Impaired synaptic plasticity in an animal model of autism exhibiting early hippocampal GABAergic-BDNF/TrkB signaling alterations

Efficacy of sialic acid supplementation in early life in autism model rats

Autism spectrum disorder (ASD) is a set of heterogeneous neurodevelopmental conditions, the etiology of which remains elusive. Sialic acid (SA) is an essential nutrient for nervous system development, and previous studies reported that the levels of SA were decreased in the blood and saliva of ASD children. However, it is not clear whether SA supplementation can alleviate behavioral problems in autism. We administered SA intervention in the VPA-induced autism model rats, evaluated behavior performance, and measured the levels of Gne and St8sia2 genes, BDNF and anti-GM1. At the same time, untargeted metabolomics was used to characterize the metabolites. It was found that the stereotypical behaviors, social preference and cognitive function were improved after SA supplementation. Additionally, the number of hippocampal neurons was increased, and the shape was normalized. Moreover, 94 differentially abundant metabolites were identified between the high dose SA and VPA groups. These changes in metabolites were correlated with pyrimidine metabolism, lysine degradation metabolism, biosynthesis of amino acids, mineral absorption, protein digestion and absorption, galactose metabolism, phenylalanine, tyrosine and tryptophan biosynthesis and phenylalanine metabolism. In conclusion, SA could ameliorate ASD-like phenotypes and change metabolites in autistic animals, which suggests that it may be a therapeutic approach for ASD.

The Ambiguous Role of Growth Factors in Autism: What Do We Really Know?

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with multifactorial origins, including the potential involvement of neurotrophins and growth factors. These molecules, which are crucial for neuronal survival, synaptic plasticity, and brain development, have been implicated in ASD pathophysiology. Altered levels of neurotrophins such as NGF, BDNF, NT3, and NT4, as well as growth factors like IGF1, VEGF, and FGF, have been associated with cognitive deficits, sensory processing abnormalities, and behavioral issues in ASD patients. However, the literature presents conflicting results, often due to differences in research methodologies, sample sizes, patient populations, and diagnostic criteria. Despite these inconsistencies, the potential of neurotrophins and growth factors as biomarkers and therapeutic targets for ASD remains promising. Future research with standardized methodologies, larger cohorts, and a clearer understanding of genetic influences is needed to further elucidate their roles in ASD diagnosis and treatment.

Pairing tones with vagus nerve stimulation improves brain stem responses to speech in the valproic acid model of autism

Receptive language deficits and aberrant auditory processing are often observed in individuals with autism spectrum disorders (ASD). Symptoms associated with ASD are observed in rodents prenatally exposed to valproic acid (VPA), including deficits in speech sound discrimination ability. These perceptual difficulties are accompanied by changes in neural activity patterns. In both cortical and subcortical levels of the auditory pathway, VPA-exposed rats have impaired responses to speech sounds. Developing a method to improve these neural deficits throughout the auditory pathway is necessary. The purpose of this study was to investigate the ability of vagus nerve stimulation (VNS) paired with sounds to restore degraded inferior colliculus (IC) responses in VPA-exposed rats. VNS paired with the speech sound "dad" was presented to a group of VPA-exposed rats 300 times per day for 20 days. Another group of VPA-exposed rats were presented with VNS paired with multiple tone frequencies for 20 days. The IC responses were recorded from 19 saline-exposed control rats and 18 VPA-exposed with no VNS, 8 VNS-speech paired VPA-exposed, and 7 VNS-tone paired VPA-exposed female and male rats. Pairing VNS with tones increased the IC response strength to speech sounds by 44% compared to VPA-exposed rats alone. Contrarily, VNS-speech pairing significantly decreased the IC response to speech compared with VPA-exposed rats by 5%. The present research indicates that pairing VNS with tones improved sound processing in rats exposed to VPA and suggests that auditory processing can be improved through targeted plasticity.NEW & NOTEWORTHY Pairing vagus nerve stimulation (VNS) with sounds has improved auditory processing in the auditory cortex of normal-hearing rats and autism models of rats. This study tests the ability of VNS-sound pairing to restore auditory processing in the inferior colliculus (IC) of valproic acid (VPA)-exposed rats. Pairing VNS with tones significantly reversed the degraded sound processing in the IC in VPA-exposed rats. The findings provide evidence that auditory processing in autism rat models can be improved through VNS.

