The current study assessed serotonin functioning of nine male and 11 female recreational ecstasy polydrug users by measuring neuroendocrine (prolactin, cortisol) responses to pharmacological challenge with the selective serotonin reuptake inhibitor citalopram, compared with nine male and five female cannabis polydrug users and 11 male and 11 female non-drug using controls. A single-blind, randomised, placebo-controlled design was used. Subjective responses, other substance use, mood, personality traits and demographic variables were measured to control for potentially confounding variables. There were no significant differences between ecstasy polydrug users, cannabis polydrug users and non-drug using controls in neuroendocrine or subjective responses to serotonergic challenge, and there were no sex by drug group interactions. There was no relationship between extent of ecstasy use and neuroendocrine functioning, alone or in combination with potential confounding variables. Subjective responses to the pharmacological challenge (nausea, tremor, dry mouth), novelty seeking and lifetime dose of alcohol were the only variables that contributed to one or more of the neuroendocrine outcome variables. These data do not support the premise that recreational ecstasy/MDMA use results in measurable impairment of serotonergic control of endocrine activity.

Time trial performance in normal and high ambient temperature: is there a role for 5-HT?

The original central fatigue hypothesis suggested that fatigue during prolonged exercise might be due to higher 5-HT activity. Therefore, we examined the effects of acute administration of a selective 5-HT reuptake inhibitor (SSRI) on performance and thermoregulation. Eleven healthy trained male cyclists completed four experimental trials (two in 18 degrees C, two in 30 degrees C) in a double-blind randomised crossover design. Subjects ingested either a placebo (PLA: lactose 2 x 10 mg) or citalopram (CITAL 2 x 10 mg) on the evening before and the morning of the trial. Subjects cycled for 60 min at 55% W(max), immediately followed by a time trial (TT) to measure performance. The significance level was set at P < 0.05. Acute SSRI did not significantly change performance on the TT (18 degrees C P = 0.518; 30 degrees C P = 0.112). During recovery at 30 degrees C, core temperature was significantly lower in the CITAL trial (P < 0.012). At 30 degrees C heart rate was significantly lower after exercise in CITAL (P = 0.013). CITAL significantly increased cortisol concentrations at rest (P = 0.016), after the TT (P = 0.006) and after 15-min recovery (P = 0.041) at 30 degrees C. 5-HT reuptake inhibition did not cause significant reductions in performance. Core temperature was significantly lower only after the time trial in heat after CITAL administration. The present work failed to prove whether or not 5-HT has an exclusive role in the onset of centrally mediated fatigue during prolonged exercise in both normal and high ambient temperature.

An examination of acute changes in serotonergic neurotransmission using the loudness dependence measure of auditory cortex evoked activity: effects of citalopram, escitalopram and sertraline

OBJECTIVE

The underlying effect of serotonergic neurotransmission has been implicated in several psychiatric disorders. The inability to routinely and non-invasively determine the integrity of the serotonergic system in vivo has limited our understanding of disorders with a putative serotonergic abnormality. The loudness dependence of the auditory evoked potential (LDAEP) has been proposed as a reliable measure of central serotonin function in humans. While animal studies suggest that the LDAEP is sensitive to changes in central serotonin neurotransmission, evidence in humans has been indirect and inconsistent. The aim of this study was to assess the sensitivity of the LDAEP to acute augmentation in central serotonergic neurotransmission in humans.

METHODS

The study used a double-blind, placebo-controlled cross-over design, in which healthy subjects were tested under four acute treatment conditions, with pharmacologically equivalent single doses of placebo, escitalopram (10 mg), citalopram (20 mg) and sertraline (50 mg) to examine the direct effect of acute enhancement of synaptic serotonin on the LDAEP. Furthermore, the outcome of the serotonergic modulatory effects on the LDAEP was also examined using two methods (dipole source analysis (DSA) vs. scalp analysis).

RESULTS

Escitalopram, citalopram and sertraline had no effects on the LDAEP and were independent of the analysis method used.

CONCLUSION

These findings question the sensitivity of the LDAEP to acute changes in serotonin neurotransmission and its validity as a reliable measure of central serotonin function in humans.

The effects of increased central serotonergic activity on prepulse inhibition and habituation of the human startle response

Sensorimotor gating is critical to normal brain functioning, and disruptions are associated with certain mental illnesses, such as schizophrenia. Prepulse inhibition of the acoustic startle reflex (ASR) (PPI) is an operational measure of sensorimotor gating, of which evidence for a serotonergic modulation is currently inconsistent. In a double-blind placebo-controlled crossover design, 18 healthy male volunteers received either placebo or a dose of 10 mg of escitalopram (SSRI), after which they were tested in both PPI and habituation of the startle reflex paradigms. No significant differences between the two treatments were observed on PPI, although escitalopram was found to significantly delay habituation of the ASR. In the current study, escitalopram was found to delay habituation, but it did not affect PPI in healthy male volunteers. As escitalopram is a highly specific SSRI, the results suggest that an increased serotonergic activity disrupts habituation, but not PPI in healthy volunteers.

