Maternal immune activation affects socio-communicative behavior in adult rats

Maternal immune activation with toll-like receptor 7 agonist during mid-gestation alters juvenile and adult developmental milestones and behavior

Infections during pregnancy are associated with increased risk for adult neuropsychiatric disease, such as major depressive disorder, schizophrenia, and autism spectrum disorder. In mouse models of maternal immune activation (MIA), different toll-like receptors (TLRs) are stimulated to initiate inflammatory responses in mother and fetus. The goal of this study was to determine sex-dependent aspects of MIA using a TLR7/8 agonist, Resiquimod (RQ), on neurodevelopment. RQ was administered to timed-pregnant mice on embryonic day (E) 12.5. At E15, maternal/fetal plasma cytokines were measured by enzyme-linked immunosorbent assay (ELISA). Maternal cytokines interleukin (IL)-6 and IL-10 were higher while tumor necrosis factor (TNF)-α and IL-17 were lower in pregnant dams exposed to RQ. Fetal cytokines (E15) were altered at the same timepoint with fetal plasma IL-6 and IL-17 greater after RQ compared to vehicle, while IL-10 and TNF-α were higher in male fetuses but not female. Other timed-pregnant dams were allowed to give birth. MIA with RQ did not alter the female to male ratio of offspring born per litter. Body weights were reduced significantly in both sexes at birth, and over the next 5 weeks. Offspring from RQ-injected mothers opened their eyes 5 days later than controls. Similarly, female offspring from RQ-injected mothers exhibited pubertal delay based on vaginal opening 2-3 days later than control females. On the behavioral side, juvenile and adult male and female MIA offspring exhibited less social-like behavior in a social interaction test. Anhedonia-like behavior was greater in MIA adult female mice. This study provides support for sex-dependent influences of fetal antecedents for altered brain development and behavioral outputs that could be indicative of increased susceptibility for adult disorders through immune mechanisms. Future studies are needed to determine neural cellular and molecular mechanisms for such programming effects.

Morphological Correlates of Behavioral Variation in Autism Spectrum Disorder Groups in A Maternal Immune Activation Model

Introduction

Clinical heterogeneity is one of the biggest challenges for researchers studying underlying neurobiological mechanisms in Autism Spectrum Disorder (ASD). We aimed to use polyinosinic-polycytidylic acid [Poly (I:C)] induced maternal immune activation mice model to investigate the behavioral variation and the role of brain circuits related to symptom clusters in ASD. For this purpose, behavioral tests were applied to offsprings and regional thickness was measured from histological brain sections in medial prefrontal cortex, hippocampus and striatum.

Methods

Pups of intraperitoneal Poly (I:C)-applied mothers (n: 14) and phosphate buffered saline-applied mothers (n: 6) were used for this study. We used three chamber socialization test and social memory test to evaluate social behavior deficit in mice. Marble burying test was used for assessing stereotypic behavior and new object recognition test for learning and cognitive flexibility. Three subgroups (n: 4 for each) were determined according to behavioral test parameters. Regional thickness was measured in medial prefrontal cortex, hippocampus and striatum and compared between subgroups.

Results

We detected that the behavioral differences were distributed in a spectrum as expected in the clinic and also detected increased hippocampus thickness in the stereotypic behavior dominant Poly (I:C) subgroup.

Conclusion

Poly (I:C) induced maternal immune activation model creates the behavioral variation and cortical development differences that are seen in relation with symptom groups in ASD.

Neuroplasticity of children in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that encompasses a range of symptoms including difficulties in verbal communication, social interaction, limited interests, and repetitive behaviors. Neuroplasticity refers to the structural and functional changes that occur in the nervous system to adapt and respond to changes in the external environment. In simpler terms, it is the brain's ability to learn and adapt to new environments. However, individuals with ASD exhibit abnormal neuroplasticity, which impacts information processing, sensory processing, and social cognition, leading to the manifestation of corresponding symptoms. This paper aims to review the current research progress on ASD neuroplasticity, focusing on genetics, environment, neural pathways, neuroinflammation, and immunity. The findings will provide a theoretical foundation and insights for intervention and treatment in pediatric fields related to ASD.