Effects of Boron on Learning and Behavioral Disorders in Rat Autism Model Induced by Intracerebroventricular Propionic Acid

Autism spectrum disorder is a neurodevelopmental disorder in which learning, communication, and social interaction are impaired. Research has sought to minimize the neural impairments associated with autism spectrum disorder and improve the quality of life. Recent studies suggest that boron may benefit nerve cells, with effects varying depending on the dosage. This study explored the impact of boron, administered as boric acid, on behavioral, biochemical, and histopathological parameters in a rat model of autism induced by propionic acid (PPA). Thirty-two male Sprague-Dawley rats were divided into control, autism model, and boron-treated groups. Behavioral tests were conducted pre- and post-PPA induction, with brain tissue analyzed post-euthanasia. Proinflammatory cytokines (tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6)) and brain-derived neurotrophic factor (BDNF) levels were assessed in the hippocampus. Histopathological evaluations were conducted on the hippocampus and cerebellum. Autism model rats displayed impaired learning, elevated BDNF and cytokine levels, microglial and astrocytic activation, and decreased Purkinje cell count. The boron-treated groups showed improvements, particularly with the 4 mg/kg dose. This dose enhanced learning and social interaction, reduced proinflammatory cytokine levels, prevented microglial and astrocytic activation, and increased Purkinje cell count. Boron treatment exhibited neuroprotective potential, ameliorating autism spectrum disorder deficits by modulating cytokines, BDNF, microglia, and astrocytes, with low doses yielding pronounced effects.

Neurotrophins and Their Receptors: BDNF's Role in GABAergic Neurodevelopment and Disease

Neurotrophins and their receptors are distinctly expressed during brain development and play crucial roles in the formation, survival, and function of neurons in the nervous system. Among these molecules, brain-derived neurotrophic factor (BDNF) has garnered significant attention due to its involvement in regulating GABAergic system development and function. In this review, we summarize and compare the expression patterns and roles of neurotrophins and their receptors in both the developing and adult brains of rodents, macaques, and humans. Then, we focus on the implications of BDNF in the development and function of GABAergic neurons from the cortex and the striatum, as both the presence of BDNF single nucleotide polymorphisms and disruptions in BDNF levels alter the excitatory/inhibitory balance in the brain. This imbalance has different implications in the pathogenesis of neurodevelopmental diseases like autism spectrum disorder (ASD), Rett syndrome (RTT), and schizophrenia (SCZ). Altogether, evidence shows that neurotrophins, especially BDNF, are essential for the development, maintenance, and function of the brain, and disruptions in their expression or signaling are common mechanisms in the pathophysiology of brain diseases.

Potential Neuroprotective Effect of Melatonin in the Hippocampus of Male BTBR Mice

Autism spectrum disorder (ASD) is a neurodevelopmental disorder identified by impairments in common social interactions and repetitive behaviors. In ASD patients, substantial morphological alterations have been observed in the hippocampus, which represents an important region for the development of social skills. Melatonin, commonly found in many foods and plants, is also produced by the pineal gland. This indolamine, known to regulate the circadian rhythm, shows antioxidant and anti-inflammatory properties. We therefore hypothesized that melatonin may reduce oxidative stress and inflammation in the hippocampus of ASD patients. We explored our hypothesis using the BTBR mouse, a well-regarded murine transgenic model for ASD. Immediately after weaning, male BTBR and C57BL/6 mice underwent an 8-week treatment with melatonin or vehicle. Later, through immunohistochemistry and the immunoblotting analysis of the hippocampus, we evaluated the overall expression and cellular localization of Nrf2 and SOD1, two enzymes involved in the oxidative stress response. Similarly, we evaluated NLRP3 and NFkB, two mediators of inflammation, and GAD67, an enzyme responsible for the synthesis of GABA. Ultimately, we addressed melatonin's potential to regulate iron metabolism through a DAB-enhanced Perls reaction assay. Results showed melatonin's potential for modulating the analyzed markers in BTBR mice, suggesting a potential neuroprotective effect in ASD patients.

The Influence of Neurotrophins on the Brain-Lung Axis: Conception, Pregnancy, and Neonatal Period

Neurotrophins (NTs) are four small proteins produced by both neuronal and non-neuronal cells; they include nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). NTs can exert their action through both genomic and non-genomic mechanisms by interacting with specific receptors. Initial studies on NTs have identified them only as functional molecules of the nervous system. However, recent research have shown that some tissues and organs (such as the lungs, skin, and skeletal and smooth muscle) as well as some structural cells can secrete and respond to NTs. In addition, NTs perform several roles in normal and pathological conditions at different anatomical sites, in both fetal and postnatal life. During pregnancy, NTs are produced by the mother, placenta, and fetus. They play a pivotal role in the pre-implantation process and in placental and embryonic development; they are also involved in the development of the brain and respiratory system. In the postnatal period, it appears that NTs are associated with some diseases, such as sudden infant death syndrome (SIDS), asthma, congenital central hypoventilation syndrome (CCHS), and bronchopulmonary dysplasia (BPD).

Neurodevelopmental functions of CHD8: new insights and questions

Heterozygous, de novo, loss-of-function variants of the CHD8 gene are associated with a high penetrance of autism and other neurodevelopmental phenotypes. Identifying the neurodevelopmental functions of high-confidence autism risk genes like CHD8 may improve our understanding of the neurodevelopmental mechanisms that underlie autism spectrum disorders. Over the last decade, a complex picture of pleiotropic CHD8 functions and mechanisms of action has emerged. Multiple brain and non-brain cell types and progenitors appear to be affected by CHD8 haploinsufficiency. Behavioural, cellular and synaptic phenotypes are dependent on the nature of the gene mutation and are modified by sex and genetic background. Here, I review some of the CHD8-interacting proteins and molecular mechanisms identified to date, as well as the impacts of CHD8 deficiency on cellular processes relevant to neurodevelopment. I endeavour to highlight some of the critical questions that still require careful and concerted attention over the next decade to bring us closer to the goal of understanding the salient mechanisms whereby CHD8 deficiency causes neurodevelopmental disorders.

