Serotonin Transporter Binding Research Articles

Dextromethorphan moderates reward deficiency associated with central serotonin transporter availability in 3,4-methylenedioxy-methamphetamine-treated animals.

The neurotoxicity of 3,4-methylenedioxy-methamphetamine (MDMA) to the serotonergic system is well-documented. Dextromethorphan (DM), an antitussive drug, decreased morphine- or methamphetamine (MA)-induced reward in rats and may prevent MDMA-induced serotonergic deficiency in primates, as indicated by increased serotonin transporter (SERT) availability. We aimed to investigate the effects of DM on reward, behavioral sensitization, and neurotoxicity associated with loss of SERT induced by chronic MDMA administration in rats. Conditioned place preference (CPP) and locomotor activity tests were used to evaluate drug-induced reward and behavioral sensitization; 4-[18F]-ADAM/animal-PET and immunohistochemistry were used to explore the effects of DM on MDMA-induced loss of SERT. MDMA significantly reduced SERT binding in the rat brain; however, co-administration of DM significantly restored SERT, enhancing the recovery rate at day 14 by an average of ~23% compared to the MDMA group. In confirmation of the PET findings, immunochemistry revealed MDMA reduced SERT immunoactivity in all brain regions, whereas DM markedly increased the serotonergic fiber density after MDMA induction. Behavioral tests and in vivo longitudinal PET imaging demonstrated the CPP indexes and locomotor activities of the reward system correlate negatively with PET 4-[18F]ADAM SERT activity in the reward system. Our findings suggest MDMA induces functional abnormalities in a network of brain regions important to decision-making processes and the motivation circuit. DM may exert neuroprotective effects to reverse MDMA-induced neurotoxicity.

Effectiveness of vortioxetine for winter depression in bipolar disorder: A case report

AbstractBackgroundWe present a case report on the efficacy of the short‐term application of vortioxetine in managing winter depression in patients with seasonal bipolar disorder (BP). Standard treatment strategies for BP may not adequately address seasonal depressive symptoms during winter in patients with seasonal BP patterns. Depressive symptoms during winter may be linked to seasonal changes in serotonin transporter binding, such as a decrease in synaptic serotonin levels, necessitating alternative approaches. Although antidepressants, including vortioxetine, are effective in treating seasonal monopolar depression, their efficacy and safety in treating depression in patients with seasonal BP patterns remain unclear.Case PresentationThis case report focuses on a 44‐year‐old male patient diagnosed with seasonal BP who had recurrent depressive episodes, specifically during winter. Notably, the patient had a significant decrease in recurrent episodes after short‐term seasonal vortioxetine use without inducing mania or rapid cycling.ConclusionOur study highlights the potential effectiveness of a seasonal, short‐term treatment strategy with antidepressants, including vortioxetine, for winter depression in individuals with BP.

Series of (([1,1'-Biphenyl]-2-yl)methyl)sulfinylalkyl Alicyclic Amines as Novel and High Affinity Atypical Dopamine Transporter Inhibitors with Reduced hERG Activity.

Currently, there are no FDA-approved medications for the treatment of psychostimulant use disorders (PSUD). We have previously discovered "atypical" dopamine transporter (DAT) inhibitors that do not display psychostimulant-like behaviors and may be useful as medications to treat PSUD. Lead candidates (e.g., JJC8-091, 1) have shown promising in vivo profiles in rodents; however, reducing hERG (human ether-à-go-go-related gene) activity, a predictor of cardiotoxicity, has remained a challenge. Herein, a series of 30 (([1,1'-biphenyl]-2-yl)methyl)sulfinylalkyl alicyclic amines was synthesized and evaluated for DAT and serotonin transporter (SERT) binding affinities. A subset of analogues was tested for hERG activity, and the IC50 values were compared to those predicted by our hERG QSAR models, which showed robust predictive power. Multiparameter optimization scores (MPO > 3) indicated central nervous system (CNS) penetrability. Finally, comparison of affinities in human DAT and its Y156F and Y335A mutants suggested that several compounds prefer an inward facing conformation indicating an atypical DAT inhibitor profile.

The 5-HT1A receptor agonist 8-OH-DPAT modulates motor/exploratory activity, recognition memory and dopamine transporter binding in the dorsal and ventral striatum

