Effects of C825T polymorphism of the GNB3 gene on availability of dopamine transporter in healthy volunteers — A SPECT study

Striatal Dopamine Transporter Availability is Associated with Sleep Disturbance among Patients with Bipolar I Disorder: A Single-photon Emission Computed Tomography Study Using [99mTc] TRODAT-1

OBJECTIVE

Bipolar disorder (BD) is characterized by the poor sleep quality. Whether the striatal dopamine transporter (DAT) availability is related to sleep quality among patients with BD is unclear.

METHODS

Fifty-three euthymic patients with BD (24 BD-I and 29 BD-II) and sixty-eight healthy controls were enrolled. The Chinese Version of the Pittsburgh Sleep Quality Index (PSQI) was used, and the availability of DAT was assessed by single-photon emission computed tomography (SPECT) using [^99mTc] TRODAT-1.

RESULTS

The sleep disturbance component of the PSQI was significantly associated with the level of DAT availability among patients with BD.

CONCLUSION

The striatal dopaminergic activity that contributes to resilience to adversity was associated with sleep pattern among patients with BD.

A pilot study on the association between the blood oxygen level-dependent signal in the reward system and dopamine transporter availability in adults with attention deficit hyperactivity disorder

BACKGROUND

It is well-known that attention deficit hyperactivity disorder (ADHD) is associated with changes in the dopaminergic system. However, the relationship between central dopaminergic tone and the blood oxygen level-dependent (BOLD) signal during receipt of rewards and penalties in the corticostriatal pathway in adults with ADHD is unclear.

METHODS

Single-photon emission computed tomography with [99mTC]TRODAT-1 was used to assess striatal dopamine transporter (DAT) availability. Event-related functional magnetic resonance imaging was conducted on subjects performing the Iowa Gambling Test.

RESULT

DAT availability was found to be associated with the BOLD response, which was a covariate of monetary loss, in the medial prefrontal cortex (r = 0.55, P = .03), right ventral striatum (r = 0.69, P = .003), and right orbital frontal cortex (r = 0.53, P = .03) in adults with ADHD. However, a similar correlation was not found in the controls.

CONCLUSIONS

The results confirmed that dopaminergic tone may play a different role in the penalty-elicited response of adults with ADHD. It is plausible that a lower neuro-threshold accompanied by insensitivity to punishment could be exacerbated by the hypodopaminergic tone in ADHD.

Availability of Striatal Dopamine Transporter in Healthy Individuals With and Without a Family History of ADHD

OBJECTIVE

ADHD is the most prevalent neurodevelopmental disorder. It is highly heritable and multifactorial, but the definitive causes remain unknown. Abnormal dopamine transporter (DAT) availability has been reported, but the data are inconsistent. The aim of this study was to examine whether DAT availability differs between healthy parents with and without ADHD offspring.

METHOD

Eleven healthy parents with ADHD offspring and 11 age- and sex-matched healthy controls without ADHD offspring were recruited. The availability of DAT was approximated using single-photon emission computed tomography, with [^99mTc] TRODAT-1 as the ligand.

RESULTS

DAT availability in the basal ganglia, caudate nucleus, and putamen was significantly lower in the parents with ADHD offspring than in the healthy controls without ADHD offspring.

CONCLUSION

The results suggest that ADHD could be heritable via abnormal DAT activities.

Availability of dopamine transporters and auditory P300 abnormalities in adults with attention-deficit hyperactivity disorder: preliminary results

OBJECTIVE

Previous studies have indicated that there is dopamine transporter (DAT) dysregulation and P300 abnormality in adults with attention-deficit hyperactivity disorder (ADHD); however, the correlations among the three have not been fully explored.

METHODS

A total of 11 adults (9 males and 2 females) with ADHD and 11 age-, sex-, and education-level-matched controls were recruited. We explored differences in DAT availability using single-photon emission computed tomography and P300 wave of event-related potentials between the two groups. The correlation between DAT availability and P300 performance was also examined.

RESULTS

DAT availability in the basal ganglia, caudate nucleus, and putamen was significantly lower in the ADHD group. Adults with ADHD had lower auditory P300 amplitudes at the Pz and Cz sites, as well as longer Fz latency than controls. DAT availability was negatively correlated to P300 latency at Pz and Fz.