A single dose of citalopram increases fear recognition in healthy subjects

We have previously shown that a single dose of intravenous citalopram in healthy volunteers enhances the detection of fearful facial expressions, suggesting an effect of acute selective serotonin re-uptake inhibitor (SSRI) treatment on the processing of anxiety-related stimuli. The aim of the present study was to confirm and extend this finding by studying the effects of a single dose of oral citalopram on a range of tasks designed to assess different aspects of emotional processing. A total of 32 healthy volunteers were randomly allocated to double-blind treatment with either citalopram 20 mg orally or placebo. Participants then completed a series of tasks assessing emotional aspects of attention (visual-probe task), perception (categorization of facial affect), memory (emotional memory task) and reactivity to threat (emotion potentiated startle). Relative to placebo-treated subjects, participants treated with citalopram demonstrated improved recognition of fearful faces and increased baseline startle response. However, the citalopram group also showed an attentional bias towards positive words. Our data suggest that acute oral citalopram increases the processing of anxiety-related stimuli in healthy volunteers. This mechanism could underlie the known tendency of SSRIs to increase anxiety in patients early in treatment. Our data also suggests that some of the positive biases in emotional processing produced by SSRI treatment might be detectable at the beginning of treatment.

Atomoxetine increases salivary cortisol in healthy volunteers

It has been proposed that acute hypothalamo-pituitary-adrenal (HPA) axis challenge using noradrenergic drugs may be of utility in assessing the functional integrity of central noradrenaline pathways. Atomoxetine (formerly tomoxetine) is a highly selective noradrenaline reuptake inhibitor, which has recently been licensed for the treatment of attention deficit hyperactivity disorder (ADHD). The aim of this study was to assess the effects of acute atomoxetine on salivary cortisol levels for the first time.A total of 60 healthy male volunteers received 60 mg atomoxetine, 30 mg citalopram, or placebo per os in a double-blind parallel groups design (n = 20 per group). Salivary cortisol, blood pressure and pulse rates were recorded at baseline and at +1.0, +1.5, +2.5 and +3.5 hours after capsule administration.60 mg atomoxetine led to highly significant increases in salivary cortisol and a moderate increase in pulse rate, in the absence of significant effects on blood pressure. 30 mg citalopram had no significant effects on cortisol or cardiovascular parameters. These data support the utility of atomoxetine neuroendocrine challenge for evaluating central noradrenaline pathways, which may be of future use in neuropsychiatric patient studies. Furthermore, the effects of atomoxetine on HPA axis function may have clinical implications given the use of this agent in the treatment of ADHD.

Escitalopram: a review of its use in the management of anxiety disorders

Escitalopram (Cipralex, Lexapro, Seroplex, Sipralexa), the therapeutically active S-enantiomer of racemic citalopram (RS-citalopram), is a potent and highly selective serotonin reuptake inhibitor. It is effective and generally well tolerated in the treatment of moderate to severe generalised anxiety disorder (GAD) or social anxiety disorder (SAD), panic disorder (with or without agoraphobia) as well as obsessive-compulsive disorder (OCD). Moreover, escitalopram is at least as effective as paroxetine for the treatment of GAD, SAD or OCD and appears to achieve a more rapid response than racemic citalopram in the management of panic disorder. Generally, it has a more favourable tolerability profile than paroxetine in terms of fewer discontinuation symptoms. In addition, a favourable pharmacokinetic profile permits once-daily administration of the drug. Additional comparative studies are required to definitively position escitalopram with respect to other SSRIs and venlafaxine. Nevertheless, available clinical data indicate that escitalopram is an effective first-line treatment option for the management of GAD, SAD, panic disorder and OCD.

Antidepressants and sexual dysfunction

OBJECTIVE

Many patients with depression suffer from sexual dysfunction and sexual dysfunction is a recognized side-effect of antidepressants. The aim of this review was to examine the prevalence of psychosexual dysfunction associated with antidepressants, and to review treatment options which are specific to the affected component of sexual functioning and antidepressants.

METHOD

Comprehensive literature review using Medline and Cochrane databases.