In the present studies, we assessed the effect of the 5-HT1A receptor (R) agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on motor and exploratory behaviors, object and place recognition and dopamine transporter (DAT) and serotonin transporter (SERT) binding in the rat brain. In Experiment I, motor/exploratory behaviors were assessed in an open field after injection of either 8-OH-DPAT (0.1 and 3 mg/kg) or vehicle for 30 min without previous habituation to the open field. In Experiment II, rats underwent a 5-min exploration trial in an open field with two identical objects. After injection of either 8-OH-DPAT (0.1 and 3 mg/kg) or vehicle, rats underwent a 5-min test trial with one of the objects replaced by a novel one and the other object transferred to a novel place. Subsequently, N-o-fluoropropyl-2b-carbomethoxy-3b-(4-[123I]iodophenyl)-nortropane ([123I]FP-CIT; 11 ± 4 MBq) was injected into the tail vein. Regional radioactivity accumulations were determined post mortem with a well counter. In both experiments, 8-OH-DPAT dose-dependently increased ambulation and exploratory head-shoulder motility, whereas rearing was dose-dependently decreased. In the test rial of Experiment II, there were no effects of 8-OH-DPAT on overall activity, sitting and grooming. 8-OH-DPAT dose-dependently impaired recognition of object and place. 8-OH-DPAT (3 mg/kg) increased DAT binding in the dorsal striatum relative to both vehicle and 0.1 mg/kg 8-OH-DPAT. Furthermore, in the ventral striatum, DAT binding was decreased after 3 mg/kg 8-OH-DPAT relative to vehicle. Findings indicate that motor/exploratory behaviors, memory for object and place and regional dopamine function may be modulated by the 5-HT1AR. Since, after 8-OH-DPAT, rats exhibited more horizontal and less (exploratory) vertical motor activity, while overall activity was not different between groups, it may be inferred, that the observed impairment of object recognition was not related to a decrease of motor activity as such, but to a decrease of intrinsic motivation, attention and/or awareness, which are relevant accessories of learning. Furthermore, the present findings on 8-OH-DPAT action indicate associations not only between motor/exploratory behavior and the recognition of object and place but also between the respective parameters and the levels of available DA in dorsal and ventral striatum.

Is serotonin transporter brain binding associated with the cortisol awakening response? An independent non-replication.

Serotonergic brain signaling is considered critical for an appropriate and dynamic adaptation to stress, seemingly through modulating limbic system functions, such as the hypothalamic-pituitary-adrenal (HPA)-axis. This interplay is of great interest since it holds promise as a target for preventing stress-related brain disorders, e.g., major depression. Our group has previously observed that prefrontal serotonin transporter (5-HTT) binding, imaged with positron emission tomography (PET), is positively associated with the cortisol awakening response (CAR), an index of HPA axis stress hormone dynamics. The aim of this cross-sectional study was to replicate the previous finding in a larger independent group of healthy individuals. Molecular imaging and cortisol data were available for 90 healthy individuals. Prefrontal 5-HTT binding was imaged with [11C]DASB brain PET. Non-displaceable 5-HTT binding potential (BPND) was quantified using the Multilinear Reference Tissue Model 2 (MRTM2) with cerebellum as the reference region. CAR was based on five serial salivary cortisol samples within the first hour upon awakening. The association between CAR and prefrontal 5-HTT BPND was evaluated using a multiple linear regression model adjusted for age and sex. Further, we tested for sex differences in the association. Finally, an exploratory analysis of the association, was performed in 8 additional brain regions. We observed no statistically significant association between 5-HTT binding and CAR corrected for age and sex in the prefrontal cortex (β = -0.28, p = 0.26). We saw no interaction with sex on the association (p = 0.99). We could not confirm a positive association between CAR and prefrontal 5-HTT BPND in this independent dataset. Also, sex differences in the association were not apparent. Our data do not exclude that the serotonin transporter system is involved in the regulation of stress responses in at-risk or manifest depressed states.

Quantitative [123]I-Ioflupane DaTSCAN single-photon computed tomography-computed tomography in Parkinsonism.

[123]I-Ioflupane (DaTSCAN) binds to the presynaptic dopamine transporter (DAT) and with a lower affinity to the serotonin transporter (SERT). We aimed to develop a novel method to quantify absolute uptake in the striatal (predominantly DAT binding) and extra-striatal regions (mainly SERT binding) using single-photon computed tomography-computed tomography (SPECT-CT) DaTSCAN and to improve DaTSCAN image quality. Twenty-six patients with Parkinsonism underwent DaTSCAN SPECT-CT prospectively. The scans were visually analyzed independently by two experienced reporters. Specific binding ratios (SBRs) from Chang attenuation corrected SPECT were obtained using GE DaTQuant. Normalized concentrations and specific uptakes (NSU) from measured attenuation and modelled scatter-corrected SPECT-CT were obtained using HERMES Hybrid Recon and Affinity and modified EARL volumes of interest. Striatal NSU and SBR positively correlate ( R  = 0.65-0.88, P  = 0.00). SBR, normalized concentrations, and NSU box plots differentiated between scans without evidence of dopaminergic deficit and abnormal scans. Interestingly, body weight inversely correlated with normalized concentrations values in extra-striatal regions [frontal ( R  = 0.81, P  = 0.00); thalamus ( R  = 0.58, P  = 0.00); occipital ( R  = 0.69, P  = 0.00)] and both caudate nuclei [ R  = 0.42, P  = 0.03 (Right), R  = 0.52, P  = 0.01 (Left)]. Both reporters noted improved visual quality of SPECT-CT versus SPECT images for all scans. DaTSCAN SPECT-CT resulted in more accurate quantification, improved image quality, and enabled absolute quantification of extra-striatal regions. More extensive studies are required to establish the full value of absolute quantification for diagnosis and monitoring the progression of neurodegenerative disease, to assess an interplay between DAT and SERT, and to verify whether serotonin and DATs are potentially dysfunctional in obesity.

