The effects of antenatal depression and antidepressant treatment on placental gene expression

Antidepressants - The new endocrine disruptors? The case of crustaceans

Antidepressants are high-volume pharmaceuticals that accumulate to concentrations in the μg·L-1 range in surface waters. The release of peptide hormones via neurosecretory cells appears as a natural target for antidepressants. Here I review research that suggests that antidepressants indeed disrupt endocrine signalling in crustaceans, by acting on the synthesis and release of neurohormones, such as crustacean hyperglycaemic hormone, moult inhibiting hormone and pigment dispersing hormone in decapods, as well as methyl farnesoate in Daphnids. Hence, antidepressants can affect hormonal regulation of physiological functions: increase in energy metabolism and activity, lowered ecdysteroid levels, potentially disrupting moult and somatic growth, reducing colour change capacity and compromising camouflage, as well as induction of male sex determination. Several studies further suggest effects of antidepressants on crustacean reproduction, but the hormonal regulation of these effects remains elusive. All things considered, a body of evidence strongly suggests that antidepressants are endocrine disrupting compounds in crustaceans.

Molecular basis underlying default mode network functional abnormalities in postpartum depression with and without anxiety

Although Postpartum depression (PPD) and PPD with anxiety (PPD-A) have been well characterized as functional disruptions within or between multiple brain systems, however, how to quantitatively delineate brain functional system irregularity and the molecular basis of functional abnormalities in PPD and PPD-A remains unclear. Here, brain sample entropy (SampEn), resting-state functional connectivity (RSFC), transcriptomic and neurotransmitter density data were used to investigate brain functional system irregularity, functional connectivity abnormalities and associated molecular basis for PPD and PPD-A. PPD-A exhibited higher SampEn in medial prefrontal cortex (MPFC) and posterior cingulate cortex (PPC) than healthy postnatal women (HPW) and PPD while PPD showed lower SampEn in PPC compared to HPW and PPD-A. The functional connectivity analysis with MPFC and PPC as seed areas revealed decreased functional couplings between PCC and paracentral lobule and between MPFC and angular gyrus in PPD compared to both PPD-A and HPW. Moreover, abnormal SampEn and functional connectivity were associated with estrogenic level and clinical symptoms load. Importantly, spatial association analyses between functional changes and transcriptome and neurotransmitter density maps revealed that these functional changes were primarily associated with synaptic signaling, neuron projection, neurotransmitter level regulation, amino acid metabolism, cyclic adenosine monophosphate (cAMP) signaling pathways, and neurotransmitters of 5-hydroxytryptamine (5-HT), norepinephrine, glutamate, dopamine and so on. These results reveal abnormal brain entropy and functional connectivities primarily in default mode network (DMN) and link these changes to transcriptome and neurotransmitters to establish the molecular basis for PPD and PPD-A for the first time. Our findings highlight the important role of DMN in neuropathology of PPD and PPD-A.

Sex-Specific Transcriptomic Changes in the Villous Tissue of Placentas of Pregnant Women Using a Selective Serotonin Reuptake Inhibitor

About 5% of pregnant women are treated with selective serotonin reuptake inhibitor (SSRI) antidepressants to treat their depression. SSRIs influence serotonin levels, a key factor in neural embryonic development, and their use during pregnancy has been associated with adverse effects on the developing embryo. However, the role of the placenta in transmitting these negative effects is not well understood. In this study, we aim to elucidate how disturbances in the maternal serotonergic system affect the villous tissue of the placenta by assessing whole transcriptomes in the placentas of women with healthy pregnancies and women with depression and treated with the SSRI fluoxetine during pregnancy. Twelve placentas of the Biology, Affect, Stress, Imaging and Cognition in Pregnancy and the Puerperium (BASIC) project were selected for RNA sequencing to examine differentially expressed genes: six male infants and six female infants, equally distributed over women treated with SSRI and without SSRI treatment. Our results show that more genes in the placenta of male infants show changed expression associated with fluoxetine treatment than in placentas of female infants, stressing the importance of sex-specific analyses. In addition, we identified genes related to extracellular matrix organization to be significantly enriched in placentas of male infants born to women treated with fluoxetine. It remains to be established whether the differentially expressed genes that we found to be associated with SSRI treatment are the result of the SSRI treatment itself, the underlying depression, or a combination of the two.

