Perinatal selective serotonin reuptake inhibitor exposure and behavioral outcomes: A systematic review and meta-analyses of animal studies

Maternal fluoxetine impairs synaptic transmission and plasticity in the medial prefrontal cortex and alters the structure and function of dorsal raphe nucleus neurons in offspring mice

Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are commonly prescribed to women during pregnancy and breastfeeding despite posing a risk of adverse cognitive outcomes and affective disorders for the child. The consequences of SSRI-induced excess of 5-HT during development for the brain neuromodulatory 5-HT system remain largely unexplored. In this study, an SSRI - fluoxetine (FLX) - was administered to C57BL/6 J mouse dams during pregnancy and lactation to assess its effects on the offspring. We found that maternal FLX decreased field potentials, impaired long-term potentiation, facilitated long-term depression and tended to increase the density of 5-HTergic fibers in the medial prefrontal cortex (mPFC) of female but not male adolescent offspring. These effects were accompanied by deteriorated performance in the temporal order memory task and reduced sucrose preference with no change in marble burying behavior in FLX-exposed female offspring. We also found that maternal FLX reduced the axodendritic tree complexity of 5-HT dorsal raphe nucleus (DRN) neurons in female but not male offspring, with no changes in the excitability of DRN neurons of either sex. While no effects of maternal FLX on inhibitory postsynaptic currents (sIPSCs) in DRN neurons were found, we observed a significant influence of FLX exposure on kinetics of spontaneous excitatory postsynaptic currents (sEPSCs) in DRN neurons. Finally, we report that no changes in field potentials and synaptic plasticity were evident in the mPFC of the offspring after maternal exposure during pregnancy and lactation to a new antidepressant, vortioxetine. These findings show that in contrast to the mPFC, long-term consequences of maternal FLX exposure on the structure and function of DRN 5-HT neurons are mild and suggest a sex-dependent, distinct sensitivity of cortical and brainstem neurons to FLX exposure in early life. Vortioxetine appears to exert fewer side effects with regards to the mPFC when compared with FLX.

Fetal behavior and gestational serotonin reuptake inhibitor exposure: relationships between behavior, drug dosage, plasma drug level, and a measure of drug bioeffect

Determination of the relationships between drug dosage, maternal and infant (cord blood) plasma drug concentrations, and serotonin reuptake inhibitor (SRI) bioeffect on offspring neurobehavior is crucial to assessing the effects of gestational SRI exposure. Measurement of maternal and cord blood platelet serotonin (5-HT) provides an index of inhibitory bioeffect at the 5-HT transporter and complements other measures of drug exposure. Three groups of mother-infant pairs were evaluated: (1) mothers with depression untreated with SRIs (DEP, n = 17), (2) mothers treated for depression with SRIs (DEP + SRI, n = 17), and (3) mothers who were not depressed and untreated (ND, n = 29). Fetal movement was assessed using a standardized ultrasound imaging and rating protocol. Maternal and cord blood platelet 5-HT levels were obtained from all participants. For the SRI + DEP group, maternal and infant plasma drug concentrations and an estimate of third-trimester maternal SRI drug exposure were obtained. As expected, substantially lower median platelet 5-HT levels were observed in the DEP + SRI group than in the non-exposed, combined ND and DEP groups. In non-exposed mothers and infants, platelet 5-HT levels were not affected by the presence of maternal depression. Lower maternal and infant platelet 5-HT levels were associated with more immature fetal movement quality. Although these data are limited by small sample size, the bioeffect index of in vivo platelet 5-HT transporter inhibition appears to provide a valuable approach for elucidating and possibly predicting the effects of gestational SRI exposure on fetal and perinatal neurobehavior.

Citalopram exposure of hESCs during neuronal differentiation identifies dysregulated genes involved in neurodevelopment and depression

Selective serotonin reuptake inhibitors (SSRIs), including citalopram, are widely used antidepressants during pregnancy. However, the effects of prenatal exposure to citalopram on neurodevelopment remain poorly understood. We aimed to investigate the impact of citalopram exposure on early neuronal differentiation of human embryonic stem cells using a multi-omics approach. Citalopram induced time- and dose-dependent effects on gene expression and DNA methylation of genes involved in neurodevelopmental processes or linked to depression, such as BDNF, GDF11, CCL2, STC1, DDIT4 and GAD2. Single-cell RNA-sequencing analysis revealed distinct clusters of stem cells, neuronal progenitors and neuroblasts, where exposure to citalopram subtly influenced progenitor subtypes. Pseudotemporal analysis showed enhanced neuronal differentiation. Our findings suggest that citalopram exposure during early neuronal differentiation influences gene expression patterns associated with neurodevelopment and depression, providing insights into its potential neurodevelopmental impact and highlighting the importance of further research to understand the long-term consequences of prenatal SSRI exposure.