The association between brain serotonin transporter binding and impulsivity and aggression in healthy individuals

The serotonin system plays a critical role in the modulation of impulsive aggression. Although serotonin transporters (SERT) are key in modulating synaptic serotonin levels, few studies have investigated the role of SERT levels in human impulsive aggression. The aim of this study was to investigate whether brain SERT levels are associated with trait impulsive aggression. We included 148 healthy individuals (mean age 29.3 ± 13.0, range 18–80 years, 91 females) who had undergone positron emission positron (PET) examinations with the SERT tracer [11C]DASB and filled in self-report questionnaires of trait aggression, trait impulsivity and state aggression. We evaluated the association between cerebral SERT binding (BPND) and trait impulsive aggression in a latent variable model, with one latent variable (LVSERT) modelled from SERT BPND in frontostriatal and frontolimbic networks implicated in impulsive aggression, and another latent variable (LVIA) modelled from various trait measures of impulsivity and aggression. The LVSERT was not significantly associated with the LVIA (p = 0.8). Post-hoc univariate analyses did not reveal any significant associations between regional SERT levels and trait aggression, trait impulsivity or state aggression, but we found that state aggression at the day of PET scan was significantly lower in LA/LA homozygotes vs S-carriers of the 5-HTTLPR gene (p = 0.008). We conclude that brain SERT binding was not related to variations in trait impulsive aggression or state aggression. Our findings do not support that SERT is involved in mediating the serotonergic effects on aggression and impulsivity, at least not in individuals with non-pathological levels of impulsive aggression.

Dopamine transporter binding in the brain is linked to irritable bowel syndrome in Parkinson's disease.

Gastrointestinal symptoms are common in Parkinson's disease (PD), but their neurophysiological correlates are not well understood. We recently reported that functional gastrointestinal symptoms were not associated with asymmetry per se but might be associated with lower left striatal dopamine transporter (DAT) binding. The purpose of this study was to further investigate if specific gastrointestinal symptoms associate with monoamine transporter changes in specific striatal or extrastriatal areas. Ninety PD patients, who underwent DAT ¹2 3 I-FP-CIT SPECT imaging, were assessed using the MDS-Unified Parkinson's Disease Rating Scale part III, Rome III, and Wexner constipation score. DAT binding was calculated from striatal subregions using region-to-occipital cortex ratio. Voxel-wise analysis was used to assess the relationship between gastrointestinal symptoms and striatal DAT and extrastriatal serotonin transporter (SERT) binding. Irritable bowel syndrome (IBS) criteria were fulfilled in 17 patients and were linked to higher ¹2 3 I-FP-CIT binding in the right posterior putamen and adjacent areas as compared to patients without IBS. No other significant associations between gastrointestinal symptoms and DAT or SERT binding were found. These findings suggest that PD patients with IBS may have higher DAT binding in the right hemisphere. This finding implicates alterations of brain neurotransmitter physiology in the gastrointestinal symptoms of PD patients.

A Role for the Serotonin Transporter in the Largely Unknown Molecular Pathophysiology of Premenstrual Dysphoric Disorder

Despite a prevalence of approximately 5% in females, premenstrual dysphoric disorder (PMDD) suffers from a lack of investigation at the neurochemical level in humans. The preferred fundamental study design in PMDD is to investigate neurobiology across the menstrual cycle, which inherently rules out direct brain tissue assays from postmortem study that are unable to be repeated in the same participant. Therefore, molecular imaging methods applicable for longitudinal designs are highly relevant for creating advances in PMDD. SEE CORRESPONDING ARTICLE ON PAGE 1081 SEE CORRESPONDING ARTICLE ON PAGE 1081 Increase in Serotonin Transporter Binding in Patients With Premenstrual Dysphoric Disorder Across the Menstrual Cycle: A Case-Control Longitudinal Neuroreceptor Ligand Positron Emission Tomography Imaging StudyBiological PsychiatryVol. 93Issue 12PreviewPremenstrual dysphoric disorder (PMDD) disrupts the lives of millions of people each month. The timing of symptoms suggests that hormonal fluctuations play a role in the pathogenesis. Here, we tested whether a heightened sensitivity of the serotonin system to menstrual cycle phase underlies PMDD, assessing the relationship of serotonin transporter (5-HTT) changes with symptom severity across the menstrual cycle. Full-Text PDF

Permutation-based inference for function-on-scalar regression with an application in PET brain imaging

The density of various proteins throughout the human brain can be studied through the use of positron emission tomography (PET) imaging. We report here on data from a study of serotonin transporter (5-HTT) binding. While PET imaging data analysis is most commonly performed on data that are aggregated into several discrete a priori regions of interest, in this study, primary interest is on measures of 5-HTT binding potential that are made at many locations along a continuous anatomically defined tract, one that was chosen to follow serotonergic axons. Our goal is to characterise the binding patterns along this tract and also to determine how such patterns differ between control subjects and depressed patients. Due to the nature of our data, we utilise function-on-scalar regression modelling to make optimal use of our data. Inference on both main effects (position along the tract; diagnostic group) and their interactions are made using permutation testing strategies that do not require distributional assumptions. Also, to investigate the question of homogeneity we implement a permutation testing strategy, which adapts a ‘block bootstrapping’ approach from time series analysis to the functional data setting.

