Dose-dependent effects of neonatal SSRI exposure on adult behavior in the rat

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.

Gestational Factors throughout Fetal Neurodevelopment: The Serotonin Link

Serotonin (5-HT) is a critical player in brain development and neuropsychiatric disorders. Fetal 5-HT levels can be influenced by several gestational factors, such as maternal genotype, diet, stress, medication, and immune activation. In this review, addressing both human and animal studies, we discuss how these gestational factors affect placental and fetal brain 5-HT levels, leading to changes in brain structure and function and behavior. We conclude that gestational factors are able to interact and thereby amplify or counteract each other's impact on the fetal 5-HT-ergic system. We, therefore, argue that beyond the understanding of how single gestational factors affect 5-HT-ergic brain development and behavior in offspring, it is critical to elucidate the consequences of interacting factors. Moreover, we describe how each gestational factor is able to alter the 5-HT-ergic influence on the thalamocortical- and prefrontal-limbic circuitry and the hypothalamo-pituitary-adrenocortical-axis. These alterations have been associated with risks to develop attention deficit hyperactivity disorder, autism spectrum disorders, depression, and/or anxiety. Consequently, the manipulation of gestational factors may be used to combat pregnancy-related risks for neuropsychiatric disorders.

The effects of exposure to fluoxetine during lactation on testicular tissue and sperm parameters in mice offspring

Fluoxetine is a selective serotonin reuptake inhibitor is commonly prescribed to treat maternal depression in pregnancy and lactation. This study aimed to investigate the effects of maternal exposure to fluoxetine via lactation on testicular tissue, sperm parameters including count, motility, viability, and normal morphology and testicular oxidative stress status in male mice offspring. Ten mice dams were divided into control and experimental groups. The control group received water and the experimental group received fluoxetine (20.00 mg kg^-1) by gavage daily from postnatal days of 0-21. Histology of testis, sperm parameters and oxidative stress in the testicular tissue were analyzed at 80 days after birth in their male offspring (n = 8). Significant reductions in the body and testes weights were observed in animals exposed to fluoxetine. Additionally, fluoxetine exposure significantly reduced all sperm parameters, tubular diameter and epithelial height of the seminiferous tubules as well as Leydig cells number. Significant increases in the testicular malondialdehyde levels and percentage of sperm with chromatin/DNA damage were observed in mice exposed to fluoxetine compared to control. These findings suggest that maternal exposure to fluoxetine during lactation in mice has a negative effect on the testicular tissue of their offspring and impairs the spermatogenesis process which in turn can induce infertility.

Perinatal fluoxetine treatment and dams' early life stress history have opposite effects on aggressive behavior while having little impact on sexual behavior of male rat offspring

RATIONALE

Many depressed women continue antidepressant treatment during pregnancy. Selective serotonin reuptake inhibitor (SSRI) treatment during pregnancy increases the risk for abnormal social development of the child, including increased aggressive or defiant behavior, with unknown effects on sexual behavior.

OBJECTIVES

Our aim was to investigate the effects of perinatal SSRI treatment and maternal depression, both separately and combined, on aggressive and sexual behavior in male rat offspring.

METHODS

Heterozygous serotonin transporter (SERT^± ) knockout dams exposed to early life stress (ELSD) were used as an animal model of maternal depression. Early life stress consisted of separating litters from their mother for 6 h a day on postnatal day (PND)2-15, resulting in a depressive-like phenotype in adulthood. Depressive-like dams were treated with fluoxetine (FLX, 10 mg/kg) or vehicle throughout pregnancy and lactation (gestational day 1 until PND 21). Male offspring were tested for aggressive and sexual behavior in adulthood. As lifelong reductions in SERT expression are known to alter behavioral outcome, offspring with normal (SERT^+/+) and reduced (SERT^± ) SERT expression were assessed.

RESULTS

Perinatal FLX treatment reduced offensive behavior and the number of animals attacking and increased the latency to attack, especially in SERT^+/+ offspring. Perinatal FLX treatment reduced the mounting frequency in SERT^+/+ offspring. ELSD increased offensive behavior, without affecting sexual behavior in SERT^± offspring.