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.

Perinatal serotonergic manipulation shapes anhedonic and cognitive behaviors in a sex- and age-dependent manner: Identification of related biological functions at central and peripheral level

Poor knowledge about psychiatric disorders often results in similar diagnoses for patients with different symptoms, thus limiting the effectiveness of the available medications. As suggested by several lines of evidence, to improve these shortcomings, it is essential to identify biomarkers associated with specific symptoms and to stratify patients into more homogeneous populations taking a further step toward personalized medicine. Here, we aimed to associate specific behavioral phenotypes with specific molecular alterations by employing an animal model based on the pharmacological manipulation of the serotonergic system, which mimics a condition of vulnerability to develop psychiatric disorders. In particular, we treated female and male rats with fluoxetine (FLX 15 mg/kg dissolved in drinking water) during prenatal or early postnatal life, and we evaluated different pathological-like phenotypes (cognitive deficit, anhedonia, and anxiety) by exposing the rats to a battery of behavioral tests during adolescence and adulthood. In addition, we carried out molecular analyses on specific brain areas and in the blood. Our results showed that perinatal FLX administration determined age- and sex-dependent effects, with males being more sensitive to prenatal manipulation and manifesting anhedonic-like behavior and females to early postnatal exposure, exhibiting cognitive deficits and a less anxious phenotype. Furthermore, we identified, peripherally and centrally, biological functions altered by perinatal serotonin modulation regardless of the timing of exposure and sex, and other pathways specific for the pathological-like phenotypes. The results presented here provide new insights into potential biomarkers associated with specific behavioral phenotypes that may be useful for broadening knowledge about psychiatric conditions.

Neonicotinoids and pharmaceuticals in hair of the Red fox (Vulpes vulpes) from the Cavallino-Treporti peninsula, Italy

Neonicotinoids (NEOs) and active pharmaceuticals ingredients (API) are contaminants widely diffused worldwide, causing increasing concern for potential adverse effects on wildlife. However, research on these contaminants have focused on target and non-target invertebrates, while information on potential effects in terrestrial mammals is lacking. We performed preliminary non-invasive monitoring of NEOs and API in a suburban and agricultural area using hair of the Red fox. The Red fox is a widely diffused mesopredator in Europe, and its plasticity in feeding habits makes it an excellent indicator for assessing exposure to environmental contamination. We observed the presence of NEOs in many Red fox hair samples (n = 11), including imidacloprid (IMI), acetamiprid (ACE), and clothianidin (CLO). The highest quantified concentrations were 6.4 ng g^-1 dry weight (dw), 6.7 ng g^-1 dw, and 0.9 ng g^-1 dw for IMI, ACE, and CLO, respectively. The targeted APIs included non-steroidal anti-inflammatory drugs (NSAIDs) and antidepressants. APIs were less frequently detected than NEOs, and the compounds with the highest prevalence were the NSAID ketoprofen (36%), the antidepressant sertraline (36%), and its active metabolite norsertraline (27%). The presence of human pharmaceuticals such as the NSAID ibuprofen and the antidepressants sertraline, fluoxetine, and their active metabolites norsertraline and norfluoxetine suggest environmental contamination due to untreated and partially treated wastewater discharged in surface waters and soils of the study area. The detection and quantification of ketoprofen and flunixin also suggest the possible use of contaminated manure on farmland. Findings indicate that hair may be used for monitoring environmental exposure to NEOs and provide evidence that hair is a good marker of exposure for antidepressants and certain NSAIDs, including ibuprofen, ketoprofen, and flunixin.