CONCLUSIONS

Adults with ADHD had both abnormal DAT availability and P300 amplitude, suggesting that ADHD is linked to dysfunction of the central dopaminergic system and poor cognitive processes related to response selection and execution.

Effect of rs3910105 in the Synuclein Gene on Dopamine Transporter Availability in Healthy Subjects

PURPOSE

The present study investigated associations between dopamine transporter (DAT) availability and α-synuclein levels in cerebrospinal fluid, as well as synuclein gene (SNCA) transcripts, and the effect of single nucleotide polymorphism of SNCA on DAT availability in healthy subjects.

MATERIALS AND METHODS

The study population comprised healthy controls who underwent ¹²³I-FP-CIT single-photon emission computed tomography screening. Five SNCA probes were used to target the boundaries of exon 3 and exon 4 (SNCA-E3E4), transcripts with a long 3'UTR region (SNCA-3UTR-1, SNCA-3UTR-2), transcripts that skip exon 5 (SNCA-E4E6), and the rare short transcript isoforms that comprise exons 1-4 (SNCA-007).

RESULTS

In total, 123 healthy subjects (male 75, female 48) were included in this study. DAT availability in the caudate nucleus (p=0.0661) and putamen (p=0.0739) tended to differ according to rs3910105 genotype. In post-hoc analysis, DAT availability in the putamen was lower in subjects of TT genotype than those of CC/CT (p=0.0317). DAT availability in the caudate nucleus also showed a trend similar to that in the putamen (p=0.0597). Subjects of CT genotype with rs3910105 showed negative correlations with DAT availability in the putamen with SNCA-E3E4 (p=0.037, rho=-0.277), and SNCA-E4E6 (p=0.042, rho=-0.270), but not those of CC/TT genotypes.

CONCLUSION

This is the first study to investigate the association of rs3910105 in SNCA with DAT availability. rs3910105 had an effect on DAT availability, and the correlation between DAT availability and SNCA transcripts were significant in CT genotypes of rs3910105.

Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error

Refractive errors, including myopia, are the most frequent eye disorders worldwide and an increasingly common cause of blindness. This genome-wide association meta-analysis in 160,420 participants and replication in 95,505 participants increased the number of established independent signals from 37 to 161 and showed high genetic correlation between Europeans and Asians (>0.78). Expression experiments and comprehensive in silico analyses identified retinal cell physiology and light processing as prominent mechanisms, and also identified functional contributions to refractive-error development in all cell types of the neurosensory retina, retinal pigment epithelium, vascular endothelium and extracellular matrix. Newly identified genes implicate novel mechanisms such as rod-and-cone bipolar synaptic neurotransmission, anterior-segment morphology and angiogenesis. Thirty-one loci resided in or near regions transcribing small RNAs, thus suggesting a role for post-transcriptional regulation. Our results support the notion that refractive errors are caused by a light-dependent retina-to-sclera signaling cascade and delineate potential pathobiological molecular drivers.

Effects of rs591323 on serotonin transporter availability in healthy male subjects

OBJECTIVES

We aimed to investigate the association between genetic factors of SNPs dopamine transporter (DAT) and serotonin transporter (SERT) availabilities in healthy controls.

METHODS

The study population consisted of healthy controls with screening ¹²³I-FP-CIT single-photon emission computed tomography. Specific binding of ¹²³I-FP-CIT regarding DAT and SERT was calculated using a region of interest analysis. VOI template was applied to measure specific binding ratios (SBRs) of caudate nucleus, putamen, striatum, midbrain, and pons.

RESULTS

One hundred sixty healthy controls (male 106, female 54, 61.0 ± 11.5 years) were included in this study. Sex difference did not exist in DAT availabilities of caudate nucleus (p = 0.5344), putamen (p = 0.5006), and striatum (p = 0.5056). However, male subjects had higher SERT availabilities of both midbrain (p = 0.0436), and pons (p = 0.0061). Therefore, we analyzed the effect of SNP on DAT availabilities of subjects in all, and that on SERT availabilities of males and females separately. None of 19 SNPs included in this study showed the effect on DAT availabilities. However, rs591323 in Fibroblast Growth Factor 20 on chromosome 8 had a significant impact on SERT availability of both midbrain (p = 0.0056) and pons (p = 0.0007).

CONCLUSION

SNP rs591323 of risk loci for Parkinson's disease is associated with SERT availability of healthy male subjects.