CONCLUSIONS

Overall, our research demonstrates that perinatal FLX treatment and ELSD have opposite effects on aggressive behavior, with little impact on sexual behavior of male offspring.

The effects of perinatal SSRI exposure on anxious behavior and neurobiology in rodent and human offspring

While the postpartum period is typically associated with increased positive affect, many women will develop a depressive- or anxiety-related disorder during this time, which can degrade the mother-infant bond and lead to detrimental consequences for the infant. Given the potential for negative consequences, effective treatments have been critical, with selective serotonin reuptake inhibitors (SSRIs) being the most commonly-prescribed pharmaceutical agents to treat postpartum depression and anxiety. However, SSRIs can readily cross the placenta and are present in breast milk, so they might, therefore, unintentionally interact with the developing fetus/infant. There is already experimental evidence that perinatal SSRI exposure has a number of long-term effects on offspring, but this review focuses on the current literature examining the timing and consequences of perinatal SSRI exposure specifically on anxiety-like behaviors in rodents and humans, with an emphasis on the anxiety-related brain regions of the amygdala and hippocampus. This review also discusses discrepancies between the rodent and human literatures and how they might inform future studies. Finally, some key factors to consider when examining the role of perinatal SSRIs on offspring anxiety will be discussed, such as the duration of SSRI exposure and the potential neuroprotective effects of SSRIs. Given the extensive prescribing of SSRIs, the potential health consequences of perinatal SSRI exposure, and the discrepancies in the literature, it will be necessary to critically examine the factors underlying offspring anxiety outcomes.

Trick or treat? Evaluating contributing factors and sex-differences for developmental effects of maternal depression and its treatment

Maternal depression and treatment with selective serotonin reuptake inhibitors (SSRIs), the most common form of pharmaceutical intervention, can both have an impact on infant development. As such, it is difficult for healthcare providers to recommend a course of treatment to expectant mothers suffering from depression, or to women on antidepressant medication prior to pregnancy. This review will discuss the existing research on the developmental impacts of maternal depression and its treatment with SSRIs, with a particular focus on contributing factors that complicate our attempt to disentangle the consequences of maternal depression and its treatment such as the timing or severity of the depression. We will explore avenues for translational animal models to help address the question of "Trick or Treat", i.e.: which is worse for offspring development: exposure to maternal depression, or the SSRI treatment? Further, we will explore sex-dependent outcomes for the offspring in human and animal studies as male and female offspring may react differently to the presence of maternal depression or antidepressant treatment. Without more clinical and preclinical data, it remains difficult for women to make an informed decision regarding their depression treatment before, during, and after their pregnancy.

Perinatal fluoxetine exposure changes social and stress-coping behavior in adult rats housed in a seminatural environment

The use of selective serotonin reuptake inhibitors (SSRI) during pregnancy has increased tremendously, but the consequences for the offspring remain largely unclear. Several studies have described potential effects of perinatal SSRI-exposure on neurobehavioral outcomes using simplified rodent test set-ups, however these set-ups only assess a small fraction of the behavior. For translational purposes it is important to take the environmental influences into account which children are exposed to in real life. By using a seminatural environmental set-up, this study is the first to assess behavioral outcomes in offspring exposed to perinatal SSRI exposure under seminatural circumstances. Mothers received daily the SSRI fluoxetine (FLX, 10 mg/kg p.o.) or vehicle (CTR) from gestational day 1 until postnatal day 21. To assess the effect of FLX exposure during early development, female and male offspring were behaviorally tested in the seminatural environment at adulthood. Baseline behavior was measured in addition to responses during and after stressful white-noise events. Behavior was observed on two days, day 4 on which females were sexually non-receptive, and day 7, on which females were sexual receptive. Perinatal FLX exposure reduced general activity in females and increased behavior related to a social context in both males and females. After a stressful white-noise event some behaviors switched. Whereas FLX-females switch from resting socially to resting more solitarily, FLX-males show an increase in self-grooming behavior after the stressor and showed more freezing behavior in the open area. We conclude that perinatal FLX exposure leads to alterations in social and stress-coping behaviors in adulthood, when observed in a seminatural environment. Whether these adaptations in behavior are advantageous or disadvantageous remains to be established.