Effects of music on cognitive behavioral impairments in both sex of adult rats exposed prenatally to valproic acid

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairment in reciprocal social interactions, deficits in communication, and restrictive and repetitive behaviors and interests. In previous studies, music has been identified as an intervention therapy for children with ASD.

OBJECTIVES

The present study evaluated the effects of music on cognitive behavioral impairments in both sexes of adult rats exposed prenatally to Valproic acid.

METHODS

For induction of autism, pregnant female rats were pretreated with either saline or VPA (600 mg/kg.i.p.) at gestational day (GD) 12.5. Male and female offspring were divided into Saline.Non-Music, VPA.Non-Music, Saline.Music, and VPA.Music groups. The adult rats in the music groups were exposed to Mozart's piano sonata K.448 for 30 days (4 h/day), from postnatal day (PND) 60 to 90. Social interaction and Morris water maze (MWM) tasks were tested at PND 90.

RESULTS

Our results revealed that prenatal exposure to VPA decreased sociability and social memory performance in both sexes of adult rats. Moreover, prenatal exposure to VPA created learning and memory impairments in both sexes of adult rats in the MWM task. Music intervention improved sociability in both sexes of VPA-exposed rats and social memory in both sexes of VPA-exposed rats, especially in females. Furthermore, our results revealed that music ameliorated learning impairments in VPA-exposed female rats in the MWM task. In addition, music improved spatial memory impairments in VPA-exposed rats of both sexes, especially in females, which needs more investigation in molecular and histological fields in future studies.

CONCLUSION

Music intervention improved sociability and social memory in adult VPA-exposed rats, especially in female animals. Furthermore, music improved memory impairments in VPA-exposed rats of both sexes. It seems that music had a better influence on female rats. However, future studies need more investigations in molecular and histological fields.

BDNF and Lactate as Modulators of Hippocampal CA3 Network Physiology

Growing evidence supports the notion that brain-derived neurotrophic factor (BDNF) and lactate are potent modulators of mammalian brain function. The modulatory actions of those biomolecules influence a wide range of neuronal responses, from the shaping of neuronal excitability to the induction and expression of structural and synaptic plasticity. The biological actions of BDNF and lactate are mediated by their cognate receptors and specific transporters located in the neuronal membrane. Canonical functions of BDNF occur via the tropomyosin-related kinase B receptor (TrkB), whereas lactate acts via monocarboxylate transporters or the hydroxycarboxylic acid receptor 1 (HCAR1). Both receptors are highly expressed in the central nervous system, and some of their physiological actions are particularly well characterized in the hippocampus, a brain structure involved in the neurophysiology of learning and memory. The multifarious neuronal circuitry between the axons of the dentate gyrus granule cells, mossy fibers (MF), and pyramidal neurons of area CA3 is of great interest given its role in specific mnemonic processes and involvement in a growing number of brain disorders. Whereas the modulation exerted by BDNF via TrkB has been extensively studied, the influence of lactate via HCAR1 on the properties of the MF-CA3 circuit is an emerging field. In this review, we discuss the role of both systems in the modulation of brain physiology, with emphasis on the hippocampal CA3 network. We complement this review with original data that suggest cross-modulation is exerted by these two independent neuromodulatory systems.

GABA Signaling: Therapeutic Targets for Neurodegenerative and Neurodevelopmental Disorders

This Special Issue, "GABA Signaling: Therapeutic Targets for Neurodegenerative and Neurodevelopmental Disorders", focuses on a fundamental property of the neurotransmitter γ-aminobutyric acid (GABA), namely its capacity to shift, in particular conditions, from the hyperpolarizing to the depolarizing direction [...].

Neurotrophins: Expression of Brain-Lung Axis Development

Neurotrophins (NTs) are a group of soluble growth factors with analogous structures and functions, identified initially as critical mediators of neuronal survival during development. Recently, the relevance of NTs has been confirmed by emerging clinical data showing that impaired NTs levels and functions are involved in the onset of neurological and pulmonary diseases. The alteration in NTs expression at the central and peripheral nervous system has been linked to neurodevelopmental disorders with an early onset and severe clinical manifestations, often named "synaptopathies" because of structural and functional synaptic plasticity abnormalities. NTs appear to be also involved in the physiology and pathophysiology of several airway diseases, neonatal lung diseases, allergic and inflammatory diseases, lung fibrosis, and even lung cancer. Moreover, they have also been detected in other peripheral tissues, including immune cells, epithelium, smooth muscle, fibroblasts, and vascular endothelium. This review aims to provide a comprehensive description of the NTs as important physiological and pathophysiological players in brain and lung development.