Sex Differences in Animal Models of Sodium-Valproate-Induced Autism in Postnatal BALB/c Mice: Whole-Brain Histoarchitecture and 5-HT2A Receptor Biomarker Evidence

The protective role of prenatal administration of ascorbic acid on autistic-like behavior in a rat model of autism

Background

Autism is a complicated neurodevelopmental disorder characterized by several behavioral impairments. The pathology of autism is complex and not fully known. Several recent studies have shown alterations in the activities of antioxidant enzymes in autism. Vitamin C is a potent antioxidant that is present in high concentrations in the brain and acts as a neuromodulator. Prefrontal abnormality has been hypothesized to underlie autistic symptoms. The present study investigated the protective effect of prenatally Vitamin C on autistic-like behaviors, oxidative stress status, and histopathological change of prefrontal in valproic acid (VPA) rat model of autism.

Method

The model of autism was induced by subcutaneous administration of Valproic acid (600 mg/kg) to pregnant rats at gestational day 12.5. Vitamin C was administered 600 mg/L in drinking water from the 5th day of gestaion (GD5) up to postnatal day 23 (PND23). Thirty-two rat offspring were divided into four groups: Control, Vitamin C, VPA, and Vitamin C + VPA. The offspring were tested for repetitive behaviors and cognitive ability with a Y-maze task and social interaction with a play behavior task on 31st of Postnatal days. Glutathione (GSH), superoxide dismutase (SOD) activity, and the histological change in the prefrontal lobe were assessed at the end of the study. The number of neurons from the left prefrontal lobe was counted in duplicate from slides stained with hematoxylin-eosin.

Results

In the Y-maze apparatus, spontaneous alteration significantly decreased in the prenatal VPA treated rats compared to control rats showing autistic-like behavior; pre and postnatal Vitamin C treatment increased the alternation indicated benefit effect of Vitamin C. Prenatal VPA treatment impaired play behavior such as sniffing, grooming and darting. Vitamin C treatment attenuated the problems in male offspring social behavior. Histological examination showed an increase in the number of cells in the prefrontal cortex of valproic acid offspring rats compared to other groups. Moreover, prenatal VPA decreased antioxidant enzyme activities in the cortex (PFC) attenuated by Vitamin C administration.

Conclusion

The present study showed that valproic acid induced oxidative stress and neural changes in the prefrontal lobe when administered prenatally which in turn may cause the development of some autistic-like behaviors, and vitamin C may reduce this symptom with its antioxidant effects.

Sex-dependent alterations of inflammatory factors, oxidative stress, and histopathology of the brain-gut axis in a VPA-induced autistic-like model of rats

INTRODUCTION

In this study, we aimed to investigate the inflammatory factors, oxidative stress, and histopathological consequences of the brain-gut axis in male and female rats prenatally exposed to VPA.

METHODS

Pregnant Wistar rats were randomly divided into two groups. The animals received saline, and valproic acid (VPA) (600 mg/kg, i.p.) on embryonic day 12.5 (E12.5). All offspring were weaned on postnatal day 21, and the experiments were done in male and female rats on day 60. The brain and intestine tissues were extracted to assess histopathology, inflammation, and oxidative stress.

RESULTS

An increase of interleukin-1β (IL-1β) and interleukin-6 (IL-6) and a decrease of interleukin-10 (IL-10) were observed in the two sexes and two tissues of the autistic rats. In the VPA-exposed animals, malondialdehyde (MDA) and protein carbonyl (PC) increased in the brain of both sexes and the intestines of only the males. The total antioxidant capacity (TAC), superoxide dismutase (SOD), and catalase (CAT) significantly decreased in both tissues of male and female autistic groups. Histopathological evaluation showed that the %apoptosis of the cortex in the autistic male and female groups was more than in controls whereas this parameter in the CA1 and CA3 was significant only in the male rats. In the intestine, histopathologic changes were seen only in the male autistic animals.

CONCLUSION

The inflammatory and antioxidant factors were in line in the brain-gut axis in male and female rats prenatally exposed to VPA. Histopathological consequences were more significant in the VPA-exposed male animals.