Developmental outcomes after gestational antidepressant treatment with sertraline and its discontinuation in an animal model of maternal depression

Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed to women before or during pregnancy to manage their depressive symptoms. However, there is still little knowledge regarding the long-term development effects of SSRI exposure for the fetus or the effects of discontinuing SSRI treatment during pregnancy. This study utilized a translational animal model of maternal depression (based on giving high levels of corticosterone (CORT, 40 mg/kg, s.c.) or vehicle (Oil) for 21 days prior to conception) to investigate the effects of sertraline (a frequently prescribed SSRI; 20 mg/kg p.o., treatment started ∼7 days prior to conception) and its discontinuation during pregnancy (on gestational day 16) compared to vehicle (water) treatment on the development of the offspring. Our results revealed that both corticosterone exposure prior to pregnancy and sertraline administration and its discontinuation during gestation had sex-specific effects on behavior in the adult offspring. In particular, pre-conceptional maternal corticosterone treatment impacted the stress response, anxiety-like behavior and cognitive performance in adult female offspring, while gestational SSRI exposure and its discontinuation compared to full-term exposure affected impulsivity in females, and exploratory behavior in males. More research is needed on the effects of exposure to antidepressant medication and its discontinuation compared to depression during pregnancy and how each impacts development to better help women make informed decisions about their medication use during pregnancy.

Psychoactive drug exposure during breastfeeding: a critical need for preclinical behavioral testing

Breastfeeding women are excluded from clinical trials of psychoactive drugs because of ethical concerns. Animal testing, which often is predictive of adverse effects in humans, represents the only avenue available for assessing drug safety for human offspring exposed to drugs during lactation. I determined whether behavioral outcomes for children exposed during breastfeeding to antidepressants, anxiolytics, antipsychotics, anti-seizure medications, analgesics, sedatives, and marijuana can be predicted by rodent studies of offspring exposed to drugs during lactation. Animal data were available for only 10 of 80 CNS-active drugs canvassed. Behavioral deficits in adolescence or adulthood in rats and mice after various drug exposures during lactation included reductions in sexual behavior, increased anxiety, hyperactivity, and impaired learning and memory. Whether similar adverse effects will emerge in adulthood in children exposed to drugs during breastfeeding is unknown. Rodent research has the potential to forecast impairments in breastfed children long before information emerges from post-marketing reports and should be prioritized during preclinical drug evaluation by the FDA for new drugs and for drugs currently prescribed off-label for lactating women.

Prenatal fluoxetine modifies the behavioral and hormonal responses to stress in male mice: role for glucocorticoid insensitivity

Women with major depressive disorder during pregnancy often use selective serotonin reuptake inhibitors (SSRIs) antidepressants. These drugs readily cross the placental barrier and impact the developing fetal brain. Recently, we reported that prenatal fluoxetine (FLX), an SSRI antidepressant drug, altered corticosterone and behavioral responses to stress in female mouse offspring. The present study assessed the effects of prenatal FLX on these responses in males. The results showed that prenatal FLX significantly augmented the corticosterone response to acute stress in young prepubescent mice. The corticosterone response to continuous stress was not affected by prenatal FLX irrespective of age. In addition, continuous stress reduced general activity, and anxiety-like and depressive-like behaviors in adult animals prenatally exposed to FLX, but not in controls. The dexamethasone suppression test showed that prenatal FLX induced a state of glucocorticoid insensitivity in adult males, indicating that the negative feedback control of the hypothalamic-pituitary-adrenal axis response to stress was disrupted. Together, these findings indicate that prenatal FLX altered hormonal and behavioral responses to stress and suggest a role for the development of glucocorticoid insensitivity in these effects. These findings may aid understanding of the limitations and precautions that should be taken in the use of SSRIs by pregnant women.