Journal Digest: CBT With Cardiac Rehab, PMDD Neurochemistry, and More

Back to table of contents Previous article Next article Journal DigestFull AccessJournal Digest: CBT With Cardiac Rehab, PMDD Neurochemistry, and MoreNick ZagorskiNick ZagorskiSearch for more papers by this authorPublished Online:24 Mar 2023https://doi.org/10.1176/appi.pn.2023.04.3.14Antidepressants May Induce Resistance to AntibioticsiStock/SproetniekAntidepressants can induce bacterial resistance to antibiotics, according to a report in PNAS.“While antibiotics are acknowledged as the major driver of increasing antibiotic resistance, little attention is paid to the contribution of antidepressants in this process,” wrote the study authors from the University of Queensland and colleagues.For the study, the researchers exposed E. coli bacteria to five commonly prescribed antidepressants: agomelatine, bupropion, duloxetine, escitalopram, and sertraline—each at five different concentrations (0.1, 1, 10, 50 and 100 mg/ml) for 60 days.After 60 days, exposure to all antidepressants was associated with increased growth of antibiotic-resistant bacteria at significantly faster rates compared with no exposure to antidepressants. Additionally, antibiotic resistance developed faster at higher doses.“Strikingly, the antidepressants sertraline and duloxetine at clinically relevant concentrations in colon (e.g., 50 mg/L) caused an effect after only 1 [day] of exposure,” the authors noted.After examining expression of genes and proteins in these bacteria, the researchers concluded that enhanced production of reactive oxygen molecules following exposure to antidepressants was associated with increased antibiotic resistance.“[O]ur findings highlight the need to re-evaluate the antibiotic-like side effects of antidepressants,” the researchers wrote.Wang Y, Yu Z, Ding P, et al. Antidepressants Can Induce Mutation and Enhance Persistence Toward Multiple Antibiotics. Proc Natl Acad Sci USA. 2023; 120(5): e2208344120. Poor Insight May Increase Risk of Relapse for Psychotic DepressioniStock/FG TradeSome research has shown that people with psychotic depression who have poor insight about their delusions are less likely to achieve depression remission. A report in the Journal of Affective Disorders now suggests such poor insight does not increase the risk of relapse if remission is achieved.Investigators at the University of Toronto and colleagues reviewed data from the STOP-PD II trial, which evaluated the efficacy of a combination of sertraline and olanzapine versus sertraline only for treating psychotic depression in adults. STOP-PD II had three phases: acute, stabilization, and randomized continuation.For the acute phase, adults with psychotic depression received a combination of sertraline (150-200 mg/d) and olanzapine (15-20 mg/d) for up to 12 weeks. Participants who achieved remission (absence of delusions and hallucinations) were then eligible to enroll in an eight-week stabilization phase, where they continued on the same medication regimen. Participants who remained in remission during the stabilization phase were then randomized to continue taking the sertraline-olanzapine combination or switch to sertraline plus placebo; these participants were followed for up to 36 weeks. Patient insight into delusions was assessed at the beginning and end of the stabilization phase.A total of 126 participants entered the final phase of the trial; after 36 weeks, 67 remained in remission, 47 relapsed, and 12 left the study. The investigators found that neither the degree of insight at the start of follow-up nor the change in insight score during the stabilization phase of the trial was associated with relapse risk.“Although unanticipated, this finding can provide reassurance to clinicians that residual or reemergent insight impairment following acute treatment does not preclude patients from sustaining remission of psychotic depression,” the investigators wrote.Song J, Mulsant BH, Sanches M, et al. Residual or Re-emergent Impaired Insight Into Delusions Following Remission is Unrelated to Later Relapse During a Randomized Clinical Trial of Continuation Pharmacotherapy for Psychotic Depression - The STOP-PD II Study. J Affect Disord. 2023; 325: 29-34. Adjunct CBT Can Boost Cardiac Rehabilitation OutcomesiStock/bojanstoryAdding a few sessions of cognitive-behavioral therapy (CBT) to regular cardiac rehabilitation may reduce depression and anxiety symptoms in patients with heart disease. These findings come from a clinical study published in European Heart Journal.For the study, researchers at Bispebjerg and Frederiksberg Hospital in Copenhagen enrolled 147 adults (average age 54) who were recently diagnosed with coronary artery disease or valvular heart disease and were experiencing psychological distress (defined as a score of 8 or higher on the Hospital Anxiety and Depression Scale, or HADS). All participants received eight weeks of cardiac rehabilitation, which consisted of twice weekly exercise sessions along with education about heart disease, managing risk factors, dietary counseling, and more. Half of the participants also received five, two-hour sessions of group CBT delivered by a trained cardiac nurse.After three months, HADS scores (which averaged 17 at baseline) dropped by eight points among the participants who received CBT in combination with cardiac rehabilitation; in the group receiving cardiac rehabilitation only, these scores dropped by four points. The differences between the two groups remained after six months.The adults who received CBT also reported greater improvement in emotional quality of life at six months compared with those receiving cardiac rehabilitation alone. The adults in both groups reported similar physical quality of life.After 12 months, fewer adults receiving CBT were readmitted to a hospital for a cardiovascular issue than those receiving rehabilitation alone (25% vs. 49%, respectively).