Fetal serotonin reuptake inhibitor antidepressant exposure: maternal and fetal factors

Zygotic exposure to venlafaxine disrupts cortisol stress axis activity in multiple generations of zebrafish

Ubiquitous use of antidepressants has resulted in increased concentrations of these pharmaceuticals in waterways receiving municipal wastewater effluent. Amongst these, venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is commonly found at concentrations surpassing 1 ppb in surface waters. We recently showed that the deposition of venlafaxine in zebrafish (Danio rerio) embryos impacts neural development in the hypothalamus, suggesting the possibility of neuroendocrine disruptions due to this antidepressant. Here, we tested the hypothesis that early developmental exposure to venlafaxine disrupts the long-term functioning of the hypothalamus-pituitary-interrenal (HPI) axis in zebrafish. Embryos (1-4 cell stage) were injected with either 0, 1, or 10 ng venlafaxine, and the ontogeny of cortisol content, as well as changes in cortisol levels following a stressor in larvae and adults were assessed across 3 generations. Zygotic venlafaxine exposure did not affect the ontogeny of cortisol production, but there was a disruption in the cortisol response to stressor exposure, which was also evident in multiple generations. In the F₀ generation, venlafaxine exposure did not affect cortisol levels in response to stressor exposure in larvae, but adult females, and not males, showed an attenuated cortisol response compared to control fish. This reduction in cortisol levels in the females was rescued by stimulation with adrenocorticotropic hormone, suggesting that the disruption was at the level of the hypothalamus-pituitary axis. Venlafaxine-mediated disruption in HPI axis functioning was also evident in the F₁ and F₂ generations, including impaired cortisol responses to a stressor in adult female and larval fish, respectively. Taken together, our results suggest that venlafaxine is an endocrine disruptor, and early developmental exposure to this antidepressant may have long-term and generational consequences on cortisol stress axis activity in zebrafish.

Maternal Serotonin Reuptake Inhibitor Antidepressants Have Acute Effects on Fetal Heart Rate Variability in Late Gestation

Background: Prenatal exposure to serotonin reuptake inhibitor (SRI) antidepressants increases risk for adverse neurodevelopmental outcomes, yet little is known about whether effects are present before birth. In relation to maternal SRI pharmacokinetics, this study investigated chronic and acute effects of prenatal SRI exposure on third-trimester fetal heart rate variability (HRV), while evaluating confounding effects of maternal depressed mood. Methods: At 36-weeks' gestation, cardiotocograph measures of fetal HR and HRV were obtained from 148 pregnant women [four groups: SRI-Depressed (n = 31), SRI-Non-Depressed (n = 18), Depressed (unmedicated; n = 42), and Control (n = 57)] before, and ~5-h after, typical SRI dose. Maternal plasma drug concentrations were quantified at baseline (pre-dose) and four time-points post-dose. Mixed effects modeling investigated group differences between baseline/pre-dose and post-dose fetal HR outcomes. Post hoc analyses investigated sex differences and dose-dependent SRI effects. Results: Maternal SRI plasma concentrations were lowest during the baseline/pre-dose fetal assessment (trough) and increased to a peak at the post-dose assessment; concentration-time curves varied widely between individuals. No group differences in fetal HR or HRV were observed at baseline/pre-dose; however, following maternal SRI dose, short-term HRV decreased in both SRI-exposed fetal groups. In the SRI-Depressed group, these post-dose decreases were displayed by male fetuses, but not females. Further, episodes of high HRV decreased post-dose relative to baseline, but only among SRI-Non-Depressed group fetuses. Higher maternal SRI doses also predicted a greater number of fetal HR decelerations. Fetuses exposed to unmedicated maternal depressed mood did not differ from Controls. Conclusions: Prenatal SRI exposure had acute post-dose effects on fetal HRV in late gestation, which differed depending on maternal mood response to SRI pharmacotherapy. Importantly, fetal SRI effects were sex-specific among mothers with persistent depressive symptoms, as only male fetuses displayed acute HRV decreases. At trough (pre-dose), chronic fetal SRI effects were not identified; however, concurrent changes in maternal SRI plasma levels suggest that fetal drug exposure is inconsistent. Acute SRI-related changes in fetal HRV may reflect a pharmacologic mechanism, a transient impairment in autonomic functioning, or an early adaption to altered serotonergic signaling, which may differ between males and females. Replication is needed to determine significance with postnatal development.