Perinatal exposure to the selective serotonin reuptake inhibitor citalopram alters spatial learning and memory, anxiety, depression, and startle in Sprague-Dawley rats

Selective serotonin reuptake inhibitors (SSRIs) block the serotonin (5-HT) reuptake transporter (SERT) and increase synaptic 5-HT. 5-HT is also important in brain development; hence when SSRIs are taken during pregnancy there exists the potential for these drugs to affect CNS ontogeny. Prenatal SSRI exposure has been associated with an increased prevalence of autism spectrum disorder (ASD), and peripheral 5-HT is elevated in some ASD patients. Perinatal SSRI exposure in rodents has been associated with increased depression and anxiety-like behavior, decreased sociability, and impaired learning in the offspring, behaviors often seen in ASD. The present study investigated whether perinatal exposure to citalopram causes persistent neurobehavioral effects. Gravid Sprague-Dawley rats were assigned to two groups and subcutaneously injected twice per day with citalopram (10mg/kg; Cit) or saline (Sal) 6h apart on embryonic day (E)6-21, and then drug was given directly to the pups after delivery from postnatal day (P)1-20. Starting on P60, one male/female from each litter was tested in the Cincinnati water maze (CWM) and open-field before and after MK-801. A second pair from each litter was tested in the Morris water maze (MWM) and open-field before and after (+)-amphetamine. A third pair was tested as follows: elevated zero-maze, open-field, marble burying, prepulse inhibition of acoustic startle, social preference, and forced swim. Cit-exposed rats were impaired in the MWM during acquisition and probe, but not during reversal, shift, or cued trials. Cit-exposed rats also showed increased marble burying, decreased time in the center of the open-field, decreased latency to immobility in forced swim, and increased acoustic startle across prepulse intensities with no effects on CWM. The results are consistent with citalopram inducing several ASD-like effects. The findings add to concerns about use of SSRIs during pregnancy. Further research on different classes of antidepressants, dose-effect relationships, timing of exposure periods, and mechanisms for these effects are needed. It is also important to balance the effects described here against the effects of the disorders for which the drugs are given.

Prenatal SSRI alters the hormonal and behavioral responses to stress in female mice: Possible role for glucocorticoid resistance

Life time prevalence of major depression disorder (MDD) is higher in women compared to men especially during the period surrounding childbirth. Women suffering from MDD during pregnancy use antidepressant medications, particularly Selective Serotonin Reuptake Inhibitors (SSRI). These drugs readily cross the placental barrier and impact the developing fetal brain. The present study assessed the effects of prenatal exposure to fluoxetine (FLX), an SSRI antidepressant drug, on corticosterone and behavioral responses to stress in female mice. In young females, prenatal FLX significantly elevated corticosterone response to continuous stress. In adults, prenatal FLX augmented corticosterone response to acute stress and suppressed the response to continuous stress. Additionally, prenatal FLX significantly augmented stress-induced increase in locomotion and reduced anxiety- and depressive-like behaviors in adult, but not young mice. The dexamethasone suppression test revealed that prenatal FLX induced a state of glucocorticoid resistance in adult females, indicating that the negative feedback control of the hypothalamic-pituitary-adrenal axis response to stress was disrupted. These findings provide the first indication of altered hormonal and behavioral responses to continuous stress and suggest a role for the development of glucocorticoid resistance in these effects. According to these findings, prenatal environment may have implications for stress sensitivity and responsiveness to life challenges. Furthermore, this study may assist in understanding the limitations and precautions that should be taken in the use of SSRIs during pregnancy.

Of rodents and humans: A comparative review of the neurobehavioral effects of early life SSRI exposure in preclinical and clinical research

