Effects of paracetamol (acetaminophen) on gene expression and permeability properties of the rat placenta and fetal brain

Paracetamol, its metabolites, and their transfer between maternal circulation and fetal brain in mono- and combination therapies

BACKGROUND

Due to its availability and perceived safety, paracetamol is recommended even during pregnancy and for neonates. It is used frequently alone or in combination with other drugs required for the treatment of various chronic conditions. The aim of this study was to investigate potential effects of drug interactions on paracetamol metabolism and its placental transfer and entry into the developing brain.

METHODS

Sprague Dawley rats at postnatal day P4, pregnant embryonic day E19 dams, and non-pregnant adult females were administered paracetamol (15 mg/kg) either as monotherapy or in combination with one of seven other drugs: cimetidine, digoxin, fluvoxamine, lamotrigine, lithium, olanzapine, valproate. Concentrations of parent paracetamol and its metabolites (paracetamol-glucuronide, paracetamol-glutathione, and paracetamol-sulfate) in plasma, cerebrospinal fluid (CSF) and brain were measured by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and their entry into the brain, CSF and transfer across the placenta were estimated.

RESULTS

In monotherapy, concentration of parent paracetamol in plasma, CSF, and brain remained similar and at all ages brain entry was unrestricted. In combination therapies, CSF entry of paracetamol increased following co-treatment with olanzapine. Placental transfer of parent paracetamol remained unchanged, however, transfer of paracetamol-sulfate increased with lamotrigine co-administration. Acutely administered paracetamol was more extensively metabolized in adults compared to younger ages resulting in increased concentration of its metabolites with age.

CONCLUSIONS

Developmental changes in the apparent brain and CSF entry of paracetamol appear to be determined more by its metabolism, rather than by cellular control of its transfer across brain and placental barriers.

A quantitative weight-of-evidence review of preclinical studies examining the potential developmental neurotoxicity of acetaminophen

Acetaminophen [paracetamol; N-acetyl-para-aminophenol (APAP)] is an antipyretic/analgesic commonly used in the treatment of fever and mild to moderate pain, headache, myalgia, and dysmenorrhea. Recent literature has questioned the safety of acetaminophen use during pregnancy, with an emphasis on whether exposure to the developing nervous system results in behavioral changes consistent with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and/or other cognitive deficits in the offspring. No previous review has used a fully detailed, quantitative weight-of-evidence (QWoE) approach to critically examine the preclinical acetaminophen data with regards to potential developmental neurotoxicity (DNT). Following regulatory guidance, a QWoE framework using prespecified scoring criteria was developed consistent with previous approaches to characterize potential adverse DNT outcomes with considerations for biological relevance of the response to adverse outcomes (outcome score) and the strength of methods and study design (methods score). Considerations for the methods score included (1) experimental design, (2) details/reliability of measurement(s), (3) data transparency, and (4) translational/methodological relevance. Considerations for the outcome score included response-related (1) statistical significance, (2) dose-response, (3) relevance/reliability/magnitude, (4) plausibility, and (5) translational relevance, including consideration of systemic toxicity/hepatotoxicity and therapeutic and/or non-systemically toxic doses and durations of use. Application of this QWoE framework to the 34 in vivo studies identified that assess the potential DNT of acetaminophen resulted in 188 QWoE entries documented across 11 DNT endpoints: social behavior, stereotypic behavior, behavioral rigidity, attention/impulsivity, hyperactivity, anxiety-like behavior, sensorimotor function, spatial learning/memory, nonspatial learning/memory, neuroanatomy, and neurotransmission. For each endpoint, the mean outcome score and methods score were calculated for total entries and for entries segregated by sex to assist in determining data quality and potential adversity. Informed by all 188 entries, the QWoE analysis demonstrated data of moderate quality showing no consistent evidence of DNT in male and female rodents following exposure to acetaminophen at therapeutic and/or nonsystemically toxic doses. Although some of the DNT endpoints (behavioral rigidity, attention/impulsivity, spatial learning/memory, neuroanatomy, and neurotransmission) generally displayed a more limited dataset and/or relatively lower data quality, similar conclusions were drawn based on results indicating a lack of biological relevance and reliability of reported adverse effects. Overall, this QWoE analysis on the preclinical in vivo data demonstrates no consistent evidence of adverse effects following developmental exposure to acetaminophen at therapeutic and/or non-systemically toxic doses on the structure and function of the nervous system, including neuroanatomical, neurotransmission, and behavioral endpoints.