Assessing SSRIs' effects on fetal cardiomyocytes utilizing placenta-fetus model

Selective serotonin reuptake inhibitors (SSRIs) have been shown to hinder cardiomyocyte signaling, raising concerns about their safety during pregnancy. Approaches to assess SSRI-induced effects on fetal cardiovascular cells following passage of drugs through the placental barrier in vitro have only recently become available. Herein, we report that the SSRIs, fluoxetine and sertraline, lead to slowed cardiomyocyte calcium oscillations and induce increased secretion of troponin T and creatine kinase-MB with reduced secretion of NT-proBNP, three key cardiac injury biomarkers. We show the cardiomyocyte calcium handling effects are further amplified following indirect exposure through a placental barrier model. These studies are the first to investigate the effects of placental barrier co-culture with cardiomyocytes in vitro and to show cardiotoxicity of SSRIs following passage through the placental barrier. STATEMENT OF SIGNIFICANCE: Use of selective serotonin reuptake inhibitors (SSRIs), a class of antidepressants, during pregnancy continues to rise despite multiple studies showing potential for detrimental effects on the developing fetus. SSRIs are particularly thought to slow cardiovascular electrical activity, such as ion signaling, yet few, if any, methods exist to rigorously study these drug-induced effects on human pregnancy and the developing fetus. Within this study, we utilized a placenta-fetus model to evaluate these drug-induced effects on cardiomyocytes, looking the drugs' effects on calcium handling and secretion of multiple cardiac injury biomarkers. Together, with existing literature, this study provides a platform for assessing pharmacologic effects of drugs on cells mimicking the fetus and the role the placenta plays in this process.

Model Placental Barrier Phenotypic Response to Fluoxetine and Sertraline: A Comparative Study

Medications taken during pregnancy may significantly impact fetal development, yet there are few studies that rigorously assess medication safety due to ethical concerns. Selective serotonin reuptake inhibitors (SSRIs) are a class of drug increasingly being prescribed for depression, yet multiple studies have shown that taking SSRIs during pregnancy can lead to preterm birth and potential health concerns for the baby. Therefore, a biomimetic placental barrier model is utilized herein to assess transport profiles and phenotypic effects resulting from SSRI exposure, comparing fluoxetine and sertraline. Results show that the placental barrier quickly uptakes drug from the maternal side, but slowly releases on the fetal side. Phenotypically, there is a dose-dependent change in cell adhesion molecule (CAM) and transforming growth factor beta (TGFβ) secretions, markers of cell adhesion and angiogenesis. Both drugs impact CAM secretions, whereas sertraline alone impacts TGFβ secretions. When evaluating cell type, it becomes clear that endothelial cells, not trophoblast, are the main cell type involved in these phenotypic changes. Overall, these findings further the understanding of SSRI transplacental transport and drug-induced effects on the placental barrier.

Commentary: Studies of prenatal antidepressant exposures: what can you recommend? A reflection on Sujan et al. (2019)

The review by Sujan et al. asks a question of clinical and public health importance: are antidepressant medications safe to use during pregnancy from the perspective of their potential effects on the infant and growing child? They provide a thorough review of the animal and human literature to date, focusing primarily on offspring neurodevelopmental outcomes (autism spectrum disorder, ASD, and attention deficit hyperactivity disorder, ADHD). They conclude, based on their review, that antidepressant exposure in pregnancy does not substantially increase the risk of these outcomes, and that women should therefore be reassured about the safety of these medications when used in pregnancy. While their review should be of interest to clinicians and researchers, we would advocate a more conservative approach. Even if associations with ASD and ADHD are equivocal, there is still evidence that SSRI exposure may be associated with outcomes occurring at other developmental timepoints. Clinical recommendations should be based on a fuller picture of potential risks and benefits to both the mother and the fetus, in the context of the mother's underlying depression. In this commentary, we also suggest some approaches that future observational studies may adopt to help strengthen the interpretability of findings.

Maternal depression, antidepressant use and placental oxytocin receptor DNA methylation: Findings from the MPEWS study

The aim of this study was to investigate placental DNA methylation of the oxytocin receptor gene (OXTR) in women with depression in pregnancy. We also explored the role of antidepressant medication in pregnancy on placental OXTR methylation. Data were obtained from 239 women in the Mercy Pregnancy and Emotional Wellbeing Study (MPEWS), a selected pregnancy cohort. Current depressive disorders were diagnosed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (SCID-IV). Depressive symptoms were measured during the third trimester in pregnancy using the Edinburgh Postnatal Depression Scale (EPDS). Plasma levels of antidepressant drugs were measured in maternal and cord blood obtained at delivery. OXTR DNA methylation was measured in placenta samples. Depressive symptoms in pregnancy were not associated with significant changes in DNA methylation of OXTR in the placenta. Cord plasma antidepressant levels were more strongly associated than maternal antidepressant dose or circulating blood antidepressant levels with increased DNA methylation of a specific unit within the promotor region of OXTR. This study provides preliminary data to suggest that antidepressant use during pregnancy can alter OXTR methylation in placental tissue. Our findings also indicate that the way exposures are measured in pregnancy can influence the direction and strength of findings. Future studies should investigate whether altered OXTR methylation might mediate the impacts of maternal antidepressant treatment on pregnancy and offspring outcomes.