Epigenome-wide association studies of prenatal maternal mental health and infant epigenetic profiles: a systematic review

Prenatal stress and poor maternal mental health are associated with adverse offspring outcomes; however, the biological mechanisms are unknown. Epigenetic modification has linked maternal health with offspring development. Epigenome-wide association studies (EWAS) have examined offspring DNA methylation profiles for association with prenatal maternal mental health to elucidate mechanisms of these complex relationships. The objective of this study is to provide a comprehensive, systematic review of EWASs of infant epigenetic profiles and prenatal maternal anxiety, depression, or depression treatment. We conducted a systematic literature search following PRISMA guidelines for EWAS studies between prenatal maternal mental health and infant epigenetics through May 22, 2023. Of 645 identified articles, 20 fulfilled inclusion criteria. We assessed replication of CpG sites among studies, conducted gene enrichment analysis, and evaluated the articles for quality and risk of bias. We found one repeated CpG site among the maternal depression studies; however, nine pairs of overlapping differentially methylatd regions were reported in at least two maternal depression studies. Gene enrichment analysis found significant pathways for maternal depression but not for any other maternal mental health category. We found evidence that these EWAS present a medium to high risk of bias. Exposure to prenatal maternal depression and anxiety or treatment for such was not consistently associated with epigenetic changes in infants in this systematic review and meta-analysis. Small sample size, potential bias due to exposure misclassification and statistical challenges are critical to address in future efforts to explore epigenetic modification as a potential mechanism by which prenatal exposure to maternal mental health disorders leads to adverse infant outcomes.

Maternal exposure to SSRIs or SNRIs and the risk of congenital abnormalities in offspring: A systematic review and meta-analysis

BACKGROUND

The association of maternal exposure to selective serotonin reuptake inhibitors (SSRIs) or serotonin and norepinephrine reuptake inhibitors (SNRIs) with the risk of system-specific congenital malformations in offspring remains unclear. We conducted a meta-analysis to examine this association and the risk difference between these two types of inhibitors.

METHODS

A literature search was performed from January 2000 to May 2023 using PubMed and Web of Science databases. Cohort and case-control studies that assess the association of maternal exposure to SSRIs or SNRIs with the risk of congenital abnormalities were eligible for the study.

RESULTS

Twenty-one cohort studies and seven case-control studies were included in the meta-analysis. Compared to non-exposure, maternal exposure to SNRIs is associated with a higher risk of congenital cardiovascular abnormalities (pooled OR: 1.64 with 95% CI: 1.36, 1.97), anomalies of the kidney and urinary tract (pooled OR: 1.63 with 95% CI: 1.21, 2.20), malformations of nervous system (pooled OR: 2.28 with 95% CI: 1.50, 3.45), anomalies of digestive system (pooled OR: 2.05 with 95% CI: 1.60, 2.64) and abdominal birth defects (pooled OR: 2.91 with 95%CI: 1.98, 4.28), while maternal exposure to SSRIs is associated with a higher risk of congenital cardiovascular abnormalities (pooled OR: 1.25 with 95%CI: 1.20, 1.30), anomalies of the kidney and urinary tract (pooled OR: 1.14 with 95%CI: 1.02, 1.27), anomalies of digestive system (pooled OR: 1.11 with 95%CI: 1.01, 1.21), abdominal birth defects (pooled OR: 1.33 with 95%CI: 1.16, 1.53) and musculoskeletal malformations (pooled OR: 1.44 with 95%CI: 1.32, 1.56).

CONCLUSIONS

SSRIs and SNRIs have various teratogenic risks. Clinicians must consider risk-benefit ratios and patient history when prescribing medicines.

Maternal serotonin: implications for the use of selective serotonin reuptake inhibitors during gestation†

Maternal use of antidepressants has increased throughout the last decades; selective serotonin reuptake inhibitors (SSRI) are the most prescribed antidepressants. Despite the widespread use of SSRI by women during reproductive age and pregnant women, an increasing amount of research warns of possible detrimental effects of maternal use of SSRI during pregnancy including low birthweight/small for gestational age and preterm birth. In this review, we revisited the impact of maternal use of SSRI during pregnancy, its impact on serotonin homeostasis in the maternal and fetal circulation and the placenta, and its impact on pregnancy outcomes-particularly intrauterine growth restriction and preterm birth. Maternal use of SSRI increases maternal and fetal serotonin. The increase in maternal circulating serotonin and serotonin signaling likely promotes vasoconstriction of the uterine and placental vascular beds decreasing blood perfusion to the uterus and consequently to the placenta and fetus with potential impact on placental function and fetal development. Several adverse pregnancy outcomes are similar between women, sheep, and rodents (decreased placental size, decreased birthweight, shorter gestation length/preterm birth, neonatal morbidity, and mortality) highlighting the importance of animal studies to assess the impacts of SSRI. Herein, we address the complex interactions between maternal SSRI use during gestation, circulating serotonin, and the regulation of blood perfusion to the uterus and fetoplacental unit, fetal growth, and pregnancy complications.