Selective serotonin reuptake inhibitors (SSRIs) have been a mainstay pharmacological treatment for women experiencing depression during pregnancy and postpartum for the past 25 years. SSRIs act via blockade of the presynaptic serotonin transporter and result in a transient increase in synaptic serotonin. Long-lasting changes in cellular function such as serotonergic transmission, neurogenesis, and epigenetics, are thought to underlie the therapeutic benefits of SSRIs. In recent years, though, growing evidence in clinical and preclinical settings indicate that offspring exposed to SSRIs in utero or as neonates exhibit long-lasting behavioral adaptions. Clinically, children exposed to SSRIs in early life exhibit increased internalizing behavior reduced social behavior, and increased risk for depression in adolescence. Similarly, rodents exposed to SSRIs perinatally exhibit increased traits of anxiety- or depression-like behavior. Furthermore, certain individuals appear to be more susceptible to early life SSRI exposure than others, suggesting that perinatal SSRI exposure may pose greater risks for negative outcome within certain populations. Although SSRIs trigger a number of intracellular processes that likely contribute to their therapeutic effects, early life antidepressant exposure during critical neurodevelopmental periods may elicit lasting negative effects in offspring. In this review, we cover the basic development and structure of the serotonin system, how the system is affected by early life SSRI exposure, and the behavioral outcomes of perinatal SSRI exposure in both clinical and preclinical settings. We review recent evidence indicating that perinatal SSRI exposure perturbs the developing limbic system, including altered serotonergic transmission, neurogenesis, and epigenetic processes in the hippocampus, which may contribute to behavioral domains (e.g., sociability, cognition, anxiety, and behavioral despair) that are affected by perinatal SSRI treatment. Identifying the molecular mechanisms that underlie the deleterious behavioral effects of perinatal SSRI exposure may highlight biological mechanisms in the etiology of mood disorders. Moreover, because recent studies suggest that certain individuals may be more susceptible to the negative consequences of early life SSRI exposure than others, understanding mechanisms that drive such susceptibility could lead to individualized treatment strategies for depressed women who are or plan to become pregnant.

Perinatal reduction of functional serotonin transporters results in developmental delay

While there is strong evidence from rodent and human studies that a reduction in serotonin transporter (5-HTT) function in early-life can increase the risk for several neuropsychiatric disorders in adulthood, the effects of reduced 5-HTT function on behavior across developmental stages are underinvestigated. To elucidate how perinatal pharmacological and lifelong genetic inactivation of the 5-HTT affects behavior across development, we conducted a battery of behavioral tests in rats perinatally exposed to fluoxetine or vehicle and in 5-HTT(-/-) versus 5-HTT(+/+) rats. We measured motor-related behavior, olfactory function, grooming behavior, sensorimotor gating, object directed behavior and novel object recognition in the first three postnatal weeks and if possible the tests were repeated in adolescence and adulthood. We also measured developmental milestones such as eye opening, reflex development and body weight. We observed that both pharmacological and genetic inactivation of 5-HTT resulted in a developmental delay. Except for hypo-locomotion, most of the observed early-life effects were normalized later in life. In adolescence and adulthood we observed object directed behavior and decreased novel object recognition in the 5-HTT(-/-) rats, which might be related to the lifelong inactivation of 5-HTT. Together, these data provide an important contribution to the understanding of the effects of perinatal and lifelong 5-HTT inactivation on behavior across developmental stages.

Early-life exposure to the SSRI paroxetine exacerbates depression-like behavior in anxiety/depression-prone rats

Selective serotonin reuptake inhibitor (SSRI) antidepressants are the mainstay treatment for the 10-20% of pregnant and postpartum women who suffer major depression, but the effects of SSRIs on their children's developing brain and later emotional health are poorly understood. SSRI use during pregnancy can elicit antidepressant withdrawal in newborns and increase toddlers' anxiety and social avoidance. In rodents, perinatal SSRI exposure increases adult depression- and anxiety-like behavior, although certain individuals are more vulnerable to these effects than others. Our study establishes a rodent model of individual differences in susceptibility to perinatal SSRI exposure, utilizing selectively bred Low Responder (bLR) and High Responder (bHR) rats that were previously bred for high versus low behavioral response to novelty. Pregnant bHR/bLR females were chronically treated with the SSRI paroxetine (10 mg/kg/day p.o.) to examine its effects on offspring's emotional behavior and gene expression in the developing brain. Paroxetine treatment had minimal effect on bHR/bLR dams' pregnancy outcomes or maternal behavior. We found that bLR offspring, naturally prone to an inhibited/anxious temperament, were susceptible to behavioral abnormalities associated with perinatal SSRI exposure (which exacerbated their Forced Swim Test immobility), while high risk-taking bHR offspring were resistant. Microarray studies revealed robust perinatal SSRI-induced gene expression changes in the developing bLR hippocampus and amygdala (postnatal days 7-21), including transcripts involved in neurogenesis, synaptic vesicle components, and energy metabolism. These results highlight the bLR/bHR model as a useful tool to explore the neurobiology of individual differences in susceptibility to perinatal SSRI exposure.