Maternal administration of APAP induces angiogenesis disorders in mouse placenta via SOCS3/JAK1/STAT3 pathway

Acetaminophen (APAP, also known as paracetamol) is a commonly used antipyretic and analgesic that is considered safe to use during pregnancy. However, a growing body of research indicates that gestational administration of APAP increased the risk of neurodevelopmental, reproductive and genitourinary disorders in offspring, alongside impairments in placental development. Notably, over-dosed APAP exhibits direct toxicity to endothelial cells, but there is very limited research investigating the impact of APAP on placental angiogenesis, a gap we aim to address in this study. Pregnant mice were gavaged with APAP (15, 50 and 150 mg/kg/d) from embryonic day 11.5 (E11.5) to E13.5. Administration of 150 mg/kg/d APAP leads to low birth weight (LBW) of the offspring and disordered vascular structures within the labyrinthine (Lab) layer of the placenta. This disruption is accompanied by a significant increase in Suppressor of Cytokine Signaling 3 (SOCS3) level, a negative regulator of the Janus kinase signal transducer 1 and activator of the transcription 3 (JAK1/STAT3) signaling. Meanwhile, Human umbilical vein endothelial Cells (HUVECs) with the treatment of 3 mM APAP exhibited reduced cell viability, whereas 1 mM APAP significantly affected the proliferation, migration, invasion and angiogenic capacities of HUVECs. Further, SOCS3 was up-regulated in HUVECs, accompanied by inhibition of JAK1/STAT3 pathways. Knocking-down SOCS3 in HUVECs restored the nuclear translocation of STAT3 and efficiently promoted cellular capacity of tube formation. Overall, short-term maternal administration of overdosed APAP impairs angiogenic capacities of fetal endothelial cells via SOCS3/JAK1/STAT3 pathway in the mouse placenta. This study reveals that overdose of APAP during pregnancy may adversely affect placental angiogenesis, emphasizing the importance of adhering to the safe principles of smallest effective dose for the shortest required durations.

Beyond defence: Immune architects of ovarian health and disease

Throughout the individual's reproductive period of life the ovary undergoes continues changes, including cyclic processes of cell death, tissue regeneration, proliferation, and vascularization. Tissue-resident leucocytes particularly macrophages, play a crucial role in shaping ovarian function and maintaining homeostasis. Macrophages crucially promote angiogenesis in the follicles and corpora lutea, thereby supporting steroidogenesis. Recent research on macrophage origins and early tissue seeding has unveiled significant insights into their role in early organogenesis, e.g. in the testis. Here, we review evidence about the prenatal ovarian seeding of leucocytes, primarily macrophages with angiogenic profiles, and its connection to gametogenesis. In the prenatal ovary, germ cells proliferate, form cysts, and undergo changes that, following waves of apoptosis, give rice to the oocytes contained in primordial follicles. These follicles constitute the ovarian reserve that lasts throughout the female's reproductive life. Simultaneously, yolk-sac-derived primitive macrophages colonizing the early ovary are gradually replaced or outnumbered by monocyte-derived fetal macrophages. However, the cues indicating how macrophage colonization and follicle assembly are related are elusive. Macrophages may contribute to organogenesis by promoting early vasculogenesis. Whether macrophages contribute to ovarian lymphangiogenesis or innervation is still unknown. Ovarian organogenesis and gametogenesis are vulnerable to prenatal insults, potentially programming dysfunction in later life, as observed in polycystic ovary syndrome. Experimental and, more sparsely, epidemiological evidence suggest that adverse stimuli during pregnancy can program defective folliculogenesis or a diminished follicle reserve in the offspring. While the ovary is highly sensitive to inflammation, the involvement of local immune responses in programming ovarian health and disease remains to be thoroughly investigated.