Perinatal Stressors as a Factor in Impairments to Nervous System Development and Functions: Review of In Vivo Models

The human body is faced with stress throughout ontogeny. At the stage of intrauterine development, the mother’s body serves as a source of resources and most of the humoral factors supporting the development of the fetus. In normal conditions, maternal stress-related humoral signals (e.g., cortisol) regulate fetal development; however, distress (excessive pathological stress) in the perinatal period leads to serious and sometimes irreversible changes in the developing brain. The mother being in an unfavorable psychoemotional state, toxins and teratogens, environmental conditions, and severe infectious diseases are the most common risk factors for the development of perinatal nervous system pathology in the modern world. In this regard, the challenge of modeling situations in which prenatal or early postnatal stresses lead to serious impairments to brain development and functioning is extremely relevant. This review addresses the various models of perinatal pathology used in our studies (hypoxia, exposure to valproate, hyperserotoninemia, alcoholization), and assesses the commonality of the mechanisms of the resulting disorders and behavioral phenotypes forming in these models, as well as their relationship with models of perinatal pathology based on the impact of psychoemotional stressors.

Early prenatal and late prenatal escitalopram exposure differentially impacts behavioral flexibility and anxiety-related behaviors in adulthood

Selective serotonin reuptake inhibitors (SSRIs) are medications commonly used by pregnant women. While SSRIs have been considered safe during pregnancy, there is limited understanding of the long-term consequences of prenatal SSRI exposure on adult behavioral processes. Recent human studies have demonstrated prenatal exposure to some SSRIs in humans may increase susceptibility to autism spectrum disorder (ASD) and developmental delays. While escitalopram is one of the most effective antidepressants, it is also one of the newer available SSRIs, resulting in less information on its safety profile during pregnancy. The current study administered escitalopram (0 or 10 mg/kg, s.c.) to nulliparous female Long-Evans rats for the first (G1-10) or last half (G11-20) of the gestational period. Young adult male and female offspring were subsequently tested on a battery of behavioral tasks consisting of probabilistic reversal learning task, open field conflict, marble burying and social approach tasks. Results demonstrate that escitalopram exposure during the first half of pregnancy resulted in reduced anxiety-like behavior (disinhibition) on the modified open field and enhanced flexibility on the probabilistic reversal learning task. Exposure to escitalopram later in pregnancy resulted in an increase in marble burying behavior, but no differences were found with the other measures. These results suggest that exposure to escitalopram during the first half of prenatal development can have long lasting changes on adult behavior demonstrating better behavioral flexibility and lower anxiety-like behavior compared to non-exposed controls.

Advanced methods and implementations for the meta-analyses of animal models: Current practices and future recommendations

Meta-analytic techniques have been widely used to synthesize data from animal models of human diseases and conditions, but these analyses often face two statistical challenges due to complex nature of animal data (e.g., multiple effect sizes and multiple species): statistical dependency and confounding heterogeneity. These challenges can lead to unreliable and less informative evidence, which hinders the translation of findings from animal to human studies. We present a literature survey of meta-analysis using animal models (animal meta-analysis), showing that these issues are not adequately addressed in current practice. To address these challenges, we propose a meta-analytic framework based on multilevel (linear mixed-effects) models. Through conceptualization, formulations, and worked examples, we illustrate how this framework can appropriately address these issues while allowing for testing new questions. Additionally, we introduce other advanced techniques such as multivariate models, robust variance estimation, and meta-analysis of emergent effect sizes, which can deliver robust inferences and novel biological insights. We also provide a tutorial with annotated R code to demonstrate the implementation of these techniques.

Prenatal exposure to sertraline, associated or not with stress, can negatively program somatic and neurobehavioral development of female rats, and dysregulate reproductive function in adulthood

Selective serotonin reuptake inhibitors (SSRIs) are prescribed to pregnant women for treating mental illnesses. Among the drugs of this class, sertraline (ST) is the antidepressant therapy recommended most frequently. Therefore, this study aimed to evaluate the impact of gestational ST treatment on reproductive parameters and toxicological target organs of rat female offspring, as well as on somatic, reflex and neurobehavioral development, in a model of maternal adversity. Pregnant Wistar rats received vehicle (filtered water) or ST hydrochloride (20 mg/Kg/day diluted in vehicle) by oral gavage, associated or not with restraint stress for 1 h/day from gestational days 13-20. F1 female offspring was evaluated on reproductive parameters, body weight and somatic and reflex milestones from postnatal day (PND) 1. On PNDs 25 and 72, the elevated-plus-maze test was performed, while toxicological target organs were evaluated on PNDs 42 and 80. In utero exposure to ST, regardless of exposure to stress, reduced body weight at birth and affected the somatic development and estrous cycle. The absolute and relative thyroid weights were increased in Stress/ST group during puberty and adulthood, while the percentage of ovarian structures and the absolute uterine weight were altered in this group on PND 80. Prenatal exposure only to ST reduced initial body weight gain, delayed fur development and increased anxiety-like behavior on PND 25. Thus, this experimental study suggests that intrauterine exposure to ST disrupts the fetal environment and can negatively program serotonin-regulated processes. Furthermore, it impacts thyroid weight when associated with stress.