Maternal selenium dietary supplementation alters sociability and reinforcement learning deficits induced by in utero exposure to maternal immune activation in mice

Maternal immune activation (MIA) during pregnancy increases the risk for the unborn foetus to develop neurodevelopmental conditions such as autism spectrum disorder and schizophrenia later in life. MIA mouse models recapitulate behavioural and biological phenotypes relevant to both conditions, and are valuable models to test novel treatment approaches. Selenium (Se) has potent anti-inflammatory properties suggesting it may be an effective prophylactic treatment against MIA. The aim of this study was to determine if Se supplementation during pregnancy can prevent adverse effects of MIA on offspring brain and behaviour in a mouse model. Selenium was administered via drinking water (1.5 ppm) to pregnant dams from gestational day (GD) 9 to birth, and MIA was induced at GD17 using polyinosinic:polycytidylic acid (poly-I:C, 20 mg/kg via intraperitoneal injection). Foetal placenta and brain cytokine levels were assessed using a Luminex assay and brain elemental nutrients assessed using inductively coupled plasma- mass spectrometry. Adult offspring were behaviourally assessed using a reinforcement learning paradigm, the three-chamber sociability test and the open field test. MIA elevated placental IL-1β and IL-17, and Se supplementation successfully prevented this elevation. MIA caused an increase in foetal brain calcium, which was prevented by Se supplement. MIA caused in offspring a female-specific reduction in sociability, which was recovered by Se, and a male-specific reduction in social memory, which was not recovered by Se. Exposure to poly-I:C or selenium, but not both, reduced performance in the reinforcement learning task. Computational modelling indicated that this was predominantly due to increased exploratory behaviour, rather than reduced rate of learning the location of the food reward. This study demonstrates that while Se may be beneficial in ameliorating sociability deficits caused by MIA, it may have negative effects in other behavioural domains. Caution in the use of Se supplementation during pregnancy is therefore warranted.

Effects of ketamine on rat social behavior as analyzed by DeepLabCut and SimBA deep learning algorithms

Traditional methods of rat social behavior assessment are extremely time-consuming and susceptible to the subjective biases. In contrast, novel digital techniques allow for rapid and objective measurements. This study sought to assess the feasibility of implementing a digital workflow to compare the effects of (R,S)-ketamine and a veterinary ketamine preparation Vetoquinol (both at 20 mg/kg) on the social behaviors of rat pairs. Historical and novel videos were used to train the DeepLabCut neural network. The numerical data generated by DeepLabCut from 14 video samples, representing various body parts in time and space were subjected to the Simple Behavioral Analysis (SimBA) toolkit, to build classifiers for 12 distinct social and non-social behaviors. To validate the workflow, previously annotated by the trained observer historical videos were analyzed with SimBA classifiers, and regression analysis of the total time of social interactions yielded R 2 = 0.75, slope 1.04; p < 0.001 (N = 101). Remarkable similarities between human and computer annotations allowed for using the digital workflow to analyze 24 novel videos of rats treated with vehicle and ketamine preparations. Digital workflow revealed similarities in the reduction of social behavior by both compounds, and no substantial differences between them. However, the digital workflow also demonstrated ketamine-induced increases in self-grooming, increased transitions from social contacts to self-grooming, and no effects on adjacent lying time. This study confirms and extends the utility of deep learning in analyzing rat social behavior and highlights its efficiency and objectivity. It provides a faster and objective alternative to human workflow.