ABC Efflux Transporters and Solute Carriers in the Early Developing Brain of a Marsupial Monodelphis domestica (South American Gray Short-Tailed Opossum)

This study used a marsupial Monodelphis domestica, which is born very immature and most of its development is postnatal without placental protection. RNA-sequencing (RNA-Seq) was used to identify the expression of influx and efflux transporters (ATP-binding cassettes [ABCs] and solute carriers [SLCs]) and metabolizing enzymes in brains of newborn to juvenile Monodelphis. Results were compared to published data in the developing eutherian rat. To test the functionality of these transporters at similar ages, the entry of paracetamol (acetaminophen) into the brain and cerebrospinal fluid (CSF) was measured using liquid scintillation counting following a single administration of the drug along with its radiolabelled tracer [3H]. Drug permeability studies found that in Monodelphis, brain entry of paracetamol was already restricted at P5; it decreased further in the first week of life and then remained stable until the oldest age group tested (P110). Transcriptomic analysis of Monodelphis brain showed that expression of transporters and their metabolizing enzymes in early postnatal (P) pups (P0, P5, and P8) was relatively similar, but by P109, many more transcripts were identified. When transcriptomes of newborn Monodelphis brain and E19 rat brain and placenta were compared, several transporters present in the rat placenta were also found in the newborn Monodelphis brain. These were absent from E19 rat brain but were present in the adult rat brain. These data indicate that despite its extreme immaturity, the newborn Monodelphis brain may compensate for the lack of placental protection during early brain development by upregulating protective mechanisms, which in eutherian animals are instead present in the placenta.

Effects of paracetamol/acetaminophen on the expression of solute carriers (SLCs) in late-gestation fetal rat brain, choroid plexus and the placenta

Solute carriers (SLCs) regulate transfer of a wide range of molecules across cell membranes using facilitative or secondary active transport. In pregnancy, these transporters, expressed at the placental barrier, are important for delivery of nutrients to the fetus, whilst also limiting entry of potentially harmful substances, such as drugs. In the present study, RNA-sequencing analysis was used to investigate expression of SLCs in the fetal (embryonic day 19) rat brain, choroid plexus and placenta in untreated control animals and following maternal paracetamol treatment. In the treated group, paracetamol (15 mg/kg) was administered to dams twice daily for 5 days (from embryonic day 15 to 19). In untreated animals, overall expression of SLCs was highest in the placenta. In the paracetamol treatment group, expression of several SLCs was significantly different compared with control animals, with ion, amino acid, neurotransmitter and sugar transporters most affected. The number of SLC transcripts that changed significantly following treatment was the highest in the choroid plexus and lowest in the brain. All SLC transcripts that changed in the placenta following paracetamol treatment were downregulated. These results suggest that administration of paracetamol during pregnancy could potentially disrupt fetal nutrient homeostasis and affect brain development, resulting in major consequences for the neonate and extending into childhood.

Multi-omics approach reveals dysregulated genes during hESCs neuronal differentiation exposure to paracetamol

Prenatal paracetamol exposure has been associated with neurodevelopmental outcomes in childhood. Pharmacoepigenetic studies show differences in cord blood DNA methylation between unexposed and paracetamol-exposed neonates, however, causality and impact of long-term prenatal paracetamol exposure on brain development remain unclear. Using a multi-omics approach, we investigated the effects of paracetamol on an in vitro model of early human neurodevelopment. We exposed human embryonic stem cells undergoing neuronal differentiation with paracetamol concentrations corresponding to maternal therapeutic doses. Single-cell RNA-seq and ATAC-seq integration identified paracetamol-induced chromatin opening changes linked to gene expression. Differentially methylated and/or expressed genes were involved in neurotransmission and cell fate determination trajectories. Some genes involved in neuronal injury and development-specific pathways, such as KCNE3, overlapped with differentially methylated genes previously identified in cord blood associated with prenatal paracetamol exposure. Our data suggest that paracetamol may play a causal role in impaired neurodevelopment.