Prenatal exposure to fluoxetine modulates emotionality and aversive memory in male and female rat offspring

During pregnancy, women are prone to depression, for which selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, are usually the first-line treatment. However, fluoxetine can cross the placental barrier and affect fetuses, causing changes in serotonin levels early in life. Long-term effects in the brain circuits that control cognitive and emotional behavior are related to early fluoxetine exposure during development. In this study, we aimed to investigate whether fluoxetine exposure (10 mg/kg/day) from the 13th gestational day (GD13) to GD21 may lead to behavioral emotional-cognitive changes in male and female rat offspring approximately 90 days postnatally (~PN90). We have analyzed the performance of individuals in the open field and in the plus-maze discriminative avoidance task, which assesses anxiety and learning/memory processing behaviors. We have found that prenatal (GD13-GD21) exposure to fluoxetine strengthened aversive memory and induced higher anxiety levels in males, and quick extinction of aversive memory in females. Taken together, these results suggest that early exposure to fluoxetine impairs the basal state of anxiety and the cognitive functions of rats during adulthood, which may be in a sex-specific manner because males appear more susceptible than females.

Perinatal exposure to fluoxetine and maternal adversity affect myelin-related gene expression and epigenetic regulation in the corticolimbic circuit of juvenile rats

Many pregnant women experience symptoms of depression, and are often treated with selective serotonin reuptake inhibitor (SSRI) antidepressants, such as fluoxetine. In utero exposure to SSRIs and maternal depressive symptoms is associated with sex-specific effects on the brain and behavior. However, knowledge about the neurobiological mechanisms underlying these sex differences is limited. In addition, most animal research into developmental SSRI exposure neglects the influence of maternal adversity. Therefore, we used a rat model relevant to depression to investigate the molecular effects of perinatal fluoxetine exposure in male and female juvenile offspring. We performed RNA sequencing and targeted DNA methylation analyses on the prefrontal cortex and basolateral amygdala; key regions of the corticolimbic circuit. Perinatal fluoxetine enhanced myelin-related gene expression in the prefrontal cortex, while inhibiting it in the basolateral amygdala. SSRI exposure and maternal adversity interacted to affect expression of genes such as myelin-associated glycoprotein (Mag) and myelin basic protein (Mbp). We speculate that altered myelination reflects altered brain maturation. In addition, these effects are stronger in males than in females, resembling known behavioral outcomes. Finally, Mag and Mbp expression correlated with DNA methylation, highlighting epigenetic regulation as a potential mechanism for developmental fluoxetine-induced changes in myelination.

Neonatal D-fenfluramine treatment promotes long-term behavioral changes in adult mice

Serotonin exerts a significant role in the mammalian central nervous system embryogenesis and brain ontogeny. Therefore, we investigate the effect of neonatal treatment of d-fenfluramine (d-FEN), a serotonin (5-HT) releaser, on the behavioral expression of adult male Swiss mice. For this purpose, we divided pregnant female Swiss mice into two groups (n = 6 each and ~35 g). Their offspring were treated with d-FEN (3 mg/kg, s.c.) from postnatal days (PND) 5 to 20. At PND 21, one male puppy of each litter was euthanized; the midbrain and the hippocampus were dissected for RNA analysis. At PND 70, the male offspring underwent a behavioral assessment in the open field, elevated plus-maze, light-dark box, tail suspension, and rotarod test. The programmed animals had a decrease in 5HT1a, serotonin transporter (SERT), and brain-derived neurotrophic factor (BDNF) expression in the mesencephalic raphe region. Alternatively, there was a reduction only in the tryptophan hydroxylase (TPH2) and BDNF expression in the hippocampus. In the light-dark box test, offspring of the treated group had higher latency to light and less time on the light side than the control. Also, it was observed less time of immobility in the tail suspension test. We also observed low motor skill learning in the rotarod test. These findings suggest that programming with d-FEN during the neonatal period alters a mesencephalic and hippocampal serotonergic system, promoting anxiety, antidepressant behavior, low coordination, and motor learning in adults.