Antidepressants induce toxicity in human placental BeWo cells

Selective serotonin reuptake inhibitors (SSRIs), serotonin and noradrenaline reuptake inhibitors (SNRIs), and noradrenergic and specific serotonergic antidepressants (NaSSAs) are broadly used for the treatment of depression. Depression is one of the most common psychiatric disorders in pregnant women and SSRIs are commonly prescribed for depression during pregnancy. The placenta regulates the transport of nutrients and oxygen between the maternal and fetal circulation, and is essential for the survival and growth of the fetus. The present study investigated the effects of antidepressants on human placental BeWo cells. BeWo cell viability was significantly decreased following exposure to sertraline (SSRI), paroxetine (SSRI), fluvoxamine (SSRI), and duloxetine (SNRI), whereas escitalopram (SSRI), venlafaxine (SNRI), and mirtazapine (NaSSA) showed little or no effects. Extracellular lactate dehydrogenase activity was increased by sertraline, paroxetine, fluvoxamine, and duloxetine, indicating toxicity to the cells. Sertraline increased the production of cellular reactive oxygen species (ROS) and decreased the mitochondrial membrane potential. Sertraline decreased the cellular ATP content in a time and concentration-dependent manner. Caspase-3/7 activity and apoptotic cells, detected using the phosphatidylserine-specific fluorescent probe Apotracker Green, were increased by sertraline. Our findings suggest that antidepressants, such as sertraline, paroxetine, fluvoxamine, and duloxetine, induce toxicity in human placental BeWo cells. Sertraline may induce ROS-dependent apoptosis in human placental cells. These results are useful for further studies to determine the optimal dosage of antidepressants for pregnant women.

Current approaches and developments in transcript profiling of the human placenta

BACKGROUND

The placenta is the active interface between mother and foetus, bearing the molecular marks of rapid development and exposures in utero. The placenta is routinely discarded at delivery, providing a valuable resource to explore maternal-offspring health and disease in pregnancy. Genome-wide profiling of the human placental transcriptome provides an unbiased approach to study normal maternal–placental–foetal physiology and pathologies.

OBJECTIVE AND RATIONALE

To date, many studies have examined the human placental transcriptome, but often within a narrow focus. This review aims to provide a comprehensive overview of human placental transcriptome studies, encompassing those from the cellular to tissue levels and contextualize current findings from a broader perspective. We have consolidated studies into overarching themes, summarized key research findings and addressed important considerations in study design, as a means to promote wider data sharing and support larger meta-analysis of already available data and greater collaboration between researchers in order to fully capitalize on the potential of transcript profiling in future studies.

SEARCH METHODS

The PubMed database, National Center for Biotechnology Information and European Bioinformatics Institute dataset repositories were searched, to identify all relevant human studies using ‘placenta’, ‘decidua’, ‘trophoblast’, ‘transcriptome’, ‘microarray’ and ‘RNA sequencing’ as search terms until May 2019. Additional studies were found from bibliographies of identified studies.

OUTCOMES

The 179 identified studies were classifiable into four broad themes: healthy placental development, pregnancy complications, exposures during pregnancy and in vitro placental cultures. The median sample size was 13 (interquartile range 8–29). Transcriptome studies prior to 2015 were predominantly performed using microarrays, while RNA sequencing became the preferred choice in more recent studies. Development of fluidics technology, combined with RNA sequencing, has enabled transcript profiles to be generated of single cells throughout pregnancy, in contrast to previous studies relying on isolated cells. There are several key study aspects, such as sample selection criteria, sample processing and data analysis methods that may represent pitfalls and limitations, which need to be carefully considered as they influence interpretation of findings and conclusions. Furthermore, several areas of growing importance, such as maternal mental health and maternal obesity are understudied and the profiling of placentas from these conditions should be prioritized.