Unaltered Dopamine Transporter Availability in Drug-Naive Patients With Schizophrenia After 6 Months of Antipsychotics Treatment: A Naturalistic Study

BACKGROUND

Dopaminergic dysfunction, namely, dopamine transporter (DAT) availability variations in patients with drug-naive schizophrenia after long-term treatment, is still not well understood. The aims of the study were to explore (i) whether the DAT availability in patients with drug-naive schizophrenia differed after antipsychotic treatment and (ii) whether treatment with different generations of antipsychotics influenced the DAT availability after follow-up for 6 months.

METHODS

Twenty-four first-episode, drug-naive patients with schizophrenia were divided into first- and second-generation antipsychotic groups naturalistically. After 6 months of follow-up, 7 patients who received first-generation antipsychotic treatment and 17 patients who received second-generation antipsychotic treatment completed the study. The patients underwent premedication and 6-month follow-up measurements using single-photon emission computed tomography with technetium Tc 99m (Tc) TRODAT-1. Psychopathological evaluations and adverse effects were recorded using appropriate scales.

RESULTS

Both of the treatment groups significantly improved according to Positive and Negative Symptoms Scale evaluation. However, no significant difference was noticed between the premedication and 6-month follow-up DAT scans. Nonsignificant differences existed even in the groups of different generations of antipsychotics.

CONCLUSIONS

Improvements in psychotic symptoms in patients with schizophrenia may not be influenced by DAT availability, even under treatment with different antipsychotics for a sufficient treatment period.

DAT versus D2 receptor binding in the rat striatum: l-DOPA-induced motor activity is better predicted by reuptake than release of dopamine

The reuptake and release of dopamine (DA) can be estimated using in vivo imaging methods by assessing the competition between endogenous DA and an administered exogenous DA transporter (DAT) and D2 receptor (D2 R) radioligand, respectively. The aim of this study was to investigate the comparative roles of DA release vs DA reuptake in the rat striatum with small animal SPECT in relation to l-DOPA-induced behaviors. DAT and D2 R binding, together with behavioral measures, were obtained in 99 rats in response to treatment with either 5 or 10 mg/kg l-DOPA or vehicle. The behavioral parameters included the distance travelled, and durations and frequencies of ambulation, sitting, rearing, head-shoulder motility, and grooming. Data were subjected to a cluster analysis and to a multivariate principal component analysis. The highest DAT binding (i.e., the lowest DA reuptake) was associated with the highest, and the lowest DAT binding (i.e., the highest DA reuptake) was associated with the lowest motor/exploratory activity. The highest and the lowest D2 R binding (i.e., the lowest and the highest DA release, respectively) were merely associated with the second highest and second lowest levels of motor/exploratory activity. These findings indicate that changes in DA reuptake in response to fluctuating DA levels offer a better prediction of motor activity than the release of DA into the synaptic cleft. This dissociation, as reflected by in vivo DAT and D2 R binding data, may be accounted for by the regulatory sensitization meachnisms that occur at D2 R binding sites in response to altered levels of DA. Synapse 70:369-377, 2016. © 2016 Wiley Periodicals, Inc.

The C825T Polymorphism of the G-Protein β3 Gene as a Risk Factor for Depression: A Meta-Analysis

Background

TheG-protein β3 gene (GNβ3) has been implicated in psychiatric illness through its effects upon intracellular transduction of several neurotransmitter receptors. Multiple studies have investigated the relationship of the C825T polymorphism of the GNβ3 gene (GNβ3 C825T) to depression and antidepressant response. However, the relationship between GNβ3 C825T and depression remains inconsistent. Therefore, here we performed a meta-analysis to investigate the role of GNβ3 C825Tin depression risk.

Methods

Published case-control studies examining the association between GNβ3 C825T and depression were systematically searched for through several electronic databases (PubMed, Scopus, Science Direct, Springer, Embase, psyINFO, and CNKI). The association between GNβ3 C825T and depression risk were assessed by odd ratios (ORs) and their 95% confidence intervals (CIs) for each study. Pooled ORs were constructed for allele contrast (C versus T), homozygote (CC versus TT) model, heterozygote (CC versus CT) model, dominant model (CC + CT versus TT), and recessive (CC versus TT+CT) model. In order to evaluate possible biases, a sensitivity analysis was conducted by sequential deletion of individual studies in an attempt to assess the contribution of each individual dataset to the pooled OR.