Translational validity and methodological underreporting in animal research: A systematic review and meta-analysis of the Fragile X syndrome (Fmr1 KO) rodent model

Predictive models are essential for advancing knowledge of brain disorders. High variation in study outcomes hampers progress. To address the validity of predictive models, we performed a systematic review and meta-analysis on behavioural phenotypes of the knock-out rodent model for Fragile X syndrome according to the PRISMA reporting guidelines. In addition, factors accountable for the heterogeneity between findings were analyzed. The knock-out model showed good translational validity and replicability for hyperactivity, cognitive and seizure phenotypes. Despite low replicability, translational validity was also found for social behaviour and sensory sensitivity, but not for attention, aggression and cognitive flexibility. Anxiety, acoustic startle and prepulse inhibition phenotypes, despite low replicability, were opposite to patient symptomatology. Subgroup analyses for experimental factors moderately explain the low replicability, these analyses were hindered by under-reporting of methodologies and environmental conditions. Together, the model has translational validity for most clinical phenotypes, but caution must be taken due to low effect sizes and high inter-study variability. These findings should be considered in view of other rodent models in preclinical research.

Effects of prenatal exposure to fluoxetine on circadian rhythmicity in the locomotor activity and neuropeptide Y and 5-HT expression in male and female adult Wistar rats

Serotonin (5-HT) reuptake inhibitors, such as fluoxetine, are the most prescribed antidepressant for maternal depression. In this sense, it exposes mothers and the brains of infants to increased modulatory and trophic effects of serotonergic neurotransmission. 5-HT promotes essential brain changes throughout its development, which include neuron migration, differentiation, and organization of neural circuitries related to emotional, cognitive, and circadian behavior. Early exposure to the SSRIs induces long-term effects on behavioral and neural serotonergic signalization. We have aimed to evaluate the circadian rhythm of locomotor activity and the neurochemical content, neuropeptide Y (NPY) and 5-HT in three brain areas: intergeniculate leaflet (IGL), suprachiasmatic nuclei (SCN) and raphe nuclei (RN), at two zeitgebers (ZT6 and ZT18), in male and female rat's offspring early exposed (developmental period GD13-GD21) to fluoxetine (20mg/kg). First, we have conducted daily records of the locomotor activity rhythm using activity sensors coupled to individual cages over four weeks. We have lastly evaluated the immunoreactivity of NPY in both SCN and IGL, and as well the 5-HT expression in the dorsal and medial RN. In summary, our results showed that (1) prenatal fluoxetine affects phase entrainment of the rest/activity rhythm at ZT6 and ZT18, more in male than female specimens, and (2) modulates the NPY and 5-HT expression. Here, we show male rats are more susceptible to phase entrainment and the NPY and 5-HT misexpression compared to female ones. The sex differences induced by early exposure to fluoxetine in both the circadian rhythm of locomotor activity and the neurochemical expression into SCN, IGL, and midbrain raphe are an important highlight in the present work. Thus, our results may help to improve the knowledge on neurobiological mechanisms of circadian rhythms and are relevant to understanding the "broken brains" and behavioral abnormalities of offspring early exposed to antidepressants.

Interactions between maternal fluoxetine exposure, the maternal gut microbiome and fetal neurodevelopment in mice

