Perturbed Developmental Serotonin Signaling Affects Prefrontal Catecholaminergic Innervation and Cortical Integrity

Serotonin transporter knockout in rats reduces beta- and gamma-band functional connectivity between the orbitofrontal cortex and amygdala during auditory discrimination

The orbitofrontal cortex and amygdala collaborate in outcome-guided decision-making through reciprocal projections. While serotonin transporter knockout (SERT-/-) rodents show changes in outcome-guided decision-making, and in orbitofrontal cortex and amygdala neuronal activity, it remains unclear whether SERT genotype modulates orbitofrontal cortex-amygdala synchronization. We trained SERT-/- and SERT+/+ male rats to execute a task requiring to discriminate between two auditory stimuli, one predictive of a reward (CS+) and the other not (CS-), by responding through nose pokes in opposite-side ports. Overall, task acquisition was not influenced by genotype. Next, we simultaneously recorded local field potentials in the orbitofrontal cortex and amygdala of both hemispheres while the rats performed the task. Behaviorally, SERT-/- rats showed a nonsignificant trend for more accurate responses to the CS-. Electrophysiologically, orbitofrontal cortex-amygdala synchronization in the beta and gamma frequency bands during response selection was significantly reduced and associated with decreased hubness and clustering coefficient in both regions in SERT-/- rats compared to SERT+/+ rats. Conversely, theta synchronization at the time of behavioral response in the port associated with reward was similar in both genotypes. Together, our findings reveal the modulation by SERT genotype of the orbitofrontal cortex-amygdala functional connectivity during an auditory discrimination task.

The impact of the mesoprefrontal dopaminergic system on the maturation of interneurons in the murine prefrontal cortex

The prefrontal cortex (PFC) undergoes a protracted maturation process. This is true both for local interneurons and for innervation from midbrain dopaminergic (mDA) neurons. In the striatum, dopaminergic (DA) neurotransmission is required for the maturation of medium spiny neurons during a critical developmental period. To investigate whether DA innervation influences the maturation of interneurons in the PFC, we used a conditional knockout (cKO) mouse model in which innervation from mDA neurons to the mPFC (mesoprefrontal innnervation) is not established during development. In this mouse model, the maturation of parvalbumin (PV) and calbindin (CB) interneuron populations in the PFC is dysregulated during a critical period in adolescence with changes persisting into adulthood. PV interneurons are particularly vulnerable to lack of mesoprefrontal input, showing an inability to maintain adequate PV expression with a concomitant decrease in Gad1 expression levels. Interestingly, lack of mesoprefrontal innervation does not appear to induce compensatory changes such as upregulation of DA receptor expression in PFC neurons or increased innervation density of other neuromodulatory (serotonergic and noradrenergic) innervation. In conclusion, our study shows that adolescence is a sensitive period during which mesoprefrontal input plays a critical role in promoting the maturation of specific interneuron subgroups. The results of this study will help to understand how a dysregulated mesoprefrontal DA system contributes to the pathophysiology of neurodevelopmental disorders.

Individuals being high in their sensitivity to the environment: Are sensitive period changes in play?

All individuals on planet earth are sensitive to the environment, but some more than others. These individual differences in sensitivity to environments are seen across many animal species including humans, and can influence personalities as well as vulnerability and resilience to mental disorders. Yet, little is known about the underlying brain mechanisms. Key genes that contribute to individual differences in environmental sensitivity are the serotonin transporter, dopamine D4 receptor and brain-derived neurotrophic factor genes. By synthesizing neurodevelopmental findings of these genetic factors, and discussing them through the lens of mechanisms related to sensitive periods, which are phases of heightened neuronal plasticity during which a certain network is being finetuned by experiences, we propose that these genetic factors delay but extend postnatal sensitive periods. This may explain why sensitive individuals show behavioral features that are characteristic of a young brain state at the level of sensory information processing, such as reduced filtering or blockade of irrelevant information, resulting in a sensory processing system that 'keeps all options open'.