Effects of neonatal fluvoxamine administration on the physical development and activity of the serotoninergic system in white rats

Selective serotonin reuptake inhibitors (SSRIs), including fluvoxamine, are widely used to treat depressive disorders in pregnant women. These antidepressants effectively penetrate through the placental barrier, affecting the fetus during the critical phase of neurodevelopment. Some clinical studies have linked prenatal exposure to SSRIs with increased neonatal mortality, premature birth, decreased fetal growth and delay in psychomotor development. However, the effects of prenatal exposure to SSRIs remain unknown. The administration of SSRIs in rodents during the first postnatal weeks is considered as an model for studying the effects of prenatal SSRIs exposure in human. The aim of this work was to study the acute effects of chronic fluvoxamine (FA) administration in white rat pups. The study was carried out in male and female rat pups treated with FA (10 mg/kg/day, intraperitoneally) from postnatal days 1 to 14. The lethality level, body weight, age of eye opening, and motor reflex maturation were recorded. The contents of biogenic amines and their metabolites in different brain structures were also determined. It was shown that neonatal FA administration led to increased lethality level, reduced body weight, and delayed maturation of motor reflexes. Furthermore, increased noradrenalin level in hypothalamus, serotonin level in hippocampus and serotonin metabolite 5-HIAA level in frontal cortex, hypothalamus, hippocampus, and striatum were observed in drug-treated animals compared to the control group. We can conclude that the altered activity of the serotoninergic system induced by fluvoxamine administration at early developmental stages leads to a delay in physical and motor development.

Fluoxetine induces changes in the testicle and testosterone in adult male rats exposed via placenta and lactation

Fluoxetine is a selective serotonin reuptake inhibitor used to treat depression in pregnant and nursing women. However, recent studies have shown adverse effects in the male reproductive system after fluoxetine treatment. Aiming to analyze the extent of damage caused by fluoxetine in the testicle and safe doses for treatment during the perinatal period, the present study analyzed the effects of in utero exposure and exposure during lactation to fluoxetine in spermatogenesis of male rat offspring in adulthood. Wistar rat dams were orally treated with fluoxetine (5, 10, and 20 mg/kg) from 13 days of gestation to lactation day 21 and their offspring were analyzed at 90 days old. Results showed a reduction in the weight of testes (16%), epididymis (28%), and seminal glands (18%) in animals exposed to fluoxetine 20 mg/kg compared to the control. Seminal gland weight was also reduced 25% and 30% in animals exposed to 5 mg/kg and 10 mg/kg fluoxetine, respectively. Body weight of animals exposed to 20 mg/kg fluoxetine was reduced from post-natal day 9 to 36 compared to controls but from the post-natal day 9 to 36 there was no statistical difference. The volume of seminiferous epithelium reduced 17% and the total volume of Leydig cells reduced 30% in the group exposed to fluoxetine at 20 mg/kg. Furthermore, Leydig cells volume reduced 29% in the 5 mg/kg group. The length of the seminiferous tubules reduced 17% and daily sperm production per testicle also reduced 18% in animals exposed to the highest dose of fluoxetine compared to controls. The individual area of Leydig cells increased 7% and plasma testosterone increased 49% in animals exposed to fluoxetine at 20 mg/kg. In conclusion, exposure to 20 mg/kg fluoxetine via the placenta and during lactation may change testosterone and testicular parameters important for sperm production and male fertility in adulthood.

Reprint of "Effects of the SSRI citalopram on behaviours connected to stress and reproduction in Endler guppy, Poecilia wingei"