Selective serotonin reuptake inhibitors (SSRIs) are the most widely used treatment by women experiencing depression during pregnancy. However, the effects of maternal SSRI use on early offspring development remain poorly understood. Recent studies suggest that SSRIs can modify the gut microbiota and interact directly with particular gut bacteria, raising the question of whether the gut microbiome impacts host responses to SSRIs. In this study, we investigate effects of prenatal SSRI exposure on fetal neurodevelopment and further evaluate potential modulatory influences of the maternal gut microbiome. We demonstrate that maternal treatment with the SSRI fluoxetine induces widespread alterations in the fetal brain transcriptome during midgestation, including increases in the expression of genes relevant to synaptic organization and neuronal signaling and decreases in the expression of genes related to DNA replication and mitosis. Notably, maternal fluoxetine treatment from E7.5 to E14.5 has no overt effects on the composition of the maternal gut microbiota. However, maternal pretreatment with antibiotics to deplete the gut microbiome substantially modifies transcriptional responses of the fetal brain to maternal fluoxetine treatment. In particular, maternal fluoxetine treatment elevates localized expression of the opioid binding protein/cell adhesion molecule like gene Opcml in the fetal thalamus and lateral ganglionic eminence, which is prevented by maternal antibiotic treatment. Together, these findings reveal that maternal fluoxetine treatment alters gene expression in the fetal brain through pathways that are impacted, at least in part, by the presence of the maternal gut microbiota.

Postnatal exposure to fluoxetine led to cognitive-emotional alterations and decreased parvalbumin positive neurons in the hippocampus of juvenile Wistar rats

The exposure to selective serotonin reuptake inhibitors (SSRIs) during development results in behavioural impairment in adulthood in humans and animal models. Indeed, serotonergic overexpression in early life leads to structural and functional changes in brain circuits that control cognition and emotion. However, the effects of developmental exposure to these substances on the behaviour of adolescent rats are conflicting and remain poorly characterised. We performed a behavioural screening to investigate the effects of postnatal exposure to fluoxetine on memory and behaviours related to anxiety, anhedonia, and depression, as well we evaluate the parvalbumin expression in hippocampus of juvenile (~PND45) female and male rats. Fluoxetine (daily 20 mg/kg s.c. injections from PND7-PND21)- or vehicle-treated adolescent rats went through several behavioural tasks (from PND 38 to PND52) and were subject to transcardial perfusion and brain removal for immunohistochemical analysis (PND53). We found that postnatal exposure to fluoxetine increased anxiety- and depression-like behaviours in the open field and sucrose preference and forced swimming tests, respectively. In addition, this treatment induced working memory and short-term (but not long-term) recognition memory impairments, and reduced parvalbumin-positive interneurons in the hippocampus. In addition, the results revealed developmental sex-dependent effects of fluoxetine postnatal treatment on adolescent rats' behaviour. These outcomes indicate that affective disorders and mnemonic alterations caused by SSRIs perinatal exposure can be present at adolescence.

Perinatal fluoxetine dose-dependently affects prenatal stress-induced neurobehavioural abnormalities, HPA-axis functioning and underlying brain alterations in rat dams and their offspring

Both untreated and SSRI antidepressant treated maternal depression during the perinatal period can pose both short-and long-term health risks to the offspring. Therefore, it is essential to have an effective SSRI treatment consisting of the lowest effective dose beneficial to the mother, without causing adverse effects on offspring development. The effects of prenatal stress on neurobehavioral outcomes were studied in the pregnant and lactating rat dam, and her offspring. Furthermore, stressed dams were treated with different doses of fluoxetine (FLX; 5, 10and 25 mg/kg) during pregnancy and the postpartum period. We found that prenatal stress-induced anxiety-and depressive-like behaviour and increased HPA-axis function in pregnant and postpartum dams, and in offspring. Maternal stress impaired object recognition but did not affect spatial memory in offspring. Prenatal stress decreased whole-brain serotonin and brain-derived-neurotrophic-factor, and increased interleukin-17 and malondialdehyde, but did not affect oxytocin and interleukin-6 in the brains of offspring. Maternal treatment with 5 mg/kg FLX during the perinatal period did not rescue any stress-induced anxiety/depressive-like behaviour in the pregnant and postpartum dam and had only a few rescuing effects in offspring. Maternal FLX treatment with 10 mg/kg did rescue most stress-induced anxiety-and depressive-like behaviour or HPA-axis-function in dams and offspring. The highest dose tested, 25 mg/kg FLX, had the rescuing properties in dams while having the same, or an even greater, detrimental effect as prenatal stress on offspring behaviour and molecular alterations in the brain. Our results show prenatal stress rescuing properties for FLX treatment in the pregnant and postpartum dam, with dose-dependent effects on the offspring.