Maternal separation stress through triggering of the neuro-immune response in the hippocampus induces autistic-like behaviors in male mice

Autism spectrum disorder (ASD) is the fastest-growing neurodevelopmental disease throughout the world. Neuro-immune responses from prenatal to adulthood stages of life induce developmental defects in synaptic signaling, neurotransmitter imbalance, and even structural changes in the brain. In this study, we aimed to focus on the possible role of neuroinflammatory response in the hippocampus in development of the autistic-like behaviors following maternal separation (MS) stress in mice. To do this, mice neonates daily separated from their mothers from postnatal day (PND) 2 to PND 14 for 3 h. During PND45-60, behavioral tests related to autistic-like behaviors including three-chamber sociability, Morris water maze (MWM), shuttle box, resident-intruder, and marble burying tests were performed. Then, hippocampi were dissected out, and the gene expression of inflammatory mediators including TNF-α, IL-1β, TLR4, HMGB1, and NLRP3 was assessed in the hippocampus using RT-PCR. Results showed that MS mice exerted impaired sociability preference, repetitive behaviors, impaired passive avoidance, and spatial memories. The gene expression of inflammatory mediators significantly increased in the hippocampi of MS mice. We concluded that MS stress probably via activating of the HMGB1/TLR4 signaling cascade in the hippocampus induced autistic-like behaviors in mice.

GABAB1 receptor knockdown in prefrontal cortex induces behavioral aberrations associated with autism spectrum disorder in mice

Autism spectrum disorder (ASD) is a set of heterogeneous neurodevelopmental disorders, characterized by social interaction deficit, stereotyped or repetitive behaviors. Apart from these core symptoms, a great number of individuals with ASD exhibit higher levels of anxiety and memory deficits. Previous studies demonstrate pronounced decrease of γ-aminobutyric acid B1 receptor (GABAB1R) protein level of frontal lobe in both ASD patients and animal models. The aim of the present study was to determine the role of GABAB1R in ASD-related behavioral aberrations. Herein, the protein and mRNA levels of GABAB1R in the prefrontal cortex (PFC) of sodium valproic acid (VPA)-induced mouse ASD model were determined by Western blot and qRT-PCR analysis, respectively. Moreover, the behavioral abnormalities in naive mice with GABAB1R knockdown mediated by recombinant adeno-associated virus (rAAV) were assessed in a comprehensive test battery consisted of social interaction, marble burying, self-grooming, open-field, Y-maze and novel object recognition tests. Furthermore, the action potential changes induced by GABAB1R deficiency were examined in neurons within the PFC of mouse. The results show that the mRNA and protein levels of GABAB1R in the PFC of prenatal VPA-induced mouse ASD model were decreased. Concomitantly, naive mice with GABAB1R knockdown exhibited ASD-like behaviors, such as impaired social interaction and communication, elevated stereotypes, anxiety and memory deficits. Patch-clamp recordings also revealed that GABAB1R knockdown provoked enhanced neuronal excitability by increasing action potential discharge frequencies. Overall, these findings support a notion that GABAB1R deficiency might contribute to ASD-like phenotypes, with the pathogenesis most likely resulting from enhanced neuronal excitability. SUBHEADINGS: GABAB1 Knockdown Induces Behavioral Aberrations with ASD.

Neurobiology of Behavior-Influences of Neuropsychiatric Disorders on Neurobiology and Behavior

The field of neuroscience continues to unravel the mysteries of the human brain and its association with neuropsychiatric disorders [...].

The Absence of Caspase-8 in the Dopaminergic System Leads to Mild Autism-like Behavior

In the last decade, new non-apoptotic roles have been ascribed to apoptotic caspases. This family of proteins plays an important role in the sculpting of the brain in the early stages of development by eliminating excessive and nonfunctional synapses and extra cells. Consequently, impairments in this process can underlie many neurological and mental illnesses. This view is particularly relevant to dopamine because it plays a pleiotropic role in motor control, motivation, and reward processing. In this study, we analyze the effects of the elimination of caspase-8 (CASP8) on the development of catecholaminergic neurons using neurochemical, ultrastructural, and behavioral tests. To do this, we selectively delete the CASP8 gene in cells that express tyrosine hydroxylase with the help of recombination through the Cre-loxP system. Our results show that the number of dopaminergic neurons increases in the substantia nigra. In the striatum, the basal extracellular level of dopamine and potassium-evoked dopamine release decreased significantly in mice lacking CASP8, clearly showing the low dopamine functioning in tissues innervated by this neurotransmitter. This view is supported by electron microscopy analysis of striatal synapses. Interestingly, behavioral analysis demonstrates that mice lacking CASP8 show changes reminiscent of autism spectrum disorders (ASD). Our research reactivates the possible role of dopamine transmission in the pathogenesis of ASD and provides a mild model of autism.