Hepatoprotective and nephroprotective effects of Sedum adenotrichum in paracetamol-induced hepatotoxicity in rabbits

Sedum adenotrichum (SA) has been traditionally used against various ailments due to the presence of several important phenolic compounds. This study provides a scientific basis for the hepatoprotective and nephroprotective potentials of Sedum adenotrichum in paracetamol-induced toxicity in rabbits. Methanolic extract of Sedum adenotrichum along with paracetamol was administered orally to rabbits alone or in combination with paracetamol for 2 weeks. Results showed that paracetamol-induced toxicity was correlated with a significant change in biochemical, hematological parameters, and loss in body weight of rabbits, and the curative effect of SA methanolic extract was found. Liver and kidney histological studies showed significant induced toxicity of paracetamol and correspondence restoration power of SA methanolic extract. The levels of reduced glutathione, radical scavenging activity, and lipid peroxidation in the liver were restored to normal by the methanolic extract of SA. This study confirmed the protective effect of SA methanolic extract against hepatotoxicity and nephrotoxicity caused by paracetamol. Biochemical analysis of the methanolic extract of SA confirmed the presence of bioactive phenolic compounds which have hepatic and nephroprotective potentials.

Temporal effects on death by suicide: empirical evidence and possible molecular correlates

Popular culture and medical lore have long postulated a connection between full moon and exacerbations of psychiatric disorders. We wanted to empirically analyze the hypothesis that suicides are increased during the period around full moons. We analyzed pre-COVID suicides from the Marion County Coroner's Office (n = 776), and show that deaths by suicide are significantly increased during the week of the full moon (p = 0.037), with older individuals (age ≥ 55) showing a stronger effect (p = 0.019). We also examined in our dataset which hour of the day (3-4 pm, p = 0.035), and which month of the year (September, p = 0.09) show the most deaths by suicide. We had blood samples on a subset of the subjects (n = 45), which enabled us to look at possible molecular mechanisms. We tested a list of top blood biomarkers for suicidality (n = 154) from previous studies of ours 7, to assess which of them are predictive. The biomarkers for suicidality that are predictive of death by suicide during full moon, peak hour of day, and peak month of year, respectively, compared to outside of those periods, appear to be enriched in circadian clock genes. For full moon it is AHCYL2, ACSM3, AK2, and RBM3. For peak hour it is GSK3B, AK2, and PRKCB. For peak month it is TBL1XR1 and PRKCI. Half of these genes are modulated in expression by lithium and by valproate in opposite direction to suicidality, and all of them are modulated by depression and alcohol in the same direction as suicidality. These data suggest that there are temporal effects on suicidality, possibly mediated by biological clocks, pointing to changes in ambient light (timing and intensity) as a therapeutically addressable target to decrease suicidality, that can be coupled with psychiatric pharmacological and addiction treatment preventive interventions.

Developmental toxicity and programming alterations of multiple organs in offspring induced by medication during pregnancy

Medication during pregnancy is widespread, but there are few reports on its fetal safety. Recent studies suggest that medication during pregnancy can affect fetal morphological and functional development through multiple pathways, multiple organs, and multiple targets. Its mechanisms involve direct ways such as oxidative stress, epigenetic modification, and metabolic activation, and it may also be indirectly caused by placental dysfunction. Further studies have found that medication during pregnancy may also indirectly lead to multi-organ developmental programming, functional homeostasis changes, and susceptibility to related diseases in offspring by inducing fetal intrauterine exposure to too high or too low levels of maternal-derived glucocorticoids. The organ developmental toxicity and programming alterations caused by medication during pregnancy may also have gender differences and multi-generational genetic effects mediated by abnormal epigenetic modification. Combined with the latest research results of our laboratory, this paper reviews the latest research progress on the developmental toxicity and functional programming alterations of multiple organs in offspring induced by medication during pregnancy, which can provide a theoretical and experimental basis for rational medication during pregnancy and effective prevention and treatment of drug-related multiple fetal-originated diseases.

The choroid plexus: a missing link in our understanding of brain development and function

Studies of the choroid plexus lag behind those of the more widely known blood-brain barrier, despite a much longer history. This review has two overall aims. The first is to outline long-standing areas of research where there are unanswered questions, such as control of cerebrospinal fluid (CSF) secretion and blood flow. The second aim is to review research over the past 10 years where the focus has shifted to the idea that there are choroid plexuses located in each of the brain's ventricles that make specific contributions to brain development and function through molecules they generate for delivery via the CSF. These factors appear to be particularly important for aspects of normal brain growth. Most research carried out during the twentieth century dealt with the choroid plexus, a brain barrier interface making critical contributions to the composition and stability of the brain's internal environment throughout life. More recent research in the twenty-first century has shown the importance of choroid plexus-generated CSF in neurogenesis, influence of sex and other hormones on choroid plexus function, and choroid plexus involvement in circadian rhythms and sleep. The advancement of technologies to facilitate delivery of brain-specific therapies via the CSF to treat neurological disorders is a rapidly growing area of research. Conversely, understanding the basic mechanisms and implications of how maternal drug exposure during pregnancy impacts the developing brain represents another key area of research.