Neonatal hypoxia impairs serotonin release and cognitive functions in adult mice

Children who experienced moderate perinatal asphyxia (MPA) are at risk of developing long lasting subtle cognitive and behavioral deficits, including learning disabilities and emotional problems. The prefrontal cortex (PFC) regulates cognitive flexibility and emotional behavior. Neurons that release serotonin (5-HT) project to the PFC, and compounds modulating 5-HT activity influence emotion and cognition. Whether 5-HT dysregulations contribute to MPA-induced cognitive problems is unknown. We established a MPA mouse model, which displays recognition and spatial memory impairments and dysfunctional cognitive flexibility. We found that 5-HT expression levels, quantified by immunohistochemistry, and 5-HT release, quantified by in vivo microdialysis in awake mice, are reduced in PFC of adult MPA mice. MPA mice also show impaired body temperature regulation following injection of the 5-HT1A receptor agonist 8-OH-DPAT, suggesting the presence of deficits in 5-HT auto-receptor function on raphe neurons. Finally, chronic treatment of adult MPA mice with fluoxetine, an inhibitor of 5-HT reuptake transporter, or the 5-HT1A receptor agonist tandospirone rescues cognitive flexibility and memory impairments. All together, these data demonstrate that the development of 5-HT system function is vulnerable to moderate perinatal asphyxia. 5-HT hypofunction might in turn contribute to long-term cognitive impairment in adulthood, indicating a potential target for pharmacological therapies.

olf413 an octopamine biogenesis pathway gene is required for axon growth and pathfinding during embryonic nervous system development in Drosophila melanogaster

OBJECTIVE

Neurotransmitters have been extensively studied as neural communication molecules. Genetic associations discovered, and indirect intervention studies in Humans and mammals have led to a general proposition that neurotransmitters have a role in structuring of neuronal network during development. olf413 is a Drosophila gene annotated as coding for dopamine beta-monooxygenase enzyme with a predicted function in octopaminergic pathway. The biological function of this gene is very little worked out. In this study we investigate the requirement of olf413 gene function for octopamine biogenesis and developmental patterning of embryonic nervous system.

RESULT

In our study we have used the newly characterized neuronal specific allele olf413SG1.1, and the gene disruption strain olf413MI02014 to dissect out the function of olf413. olf413 has an enhancer activity as depicted by reporter GFP expression, in the embryonic ventral nerve cord, peripheral nervous system and the somatic muscle bundles. Homozygous loss of function mutants show reduced levels of octopamine, and this finding supports the proposed function of the gene in octopamine biogenesis. Further, loss of function of olf413 causes embryonic lethality. FasII staining of these embryos reveal a range of phenotypes in the central and peripheral motor nerves, featuring axonal growth, pathfinding, branching and misrouting defects. Our findings are important as they implicate a key functional requirement of this gene in precise axonal patterning events, a novel developmental role imparted for an octopamine biosynthesis pathway gene in structuring of embryonic nervous system.

What risk factors for Developmental Language Disorder can tell us about the neurobiological mechanisms of language development

Language is a complex multidimensional cognitive system that is connected to many neurocognitive capacities. The development of language is therefore strongly intertwined with the development of these capacities and their neurobiological substrates. Consequently, language problems, for example those of children with Developmental Language Disorder (DLD), are explained by a variety of etiological pathways and each of these pathways will be associated with specific risk factors. In this review, we attempt to link previously described factors that may interfere with language development to putative underlying neurobiological mechanisms of language development, hoping to uncover openings for future therapeutical approaches or interventions that can help children to optimally develop their language skills.

Autism spectrum disorders pathogenesis: Toward a comprehensive model based on neuroanatomic and neurodevelopment considerations

Autism spectrum disorder (ASD) involves alterations in neural connectivity affecting cortical network organization and excitation to inhibition ratio. It is characterized by an early increase in brain volume mediated by abnormal cortical overgrowth patterns and by increases in size, spine density, and neuron population in the amygdala and surrounding nuclei. Neuronal expansion is followed by a rapid decline from adolescence to middle age. Since no known neurobiological mechanism in human postnatal life is capable of generating large excesses of frontocortical neurons, this likely occurs due to a dysregulation of layer formation and layer-specific neuronal migration during key early stages of prenatal cerebral cortex development. This leads to the dysregulation of post-natal synaptic pruning and results in a huge variety of forms and degrees of signal-over-noise discrimination losses, accounting for ASD clinical heterogeneities, including autonomic nervous system abnormalities and comorbidities. We postulate that sudden changes in environmental conditions linked to serotonin/kynurenine supply to the developing fetus, throughout the critical GW7 - GW20 (Gestational Week) developmental window, are likely to promote ASD pathogenesis during fetal brain development. This appears to be driven by discrete alterations in differentiation and patterning mechanisms arising from in utero RNA editing, favoring vulnerability outcomes over plasticity outcomes. This paper attempts to provide a comprehensive model of the pathogenesis and progression of ASD neurodevelopmental disorders.