“Brief group cognitive-behavioral therapy delivered by cardiac nurses may reduce psychological distress and morbidity in the short term, and may be integrated with existing [cardiac rehabilitation] programmes,” the authors concluded.Holdgaard A, Eckhardt-Hansen C, Lassen CF, et al. Cognitive-Behavioural Therapy Reduces Psychological Distress in Younger Patients With Cardiac Disease: A Randomized Trial. Eur Heart J. 2023; 44(11):986-996. Autism Does Not Appear to Accelerate Cognitive AgingiStock/Yaraslau SaulevichGiven the cognitive symptoms associated with autism spectrum disorder (ASD), some researchers have hypothesized that adults with ASD may be prone to accelerated cognitive aging. A longitudinal study appearing in Psychiatry Research now questions this theory.“Even on cognitive domains where autistic adults generally seem to experience more difficulties compared to non-autistic adults (fluency, theory of mind), and on tasks where longitudinal changes were most prominent across groups (response speed, fluency, inhibition, verbal memory) no significant differences in cognitive change between those with and without an autism diagnosis were observed,” wrote the authors from the University of Amsterdam.The study involved adults aged 25 to 85 years, including 128 with ASD and 112 without ASD. These participants received a cognitive test battery multiple times over an average of 3.5 years. The tests assessed 15 different cognitive variables.Although the adults with ASD self-reported more cognitive difficulties at baseline, the researchers found age-related changes in cognition appeared similar in adults with and without ASD.“[D]ifferences in development in various cognitive domains observed in the first stages of life of autistic individuals do not seem to persist or retrace in later stages of life,” the authors wrote. Still, they cautioned that “careful interpretation of the current conclusions is essential, and more longitudinal research is key to understand cognitive decline in older autistic adults precisely, and more generally throughout the autistic population.”Torenvliet C, Groenman AP, Radhoe TA, et al. A Longitudinal Study on Cognitive Aging in Autism. Psychiatry Research. 2023; 321: 115063. PMDD Symptoms May Be Tied to Serotonin UptakeiStock/AndreusA brain imaging study suggests that women with premenstrual dysphoric disorder (PMDD) have more unused serotonin transporters during their premenstrual cycle than women without the disorder. This study, which was published in Biological Psychiatry, also showed that the number of available transporters correlated with the severity of depressive symptoms in the women with PMDD.Investigators at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, and colleagues conducted PET scans of 30 women with PMDD and 29 matched women without this disorder. All participants were scanned during both their premenstrual phase and preceding periovulatory phase and they completed mood and irritability assessments shortly before each scan.During periovulation, both groups of women showed similar levels of occupied versus available serotonin transporters in the midbrain. During the premenstrual phase, however, the number of available serotonin transporters increased by 18% in women with PMDD (indicating less serotonin movement across neural synapses) while it decreased by 10% in women without PMDD. Women with PMDD who experienced the greatest changes in serotonin transporter availability between the premenstrual and periovulatory phases also reported the greatest increases in depressive symptoms. There was no association between transporter availability and irritability scores.“These data suggest cycle-specific dynamics with increased central serotonergic uptake followed by extracellular serotonin loss underlying the premenstrual onset of depressed mood in patients,” the authors wrote. “These neurochemical findings argue for systematic testing of presymptom-onset dosing of selective serotonin reuptake inhibitors or non-pharmacological strategies to augment extracellular serotonin in PMDD.”Sacher J, Zsido RG, Barth C, et al. Increase in Serotonin Transporter Binding in Patients with Premenstrual Dysphoric Disorder Across the Menstrual Cycle: A Case-Control Longitudinal Neuroreceptor Ligand PET Imaging Study. Biol Psychiatry. January 18, 2023. Online ahead of print. Psychotrauma Screen Trauma Screen Adapted for Use in IraniStock/FatCameraTrauma is a global issue and a public health concern. A multinational team led by investigators at Iran’s Kermanshah University of Medical Sciences has created and tested a Persian version of the Global Psychotrauma Screen (GPS)—a brief self-report instrument that screens for a range of trauma-related psychological symptoms.The GPS is a 22-item yes/no screen that assesses symptoms of posttraumatic stress disorder (PTSD), depression, anxiety, sleep problems, and dissociation, as well as risk and protective factors.“Kermanshah city, located in the western part of Iran, has experienced multiple wars over the past eight years, involving both airstrikes and ground battles. The area is also one of the most earthquake-prone areas of the world,” the investigators wrote in BMC Psychiatry. “Although several [PTSD] instruments exist in Iran, there is no brief screening tool available that assesses the wide range of psychological reactions to a potentially traumatic event.”The team first constructed a Persian-language version of the GPS with the aid of psychotrauma experts and 30 lay volunteers. The proposed screen was then tested alongside the PTSD Checklist for DSM-5 (PCL-5) and the General Health Questionnaire (GHQ) in 800 adults who had lived through the 2017 Kermanshah earthquake.A comparison of the three assessments suggested that the Persian GPS was consistent and reliable at measuring participants’ trauma symptoms, and that a score above nine suggests a possible PTSD diagnosis. They also found that 52% of the respondents scored above nine, highlighting the high degree of trauma in the region. ■Salimi Y, Hoeboer C, Motevalli Haghi SA, et al. Trauma and its Consequences in Iran: Cross-Cultural Adaption and Validation of the Global Psychotrauma Screen in a Representative Sample. BMC Psychiatry. 2023; 23(1): 65. ISSUES NewArchived