Lithium administered to pregnant, lactating and neonatal rats: entry into developing brain

Background

Little is known about the extent of drug entry into developing brain, when administered to pregnant and lactating women. Lithium is commonly prescribed for bipolar disorder. Here we studied transfer of lithium given to dams, into blood, brain and cerebrospinal fluid (CSF) in embryonic and postnatal animals as well as adults.

Methods

Lithium chloride in a clinically relevant dose (3.2 mg/kg body weight) was injected intraperitoneally into pregnant (E15–18) and lactating dams (birth-P16/17) or directly into postnatal pups (P0–P16/17). Acute treatment involved a single injection; long-term treatment involved twice daily injections for the duration of the experiment. Following terminal anaesthesia blood plasma, CSF and brains were collected. Lithium levels and brain distribution were measured using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry and total lithium levels were confirmed by Inductively Coupled Plasma-Mass Spectrometry.

Results

Lithium was detected in blood, CSF and brain of all fetal and postnatal pups following lithium treatment of dams. Its concentration in pups’ blood was consistently below that in maternal blood (30–35%) indicating significant protection by the placenta and breast tissue. However, much of the lithium that reached the fetus entered its brain. Levels of lithium in plasma fluctuated in different treatment groups but its concentration in CSF was stable at all ages, in agreement with known stable levels of endogenous ions in CSF. There was no significant increase of lithium transfer into CSF following application of Na⁺/K⁺ ATPase inhibitor (digoxin) in vivo, indicating that lithium transfer across choroid plexus epithelium is not likely to be via the Na⁺/K⁺ ATPase mechanism, at least early in development. Comparison with passive permeability markers suggested that in acute experiments lithium permeability was less than expected for diffusion but similar in long-term experiments at P2.

Conclusions

Information obtained on the distribution of lithium in developing brain provides a basis for studying possible deleterious effects on brain development and behaviour in offspring of mothers undergoing lithium therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00285-w.

Paracetamol (Acetaminophen) and the Developing Brain

Paracetamol is commonly used to treat fever and pain in pregnant women, but there are growing concerns that this may cause attention deficit hyperactivity disorder and autism spectrum disorder in the offspring. A growing number of epidemiological studies suggests that relative risks for these disorders increase by an average of about 25% following intrauterine paracetamol exposure. The data analyzed point to a dose-effect relationship but cannot fully account for unmeasured confounders, notably indication and genetic transmission. Only few experimental investigations have addressed this issue. Altered behavior has been demonstrated in offspring of paracetamol-gavaged pregnant rats, and paracetamol given at or prior to day 10 of life to newborn mice resulted in altered locomotor activity in response to a novel home environment in adulthood and blunted the analgesic effect of paracetamol given to adult animals. The molecular mechanisms that might mediate these effects are unknown. Paracetamol has diverse pharmacologic actions. It reduces prostaglandin formation via competitive inhibition of the peroxidase moiety of prostaglandin H2 synthase, while its metabolite N-arachidonoyl-phenolamine activates transient vanilloid-subtype 1 receptors and interferes with cannabinoid receptor signaling. The metabolite N-acetyl-p-benzo-quinone-imine, which is pivotal for liver damage after overdosing, exerts oxidative stress and depletes glutathione in the brain already at dosages below the hepatic toxicity threshold. Given the widespread use of paracetamol during pregnancy and the lack of safe alternatives, its impact on the developing brain deserves further investigation.