Results

Nine studies, including 1055 depressed patients and 1325 healthy controls, were included. A significant association between GNβ3 C825Tand depression was found to exist, suggesting that the T-allele of GNβ3 C825Tcan increase susceptibility to depression. After stratification by ethnicity, the same association was found in the Asian subpopulation, but not the Caucasian subpopulation.

Conclusions

This is the first meta-analysis to reveal a relationship between GNβ3 C825T and depression. Asian T-allele carriers of GNβ3 C825T appear to be more susceptible to depression.

Course and Predictors of Cognitive Function in Patients With Prostate Cancer Receiving Androgen-Deprivation Therapy: A Controlled Comparison

PURPOSE

Men receiving androgen-deprivation therapy (ADT) for prostate cancer may be at risk for cognitive impairment; however, evidence is mixed in the existing literature. Our study examined the impact of ADT on impaired cognitive performance and explored potential demographic and genetic predictors of impaired performance.

PATIENTS AND METHODS

Patients with prostate cancer were assessed before or within 21 days of starting ADT (n = 58) and 6 and 12 months later. Age- and education-matched patients with prostate cancer treated with prostatectomy only (n = 84) and men without prostate cancer (n = 88) were assessed at similar intervals. Participants provided baseline blood samples for genotyping. Mean-level cognitive performance was compared using mixed models; cognitive impairment was compared using generalized estimating equations.

RESULTS

ADT recipients demonstrated higher rates of impaired cognitive performance over time relative to all controls (P = .01). Groups did not differ at baseline (P > .05); however, ADT recipients were more likely to demonstrate impaired performance within 6 and 12 months (P for both comparisons < .05). Baseline age, cognitive reserve, depressive symptoms, fatigue, and hot flash interference did not moderate the impact of ADT on impaired cognitive performance (P for all comparisons ≥ .09). In exploratory genetic analyses, GNB3 single-nucleotide polymorphism rs1047776 was associated with increased rates of impaired performance over time in the ADT group (P < .001).

CONCLUSION

Men treated with ADT were more likely to demonstrate impaired cognitive performance within 6 months after starting ADT relative to matched controls and to continue to do so within 12 months after starting ADT. If confirmed, findings may have implications for patient education regarding the risks and benefits of ADT.

Lower availability of striatal dopamine transporter in generalized anxiety disorder: a preliminary two-ligand SPECT study

Dopamine and serotonin have been indirectly found to be associated with generalized anxiety disorder (GAD). The aims of this study were to examine the availabilities of the striatal dopamine transporter (DAT) and the midbrain serotonin transporter (SERT) in patients with GAD. 12 patients with GAD and 12 sex-matched, age-matched, and smoking status-matched healthy controls were recruited. The availabilities of DAT and SERT were approximated using single-photon emission computed tomography, with [Tc]TRODAT-1 and [I]ADAM as the ligands. There were several missing data for six participants with GAD in the ADAM study because of a lack of the radioligand at the time of the experiment. The DAT availability in the striatum was significantly lower in the patients with GAD than in the healthy controls. However, the SERT availability did not differ between the two groups. The results with respect to the striatal DAT level suggested a potential role in the pathophysiology of GAD.

The association between heroin expenditure and dopamine transporter availability--a single-photon emission computed tomography study

One of the consequences of heroin dependency is a huge expenditure on drugs. This underlying economic expense may be a grave burden for heroin users and may lead to criminal behavior, which is a huge cost to society. The neuropsychological mechanism related to heroin purchase remains unclear. Based on recent findings and the established dopamine hypothesis of addiction, we speculated that expenditure on heroin and central dopamine activity may be associated. A total of 21 heroin users were enrolled in this study. The annual expenditure on heroin was assessed, and the availability of the dopamine transporter (DAT) was assessed by single-photon emission computed tomography (SPECT) using [(99m)TC]TRODAT-1. Parametric and nonparametric correlation analyses indicated that annual expenditure on heroin was significantly and negatively correlated with the availability of striatal DAT. After adjustment for potential confounders, the predictive power of DAT availability was significant. Striatal dopamine function may be associated with opioid purchasing behavior among heroin users, and the cycle of spiraling dysfunction in the dopamine reward system could play a role in this association.