Psychoactive drugs, such as selective serotonin reuptake inhibitors (SSRI) have been identified in high levels in effluents from Swedish sewage treatment plants (STP) at concentrations high enough to give pharmacological effects in fish. In humans SSRIs are used in the treatment of depression and they have anxiolytic effects. In the present study we exposed Endler guppy (Poecilia wingei) of both sexes to citalopram that showed the highest concentrations of SSRIs in STP effluents and studied reproductive and non-reproductive behaviour. Male courting behaviours were not affected compared to control fish after 14-28 days exposure to 1 μgL(-1). In two experiments exposing both sexes to 0.2, 2.3 or 15 μgL(-1) for 21 days, fish exposed to the two highest doses showed anxiolytic effects when placed in a novel environment (novel tank diving test, NT). Males were only affected by exposure to 15 μgL(-1). They had significantly longer latency to explore the upper half of the aquarium, more visits and longer time spent in the upper half, and showed less bottom freezing behaviour, all markers of anxiolytic behaviour. In females exposure to 2.3 or 15 μgL(-1) significantly increased freezing behaviour, while no effects on other behaviour variables were observed. No effects on shoaling behaviour could be discerned. These results show that citalopram have anxiolytic effects on guppy fish and thus affect ecologically relevant behaviours of importance to survival of fish.

Effects of the SSRI citalopram on behaviours connected to stress and reproduction in Endler guppy, Poecilia wingei

Psychoactive drugs, such as selective serotonin reuptake inhibitors (SSRI) have been identified in high levels in effluents from Swedish sewage treatment plants (STP) at concentrations high enough to give pharmacological effects in fish. In humans SSRIs are used in the treatment of depression and they have anxiolytic effects. In the present study we exposed Endler guppy (Poecilia wingei) of both sexes to citalopram that showed the highest concentrations of SSRIs in STP effluents and studied reproductive and non-reproductive behaviour. Male courting behaviours were not affected compared to control fish after 14-28 days exposure to 1 μg L(-1). In two experiments exposing both sexes to 0.2, 2.3 or 15 μg L(-1) for 21 days, fish exposed to the two highest doses showed anxiolytic effects when placed in a novel environment (novel tank diving test, NT). Males were only affected by exposure to 15 μg L(-1). They had significantly longer latency to explore the upper half of the aquarium, more visits and longer time spent in the upper half, and showed less bottom freezing behaviour, all markers of anxiolytic behaviour. In females exposure to 2.3 or 15 μg L(-1) significantly increased freezing behaviour, while no effects on other behaviour variables were observed. No effects on shoaling behaviour could be discerned. These results show that citalopram have anxiolytic effects on guppy fish and thus affect ecologically relevant behaviours of importance to survival of fish.

Lasting neurobehavioral abnormalities in rats after neonatal activation of serotonin 1A and 1B receptors: possible mechanisms for serotonin dysfunction in autistic spectrum disorders

RATIONALE

Perinatal exposure of rats to selective serotonin reuptake inhibitors (SSRIs) produces sensory and social abnormalities paralleling those seen in autistic spectrum disorders (ASDs). However, the possible mechanism(s) by which this exposure produces behavioral abnormalities is unclear.

OBJECTIVE

We hypothesized that the lasting effects of neonatal SSRI exposure are a consequence of abnormal stimulation of 5-HT1A and/or 5-HT1B receptors during brain development. We examined whether such stimulation would result in lasting sensory and social deficits in rats in a manner similar to SSRIs using both direct agonist stimulation of receptors as well as selective antagonism of these receptors during SSRI exposure.

METHODS

Male and female rat pups were treated from postnatal days 8 to 21. In Experiment 1, pups received citalopram (20 mg/kg/day), saline, (±)-8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT; 0.5 mg/kg/day) or 7-trifluoromethyl-4(4-methyl-1-piperazinyl)-pyrrolo[1,2-a]-quinoxaline dimaleate (CGS-12066B; 10 mg/kg/day). In Experiment 2, a separate cohort of pups received citalopram (20 mg/kg/day), or saline which was combined with either N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclo-hexanecarboxamide maleate (WAY-100635; 0.6 mg/kg/day) or N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-1-1'-biphenyl-4-carboxamide (GR-127935; 6 mg/kg/day) or vehicle. Rats were then tested in paradigms designed to assess sensory and social response behaviors at different time points during development.

RESULTS

Direct and indirect neonatal stimulation of 5-HT1A or 5-HT1B receptors disrupts sensory processing, produces neophobia, increases stereotypic activity, and impairs social interactions in manner analogous to that observed in ASD.

CONCLUSION

Increased stimulation of 5-HT1A and 5-HT1B receptors plays a significant role in the production of lasting social and sensory deficits in adult animals exposed as neonates to SSRIs.