HGprt deficiency disrupts dopaminergic circuit development in a genetic mouse model of Lesch–Nyhan disease

In Lesch–Nyhan disease (LND), deficiency of the purine salvage enzyme hypoxanthine guanine phosphoribosyl transferase (HGprt) leads to a characteristic neurobehavioral phenotype dominated by dystonia, cognitive deficits and incapacitating self-injurious behavior. It has been known for decades that LND is associated with dysfunction of midbrain dopamine neurons, without overt structural brain abnormalities. Emerging post mortem and in vitro evidence supports the hypothesis that the dopaminergic dysfunction in LND is of developmental origin, but specific pathogenic mechanisms have not been revealed. In the current study, HGprt deficiency causes specific neurodevelopmental abnormalities in mice during embryogenesis, particularly affecting proliferation and migration of developing midbrain dopamine (mDA) neurons. In mutant embryos at E14.5, proliferation was increased, accompanied by a decrease in cell cycle exit and the distribution and orientation of dividing cells suggested a premature deviation from their migratory route. An abnormally structured radial glia-like scaffold supporting this mDA neuronal migration might lie at the basis of these abnormalities. Consequently, these abnormalities were associated with an increase in area occupied by TH⁺ cells and an abnormal mDA subpopulation organization at E18.5. Finally, dopaminergic innervation was disorganized in prefrontal and decreased in HGprt deficient primary motor and somatosensory cortices. These data provide direct in vivo evidence for a neurodevelopmental nature of the brain disorder in LND. Future studies should not only focus the specific molecular mechanisms underlying the reported neurodevelopmental abnormalities, but also on optimal timing of therapeutic interventions to rescue the DA neuron defects, which may also be relevant for other neurodevelopmental disorders.

Development of prefrontal cortex

During evolution, the cerebral cortex advances by increasing in surface and the introduction of new cytoarchitectonic areas among which the prefrontal cortex (PFC) is considered to be the substrate of highest cognitive functions. Although neurons of the PFC are generated before birth, the differentiation of its neurons and development of synaptic connections in humans extend to the 3rd decade of life. During this period, synapses as well as neurotransmitter systems including their receptors and transporters, are initially overproduced followed by selective elimination. Advanced methods applied to human and animal models, enable investigation of the cellular mechanisms and role of specific genes, non-coding regulatory elements and signaling molecules in control of prefrontal neuronal production and phenotypic fate, as well as neuronal migration to establish layering of the PFC. Likewise, various genetic approaches in combination with functional assays and immunohistochemical and imaging methods reveal roles of neurotransmitter systems during maturation of the PFC. Disruption, or even a slight slowing of the rate of neuronal production, migration and synaptogenesis by genetic or environmental factors, can induce gross as well as subtle changes that eventually can lead to cognitive impairment. An understanding of the development and evolution of the PFC provide insight into the pathogenesis and treatment of congenital neuropsychiatric diseases as well as idiopathic developmental disorders that cause intellectual disabilities.

The effects of neonatal procedural pain and maternal isolation on hippocampal cell proliferation and reelin concentration in neonatal and adult male and female rats

Preterm births accounted for over 10% of all U.S. live births in 2019 and the rate is rising. Neonatal stressors, especially procedural pain, experienced by preterm infants in the neonatal intensive care unit (NICU) have been associated with neurodevelopmental impairments. Parental care can alleviate stress during stressful or painful procedures; however, infants in the NICU often receive reduced parental care compared with their peers. Animal studies suggest that decreased maternal care similarly impairs neurodevelopment but also influences the effects of neonatal pain. It is important to mimic both stressors in animal models of neonatal stress exposure. In this study, researchers investigated the individual and combined impact of neonatal pain and maternal isolation on reelin protein levels and cellular proliferation in the hippocampal dentate gyrus of 8 days old and adult rats. Exposure to either stressor individually, but not both, increased reelin levels in the dentate gyrus of adult females without significantly altering reelin levels in adult males. However, cell proliferation levels at either age were unaffected by the early-life stressors. These results suggest that each early-life stressor has a unique effect on markers of brain development and more research is needed to further investigate their distinct influences.