Oxytocin receptor gene rs53576 polymorphism modulates oxytocin-dopamine interaction and neuroticism traits--a SPECT study

Brain oxytocin and dopamine systems interact to modulate social cognitive behavior. Whether the interactions are modulated by oxytocin receptor (OXTR) gene variations remains unclear. Considering the dopamine transporter (DAT) availability as an endophenotype and the degree of dopamine-mediated neuroticism as a phenotype of the OXTR genotypes, the current molecular imaging study used [(99m)Tc]TRODAT-1 single photon emission computed tomography (SPECT) to measure the striatal DAT availability and the 57-item Maudsley Personality Inventory to measure neuroticism personality traits in healthy individuals to investigate (A) the correlation between the rs53576 (G/A) of OXTR and the striatal DAT availability, (B) the correlation between the peripheral oxytocin level and striatal DAT availability among different OXTR rs53576 (G/A) genotypes, and (C) whether neuroticism traits could be modified by oxytocin in certain OXTR rs53576 genotypes. The results showed that the striatal DAT availability in the AG+GG group was significantly lower than that in the AA group (2.08±0.47 vs. 1.90±0.32, p=0.04). Only individuals with one or two copies of the G allele of rs53576 showed a negative correlation between DAT availability and oxytocin level (r=-0.41, p=0.002). Furthermore, the oxytocin×DAT interaction was significantly correlated with the MPI neuroticism score in the AA group. Further analyses showed that the DAT availability was correlated with the neuroticism score only in the AA group with a low oxytocin level (r=0.74, p=0.002). The results indicated that the OXTR rs53576 is connected with the striatal DAT availability in vivo and modulates the interactions between the oxytocinergic and dopaminergic systems. Carriers with a specific rs53576 OXTR genotype may present a greater biological sensitivity as well as stress reactivity in terms of environmental adaptation.

Differences of various region-of-interest methods for measuring dopamine transporter availability using 99mTc-TRODAT-1 SPECT

This study was to investigate whether various region-of-interest (ROI) methods for measuring dopamine transporter (DAT) availabilities by single photon emission computed tomography (SPECT) are statistically different, whether results of medical research are thereby influenced, and causes of these differences. Eighty-four healthy adults with ^99mTc-TRODAT-1 SPECT and magnetic resonance imaging (MRI) scans were included. Six major analysis approaches were compared: (1) ROI drawn on the coregistered MRI; (2) ROIs drawn on the SPECT images; (3) standard ROI templates; (4) threshold-ROIs; (5) atlas-based mappings with coregistered MRI; and (6) atlas-based mappings with SPECT images. Using the atlas-based approaches we assessed the influence of striatum ROIs by slice-wise and voxel-wise comparisons. In (5) and (6), three partial-volume correction (PVC) methods were also explored. The results showed that DAT availabilities obtained from different methods were closely related but quite different and leaded to significant differences in determining the declines of DAT availability per decade (range: 5.95–11.99%). Use of 3D whole-striatum or more transverse slices could avoid biases in measuring the striatal DAT declines per decade. Atlas-based methods with PVC may be the preferable methods for medical research.

Lower availability of midbrain serotonin transporter between healthy subjects with and without a family history of major depressive disorder - a preliminary two-ligand SPECT study

PURPOSE

Serotonin transporter (SERT) and dopamine transporter (DAT) levels differ in patients with major depressive disorder (MDD) who are in a depressed state in comparison with healthy controls. In addition, a family history of depression is a potent risk factor for developing depression, and inherited vulnerability to serotonergic and dopaminergic dysfunction is suspected in this. The aim of this study was to examine the availabilities of midbrain SERT and striatal DAT in healthy subjects with and without a first-degree family history of MDD.

METHODS

Eight healthy subjects with first-degree relatives with MDD and 16 sex- and age-matched healthy controls were recruited. The availabilities of SERT and DAT were approximated using SPECT, employing [¹²³I] 2-((2-((dimethylamino) methyl) phenyl)thio)-5-iodophenylamine (ADAM) and [(⁹⁹m)Tc] TRODAT-1 as the ligands, respectively. There are missing data for one participant with a first-degree family history of MDD from the ADAM study, due to a lack of the radio-ligand at the time of experiment.

RESULTS

SERT availability in the midbrain was significantly lower in subjects with a first-degree family history of MDD than in healthy subjects. However, DAT availability was no different between two groups.