Maternal Pharmacokinetics and Fetal Disposition of (±)-Citalopram during Mouse Pregnancy

While selective-serotonin reuptake inhibitor (SSRI) antidepressants are commonly prescribed in the treatment of depression, their use during pregnancy leads to fetal drug exposures. According to recent reports, such exposures could affect fetal development and long-term offspring health. A central question is how pregnancy-induced physical and physiological changes in mothers, fetuses, and the placenta influence fetal SSRI exposures during gestation. In this study, we examined the effects of gestational stage on the maternal pharmacokinetics and fetal disposition of the SSRI (±)-citalopram (CIT) in a mouse model. We determined the maternal and fetal CIT serum concentration-time profiles following acute maternal administration on gestational days (GD)14 and GD18, as well as the fetal brain drug disposition. The results show that pregnancy affects the pharmacokinetics of CIT and that maternal drug clearance increases as gestation progresses. The data further show that CIT and its primary metabolite desmethylcitalopram (DCIT) readily cross the placenta into the fetal compartment, and fetal exposure to CIT exceeds that of the mother during gestation 2 h after maternal administration. Enzymatic activity assays revealed that fetal drug metabolic capacity develops in late gestation, resulting in elevated circulating and brain concentrations of DCIT at embryonic day (E)18. Fetal exposure to the SSRI CIT in murine pregnancy is therefore influenced by both maternal gestational stage and embryonic development, suggesting potential time-dependent effects on fetal brain development.

Placental transfer of antidepressant medications: implications for postnatal adaptation syndrome

Seven to thirteen percent of women are either prescribed or taking (depending on the study) an antidepressant during pregnancy. Because antidepressants freely cross into the intrauterine environment, we aim to summarize the current findings on placental transfer of antidepressants. Although generally low risk, antidepressants have been associated with postnatal adaptation syndrome (PNAS). Specifically, we explore whether the antidepressants most closely associated with PNAS (paroxetine, fluoxetine, venlafaxine) cross the placenta to a greater extent than other antidepressants. We review research on antidepressants in the context of placental anatomy, placental transport mechanisms, placental metabolism, pharmacokinetics, as well as non-placental maternal and fetal factors. This provides insight into the complexity involved in understanding how placental transfer of antidepressants may relate to adverse perinatal outcomes. Ultimately, from this data there is no pattern in which PNAS is related to placental transfer of antidepressant medications. In general, there is large interindividual variability for each type of antidepressant. To make the most clinically informed decisions about the use of antidepressants in pregnancy, studies that link maternal, placental and fetal genetic polymorphisms, placental transfer rates and infant outcomes are needed.

Prenatal antidepressant exposure associated with CYP2E1 DNA methylation change in neonates

Some but not all neonates are affected by prenatal exposure to serotonin reuptake inhibitor antidepressants (SRI) and maternal mood disturbances. Distinguishing the impact of these 2 exposures is challenging and raises critical questions about whether pharmacological, genetic, or epigenetic factors can explain the spectrum of reported outcomes. Using unbiased DNA methylation array measurements followed by a detailed candidate gene approach, we examined whether prenatal SRI exposure was associated with neonatal DNA methylation changes and whether such changes were associated with differences in birth outcomes. Prenatal SRI exposure was first associated with increased DNA methylation status primarily at CYP2E1(β(Non-exposed) = 0.06, β(SRI-exposed) = 0.30, FDR = 0); however, this finding could not be distinguished from the potential impact of prenatal maternal depressed mood. Then, using pyrosequencing of CYP2E1 regulatory regions in an expanded cohort, higher DNA methylation status--both the mean across 16 CpG sites (P < 0.01) and at each specific CpG site (P < 0.05)--was associated with exposure to lower 3rd trimester maternal depressed mood symptoms only in the SRI-exposed neonates, indicating a maternal mood x SRI exposure interaction. In addition, higher DNA methylation levels at CpG2 (P = 0.04), CpG9 (P = 0.04) and CpG10 (P = 0.02), in the interrogated CYP2E1 region, were associated with increased birth weight independently of prenatal maternal mood, SRI drug exposure, or gestational age at birth. Prenatal SRI antidepressant exposure and maternal depressed mood were associated with altered neonatal CYP2E1 DNA methylation status, which, in turn, appeared to be associated with birth weight.