Loss of Social/Non-social Context Discrimination by Movement Acceleration in the Valproate Model of Autism

Sex- and social context-dependent differences in mice fine head movement during social interactions

BACKGROUND

Social decision-making is influenced by multiple factors such as age, sex, emotional state, and the individual's social environment. While various behavioural readouts have been commonly used to study social behaviour in rodents, the role of fine head movements during social interactions remains underexplored despite the presence of accelerometers in many electrophysiological recording systems.

RESULTS

Here, we used head acceleration data to analyse head movement kinematics in adult male and female mice across several social discrimination tests in various time scales. Our findings demonstrate the complementary nature of two variables derived from the raw acceleration, namely overall static (OSHA) and dynamic (ODHA) head acceleration, as well as specific head angles (Pitch and Roll). Together, these variables provide a comprehensive, detailed analysis of head movement, which cannot be easily achieved by video analysis systems such as DeepLabCut. Overall, our results suggest that head movement patterns are significantly influenced by sex, stimulus preference, and social context. Specifically, ODHA exhibited strong sex dependence and appeared to be more sensitive to internal states such as arousal and alertness. The static components were primarily influenced by social context, particularly stimulus preference, and seemed to reflect the subject's motivation to engage with the stimulus. The Roll angle also appeared strongly modulated by the broader social context.

CONCLUSIONS

Our study provides a novel method and analysis pipeline for studying the social behaviour of small rodents in high-time resolution using a head-based accelerometer. Our findings suggest that such measurements may inform the affective and motivational states of the subject during social interactions.

G protein-coupled estrogen receptor (GPER) selective agonist G1 attenuates the neurobehavioral, molecular and biochemical alterations induced in a valproic acid rat model of autism

AIMS

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with a rising prevalence in boys rather than girls. G protein-coupled estrogen receptor (GPER) activation by its agonist G1 showed a neuroprotective effect, similar to estradiol. The present study aimed to examine the potential of the selective GPER agonist G1 therapy on the behavioral, histopathological, biochemical, and molecular alterations induced in a valproic acid (VPA)-rat model of autism.

MAIN METHODS

VPA (500 mg/kg) was intraperitoneally administered to female Wistar rats (on gestational day 12.5) to induce the VPA-rat model of autism. The male offspring were intraperitoneally administered with G1 (10 and 20 μg/kg) for 21 days. After the treatment process, rats performed behavioral assessments. Then, sera and hippocampi were collected for biochemical and histopathological examinations and gene expression analysis.

KEY FINDINGS

GPER agonist G1 attenuated behavioral deficits, including hyperactivity, declined spatial memory and social preferences, anxiety, and repetitive behavior in VPA rats. G1 improved neurotransmission and reduced oxidative stress and histological alteration in the hippocampus. G1 reduced serum free T levels and interleukin-1β and up-regulated GPER, RORα, and aromatase gene expression levels in the hippocampus.

SIGNIFICANCE

The present study suggests that activation of GPER by its selective agonist G1 altered the derangements induced in a VPA-rat model of autism. G1 normalized free T levels via up-regulation of hippocampal RORα and aromatase gene expression. G1 provoked estradiol neuroprotective functions via up-regulation of hippocampal GPER expression. The G1 treatment and GPER activation provide a promising therapeutic approach to counteract the autistic-like symptoms.

The influence of continuous prenatal exposure to valproic acid on physical, nociceptive, emotional and psychomotor responses during adolescence in mice: Dose-related effects within sexes

Clinical findings show that the use of valproic acid (VPA) during pregnancy increases the risk of birth defects and autism spectrum disorder in offspring. Although there is a consensus that monitoring of potential long-term outcomes of VPA exposure is needed, especially in undiagnosed individuals, preclinical studies addressing this issue are rare. The present study examined the effects of continuous intrauterine exposure to a wide dose range of VPA (50, 100, 200, and 400 mg/kg/day) on the physical and behavioral response in peripubertal mice as a rodent model of adolescence. Body weight and the hot plate test [on postnatal days (PND) 25 and 32], the elevated plus-maze test (on PND35), and the open field test (on PND40) served to examine physical growth, the supraspinal reflex response to a painful thermal stimulus and conditional learning, anxiety-like/risk-assessment behavior, as well as novelty-induced psychomotor activity, respectively. VPA exposure produced the following responses: (i) a negative effect on body weight, except for the dose of 100 mg/kg/day in both sexes; (ii) an increase in the percentage of animals that responded to the thermal stimulus above the defined cut-off time interval and the response latency in both sexes; (iii) dose-specific changes within sexes in behavior provoked by a novel anxiogenic environment, i.e., in females less anxiety-like/risk-assessment behavior in response to the lowest exposure dose, and in males more pronounced anxiety-like/risk-assessment behavior after exposure to the highest dose and 100 mg/kg/day; (iv) dose-specific changes within sexes in novelty-induced psychomotor activity, i.e., in females a decrease in stereotypy-like activity along with an increase in rearing, and in males a decrease in stereotypy-like activity only. These findings show that continuous intrauterine exposure to VPA produces maladaptive functioning in different behavioral domains in adolescence and that the consequences are delicate to assess as they are dose-related within sexes.

An anxious relationship between Autism Spectrum Disorder and Gut Microbiota: A tangled chemistry?

Autism spectrum disorder (ASD) is a serious multifactorial neurodevelopmental disorder often accompanied by strained social communication, repetitive behaviour, immune dysregulation, and gastrointestinal (GI) issues. Recent studies have recorded a link between dysbiosis in the gut microbiota (gm) and the primary stages of ASD. A bidirectional connection (also called microbiota-gut-brain-axis) exchanges information between the gut bacteria and central nervous system. When the homeostasis of the microenvironment of the gut is dysregulated, it causes oxidative stress, affecting neuronal cells and neurotransmitters, thereby causing neurodevelopmental disorders. Studies have confirmed a difference in the constitution of gut bacteria among ASD cases and their controls. Numerous studies on animal models of ASD have shown altered gm and its association with abnormal metabolite profile and altered behaviour phenotype. This process happens due to an abnormal metabolite production in gm, leading to changes in the immune system, especially in ASD. Hence, this review aims to question the current knowledge on gm dysbiosis and its related GI discomforts and ASD behavioural symptoms and shed light on the possible therapeutic approaches available to deal with this situation. Thereby, though it is understood that more research might be needed to prove an association or causal relationship between gm and ASD, therapy with the microbiome may also be considered as an effective strategy to combat this issue.