In vivo serotonin transporter and 1A receptor binding potential and ecological momentary assessment (EMA) of stress in major depression and suicidal behavior

We examined relationships between the serotonin system and stress in major depression and suicidal behavior. Twenty-five medication-free depressed participants (13 suicide attempters) underwent same-day [11C]DASB and [11C]CUMI-101 positron emission tomography (PET) imaging. Binding potential (BPND) to the serotonin transporter (5-HTT) and serotonin 1A (5-HT1A) receptor, respectively, was quantified using the NRU 5-HT atlas, reflecting distinct spatial distributions of multiple serotonin targets. Ecological momentary assessment (EMA) measured current stress over one week proximal to imaging. EMA stress did not differ between attempters and non-attempters. In all depressed participants, 5-HTT and 5-HT1A BPND were unrelated to EMA stress. There were region-specific effects of 5-HTT (p=0.002) and 5-HT1A BPND (p=0.03) in attempters vs. nonattempters. In attempters, region-specific associations between 5-HTT (p=0.03) and 5-HT1A (p=0.005) BPND and EMA stress emerged. While no post-hoc 5-HTT BPND correlations were significant, 5-HT1A BPND correlated positively with EMA stress in attempters in 9/10 regions (p-values<0.007), including the entire cortex except the largely occipital region 5. Brodmann-based regional analyses found diminished effects for 5-HTT and subcortically localized positive corrrelations between 5-HT1A and EMA stress, in attempters only. Given comparable depression severity and childhood and current stress between attempters and nonattempters, lower 5-HTT binding in attempters vs. nonattempters may suggest a biological risk marker. Localized lower 5-HTT and widespread higher 5-HT1A binding with stress among attempters specifically may suggest that a serotonergic phenotype might be a key determinant of risk or resiliency for suicidal behavior.

Serotonergic and dopaminergic control of impulsivity in gambling disorder.

Gambling disorder (GD) is major public health issue. The disorder is often characterized by elevated impulsivity with evidence from analogous substance use disorders underlining prominent roles of brain monoamines in addiction susceptibility and outcome. Critically, GD allows the study of addiction mechanisms without the confounder of the effects of chronic substances. Here, we assessed the roles of striatal dopamine transporter binding and extrastriatal serotonin transporter binding in GD as a function of impulsivity using [123 I]FP-CIT SPECT imaging in 20 older adults with GD (DSM-5 criteria; mean age 64 years) and 40 non-GD age- and sex-matched controls. We focused on GD in older individuals because there are prominent age-related changes in neurotransmitter function and because there are no reported neuroimaging studies of GD in older adults. Volume-of-interest-based and voxelwise analyses were performed. GD patients scored clearly higher on impulsivity and had higher tracer binding in the ventromedial prefrontal cortex than controls (p < 0.001), likely reflecting serotonin transporter activity. The binding in the medial prefrontal cortex positively correlated with impulsivity over the whole sample (r = 0.62, p < 0.001) as well as separately in GD patients (r = 0.46, p = 0.04) and controls (r = 0.52, p < 0.001). Striatal tracer binding, reflecting dopamine transporter activity was also positively correlated with impulsivity but showed no group differences. These findings highlight the role of prefrontal serotonergic function in GD and impulsivity. They identify cerebral coordinates of a potential target for neuromodulation for both GD and high impulsivity, a core phenotypic dimensional cognitive marker in addictions.

Serotonin Transporter Imaging in Multiple System Atrophy and Parkinson's Disease.

Both Parkinson's disease (PD) and multiple system atrophy (MSA) exhibit degeneration of brainstem serotoninergic nuclei, affecting multiple subcortical and cortical serotoninergic projections. In MSA, medullary serotoninergic neuron pathology is well documented, but serotonin system changes throughout the rest of the brain are less well characterized. To use serotonin transporter [11 C]3-amino-4-(2-dimethylaminomethyl-phenylsulfaryl)-benzonitrile positron emission tomography (PET) to compare serotoninergic innervation in patients with MSA and PD. We performed serotonin transporter PET imaging in 18 patients with MSA, 23 patients with PD, and 16 healthy controls to explore differences in brainstem, subcortical, and cortical regions of interest. Patients with MSA showed lower serotonin transporter distribution volume ratios compared with patients with PD in the medulla, raphe pontis, ventral striatum, limbic cortex, and thalamic regions, but no differences in the dorsal striatal, ventral anterior cingulate, or total cortical regions. Controls showed greater cortical serotonin transporter binding compared with PD or MSA groups but lower serotonin transporter binding in the striatum and other relevant basal ganglia regions. There were no regional differences in binding between patients with MSA-parkinsonian subtype (n=8) and patients with MSA-cerebellar subtype (n=10). Serotonin transporter distribution volume ratios in multiple different regions of interest showed an inverse correlation with the severity of Movement Disorders Society Unified Parkinson's Disease Rating Scale motor score in patients with MSA but not patients with PD. Brainstem and some forebrain subcortical region serotoninergic deficits are more severe in MSA compared with PD and show an MSA-specific correlation with the severity of motor impairments. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Hippocampal volume changes in a pharmacological sex-hormone manipulation risk model for depression in women