Efflux transporters in rat placenta and developing brain: transcriptomic and functional response to paracetamol

Adenosine triphosphate binding cassette (ABC) transporters transfer lipid-soluble molecules across cellular interfaces either directly or after enzymatic metabolism. RNAseq analysis identified transcripts for ABC transporters and enzymes in rat E19, P5 and adult brain and choroid plexus and E19 placenta. Their functional capacity to efflux small molecules was studied by quantitative analysis of paracetamol (acetaminophen) and its metabolites using liquid scintillation counting, autoradiography and ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Animals were treated acutely (30 min) and chronically (5 days, twice daily) with paracetamol (15 mg/kg) to investigate ability of brain and placenta barriers to regulate ABC transport functionality during extended treatment. Results indicated that transcripts of many efflux-associated ABC transporters were higher in adult brain and choroid plexus than at earlier ages. Chronic treatment upregulated certain transcripts only in adult brain and altered concentrations of paracetamol metabolites in circulation of pregnant dams. Combination of changes to metabolites and transport system transcripts may explain observed changes in paracetamol entry into adult and fetal brains. Analysis of lower paracetamol dosing (3.75 mg/kg) indicated dose-dependent changes in paracetamol metabolism. Transcripts of ABC transporters and enzymes at key barriers responsible for molecular transport into the developing brain showed alterations in paracetamol pharmacokinetics in pregnancy following different treatment regimens.

Miniaturization and Automation of a Human In Vitro Blood-Brain Barrier Model for the High-Throughput Screening of Compounds in the Early Stage of Drug Discovery

Central nervous system (CNS) diseases are one of the top causes of death worldwide. As there is a difficulty of drug penetration into the brain due to the blood–brain barrier (BBB), many CNS drugs treatments fail in clinical trials. Hence, there is a need to develop effective CNS drugs following strategies for delivery to the brain by better selecting them as early as possible during the drug discovery process. The use of in vitro BBB models has proved useful to evaluate the impact of drugs/compounds toxicity, BBB permeation rates and molecular transport mechanisms within the brain cells in academic research and early-stage drug discovery. However, these studies that require biological material (animal brain or human cells) are time-consuming and involve costly amounts of materials and plastic wastes due to the format of the models. Hence, to adapt to the high yields needed in early-stage drug discoveries for compound screenings, a patented well-established human in vitro BBB model was miniaturized and automated into a 96-well format. This replicate met all the BBB model reliability criteria to get predictive results, allowing a significant reduction in biological materials, waste and a higher screening capacity for being extensively used during early-stage drug discovery studies.

Entry of antiepileptic drugs (valproate and lamotrigine) into the developing rat brain

Background: Women with epilepsy face difficult choices whether to continue antiepileptic drug treatment during pregnancy, as uncontrolled seizures carry great risk to mother and fetus but continuing treatment may have adverse effects on baby's development. This study aimed at evaluating antiepileptic drug entry into developing brain. Methods: Anaesthetised pregnant, non-pregnant adult females, postnatal and fetal rats were injected intraperitoneally with different doses, single or in combinations, of valproate and lamotrigine, within clinical range. Injectate included  3H-labelled drug. After 30min, CSF, blood and brain samples were obtained; radioactivity measured using liquid scintillation counting. Some animals were also exposed to valproate in feed throughout pregnancy and into neonatal period. Drug levels measured by liquid chromatography coupled to mass spectrometry (LC-MS). Results given as CSF or tissue/plasma% as index of drug entry. Results: Entry of valproate into brain and CSF was higher at E19 and P4 compared to adult and was dose-dependent except at E19; placental transfer increased significantly at highest dose of 100mg/kg. Lamotrigine entry into the brain was dose dependent only at E19. Chronic valproate treatment, or combination of valproate and lamotrigine had little effect on either drug entry, except for reduced valproate brain entry in adult brain with chronic treatment. Placental transfer decreased significantly after chronic valproate treatment. LC-MS measurement of valproate in adults confirmed that rat plasma values were within the clinical range and CSF/plasma and brain/plasma ratios for LC-MS and  3H-valproate were similar. Conclusion: Results suggest that entry of valproate may be higher in developing brain, the capacity of barrier mechanism is mostly unaffected by doses within the clinical range, with or without addition of lamotrigine. Chronic valproate exposure may result in upregulation in cellular mechanisms restricting its entry into the brain. Entry of lamotrigine was little different at different ages and was not dose dependent.

Entry of antiepileptic drugs (valproate and lamotrigine) into the developing rat brain

Background: Women with epilepsy face difficult choices whether to continue antiepileptic drug treatment during pregnancy, as uncontrolled seizures carry great risk to mother and fetus but continuing treatment may have adverse effects on baby’s development. This study aimed at evaluating antiepileptic drug entry into developing brain.