WIDER IMPLICATIONS

Integrative analysis of placental transcriptomics with other ‘omics’ (methylome, proteome and metabolome) and linkage with future outcomes from longitudinal studies is crucial in enhancing knowledge of healthy placental development and function, and in enabling the underlying causal mechanisms of pregnancy complications to be identified. Such understanding could help in predicting risk of future adversity and in designing interventions that can improve the health outcomes of both mothers and their offspring. Wider collaboration and sharing of placental transcriptome data, overcoming the challenges in obtaining sufficient numbers of quality samples with well-defined clinical characteristics, and dedication of resources to understudied areas of pregnancy will undoubtedly help drive the field forward.

Fetal programming pathway from maternal mental health to infant cortisol functioning: The role of placental 11β-HSD2 mRNA expression

Placental 11β-HSD2 has been a focus of research for understanding potential fetal programming associated with maternal emotional disorders. This study examined the pathway from antenatal mental health via placental 11β-HSD2 mRNA to cortisol regulation in the infant offspring. This study reports on data obtained from 236 participants in the Mercy Pregnancy and Emotional Wellbeing Study (MPEWS). At term, placental tissue was collected within 30 min of birth from 52 participants meeting current criteria for a depressive disorder, and 184 control participants. Depressive disorders were diagnosed using the SCID-IV. In addition, antidepressant use, depressive and anxiety symptoms were measured in early and late pregnancy. Placental 11β-HSD2 mRNA expression was measured using qRT-PCR. Infant salivary cortisol samples were taken at 12 months of age. Women on antidepressant medication and with higher trait anxiety had higher placental 11β-HSD2 expression compared to women not taking medication. Furthermore, the offspring of women taking an antidepressant and who also had a current depressive disorder and high trait anxiety had high cortisol reactivity at 12 months of age and this was mediated through 11β-HSD2 mRNA expression. In contrast, offspring of women not taking antidepressant medication with depressive disorder and high anxiety there was low cortisol reactivity observed. Our findings suggest that the relationship between maternal antenatal depression and anxiety and infant cortisol reactivity is mediated through placental 11β-HSD2 mRNA expression. Furthermore, the direction differed for women taking antidepressants, where infant cortisol reactivity was high whereas when compared to those with unmedicated depression and anxiety, where infant cortisol reactivity was low.

Maternal Distress and Offspring Neurodevelopment: Challenges and Opportunities for Pre-clinical Research Models

Pre-natal exposure to acute maternal trauma or chronic maternal distress can confer increased risk for psychiatric disorders in later life. Acute maternal trauma is the result of unforeseen environmental or personal catastrophes, while chronic maternal distress is associated with anxiety or depression. Animal studies investigating the effects of pre-natal stress have largely used brief stress exposures during pregnancy to identify critical periods of fetal vulnerability, a paradigm which holds face validity to acute maternal trauma in humans. While understanding these effects is undoubtably important, the literature suggests maternal stress in humans is typically chronic and persistent from pre-conception through gestation. In this review, we provide evidence to this effect and suggest a realignment of current animal models to recapitulate this chronicity. We also consider candidate mediators, moderators and mechanisms of maternal distress, and suggest a wider breadth of research is needed, along with the incorporation of advanced -omics technologies, in order to understand the neurodevelopmental etiology of psychiatric risk.

Copy number variants in siblings of Mexican origin concordant for schizophrenia or bipolar disorder

Schizophrenia (SCZ) and bipolar disorder (BD) cause similar symptomatology. A correlation between these disorders has been found. We aimed to explore shared CNVs between SCZ and BD, in 35 sibpairs diagnosed with SCZ and 21 sibpairs diagnosed with BD. CNV calling was performed using data derived of Psycharray, by PennCNV. We did not find any shared CNVs between individuals diagnosed with BD and SCZ, neither with psychotic symptoms in individuals with BD. Nevertheless, we found a significant higher CNV burden in early-onset SCZ. This is one of the first's studies analyzing shared CNVs between SCZ and BD in Mexican population.