Hormone transition phases may trigger depression in some women, yet the underlying mechanisms remain elusive. In a pharmacological sex-hormone manipulation model, we previously reported that estradiol reductions, induced with a gonadotropin-releasing hormone agonist (GnRHa), provoked subclinical depressive symptoms in healthy women, especially if neocortical serotonin transporter (SERT) binding also increased. Within this model, we here evaluated if GnRHa, compared to placebo, reduced hippocampal volume, in a manner that depended on the magnitude of the estradiol decrease and SERT binding, and if this decrease translated to the emergence of subclinical depressive symptoms.Sixty-three healthy, naturally cycling women were included in a randomized, double-blind, placebo-controlled GnRHa-intervention study. We quantified the change from baseline to follow-up (n = 60) in serum estradiol (ΔEstradiol), neocortical SERT binding ([11C] DASB positron emission tomography; ΔSERT), subclinical depressive symptoms (Hamilton depression rating scale; ΔHAMD-17), and hippocampal volume (magnetic resonance imaging data analyzed in Freesurfer 7.1, ΔHippocampus). Group differences in ΔHippocampus were evaluated in a t-test. Within the GnRHa group, associations between ΔEstradiol, ΔHippocampus, and ΔHAMD-17, in addition to ΔSERT-by-ΔEstradiol interaction effects on ΔHippocampus, were evaluated with linear regression models.Mean ΔHippocampus was not significantly different between the GnRHa and placebo group. Within the GnRHa group, hippocampal volume reductions were associated with the magnitude of estradiol decrease (p = 0.04, Cohen's f2 = 0.18), controlled for baseline SERT binding, but not subclinical depressive symptoms. There was no ΔSERT-by-ΔEstradiol interaction effects on ΔHippocampus.If replicated, our data highlight a possible association between estradiol fluctuations and hippocampal plasticity, adjusted for serotonergic contributions.

Impact of serotonin transporter (SERT) binding affinity on the risk of libido disorders related to antidepressants

IntroductionSexual dysfunction is a frequent adverse drug reaction (ADR) of antidepressants that considerably affects quality of life and adherence to therapy. We previously investigated the potential underlying neurofunctional mechanisms by neuroimaging methods and revealed a dampening of the dopaminergic mesolimbic-mesocortical reward system along with decreased sexual functioning under serotonergic antidepressants compared to placebo.ObjectivesWithin a combined pharmacoepidemiologic and pharmacodynamic approach, we examined the association between serotonin transporter (SERT) affinity of various antidepressants and corresponding alterations in sexual desire as ADR.MethodsUsing disproportionality analyses, reporting odds ratios (RORs) were calculated for reports indicating decreased sexual desire as ADR under the antidepressants. The data were extracted from the WHO global database of individual case safety reports VigiBase and several MedDRA terms were grouped for “Sexual Desire Disorders”. For the pharmacodynamic assessment, we calculated Pearson correlation coefficients between SERT affinity and corresponding RORsResults16 signals were detected for “Sexual Desire Disorders”. We observed a statistically significant (r (20) =. 65, p = 0.001) association between SERT affinity and decreased sexual desire. Higher SERT affinity was associated with higher risk of sexual desire.ConclusionsWhile sexual dysfunctions under serotonergic medication were previously described, we now elaborated that in particular attenuated sexual desire as ADR is associated with SERT affinity of the antidepressant. These results strengthen our previously described neurofunctional model regarding sexual dysfunction under antidepressant medication and indicate that the specific SERT affinity of the antidepressant drug should be considered in clinical practice to minimize the risk of this ADR.DisclosureNo significant relationships.

Serotonin transporter binding in major depressive disorder: impact of serotonin system anatomy.

Serotonin transporter (5-HTT) binding deficits are reported in major depressive disorder (MDD). However, most studies have not considered serotonin system anatomy when parcellating brain regions of interest (ROIs). We now investigate 5-HTT binding in MDD in two novel ways: (1) use of a 5-HTT tract-based analysis examining binding along serotonergic axons; and (2) using the Copenhagen University Hospital Neurobiology Research Unit (NRU) 5-HT Atlas, based on brain-wide binding patterns of multiple serotonin receptor types. [11C]DASB 5-HTT PET scans were obtained in 60 unmedicated participants with MDD in a current depressive episode and 31 healthy volunteers (HVs). Binding potential (BPP) was quantified with empirical Bayesian estimation in graphical analysis (EBEGA). Within the [11C]DASB tract, the MDD group showed significantly lower BPP compared with HVs (p = 0.02). This BPP diagnosis difference also significantly varied by tract location (p = 0.02), with the strongest MDD binding deficit most proximal to brainstem raphe nuclei. NRU 5-HT Atlas ROIs showed a BPP diagnosis difference that varied by region (p < 0.001). BPP was lower in MDD in 3/10 regions (p-values < 0.05). Neither [11C]DASB tract or NRU 5-HT Atlas BPP correlated with depression severity, suicidal ideation, suicide attempt history, or antidepressant medication exposure. Future studies are needed to determine the causes of this deficit in 5-HTT binding being more pronounced in proximal axon segments and in only a subset of ROIs for the pathogenesis of MDD. Such regional specificity may have implications for targeting antidepressant treatment, and may extend to other serotonin-related disorders.

Accelerated HF-rTMS Modifies SERT Availability in the Subgenual Anterior Cingulate Cortex: A Canine [11C]DASB Study on the Serotonergic System.