The Development of the Mesoprefrontal Dopaminergic System in Health and Disease

Midbrain dopaminergic neurons located in the substantia nigra and the ventral tegmental area are the main source of dopamine in the brain. They send out projections to a variety of forebrain structures, including dorsal striatum, nucleus accumbens, and prefrontal cortex (PFC), establishing the nigrostriatal, mesolimbic, and mesoprefrontal pathways, respectively. The dopaminergic input to the PFC is essential for the performance of higher cognitive functions such as working memory, attention, planning, and decision making. The gradual maturation of these cognitive skills during postnatal development correlates with the maturation of PFC local circuits, which undergo a lengthy functional remodeling process during the neonatal and adolescence stage. During this period, the mesoprefrontal dopaminergic innervation also matures: the fibers are rather sparse at prenatal stages and slowly increase in density during postnatal development to finally reach a stable pattern in early adulthood. Despite the prominent role of dopamine in the regulation of PFC function, relatively little is known about how the dopaminergic innervation is established in the PFC, whether and how it influences the maturation of local circuits and how exactly it facilitates cognitive functions in the PFC. In this review, we provide an overview of the development of the mesoprefrontal dopaminergic system in rodents and primates and discuss the role of altered dopaminergic signaling in neuropsychiatric and neurodevelopmental disorders.

Developmental exposure to the synthetic progestin, 17α-hydroxyprogesterone caproate, disrupts the mesocortical serotonin pathway and alters impulsive decision-making in rats

The synthetic progestin, 17α-hydroxyprogesterone caproate (17-OHPC), is administered to women at risk for preterm birth during a critical period of fetal development for mesocortical pathways. Yet, little information is available regarding the potential effects of 17-OHPC on the developing fetal brain. In rat models, the mesocortical serotonin pathway is sensitive to progestins. Progesterone receptor (PR) is expressed in layer 3 pyramidal neurons of medial prefrontal cortex (mPFC) and in serotonergic neurons of the dorsal raphe. The present study tested the hypothesis that exposure to 17-OHPC during development disrupts serotonergic innervation of the mPFC in adolescence and impairs behavior mediated by this pathway in adulthood. Administration of 17-OHPC from postnatal days 1-14 decreased the density of SERT-ir fibers within superficial and deep layers and decreased the density of synaptophysin-ir boutons in all layers of prelimbic mPFC at postnatal day 28. In addition, rats exposed to 17-OHPC during development were less likely to make impulsive choices in the Delay Discounting task, choosing the larger, delayed reward more often than controls at moderate delay times. Interestingly, 17-OHPC exposed rats were more likely to fail to make any choice (i.e., increased omissions) compared to controls at longer delays, suggesting disruptions in decision-making. These results suggest that further investigation is warranted in the clinical use of 17-OHPC to better inform a risk/benefit analysis of progestin use in pregnancy.

5-HT3 Signaling Alters Development of Sacral Neural Crest Derivatives That Innervate the Lower Urinary Tract

The autonomic nervous system derives from the neural crest (NC) and supplies motor innervation to the smooth muscle of visceral organs, including the lower urinary tract (LUT). During fetal development, sacral NC cells colonize the urogenital sinus to form pelvic ganglia (PG) flanking the bladder neck. The coordinated activity of PG neurons is required for normal urination; however, little is known about the development of PG neuronal diversity. To discover candidate genes involved in PG neurogenesis, the transcriptome profiling of sacral NC and developing PG was performed, and we identified the enrichment of the type 3 serotonin receptor (5-HT3, encoded by Htr3a and Htr3b). We determined that Htr3a is one of the first serotonin receptor genes that is up-regulated in sacral NC progenitors and is maintained in differentiating PG neurons. In vitro cultures showed that the disruption of 5-HT3 signaling alters the differentiation outcomes of sacral NC cells, while the stimulation of 5-HT3 in explanted fetal pelvic ganglia severely diminished neurite arbor outgrowth. Overall, this study provides a valuable resource for the analysis of signaling pathways in PG development, identifies 5-HT3 as a novel regulator of NC lineage diversification and neuronal maturation in the peripheral nervous system, and indicates that the perturbation of 5-HT3 signaling in gestation has the potential to alter bladder function later in life.