Chronic Social Defeat Stress Up-Regulates Spexin in the Brain of Nile Tilapia (Oreochromis niloticus)

Spexin (SPX), a neuropeptide evolutionarily conserved from fish to mammals, is widely distributed in the brain and peripheral tissues and associated with various physiological functions. Recently SPX has been suggested to be involved in neurological mechanism of stress. The current study investigates the involvement of SPX in chronic social defeat stress, using male teleost, the Nile tilapia (Oreochromis niloticus) as an animal model due to its distinct social hierarchy of dominant and subordinate relationship. The tilapia genome has SPX1a and SPX1b but has no SPX2. In the Nile tilapia, we localized SPX1a and SPX1b in the brain using in-situ hybridization. Next, using qPCR we examined gene expression of SPX1a and SPX1b in chronically stress (socially defeated) fish. SPX1a expressing cells were localized in the semicircular torus of the midbrain region and SPX1b expressing cells in the telencephalon. Chronically stress fish showed elevated plasma cortisol levels; with an upregulation of SPX1a and SPX1b gene expression in the brain compared to non-stress (control) fish. Since social defeat is a source of stress, the upregulated SPX mRNA levels during social defeat suggests SPX as a potentially inhibitory neuropeptide capable of causing detrimental changes in behaviour and physiology.

Comparison of serum protein profiles between major depressive disorder and bipolar disorder

BACKGROUND

Major depressive disorder and bipolar disorder are prevalent and debilitating psychiatric disorders that are difficult to distinguish, as their diagnosis is based on behavioural observations and subjective symptoms. Quantitative protein profile analysis might help to objectively distinguish between these disorders and increase our understanding of their pathophysiology. Thus, this study was conducted to compare the peripheral protein profiles between the two disorders.

METHODS

Serum samples were collected from 18 subjects with major depressive disorder and 15 subjects with bipolar disorder. After depleting abundant proteins, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and label-free quantification were performed. Data-dependent acquisition data were statistically analysed from the samples of 15 subjects with major depressive disorder and 10 subjects with bipolar disorder who were psychotropic drug-free. Two-sided t-tests were performed for pairwise comparisons of proteomes to detect differentially-expressed proteins (DEPs). Ingenuity Pathway Analysis of canonical pathways, disease and functions, and protein networks based on these DEPs was further conducted.

RESULTS

Fourteen DEPs were significant between subjects with major depressive disorder and those with bipolar disorder. Ras-related protein Rab-7a (t = 5.975, p = 4.3 × 10^- 6) and Rho-associated protein kinase 2 (t = 4.782, p = 8.0 × 10^- 5) were significantly overexpressed in subjects with major depressive disorder and Exportin-7 (t = -4.520, p = 1.5 × 10^- 4) was significantly overexpressed in subjects with bipolar disorder after considering multiple comparisons. Bioinformatics analysis showed that cellular functions and inflammation/immune pathways were significantly different.

CONCLUSIONS

Ras-related protein Rab-7a, Rho-associated protein kinase 2, and Exportin-7 were identified as potential peripheral protein candidates to distinguish major depressive disorder and bipolar disorder. Further large sample studies with longitudinal designs and validation processes are warranted.

Precision medicine in perinatal depression in light of the human microbiome

Perinatal depression is the most common complication of pregnancy and affects the mother, fetus, and infant. Recent preclinical studies and a limited number of clinical studies have suggested an influence of the gut microbiome on the onset and course of mental health disorders. In this review, we examine the current state of knowledge regarding genetics, epigenetics, heritability, and neuro-immuno-endocrine systems biology in perinatal mood disorders, with a particular focus on the interaction between these factors and the gut microbiome, which is mediated via the gut-brain axis. We also provide an overview of experimental and analytical methods that are currently available to researchers interested in elucidating the influence of the gut microbiome on mental health disorders during pregnancy and postpartum.

DeepWAS: Multivariate genotype-phenotype associations by directly integrating regulatory information using deep learning

Genome-wide association studies (GWAS) identify genetic variants associated with traits or diseases. GWAS never directly link variants to regulatory mechanisms. Instead, the functional annotation of variants is typically inferred by post hoc analyses. A specific class of deep learning-based methods allows for the prediction of regulatory effects per variant on several cell type-specific chromatin features. We here describe "DeepWAS", a new approach that integrates these regulatory effect predictions of single variants into a multivariate GWAS setting. Thereby, single variants associated with a trait or disease are directly coupled to their impact on a chromatin feature in a cell type. Up to 61 regulatory SNPs, called dSNPs, were associated with multiple sclerosis (MS, 4,888 cases and 10,395 controls), major depressive disorder (MDD, 1,475 cases and 2,144 controls), and height (5,974 individuals). These variants were mainly non-coding and reached at least nominal significance in classical GWAS. The prediction accuracy was higher for DeepWAS than for classical GWAS models for 91% of the genome-wide significant, MS-specific dSNPs. DSNPs were enriched in public or cohort-matched expression and methylation quantitative trait loci and we demonstrated the potential of DeepWAS to generate testable functional hypotheses based on genotype data alone. DeepWAS is available at https://github.com/cellmapslab/DeepWAS.