RESULTS

Up to 70% of patients with depression may have sexual dysfunction. Tricyclic antidepressants, selective-serotonin reuptake inhibitors and venlafaxine are most and the non-serotonergic antidepressants and duloxetine least likely to produce sexual dysfunction. Pharmacological treatment options include antidepressants less likely associated or 'antidotes' to reverse sexual dysfunction.

CONCLUSION

Sexual dysfunction may be a preventable or treatable side-effect of antidepressants. Patients need routinely to be asked about sexual function to identify problems early. If sexual dysfunction is ignored it may maintain the depression, compromise treatment outcome and lead to non-compliance.

S-Citalopram in neuroendocrine challenge-tests: serotonergic responsivity in healthy male and female human participants

The aim of the present study was to assess the usefulness of the selective serotonin-reuptake-inhibitor S-Citalopram as a serotonergic challenge probe in 24 healthy male and 24 healthy female participants. The participants received a single oral dose of 10 and 20mg of S-Citalopram in a placebo-controlled double blind crossover design. In female subjects phases of the menstrual cycle were controlled. Changes in concentrations of cortisol in saliva were used to indicate serotonergic reactivity. S-Citalopram induced a reliable dose dependent rise in cortisol concentrations. Results reveal a clear dose-response relationship in both sexes. However, in contrast to the 10mg condition the dosage of 20mg led to significantly higher cortisol levels in females, whereas no differences could be observed with respect to different phases of the menstrual cycle (follicular vs. luteal). Adverse side effects were reported only after 20mg. The results clearly indicate that the dosage of 10mg should be preferred when challenging males and females. Results will be discussed with regard to the further use of S-Citalopram in neuroendocrine challenge tests.

Usefulness of serotoninergic challenge with oral citalopram

OBJECTIVE: Challenge tests designed to evaluate serotoninergic pathways have widely used intravenous citalopram. Oral citalopram has also been used, but unsatisfactory results were obtained with a dose of 20 mg. The objective of this study was to determine whether a higher oral dose would reproduce similar to those described for intravenous administration. To that end, we evaluated cortisol, growth hormone and prolactin levels. METHOD: Eight healthy male volunteers were evaluated in a randomized crossover challenge test with 40 mg of oral citalopram or placebo. RESULTS: Cortisol levels increased at 2-4h after the oral citalopram intake, with a small amplitude peak occurring in two-thirds of the subjects. Levels of prolactin and growth hormone remained unchanged throughout the study. CONCLUSION: The use of oral citalopram might present an alternative in serotoninergic challenge tests, but higher doses are required.

Effects of oral racemic citalopram on neuroendocrine responses

Citalopram, a selective serotonin reuptake inhibitor (SSRI), has been used as a neuroendocrine probe to assess serotonin (5-HT) function in human subjects. In an effort to characterize the oral citalopram challenge, we hypothesized that oral racemic citalopram would increase plasma cortisol, prolactin and adrenocorticotropic hormone (ACTH) concentrations; ACTH had not been measured in previous studies on the neuroendocrine effects of citalopram. Nine healthy male subjects initially received 20 mg of citalopram in an open-label study, and subsequently received placebo and 40 mg of citalopram in a single-blind, randomized, cross-over study. The administration of citalopram 20 mg failed to produce a significant neuroendocrine response but 40 mg resulted in reliably increased plasma cortisol concentrations. The 40 mg dose, however, did not reliably influence the levels of plasma prolactin or plasma ACTH. The results of this study indicate that caution should be used in accepting oral racemic citalopram as a potential presynaptic serotonergic challenge agent. Further studies are needed to fully determine the validity of racemic citalopram and the active enantiomer, escitalopram, as 5-HT probes.

L-5-Hydroxytryptophan augments the neuroendocrine response to a SSRI

The objective of the study was to assess l-5-hydroxytryptophan's (l-5HTP) augmentation effect on the neuroendocrine response to a SSRI (citalopram). A neuroendocrine challenge study was conducted in healthy Asian male subjects. The neuroendocrine response to oral citalopram and l-5HTP was measured primarily as the prolactin and cortisol area under the response curve (or AUC). The study comprised 2 studies: Study 1. A double blind, randomised dose ranging study was conducted with l-5HTP (50-200 mg) to explore the prolactin and/or cortisol dose response and select a dose that provided a threshold neuroendocrine response. Study 2. A randomized comparison of citalopram 20 vs 40 mg was used to assess the effect of these doses on prolactin and cortisol. Based on the results of the dose response assessments with l-5HTP and cortisol, 200 mg l-5HTP was subsequently used in Study 2 to explore the augmentation of the neuroendocrine response to 20 mg citalopram. Citalopram, but not l-5HTP, increased prolactin AUC(0-3h) while 5HTP and citalopram increased cortisol AUC(0-3h). A 200 mg dose of l-5HTP significantly augmented the prolactin and cortisol response AUC(0-3h) to 20mg oral citalopram. The results of the study suggest that an augmented neuroendocrine challenge may be a suitable marker to demonstrate increased 5-HT-mediated responses when exploring novel agents as improved SSRIs.

