The Association Between Prenatal Exposure to Antidepressants and Autism: Some Research and Public Health Aspects

Mesenchymal Stem Cells and Purinergic Signaling in Autism Spectrum Disorder: Bridging the Gap between Cell-Based Strategies and Neuro-Immune Modulation

The prevalence of autism spectrum disorder (ASD) is still increasing, which means that this neurodevelopmental lifelong pathology requires special scientific attention and efforts focused on developing novel therapeutic approaches. It has become increasingly evident that neuroinflammation and dysregulation of neuro-immune cross-talk are specific hallmarks of ASD, offering the possibility to treat these disorders by factors modulating neuro-immunological interactions. Mesenchymal stem cell-based therapy has already been postulated as one of the therapeutic approaches for ASD; however, less is known about the molecular mechanisms of stem cell influence. One of the possibilities, although still underestimated, is the paracrine purinergic activity of MSCs, by which stem cells ameliorate inflammatory reactions. Modulation of adenosine signaling may help restore neurotransmitter balance, reduce neuroinflammation, and improve overall brain function in individuals with ASD. In our review article, we present a novel insight into purinergic signaling, including but not limited to the adenosinergic pathway and its role in neuroinflammation and neuro-immune cross-talk modulation. We anticipate that by achieving a greater understanding of the purinergic signaling contribution to ASD and related disorders, novel therapeutic strategies may be devised for patients with autism in the near future.

Prenatal SSRI Exposure Increases the Risk of Autism in Rodents via Aggravated Oxidative Stress and Neurochemical Changes in the Brain

The mechanisms underlying selective serotonin reuptake inhibitor (SSRI) use during pregnancy as a major autism risk factor are unclear. Here, brain neurochemical changes following fluoxetine exposure and in an autism model were compared to determine the effects on autism risk. The study was performed on neonatal male western albino rats which were divided into Groups one (control), two (propionic acid [PPA]-induced autism model), and three (prenatal SSRI-exposed newborn rats whose mothers were exposed to 5 mg/kg of fluoxetine over gestation days 10-20). SSRI (fluoxetine) induced significant neurochemical abnormalities in the rat brain by increasing lipid peroxide (MDA), Interferon-gamma (IFN-γ), and caspase-3 levels and by depleting Glutathione (GSH), Glutathione S-transferases (GST), Catalase, potassium (K+), and Creatine kinase (CK) levels, similarly to what has been discovered in the PPA model of autism when compared with control. Prenatal fluoxetine exposure plays a significant role in asset brain damage in newborns; further investigation of fluoxetine as an autism risk factor is thus warranted.

Should Antidepressants be Avoided in Pregnancy?

Many (> 40%) women discontinue antidepressants during pregnancy because of concerns about effects on the foetus, based on information from inadequately-controlled studies. The sibling-control study design provides the best control for confounding factors, notably maternal depression. The purpose of this review was to investigate the evidence from sibling-control analyses for adverse outcomes in offspring associated with antidepressant exposure during pregnancy. Fourteen sibling-control studies were identified through searches of PubMed and Embase. Outcomes included preterm birth, small for gestational age, neonatal size, birth defects, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), behavioural problems, neurodevelopmental deficits, and scholastic attainment. For the majority of these outcomes, no statistically significant associations were found when comparing exposed and unexposed siblings. Single studies reported associations with preterm birth, reduced gestational age, ADHD, anxiety at 36 months, and lower mathematics test scores, which persisted in the sibling-control analyses. However, differences were small and possibly not clinically significant. Moreover, effects of residual confounding could not be excluded. These findings provide evidence that many of the previously reported associations between prenatal antidepressant exposure and adverse outcomes in offspring are no longer statistically significant when exposed offspring are compared with unexposed siblings. The few statistically significant differences in sibling-control analyses were generally small with doubtful clinical significance. Decisions on antidepressant treatment during pregnancy should be made individually, based on evidence from properly controlled studies, not on misleading information based on studies that have not controlled adequately for confounding factors.

Maternal Perinatal Depression and Risk of Neurodevelopmental Disorders in Offspring: Preliminary Results from the SOS MOOD Project

The latest research is attempting to define whether there may be an association between maternal Perinatal Depression (PD), the use of psychotropic medications during pregnancy, and a higher risk of neurodevelopmental disorders in children, including Autism Spectrum Disorder (ASD). A better understanding of the relation between PD and ASD is a key element to develop early interventions. This study has been developed in the context of the SOS MOOD project. Its aim is to evaluate the possible impact of maternal PD on the child’s cognitive and behavioral phenotype with a focus on ASD. Women included in the project were screened during pregnancy (1st, 2nd trimester) for PD—categorized as affected or not—and if necessary were prescribed pharmacological therapy; offspring of both groups of women underwent at a mean age of 43 months a standardized neuropsychiatric evaluation of developmental and cognitive skills, behavioral problems, autism symptoms and parental stress. Preliminary results on 59 women and 59 children do not suggest significant long-term effects of maternal PD on offspring’s development and behavior. Nonetheless further studies on wider samples are necessary in order to confirm such results and disentangle the role of possible confounding factors associated to the maternal illness.

Sex differences in long-term behavioral alterations, especially anxiety, following prenatal fluoxetine exposure in C57BL/6 mice

Evidence demonstrates that psychiatric disorders during pregnancy are detrimental to the offspring. Many disorders are treated with SSRIs and increasing numbers of pregnant women now receive these drugs during gestation. The long-term neurobehavioral consequences of prenatal SSRI exposure require further evaluation. This study examined the effects of prenatal fluoxetine exposure in mice in an extensive battery of behaviors related to neurodevelopment, mood, social, and repetitive behaviors. C57BL/6J dams were administered fluoxetine at a low (0.6 mg/kg/day) or high (6 mg/kg/day) dose or saline from embryonic days 8 to 18. Juvenile mice were tested for changes in ultrasonic vocalizations and neuromotor development. In adulthood, offspring were tested for changes in behaviors related to anxiety, depression, social, and repetitive behaviors. Prenatal exposure to fluoxetine impaired surface righting reflex at P5, and sex-dependently reduced the frequency of ultrasonic vocalizations in juvenile males but not females. In adulthood, both males and females prenatally exposed to high, but not low, doses of fluoxetine exhibited an increase in repetitive behaviors in the marble burying task and a decrease in sucrose preference. Males, but not females, exposed to fluoxetine exhibited increased anxiety-related behaviors in the elevated plus maze. Prenatal fluoxetine exposure did not affect other adult behaviors including social preference, self-grooming, passive avoidance and open field activity. These findings suggest males are more sensitive than females to disruptions in serotonin balance during prenatal development and highlight the need for additional systematic and mechanistic studies to evaluate the impact of fluoxetine exposure during other periods of gestation.