Placental glucocorticoid receptors are not affected by maternal depression or SSRI treatment

Background: Prenatal depression is common, with an estimate that up to one in five pregnant women suffers from depressive symptoms. Maternal depression is associated with poor pregnancy outcomes such as preterm birth and low birth-weight. Such outcomes possibly affect offspring development. Previous studies suggest placental RNA levels of the glucocorticoid receptor are altered by maternal depression or anxiety; this stress may affect the placenta of male and female foetuses differently. However, it is unknown if the protein levels and activity of this receptor are additionally affected in women with depressive symptoms or being pharmacologically treated for depression.Methods: In this study, we investigated whether the glucocorticoid receptor (NR3C1) in the placenta is affected by maternal depression and/or selective serotonin reuptake inhibitor (SSRIs) treatment. Placentas from 45 women with singleton, term pregnancies were analysed by Western blot to determine glucocorticoid receptor levels, and by DNA-binding capacity to measure glucocorticoid receptor activation.Results: There were no differences in levels of the glucocorticoid receptor or activity between groups (control, depressive symptoms, and SSRI treatment; n = 45). Similarly, there was no difference in placental glucocorticoid receptor levels or activity dependent upon foetal sex.Conclusion: Maternal depression and SSRI treatment do not affect the glucocorticoid receptors in the placenta.

The effect of antenatal depression and antidepressant treatment on placental tissue: a protein-validated gene expression study

Background

Antenatal depression affects 10–20% of pregnant women. Around 2–4% of European pregnant women use antidepressant treatment, most commonly selective serotonin reuptake inhibitors (SSRIs). Poor pregnancy outcomes, such as preterm birth and low birth weight, have been described in women with antenatal depression and in pregnant women on SSRI treatment. However, the effects of antenatal depression and antidepressant treatment on the placenta are largely unknown. The aim of this work was to compare placental gene and protein expression in healthy women, women with untreated antenatal depression and women on antidepressant treatment during pregnancy.

Methods

Placental samples from 47 controls, 25 depressed and 45 SSRI-treated women were analysed by means of qPCR using custom-designed TaqMan low-density arrays (TLDAs) for 44 genes previously known to be involved in the pathophysiology of depression, and expressed in the placenta. Moreover, placental protein expression was determined by means of immunohistochemistry in 37 healthy controls, 13 women with untreated depression and 21 women on antidepressant treatment. Statistical comparisons between groups were performed by one-way ANOVA or the Kruskal–Wallis test.

Results

Nominally significant findings were noted for HTR1A and NPY2R, where women with untreated depression displayed higher gene expression than healthy controls (p < 0.05), whereas women on antidepressant treatment had similar expression as healthy controls. The protein expression analyses revealed higher expression of HTR1A in placentas from women on antidepressant treatment, than in placentas from healthy controls (p < 0.05).

Conclusion

The differentially expressed HTR1A, both at the gene and the protein level that was revealed in this study, suggests the involvement of HTR1A in the effect of antenatal depression on biological mechanisms in the placenta. More research is needed to elucidate the role of depression and antidepressant treatment on the placenta, and, further, the effect on the fetus.

Antidepressant use in pregnancy: are we closer to consensus?

We specify and summarize significant data from recent large studies in a tool with which to aim at consensus on the question of whether and how serotonin-reuptake antidepressants should be used in pregnancy, on the basis that concern for the mental health of the mother should not vie for primacy with concern for the short-, medium-, and long-term health of the child, but must be best served together. Side effects are small but significant over the majority of 11 categories, perinatal and into adolescence. In clinical practice, alternatives for serotonin-reuptake medication in pregnancy should be more actively pursued.