Serotonin-related rodent models of early-life exposure relevant for neurodevelopmental vulnerability to psychiatric disorders

Mental disorders including depression and anxiety are continuously rising their prevalence across the globe. Early-life experience of individuals emerges as a main risk factor contributing to the developmental vulnerability to psychiatric disorders. That is, perturbing environmental conditions during neurodevelopmental stages can have detrimental effects on adult mood and emotional responses. However, the possible maladaptive neural mechanisms contributing to such psychopathological phenomenon still remain poorly understood. In this review, we explore preclinical rodent models of developmental vulnerability to psychiatric disorders, focusing on the impact of early-life environmental perturbations on behavioral aspects relevant to stress-related and psychiatric disorders. We limit our analysis to well-established models in which alterations in the serotonin (5-HT) system appear to have a crucial role in the pathophysiological mechanisms. We analyze long-term behavioral outcomes produced by early-life exposures to stress and psychotropic drugs such as the selective 5-HT reuptake inhibitor (SSRI) antidepressants or the anticonvulsant valproic acid (VPA). We perform a comparative analysis, identifying differences and commonalities in the behavioral effects produced in these models. Furthermore, this review discusses recent advances on neurodevelopmental substrates engaged in these behavioral effects, emphasizing the possible existence of maladaptive mechanisms that could be shared by the different models.

The combination of fluoxetine and environmental enrichment reduces postpartum stress-related behaviors through the oxytocinergic system and HPA axis in mice

Gestational stress can increase postpartum depression in women. To treat maternal depression, fluoxetine (FLX) is most commonly prescribed. While FLX may be effective for the mother, at high doses it may have adverse effects on the fetus. As environmental enrichment (EE) can reduce maternal stress effects, we hypothesized that a subthreshold dose of FLX increases the impact of EE to reduce anxiety and depression-like behavior in postpartum dams exposed to gestational stress. We evaluated this hypothesis in mice and to assess underlying mechanisms we additionally measured hypothalamic-pituitary-adrenal (HPA) axis function and brain levels of the hormone oxytocin, which are thought to be implicated in postpartum depression. Gestational stress increased anxiety- and depression-like behavior in postpartum dams. This was accompanied by an increase in HPA axis function and a decrease in whole-brain oxytocin levels in dams. A combination of FLX and EE remediated the behavioral, HPA axis and oxytocin changes induced by gestational stress. Central administration of an oxytocin receptor antagonist prevented the remediating effect of FLX + EE, indicating that brain oxytocin contributes to the effect of FLX + EE. These findings suggest that oxytocin is causally involved in FLX + EE mediated remediation of postpartum stress-related behaviors, and HPA axis function in postpartum dams.

Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats

Selective serotonin reuptake inhibitors (SSRI) are commonly used to treat depression during pregnancy. SSRIs cross the placenta and may influence the maturation of the foetal brain. Clinical and preclinical findings suggest long-term consequences of SSRI perinatal exposure for the offspring. The mechanisms of SSRI effects on developing brain remain largely unknown and there are no directional approaches for prevention of the consequences of maternal SSRI treatment during pregnancy. The heptapeptide Semax (MEHFPGP) is a synthetic analogue of ACTH(4-10) which exerts marked nootropic and neuroprotective activities. The aim of the present study was to investigate the long-term effects of neonatal exposure to the SSRI fluvoxamine (FA) in white rats. Additionally, the study examined the potential for Semax to prevent the negative consequences of neonatal FA exposure. Rat pups received FA or vehicle injections on postnatal days 1-14, a time period equivalent to 27-40 weeks of human foetal age. After FA treatment, rats were administered with Semax or vehicle on postnatal days 15-28. During the 2nd month of life, the rats underwent behavioural testing, and monoamine levels in brain structures were measured. It was shown that neonatal FA exposure leads to the impaired emotional response to stress and novelty and delayed acquisition of food-motivated maze task in adolescent and young adult rats. Furthermore, FA exposure induced alterations in the monoamine levels in brains of 1- and 2- month-old rats. Semax administration reduced the anxiety-like behaviour, improved learning abilities and normalized the levels of brain biogenic amines impaired by the FA exposure. The results demonstrate that early-life FA exposure in rat pups produces long-term disturbances in their anxiety-related behaviour, learning abilities, and brain monoamines content. Semax exerts a favourable effect on behaviour and biogenic amine system of rats exposed to the antidepressant. Thus, peptide Semax can prevent behavioural deficits caused by altered 5-HT levels during development.