Methods: Anaesthetised pregnant, non-pregnant adult females, postnatal and fetal rats were injected intraperitoneally with different doses, single or in combinations, of valproate and lamotrigine, within clinical range. Injectate included  ³H-labelled drug. After 30min, CSF, blood and brain samples were obtained; radioactivity measured using liquid scintillation counting. Some animals were also exposed to valproate in feed throughout pregnancy and into neonatal period. Drug levels measured by liquid chromatography coupled to mass spectrometry (LC-MS). Results given as CSF or tissue/plasma% as index of drug entry.

Results: Entry of valproate into brain and CSF was higher at E19 and P4 compared to adult and was dose-dependent except at E19; placental transfer increased significantly at highest dose of 100mg/kg. Lamotrigine entry into the brain was dose dependent only at E19. Chronic valproate treatment, or combination of valproate and lamotrigine had little effect on either drug entry, except for reduced valproate brain entry in adult brain with chronic treatment. Placental transfer decreased significantly after chronic valproate treatment. LC-MS measurement of valproate in adults confirmed that rat plasma values were within the clinical range and CSF/plasma and brain/plasma ratios for LC-MS and  ³H-valproate were similar.

Conclusion: Results suggest that entry of valproate may be higher in developing brain, the capacity of barrier mechanism is mostly unaffected by doses within the clinical range, with or without addition of lamotrigine. Chronic valproate exposure may result in upregulation in cellular mechanisms restricting its entry into the brain. Entry of lamotrigine was little different at different ages and was not dose dependent.

In Silico Exploration of the Potential Role of Acetaminophen and Pesticides in the Etiology of Autism Spectrum Disorder

Recent epidemiological studies suggest that prenatal exposure to acetaminophen (APAP) is associated with increased risk of Autism Spectrum Disorder (ASD), a neurodevelopmental disorder affecting 1 in 59 children in the US. Maternal and prenatal exposure to pesticides from food and environmental sources have also been implicated to affect fetal neurodevelopment. However, the underlying mechanisms for ASD are so far unknown, likely with complex and multifactorial etiology. The aim of this study was to explore the potential effects of APAP and pesticide exposure on development with regards to the etiology of ASD by highlighting common genes and biological pathways. Genes associated with APAP, pesticides, and ASD through human research were retrieved from molecular and biomedical literature databases. The interaction network of overlapping genetic associations was subjected to network topology analysis and functional annotation of the resulting clusters. These genes were over-represented in pathways and biological processes (FDR p < 0.05) related to apoptosis, metabolism of reactive oxygen species (ROS), and carbohydrate metabolism. Since these three biological processes are frequently implicated in ASD, our findings support the hypothesis that cell death processes and specific metabolic pathways, both of which appear to be targeted by APAP and pesticide exposure, may be involved in the etiology of ASD. This novel exposures-gene-disease database mining might inspire future work on understanding the biological underpinnings of various ASD risk factors.

The impact of (ab)normal maternal environment on cortical development

The cortex in the mammalian brain is the most complex brain region that integrates sensory information and coordinates motor and cognitive processes. To perform such functions, the cortex contains multiple subtypes of neurons that are generated during embryogenesis. Newly born neurons migrate to their proper location in the cortex, grow axons and dendrites, and form neuronal circuits. These developmental processes in the fetal brain are regulated to a large extent by a great variety of factors derived from the mother - starting from simple nutrients as building blocks and ending with hormones. Thus, when the normal maternal environment is disturbed due to maternal infection, stress, malnutrition, or toxic substances, it might have a profound impact on cortical development and the offspring can develop a variety of neurodevelopmental disorders. Here we first describe the major developmental processes which generate neuronal diversity in the cortex. We then review our knowledge of how most common maternal insults affect cortical development, perturb neuronal circuits, and lead to neurodevelopmental disorders. We further present a concept of selective vulnerability of cortical neuronal subtypes to maternal-derived insults, where the vulnerability of cortical neurons and their progenitors to an insult depends on the time (developmental period), place (location in the developing brain), and type (unique features of a cell type and an insult). Finally, we provide evidence for the existence of selective vulnerability during cortical development and identify the most vulnerable neuronal types, stages of differentiation, and developmental time for major maternal-derived insults.