Linking mPFC circuit maturation to the developmental regulation of emotional memory and cognitive flexibility

The medial prefrontal cortex (mPFC) and its abundant connections with other brain regions play key roles in memory, cognition, decision making, social behaviors, and mood. Dysfunction in mPFC is implicated in psychiatric disorders in which these behaviors go awry. The prolonged maturation of mPFC likely enables complex behaviors to emerge, but also increases their vulnerability to disruption. Many foundational studies have characterized either mPFC synaptic or behavioral development without establishing connections between them. Here, we review this rich body of literature, aligning major events in mPFC development with the maturation of complex behaviors. We focus on emotional memory and cognitive flexibility, and highlight new work linking mPFC circuit disruption to alterations of these behaviors in disease models. We advance new hypotheses about the causal connections between mPFC synaptic development and behavioral maturation and propose research strategies to establish an integrated understanding of neural architecture and behavioral repertoires.

Serotonin-specific neurons differentiated from human iPSCs form distinct subtypes with synaptic protein assembly

Human induced pluripotent stem cells (hiPSCs) have revolutionized the generation of experimental disease models, but the development of protocols for the differentiation of functionally active neuronal subtypes with defined specification is still in its infancy. While dysfunction of the brain serotonin (5-HT) system has been implicated in the etiology of various neuropsychiatric disorders, investigation of functional human 5-HT specific neurons in vitro has been restricted by technical limitations. We describe an efficient generation of functionally active neurons from hiPSCs displaying 5-HT specification by modification of a previously reported protocol. Furthermore, 5-HT specific neurons were characterized using high-end fluorescence imaging including super-resolution microscopy in combination with electrophysiological techniques. Differentiated hiPSCs synthesize 5-HT, express specific markers, such as tryptophan hydroxylase 2 and 5-HT transporter, and exhibit an electrophysiological signature characteristic of serotonergic neurons, with spontaneous rhythmic activities, broad action potentials and large afterhyperpolarization potentials. 5-HT specific neurons form synapses reflected by the expression of pre- and postsynaptic proteins, such as Bassoon and Homer. The distribution pattern of Bassoon, a marker of the active zone along the soma and extensions of neurons, indicates functionality via volume transmission. Among the high percentage of 5-HT specific neurons (~ 42%), a subpopulation of CDH13 + cells presumably designates dorsal raphe neurons. hiPSC-derived 5-HT specific neuronal cell cultures reflect the heterogeneous nature of dorsal and median raphe nuclei and may facilitate examining the association of serotonergic neuron subpopulations with neuropsychiatric disorders.

Hypersensitivity to amphetamine's psychomotor and reinforcing effects in serotonin transporter knockout rats: Glutamate in the nucleus accumbens

Background and Purpose

Amphetamine (AMPH) use disorder is a serious health concern, but, surprisingly, little is known about the vulnerability to the moderate and compulsive use of this psychostimulant and its underlying mechanisms. Previous research showed that inherited serotonin transporter (SERT) down‐regulation increases the motor response to cocaine, as well as moderate (as measured during daily 1‐h self‐administration sessions) and compulsive (as measured during daily 6‐h self‐administration sessions) intake of this psychostimulant. Here, we sought to investigate whether these findings generalize to AMPH and the underlying mechanisms in the nucleus accumbens.

Experimental Approach

In serotonin transporter knockout (SERT^−/−) and wild‐type control (SERT^+/+) rats, we assessed the locomotor response to acute AMPH and i.v. AMPH self‐administration under short access (ShA: 1‐h daily sessions) and long access (LgA: 6‐h daily sessions) conditions. Twenty‐four hours after AMPH self‐administration, we analysed the expression of glutamate system components in the nucleus accumbens shell and core.

Key Results

We found that SERT^−/− animals displayed an increased AMPH‐induced locomotor response and increased AMPH self‐administration under LgA but not ShA conditions. Further, we observed changes in the vesicular and glial glutamate transporters, NMDA and AMPA receptor subunits, and their respective postsynaptic scaffolding proteins as function of SERT genotype and AMPH exposure (baseline, ShA, and LgA), specifically in the nucleus accumbens shell.

Conclusion and Implications

We demonstrate that SERT gene deletion increases the psychomotor and reinforcing effects of AMPH and that the latter is potentially mediated, at least in part, by homeostatic changes in the glutamatergic synapse of the nucleus accumbens shell and/or core.