Reduced Motivation in Perinatal Fluoxetine-Treated Mice: A Hypodopaminergic Phenotype

Early life is a sensitive period, in which enhanced neural plasticity allows the developing brain to adapt to its environment. This plasticity can also be a risk factor in which maladaptive development can lead to long-lasting behavioral deficits. Here, we test how early-life exposure to the selective-serotonin-reuptake-inhibitor (SSRI), fluoxetine, affects motivation, and dopaminergic signaling in adulthood. We show for the first time that mice exposed to fluoxetine in the early postnatal period exhibit a reduction in effort-related motivation. These mice also show blunted responses to amphetamine and reduced dopaminergic activation in a sucrose reward task. Interestingly, we find that the reduction in motivation can be rescued in the adult by administering bupropion, a dopamine-norepinephrine reuptake inhibitor used as an antidepressant and a smoke cessation aid but not by fluoxetine. Taken together, our studies highlight the effects of early postnatal exposure of fluoxetine on motivation and demonstrate the involvement of the dopaminergic system in this process.SIGNIFICANCE STATEMENT The developmental period is characterized by enhanced plasticity. During this period, environmental factors have the potential to lead to enduring behavioral changes. Here, we show that exposure to the SSRI fluoxetine during a restricted period in early life leads to a reduction in adult motivation. We further show that this reduction is associated with decreased dopaminergic responsivity. Finally, we show that motivational deficits induced by early-life fluoxetine exposure can be rescued by adult administration of bupropion but not by fluoxetine.

Effects of perinatal fluoxetine exposure on novelty-induced social and non-social investigation behaviors in a seminatural environment

Selective serotonin reuptake inhibitors (SSRIs) are increasingly prescribed as medication for various affective disorders during pregnancy. SSRIs cross the placenta and affect serotonergic neurotransmission in the fetus, but the neurobehavioral consequences for the offspring remain largely unclear. Recent rodent research has linked perinatal SSRI exposure to alterations in both social and non-social aspects of behavior. However, this research has mainly focused on behavior within simplified environments. The current study investigates the effects of perinatal SSRI exposure on social and non-social investigation behaviors of adult rat offspring upon introduction to a novel seminatural environment with unknown conspecifics. During the perinatal period (gestational day 1 until postnatal day 21), rat dams received daily treatment with either an SSRI (fluoxetine, 10 mg/kg) or vehicle. Adult male and female offspring were observed within the first hour after introduction to a seminatural environment. The results showed that perinatal fluoxetine exposure altered aspects of non-social investigation behaviors, while not altering social investigation behaviors. More specifically, both fluoxetine-exposed males and females spent more total time on locomotor activity than controls. Furthermore, fluoxetine-exposed females spent less time exploring objects and specific elements in the environment. The data suggest that perinatal exposure to SSRIs leads to a quicker, less detailed investigation strategy in novel environments and that the alteration is mostly pronounced in females.

Renal protective effects of astragaloside IV, in diabetes mellitus kidney damage animal models: A systematic review, meta-analysis

Astragaloside IV (ASIV) is the essential active component of astragalus that has diverse biological activities. Previous research has suggested its potentially beneficial effects on diabetic nephropathies. However, its effects and protective mechanism remain unclear. In this study, we conducted a preclinical systematic review to evaluate the efficacy and potential mechanisms of ASIV in reducing kidney damage in diabetes mellitus (DM) models. Studies were searched from nine databases until January 2020. A random-effects model was used to calculate combined standardised mean difference estimates and 95 % confidence intervals. Risk of bias of studies was assessed using the Systematic Review Center for Laboratory Animal Experimentation risk of bias tool 10-item checklist. RevMan 5.3 software was used for statistical analysis. Twenty-three studies involving 562 animals were included in the meta-analysis. Studies quality scores ranged from 2 to 5. The ASIV group induced a marked decrease in serum creatinine (P < 0.00001), blood urea nitrogen (P < 0.00001), 24-h urine protein (P < 0.00001) and pathological score (P < 0.001) compared with the control group. The determined potential mechanisms of ASIV action were relieving oxidative stress, delaying renal fibrosis, anti-apoptosis and anti-inflammatory action. We conclude that ASIV exerts renal protective effects in animals with DM through multiple signalling pathways.