Evolution of Structural and Functional Diversity of Spexin in Mammalian and Non-mammalian Vertebrate Species

Spexin (SPX) is a novel neuropeptide, which was first identified in the human genome using bioinformatics. Since then, orthologs of human SPX have been identified in mammalian and non-mammalian vertebrates. The mature sequence of SPX, NWTPQAMLYLKGAQ, is evolutionally conserved across vertebrate species, with some variations in teleost species where Ala at position 13 is substituted by Thr. In mammals, the gene structure of SPX comprises six exons and five introns, however, variation exists within non-mammalian species, goldfish and zebrafish having five exons while grouper has six exons. Phylogenetic and synteny analysis, reveal that SPX is grouped together with two neuropeptides, kisspeptin (KISS) and galanin (GAL) as a family of peptides with a common evolutionary ancestor. A paralog of SPX, termed SPX2 has been identified in non-mammalians but not in the mammalian genome. Ligand-receptor interaction study also shows that SPX acts as a ligand for GAL receptor 2 (2a and 2b in non-mammalian vertebrates) and 3. SPX acts as a neuromodulator with multiple central and peripheral physiological roles in the regulation of insulin release, fat metabolism, feeding behavior, and reproduction. Collectively, this review provides a comprehensive overview of the evolutionary diversity as well as molecular and physiological roles of SPX in mammalian and non-mammalian vertebrate species.

Serotonin Transporter Genotype Modulates the Gut Microbiota Composition in Young Rats, an Effect Augmented by Early Life Stress

The neurotransmitter serotonin (5-HT) plays a vital regulatory role in both the brain and gut. 5-HT is crucial for regulating mood in the brain as well as gastrointestinal motility and secretion peripherally. Alterations in 5-HT transmission have been linked to pathological symptoms in both intestinal and psychiatric disorders and selective 5-HT transporter (5-HTT) inhibitors, affecting the 5-HT system by blocking the 5-HT transporter (5-HTT) have been successfully used to treat CNS- and intestinal disorders. Humans that carry the short allele of the 5-HTT-linked polymorphic region (5-HTTLPR) are more vulnerable to adverse environmental stressors, in particular early life stress. Although, early life stress has been shown to alter the composition of the gut microbiota, it is not known whether a lower 5-HTT expression is also associated with an altered microbiome composition. To investigate this, male and female wild type (5-HTT^+/+), heterozygous (5-HTT^+/-), and knockout (5-HTT^-/-) 5-HT transporter rats were maternally separated for 6 h a day from postnatal day 2 till 15. On postnatal day 21, fecal samples were collected and the impact of 5-HTT genotype and maternal separation (MS) on the microbiome was analyzed using high-throughput sequencing of the bacterial 16S rRNA gene. MS showed a shift in the ratio between the two main bacterial phyla characterized by a decrease in Bacteroidetes and an increase in Firmicutes. Interestingly, the 5-HTT genotype caused a greater microbal dysbiosis (microbial imbalance) compared with MS. A significant difference in microbiota composition was found segregating 5-HTT^-/- apart from 5-HTT^+/- and 5-HTT^+/+ rats. Moreover, exposure of rats with 5-HTT diminished expression to MS swayed the balance of their microbiota away from homeostasis to 'inflammatory' type microbiota characterized by higher abundance of members of the gut microbiome including Desulfovibrio, Mucispirillum, and Fusobacterium, all of which are previously reported to be associated with a state of intestinal inflammation, including inflammation associated with MS and brain disorders like multiple depressive disorders. Overall, our data show for the first time that altered expression of 5-HTT induces disruptions in male and female rat gut microbes and these 5-HTT genotype-related disruptions are augmented when combined with early life stress.

The Risk of Congenital Heart Anomalies Following Prenatal Exposure to Serotonin Reuptake Inhibitors-Is Pharmacogenetics the Key?

Serotonin reuptake inhibitors (SRIs) are often prescribed during pregnancy. Previous studies that found an increased risk of congenital anomalies, particularly congenital heart anomalies (CHA), with SRI use during pregnancy have created concern among pregnant women and healthcare professionals about the safety of these drugs. However, subsequent studies have reported conflicting results on the association between CHA and SRI use during pregnancy. These discrepancies in the risk estimates can potentially be explained by genetic differences among exposed individuals. In this review, we explore the potential pharmacogenetic predictors involved in the pharmacokinetics and mechanism of action of SRIs, and their relation to the risk of CHA. In general, the risk is dependent on the maternal concentration of SRIs and the foetal serotonin level/effect, which can be modulated by the alteration in the expression and/or function of the metabolic enzymes, transporter proteins and serotonin receptors involved in the serotonin signalling of the foetal heart development. Pharmacogenetics might be the key to understanding why some children exposed to SRIs develop a congenital heart anomaly and others do not.