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.

Perinatal exposure of rats to the HIV drug efavirenz affects medial prefrontal cortex cytoarchitecture

Efavirenz (EFV) is used for antiretroviral treatment of HIV infection, and successfully inhibits viral replication and mother-to-child transmission of HIV during pregnancy and childbirth. Unfortunately, the drug induces neuropsychiatric symptoms such as anxiety and depressed mood and potentially affects cognitive performance. EFV acts on, among others, the serotonin transporter and serotonin receptors that are expressed in the developing brain. Yet, how perinatal EFV exposure affects brain cytoarchitecture remains unclear. Here, we exposed pregnant and lactating rats to EFV, and examined in the medial prefrontal cortex (mPFC) of their adult offspring the effects of the maternal EFV exposure on cortical architecture. We observed a significant decrease in the number of cells, mainly mature neurons, in the infra/prelimbic and cingulate cortices of adult offspring. Next, we found an altered cortical cytoarchitecture characterized by a significant reduction in deep- and superficial-layer cells. This was accompanied by a sharp increase in programmed cell death, as we identified a significantly higher number of cleaved Caspase-3-positive cells. Finally, the serotonergic and dopaminergic innervation of the mPFC subdomains was increased. Thus, the perinatal exposure to EFV provoked in the mPFC of adult offspring cell death, significant changes in cytoarchitecture, and disturbances in serotonergic and dopaminergic innervation. Our results are important in the light of EFV treatment of HIV-positive pregnant women, and its effect on brain development and cognitive behavior.

Changes in Serotonin Modulation of Glutamate Currents in Pyramidal Offspring Cells of Rats Treated With 5-MT during Gestation

Changes in stimuli and feeding in pregnant mothers alter the behavior of offspring. Since behavior is mediated by brain activity, it is expected that postnatal changes occur at the level of currents, receptors or soma and dendrites structure and modulation. In this work, we explore at the mechanism level the effects on Sprague-Dawley rat offspring following the administration of serotonin (5-HT) agonist 5-methoxytryptamine (5-MT). We analyzed whether 5-HT affects the glutamate-activated (IGlut) and N-methyl-D-aspartate (NMDA)-activated currents (IGlut, INMDA) in dissociated pyramidal neurons from the prefrontal cortex (PFC). For this purpose, we performed voltage-clamp experiments on pyramidal neurons from layers V-VI of the PFC of 40-day-old offspring born from 5-MT-treated mothers at the gestational days (GD) 11 to 21. We found that the pyramidal-neurons from the PFC of offspring of mothers treated with 5-MT exhibit a significant increased reduction in both the IGlut and INMDA when 5-HT was administered. Our results suggest that the concentration increase of a neuromodulator during the gestation induces changes in its modulatory action over the offspring ionic currents during the adulthood thus contributing to possible psychiatric disorders.

Neurodevelopmental and behavioral consequences of perinatal exposure to the HIV drug efavirenz in a rodent model

Efavirenz is recommended as a preferred first-line drug for women of childbearing potential living with human immunodeficiency virus. Efavirenz is known for its central nervous system side effects, which are partly mediated by serotonergic actions. The neurotransmitter serotonin exerts neurotrophic effects during neurodevelopment and antenatal exposure to serotonergic agents has been linked to developmental delay. Although the teratogenic risks of efavirenz appear to be minimal, data on long-term developmental effects remain scarce. Here, we aimed to investigate the short- and long-term behavioral and neurodevelopmental effects of perinatal efavirenz exposure. We treated pregnant rats from gestation day 1 until postnatal day 7 with efavirenz (100 mg/kg) or vehicle. We measured behavioral outcomes in male offspring during the first 3 postnatal weeks, adolescence and adulthood, and conducted brain immunohistochemistry analyses after sacrifice. Perinatal efavirenz exposure resulted in reduced body weight and delayed reflex and motor development. During adulthood, we observed a decrease in the total number of cells and mature neurons in the motor cortex, as well as an increase in the number of Caspase-3-positive cells and serotonergic fibers. Together, our data show a developmental delay and persistent changes in the brain motor cortex of rats exposed to efavirenz perinatally. Because over 1 million children born annually are exposed to antiretroviral therapy, our findings underline the need for clinical studies on long-term neurodevelopmental outcomes of perinatal exposure to efavirenz.