Developmental fluoxetine exposure facilitates sexual behavior in female offspring

RATIONALE

A growing number of infants are being exposed to selective serotonin reuptake inhibitor (SSRI) medications during the perinatal period. SSRIs target the serotoninergic system and are a popular treatment for maternal mood disorders. Serotonin itself plays a key role in the sexual differentiation through its role in the development of the hypothalamic-pituitary-gonadal axis, and previous research has shown that developmental SSRI exposure has an effect on sexual behavior in male offspring.

OBJECTIVES

Our aim was to determine the role of developmental exposure to a popular SSRI medication, fluoxetine, on sexual differentiation of the brain and behavior in female offspring using a rodent model of maternal adversity.

METHODS

Stressed and non-stressed Sprague-Dawley rat dams were chronically treated with either fluoxetine (5 mg/kg/day) or vehicle beginning on postnatal day 1. Four groups of female offspring were used: (1) control + vehicle, (2) control + fluoxetine, (3) prenatal stress + vehicle, and (4) prenatal stress + fluoxetine.

RESULTS

Primary results show that in adult female offspring, developmental fluoxetine exposure facilitates proceptive and receptive behaviors with a significant increase in the number of proceptive behaviors, a significant increase in the lordosis quotient, and a significant decrease in the rejection quotient.

CONCLUSIONS

This research contributes in the understanding of the long-term impact developmental fluoxetine exposure on the hypothalamus-pituitary-gonadal (HPG) system in adult female offspring.

Central nervous system effects of prenatal selective serotonin reuptake inhibitors: sensing the signal through the noise

RATIONALE

Women are increasingly prescribed selective serotonin reuptake inhibitors (SSRIs) during pregnancy, with potential implications for neurodevelopment. Whether prenatal SSRI exposure has an effect on neurodevelopment and behavior in the offspring is an important area of investigation.

OBJECTIVES

The aim of this paper was to review the existing preclinical and clinical literature of prenatal SSRI exposure on serotonin-related behaviors and markers in the offspring. The goal is to determine if there is a signal in the literature that could guide clinical care and/or inform research.

RESULTS

Preclinical studies (n = 4) showed SSRI exposure during development enhanced depression-like behavior. Half of rodent studies examining anxiety-like behavior (n = 13) noted adverse effects with SSRI exposure. A majority of studies of social behavior (n = 4) noted a decrease in sociability in SSRI exposed offspring. Human studies (n = 4) examining anxiety in the offspring showed no adverse effects of prenatal SSRI exposure. The outcome of one study suggested that children with autism were more likely to have a mother who was prescribed an SSRI during pregnancy.

CONCLUSIONS

Preclinical findings in rodents exposed to SSRIs during development point to an increase in depression- and anxiety-like behavior and alteration in social behaviors in the offspring, though both the methods used and the findings were not uniform. These data are not robust enough to discourage use of SSRIs during human pregnancy, particularly given the known adverse effects of maternal mental illness on pregnancy outcomes and infant neurodevelopment. Future research should focus on consistent animal models and prospective human studies with larger samples.

Perinatal exposure to fluoxetine via placenta and lactation inhibits the testicular development in male rat offspring

Due to the widespread use of fluoxetine to treat depression, including pregnant and nursing women, the present study aimed to investigate the effects of in utero and lactational exposure to fluoxetine in rat offspring at post natal day 22. Wistar rat dams were orally treated with fluoxetine (5, 10, and 20 mg/kg) from day 13 gestation to day 21 lactation. Exposure to 10 and 20 mg/kg fluoxetine reduced the body and testis weights. The volume of the seminiferous tubules and epithelium were also reduced following 20 mg/kg fluoxetine exposure. The length of the seminiferous tubules and the population of Sertoli cells changed in offspring exposed to fluoxetine. The amount of seminiferous tubules lacking tubular lumen was higher in rats exposed to 20 mg/kg fluoxetine. Plasma testosterone showed no significant change. In conclusion, fluoxetine exposure via the placenta and lactation may inhibit and delay testicular development, adversely affecting several testicular parameters important for the establishment of sperm production in adulthood.