Escitalopram: a review of its use in the management of major depressive disorder

Escitalopram (Cipralex, Lexapro), the active S-enantiomer of the racemic selective serotonin reuptake inhibitor (SSRI) citalopram (RS-citalopram), is a highly selective inhibitor of the serotonin transporter protein. It possesses a rapid onset of antidepressant activity, and is an effective and generally well tolerated treatment for moderate-to-severe major depressive disorder (MDD). Pooled analyses from an extensive clinical trial database suggest that escitalopram is consistently more effective than citalopram in moderate-to-severe MDD. Preliminary studies suggest that escitalopram is as effective as other SSRIs and the extended-release (XR) formulation of the serotonin/noradrenaline (norepinephrine) reuptake inhibitor venlafaxine, and may have cost-effectiveness and cost-utility advantages. However, additional longer-term, comparative studies evaluating specific efficacy, tolerability, health-related quality of life and economic indices would be helpful in definitively positioning escitalopram relative to these other agents in the treatment of MDD. Nevertheless, available clinical and pharmacoeconomic data indicate that escitalopram is an effective first-line option in the management of patients with MDD.

Early life trauma decreases glucocorticoid receptors in rat dentate gyrus upon adult re-stress: reversal by escitalopram

Early exposure to adverse experiences may lead to specific changes in hippocampal glucocorticoid function resulting in abnormalities within the hypothalamic-adrenal axis. Given interactions between the neuroendocrine and central serotonergic systems, we hypothesized that exposure to early trauma would lead to abnormal hypothalamic-adrenal axis activity that would be normalized by pretreatment with a selective serotonin re-uptake inhibitor. Hypothalamic-adrenal axis function was assessed by determining basal corticosterone levels and hippocampal glucocorticoid receptor immunoreactivity. Rats were subjected to a triple stressor on postnatal day 28, and again to a single swim re-stress session on postnatal day 35 and postnatal day 60. On postnatal day 61 i.e. 24 h after the last re-stress, trunk blood was collected for serum corticosterone determinations and hippocampal tissue was collected for immunohistochemistry of glucocorticoid receptors. Escitalopram (5mg/kg) or saline vehicle was administered from postnatal day 47-postnatal day 60 via osmotic mini-pumps. Animals exposed to early life trauma showed an increase in basal corticosterone levels, and a significant decrease in the ratio of glucocorticoid receptor positive cells to total cells in the hilus, granule cell layer and the dentate gyrus. Both the increase in basal corticosterone and decrease in glucocorticoid receptor immunoreactivity were reversed by escitalopram pretreatment. These data confirm alterations in hypothalamic-adrenalaxis function that may stem from decreases in glucocorticoid receptor levels, in response to early adverse experiences, and demonstrate that these alterations are reversed by serotonin re-uptake inhibitor pretreatment.

The effects of an acute serotonergic challenge on brain-gut responses in irritable bowel syndrome patients and controls

BACKGROUND

Serotonin, a key denominator of the brain-gut axis is involved in the regulation of gastrointestinal function as well as cognition, mood and hypothalamic-pituitary-adrenal axis-mediated neuroendocrine responses.

AIM

To assess the effects of an acutely increased serotonergic activity, using a 20 mg intravenous citalopram challenge test on visceral perception, affective memory performance, mood and neuroendocrine responses, respectively, in diarrhoea-predominant irritable bowel syndrome patients and controls.

METHODS

In a randomized, double-blind crossover design, 14 diarrhoea-predominant irritable bowel syndrome patients and 14 matched controls were studied under citalopram and placebo conditions, respectively. Visceral perception was scored in response to rectal distensions. Affective memory performance, mood, levels of adrenocorticotropic hormone, cortisol, prolactin and biochemical parameters of serotonergic metabolism were simultaneously assessed.

RESULTS

Visceral perception did not significantly differ between the citalopram and placebo condition. Citalopram administration enhanced affective memory performance because of a bias towards positive material but no significant changes in mood. Citalopram significantly increased plasma serotonin, adrenocorticotropic hormone and cortisol levels compared with placebo. Citalopram did not differentially affect the patient or control group.

CONCLUSIONS

We have provided evidence that acutely increased serotonergic activity influences neuroendocrine responses and cognition in diarrhoea-predominant irritable bowel syndrome and controls without a significant effect on visceral perception.