Repetitive transcranial magnetic stimulation (rTMS) is thought to partly exert its antidepressant action through the serotonergic system. Accelerated rTMS may have the potential to result in similar but faster onset of clinical improvement compared to the classical daily rTMS protocols, but given that delayed clinical responses have been reported, the neurobiological effects of accelerated paradigms remain to be elucidated including on this neurotransmitter system. This sham-controlled study aimed to evaluate the effects of accelerated high frequency rTMS (aHF-rTMS) over the left frontal cortex on the serotonin transporter (SERT) in healthy beagle dogs. A total of twenty-two dogs were randomly divided into three unequal groups: five active stimulation sessions (five sessions in one day, n = 10), 20 active stimulation sessions (five sessions/day for four days, n = 8), and 20 sham stimulation sessions (five sessions/day for four days, n = 4). The SERT binding index (BI) was obtained at baseline, 24 h post stimulation protocol, one month, and three months post stimulation by a [11C]DASB PET scan. It was found that one day of active aHF-rTMS (five sessions) did not result in significant SERT BI changes at any time point. For the 20 sessions of active aHF-rTMS, one month after stimulation the SERT BI attenuated in the sgACC. No significant SERT BI changes were found after 20 sessions of sham aHF-rTMS. A total of four days of active aHF-rTMS modified sgACC SERT BI one month post-stimulation, explaining to some extent the delayed clinical effects of accelerated rTMS paradigms found in human psychopathologies.

Translational PET Imaging of Spinal Cord Injury with the Serotonin Transporter Tracer [11C]AFM.

The descending raphespinal serotonin (5-HT) system contributes to neural activities required for locomotion. The presynaptic serotonin transporter (SERT) is a marker of 5-HT innervation. In this study, we explored the use of PET imaging with the SERT radioligand [11C]AFM as a biomarker of 5-HT axon damage after spinal cord injury (SCI) in a rodent model and its translation to imaging SCI in humans. PET imaging with [11C]AFM was performed in healthy rats under baseline and citalopram blocking conditions and a mid-thoracic transection rat model of SCI. The lumbar-to-cervical activity (L/C) ratio was calculated for the healthy and SCI animals to assess SERT binding decrease after SCI. Finally, translation of [11C]AFM PET was attempted to explore its potential to image SCI in humans. Intense uptake in the brain and intact spinal cord was observed at 30-60min post-injection of [11C]AFM in healthy rats. About 65% of [11C]AFM uptake in the spinal cord was blocked by citalopram. In the SCI rat model, the cervical uptake of [11C]AFM was similar to that in healthy rats, but the lumbar uptake was dramatically reduced, resulting in about half the L/C ratio in SCI rats compared to healthy rats. In contrast, [11C]AFM uptake in the human spinal cord showed no obvious decrease after treatment with citalopram. In the human subjects with SCI, decreases in [11C]AFM uptake were also not obvious in the section of spinal cord caudal to the injury point. [11C]AFM PET imaging of SERT provides a useful preclinical method to non-invasively visualize the rodent spinal cord and detect SERT changes in SCI rodent models. However, there appears to be little detectable specific binding signal for [11C]AFM in the human spinal cord. An SERT tracer with higher affinity and lower non-specific binding signal is needed to image the spinal cord in humans and to assess the axonal status in SCI patients.

Chronic Social Defeat During Adolescence Induces Short- and Long-Term Behavioral and Neuroendocrine Effects in Male Swiss-Webster Mice.

Chronic stress exposure during adolescence is a significant risk factor for the development of depression. Chronic social defeat (CSD) in rodents is an animal model of depression with excellent ethological, predictive, discriminative, and face validity. Because the CSD model has not been thoroughly examined as a model of stress-induced depression within the adolescence stage, the present study analyzed the short- and long-term behavioral and neuroendocrine effects of CSD during early adolescence. Therefore, adolescent male Swiss-Webster (SW) mice were exposed to the CSD model from postnatal day (PND) 28 to PND37. Twenty-four hours (mid-adolescence) or 4 weeks (early adulthood) later, mice were tested in two models of depression; the social interaction test (SIT) and forced swimming test (FST); cognitive deficits were evaluated in the Barnes maze (BM). Finally, corticosterone and testosterone content was measured before, during, and after CSD exposure, and serotonin transporter (SERT) autoradiography was studied after CSD in adolescent and adult mice. CSD during early adolescence induced enduring depression-like behaviors as inferred from increased social avoidance and immobility behavior in the SIT and FST, respectively, which correlated in an age-dependent manner with SERT binding in the hippocampus; CSD during early adolescence also induced long-lasting learning and memory impairments in the Barnes maze (BM). Finally, CSD during early adolescence increased serum corticosterone levels in mid-adolescence and early adulthood and delayed the expected increase in serum testosterone levels observed at this age. In conclusion: (1) CSD during early adolescence induced long-lasting depression-like behaviors, (2) sensitivity of SERT density during normal brain development was revealed, (3) CSD during early adolescence induced enduring cognitive deficits, and (4) results highlight the vulnerability of the adolescent brain to social stressors on the adrenal and gonadal axes, which emphasizes the importance of an adequate interaction between both axes during adolescence for normal development of brain and behavior.