The impact of maternal immune activation on GABAergic interneuron development: A systematic review of rodent studies and their translational implications

Mothers exposed to infections during pregnancy disproportionally birth children who develop autism and schizophrenia, disorders associated with altered GABAergic function. The maternal immune activation (MIA) model recapitulates this risk factor, with many studies also reporting disruptions to GABAergic interneuron expression, protein, cellular density and function. However, it is unclear if there are species, sex, age, region, or GABAergic subtype specific vulnerabilities to MIA. Furthermore, to fully comprehend the impact of MIA on the GABAergic system a synthesised account of molecular, cellular, electrophysiological and behavioural findings was required. To this end we conducted a systematic review of GABAergic interneuron changes in the MIA model, focusing on the prefrontal cortex and hippocampus. We reviewed 102 articles that revealed robust changes in a number of GABAergic markers that present as gestationally-specific, region-specific and sometimes sex-specific. Disruptions to GABAergic markers coincided with distinct behavioural phenotypes, including memory, sensorimotor gating, anxiety, and sociability. Findings suggest the MIA model is a valid tool for testing novel therapeutics designed to recover GABAergic function and associated behaviour.

Genomic diversity in functionally relevant genes modifies neurodevelopmental versus neoplastic risks in individuals with germline PTEN variants

Individuals with germline PTEN variants (PHTS) have increased risks of the seemingly disparate phenotypes of cancer and neurodevelopmental disorders (NDD), including autism spectrum disorder (ASD). Etiology of the phenotypic variability remains elusive. Here, we hypothesized that decreased genomic diversity, manifested by increased homozygosity, may be one etiology. Comprehensive analyses of 376 PHTS patients of European ancestry revealed significant enrichment of homozygous common variants in genes involved in inflammatory processes in the PHTS-NDD group and in genes involved in differentiation and chromatin structure regulation in the PHTS-ASD group. Pathway analysis revealed pathways germane to NDD/ASD, including neuroinflammation and synaptogenesis. Collapsing analysis of the homozygous variants identified suggestive modifier NDD/ASD genes. In contrast, we found enrichment of homozygous ultra-rare variants in genes modulating cell death in the PHTS-cancer group. Finally, homozygosity burden as a predictor of ASD versus cancer outcomes in our validated prediction model for NDD/ASD performed favorably.

Beyond TORCH: A narrative review of the impact of antenatal and perinatal infections on the risk of disability

Infections and inflammation during pregnancy or early life can alter child neurodevelopment and increase the risk for structural brain abnormalities and mental health disorders. There is strong evidence that TORCH infections (i.e., Treponema pallidum, Toxoplasma gondii, rubella virus, cytomegalovirus, herpes virus) alter fetal neurodevelopment across multiple developmental domains and contribute to motor and cognitive disabilities. However, the impact of a broader range of viral and bacterial infections on fetal development and disability is less well understood. We performed a literature review of human studies to identify gaps in the link between maternal infections, inflammation, and several neurodevelopmental domains. We found strong and moderate evidence respectively for a higher risk of motor and cognitive delays and disabilities in offspring exposed to a range of non-TORCH pathogens during fetal life. In contrast, there is little evidence for an increased risk of language and sensory disabilities. While guidelines for TORCH infection prevention during pregnancy are common, further consideration for prevention of non-TORCH infections during pregnancy for fetal neuroprotection may be warranted.

Behavioral analysis in laboratory rats: Challenges and usefulness of 50-kHz ultrasonic vocalizations

Many rodent species emit and detect vocalizations in the ultrasonic range. Rats use three classes of ultrasonic vocalizations depending on developmental stage, experience and the behavioral situation. Calls from one class emitted by juvenile and adult rats, the so-called 50-kHz calls, are typical for appetitive and social situations. This review provides a brief historical account on the introduction of 50-kHz calls in behavioral research followed by a survey of their scientific applications focusing on the last five years, where 50-kHz publications reached a climax. Then, specific methodological challenges will be addressed, like how to measure and report 50-kHz USV, the problem of assignment of acoustic signals to a specific sender in a social situation, and individual variability in call propensity. Finally, the intricacy of interpreting 50-kHz results will be discussed focusing on the most prevalent ones, namely as communicative signals and/or readouts of the sender's emotional status.