Placental and fetal effects of antenatal exposure to antidepressants or untreated maternal depression

OBJECTIVE

To assess systematically the effects of antidepressants and untreated maternal depression on human placenta and the developing fetus.

METHODS

Pertinent medical literature information was identified using MEDLINE/PubMed, SCOPUS and EMBASE. Electronic searches, limited to human studies published in English, provided 21 studies reporting primary data on placental and fetal effects of antidepressant exposure or untreated gestational depression.

RESULTS

The impact of antidepressants and non-medicated maternal depression on placental functioning and fetal biochemical architecture seems to be demonstrated, although its clinical significance remains unclear. More robust data seem to indicate that exposure to either antidepressants or untreated maternal depression may induce epigenetic changes and interfere with the physiological fetal behavior. Two cases of iatrogenic fetal tachyarrhythmia have also been reported.

CONCLUSIONS

Future research should clarify the clinical relevance of the impact of antidepressant and untreated maternal depression exposure on placental functioning. Moreover, ultrasound studies investigating fetal responses to antidepressants or maternal depressive symptoms are mandatory. This assessment should be performed during the whole duration of gestational period, when different fetal behavioral patterns become progressively detectable. Analyses of biochemical and epigenetic modifications associated with maternal mood symptoms and antidepressant treatment should also be implemented.

Effects of Fluoxetine on Human Embryo Development

The use of antidepressant treatment during pregnancy is increasing, and selective serotonin reuptake inhibitors (SSRIs) are the most widely prescribed antidepressants in pregnant women. Serotonin plays a role in embryogenesis, and serotonin transporters are expressed in two-cell mouse embryos. Thus, the aim of the present study was to evaluate whether fluoxetine, one of the most prescribed SSRI antidepressant world-wide, exposure influences the timing of different embryo developmental stages, and furthermore, to analyze what protein, and protein networks, are affected by fluoxetine in the early embryo development. Human embryos (n = 48) were randomly assigned to treatment with 0.25 or 0.5 μM fluoxetine in culture medium. Embryo development was evaluated by time-lapse monitoring. The fluoxetine-induced human embryo proteome was analyzed by shotgun mass spectrometry. Protein secretion from fluoxetine-exposed human embryos was analyzed by use of high-multiplex immunoassay. The lower dose of fluoxetine had no influence on embryo development. A trend toward reduced time between thawing and start of cavitation was noted in embryos treated with 0.5 μM fluoxetine (p = 0.065). Protein analysis by shotgun mass spectrometry detected 45 proteins that were uniquely expressed in fluoxetine-treated embryos. These proteins are involved in cell growth, survival, proliferation, and inflammatory response. Culturing with 0.5 μM, but not 0.25 μM fluoxetine, caused a significant increase in urokinase-type plasminogen activator (uPA) in the culture medium. In conclusion, fluoxetine has marginal effects on the timing of developmental stages in embryos, but induces expression and secretion of several proteins in a manner that depends on dose. For these reasons, and in line with current guidelines, the lowest possible dose of SSRI should be used in pregnant women who need to continue treatment.

Early pregnancy exposure to selective serotonin reuptake inhibitors, risks of major structural malformations, and hypothesized teratogenic mechanisms

INTRODUCTION

Selective serotonin reuptake inhibitors (SSRIs) are commonly used to manage antenatal depression. Hence, the aim of this systematic review is to assess the prevalence of birth defects associated with pregnancy exposure to such agents and summarize the hypothesized teratogenic mechanisms.

AREAS COVERED

Medical literature published in English (1980 - June 2015) was electronically searched to identify all articles reporting an increased prevalence of birth defects associated with prenatal SSRI exposure and hypothesizing teratogenic mechanisms.

EXPERT OPINION

The only recurrent pattern of congenital anomalies associated with antenatal SSRI exposure is heart defects. SSRIs may alter the function of serotonin and related receptors which are involved in the development of the monoamine-dependent cardiac structures. Nevertheless, the magnitude of this increase and, thus, its clinical significance are unclear. Therefore, a cautious approach of using SSRI during pregnancy only in the case of major depressive episodes should be applied. However, this risk should be balanced against the risks associated with the worsening of depressive symptoms, and take into consideration the large number of studies that found no associations between transplacental SSRI exposure and cardiac anomalies. Prenatal ultrasonography and Doppler sonography to detect early cardiac defects are also advisable. Non-pharmacological approaches are preferred for less severe psychiatric disorders.