CONCLUSIONS

The results with regard to the midbrain SERT level suggest the heritability of MDD.

Cognitive Functions across the GNB3 C825T Polymorphism in an Elderly Italian Population

To verify whether the C825T polymorphism of the GNB3 influences the response to neuropsychological tests, mini-mental state examination, digit span (DS), immediate and delayed prose memory, memory with interference at 10 and 30 seconds (MI 10 and 30), trail making tests (TMTs) A and B, abstraction task, verbal fluency (VF) test, figure drawing and copying, overlapping figures test and clock test were performed in 220 elderly men and women free from clinical dementia and from neurological and psychiatric diseases randomly taken from the Italian general population and analysed across the C825T polymorphism. The performance of DS, immediate and delayed prose memory, VF, and TMTs was worse in subjects who were TT for the polymorphism in comparison to the C-carriers. The performance of all tests declined with age. In the case of DS, immediate and delayed prose memory, MI 10 and VF, this trend was maintained in the C-carriers but not in TT. In the case of prose memory, of memory with interference, and of VF, schooling reduced the detrimental interaction between age and genotype. The C825T polymorphism of GNB3 gene therefore influences memory and verbal fluency, being additive to the effects of age and partially mitigated by schooling.

The prevalence of metabolic syndrome in drug-naïve bipolar II disorder patients before and after twelve week pharmacological intervention

BACKGROUND

Accumulating evidence indicates a high prevalence rate of metabolic disturbance in bipolar disorder (BP) patients. However, the prevalence across BP subtypes has been investigated to a lesser degree. In the current study, we surveyed the prevalence of metabolic syndrome among drug-naïve bipolar II patients. Moreover, the effects of pharmacological treatment on metabolic indexes were also evaluated.

METHODS

This study recruited fifty-six drug-naïve BP II patients diagnosed according to the DSM-IV criteria. Among them, forty-four patients completed a 12-week pharmacological intervention with valproic acid, fluoxetine and lorazepam. Metabolic profiles and body mass index (BMI) were measured at baseline and 2 weeks, 8 weeks, and 12 weeks after receiving medication.

RESULTS

The mean age of the 56 patients was 30.3±11.1. Before receiving medication, 6.5% of the patients met the ATP III criterion for metabolic syndrome. Among the 44 patients who completed the 12-week pharmacological intervention, the prevalence of metabolic syndrome increased from 7% to 10%. Repeated measurements showed that the changes in metabolic indexes were not significant, with the exceptions of BMI, waist circumference, and buttock circumference. In addition, the interaction between the improvement of hypomanic symptoms and BMI change was significant.

LIMITATIONS

The study was limited by the follow-up duration and sample size.

CONCLUSIONS

In drug-naïve BP II patients, the prevalence of metabolic syndrome was significantly lower than that observed before in BP I patients. However, medications use was also associated with an increased risk of metabolic disturbance, although the impact was lesser. Clinical evidence suggests that metabolism and emotion homeostasis might share common mechanisms.

The genetics of selective serotonin reuptake inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are among the most widely prescribed drugs in psychiatry. Based on the fact that SSRIs increase extracellular monoamine levels in the brain, the monoamine hypothesis of depression was introduced, postulating that depression is associated with too low serotonin, dopamine and noradrenaline levels. However, several lines of evidence indicate that this hypothesis is too simplistic and that depression and the efficacy of SSRIs are dependent on neuroplastic changes mediated by changes in gene expression. Because a coherent view on global gene expression is lacking, we aim to provide an overview of the effects of SSRI treatment on the final targets of 5-HT receptor signal transduction pathways, namely the transcriptional regulation of genes. We address gene polymorphisms in humans that affect SSRI efficacy, as well as in vitro studies employing human-derived cells. We also discuss the molecular targets affected by SSRIs in animal models, both in vivo and in vitro. We conclude that serotonin transporter gene variation in humans affects the efficacy and side-effects of SSRIs, whereas SSRIs generally do not affect serotonin transporter gene expression in animals. Instead, SSRIs alter mRNA levels of genes encoding serotonin receptors, components of non-serotonergic neurotransmitter systems, neurotrophic factors, hypothalamic hormones and inflammatory factors. So far little is known about the epigenetic and age-dependent molecular effects of SSRIs, which might give more insights in the working mechanism(s) of SSRIs.