Analyzing grooming microstructure in neurobehavioral experiments

Implication of the social function of excessive self-grooming behavior in BTBR T+ltpr3tf/J mice as an idiopathic model of autism

Autism spectrum disorder (ASD) is defined by two core behavioral characteristics, namely, restricted repetitive behaviors and impaired social-communicative functioning. BTBR T⁺ltpr3^tf/J (BTBR) mice provide a valuable animal model for ASD to elucidate the underlying mechanisms of these two behavioral characteristics of ASD. This study examined the social function of excessive grooming behavior in BTBR mice as a phenotype of restricted repetitive behaviors. Compared to the control C57BL/6 J (B6) strain, BTBR mice showed increased self-grooming when placed alone in a test apparatus, and this behavior was even more evident when confronted with a stimulus mouse (either B6 or BTBR) in a three-chamber test apparatus. While B6 mice tended to groom their face/snout region on the empty side of the chamber, BTBR mice showed excessive grooming with frequent transitions among grooming body regions on the side of the chamber containing a social stimulus. Acute systemic injection of buspirone,a serotonin 1A receptor agonist, as an anxiolytic, facilitated approach behavior toward social stimuli in the three-chamber setting in both B6 and BTBR mice. However, this treatment did not affect grooming behavior in B6 mice and significantly enhanced self-grooming in BTBR mice. These behaviors in BTBR mice suggest a potential signaling function of grooming in response to social stimuli, in which bodywide grooming of BTBR mice expressed in the proximity of social opponents may stimulate the release of olfactory (possibly dismissive) signals. Consequently, the putative neural mechanisms underlying excessive grooming may differ from those regulating social approaches that are associated with anxiolytic mechanisms.

Blocking NK1 receptors disrupts the sequential and temporal organization of chain grooming in rats

The basal ganglia are a group of sub-cortical structures believed to play a critical role in action selection and sequencing. The striatum is the largest input structure of the basal ganglia and contains the neuropeptide substance P in abundance. Recent computational work has suggested that substance P could play a critical role in action sequence performance and acquisition, but this has not been tested experimentally before. The aim of the present study was to test how blocking substance P's main NK1-type receptors affected the sequential and temporal organization of spontaneous behavioral patterns. We did this in rats by focusing on the grooming chain, an innate and highly stereotyped ordered sequence. We performed an open field experiment in which the NK1 receptor antagonist L-733,060 was injected intraperitoneally in rats at two doses (2 and 4 mg/kg/ml), in a within-subject counterbalanced design. We used first order transition probabilities, Variable Length Markov Models, entropy metrics and T-pattern analysis to evaluate the effects of L-733,060 on sequential and temporal aspects of spontaneously ordered behavioral sequences. Our results suggest that blocking NK1 receptors made the transitions between the grooming chain elements significantly more variable, the transition structure of the grooming bouts simpler, and it increased the probability of transitioning from active to inactive states. Overall, this suggest that blocking substance P receptors led to a general break down in the fluency of spontaneous behavioral sequences, suggesting that substance P could be playing a key role in the implementation of sequential patterns.

Danger perception and stress response through an olfactory sensor for the bacterial metabolite hydrogen sulfide

The olfactory system serves a critical function as a danger detection system to trigger defense responses essential for survival. The cellular and molecular mechanisms that drive such defenses in mammals are incompletely understood. Here, we have discovered an ultrasensitive olfactory sensor for the highly poisonous bacterial metabolite hydrogen sulfide (H₂S) in mice. An atypical class of sensory neurons in the main olfactory epithelium, the type B cells, is activated by both H₂S and low O₂. These two stimuli trigger, respectively, Cnga2- and Trpc2-signaling pathways, which operate in separate subcellular compartments, the cilia and the dendritic knob. This activation drives essential defensive responses: elevation of the stress hormone ACTH, stress-related self-grooming behavior, and conditioned place avoidance. Our findings identify a previously unknown signaling paradigm in mammalian olfaction and define type B cells as chemosensory neurons that integrate distinct danger inputs from the external environment with appropriate defense outputs.

Altered Grooming Syntax and Amphetamine-Induced Dopamine Release in EAAT3 Overexpressing Mice

The excitatory amino acid transporter EAAT3 plays an important role in the neuronal uptake of glutamate regulating the activation of glutamate receptors. Polymorphisms in the gene-encoding EAAT3 have been associated with obsessive-compulsive disorder (OCD), although the mechanisms underlying this relationship are still unknown. We recently reported that mice with increased EAAT3 expression in forebrain neurons (EAAT3 ^{g lo} /CMKII) display behavioral and synaptic features relevant to OCD, including increased grooming, higher anxiety-like behavior and altered cortico-striatal synaptic function. The dopamine neurotransmitter system is implicated in ritualistic behaviors. Indeed, dopaminergic neurons express EAAT3, and mice lacking EAAT3 exhibit decreased dopamine release and decreased expression of the dopamine D1 receptor. Moreover, EAAT3 plays a role on the effect of the psychostimulant amphetamine. As such, we sought to determine if the OCD-like behavior in EAAT3 ^{g lo} /CMKII mice is accompanied by altered nigro-striatal dopaminergic transmission. The aim of this study was to analyze dopamine transmission both in basal conditions and after an acute challenge of amphetamine, using behavioral, neurochemical, molecular, and cellular approaches. We found that in basal conditions, EAAT3 ^{g lo} /CMKII mice performed more grooming events and that they remained in phase 1 of the grooming chain syntax compared with control littermates. Administration of amphetamine increased the number of grooming events in control mice, while EAAT3 ^{g lo} /CMKII mice remain unaffected. Interestingly, the grooming syntax of amphetamine-control mice resembled that of EAAT3 ^{g lo} /CMKII mice in basal conditions. Using in vivo microdialysis, we found decreased basal dopamine levels in EAAT3 ^{g lo} /CMKII compared with control mice. Unexpectedly, we found that after acute amphetamine, EAAT3 ^{g lo} /CMKII mice had a higher release of dopamine compared with that of control mice, suggesting that EAAT3 overexpression leads to increased dopamine releasability. To determine postsynaptic effect of EAAT3 overexpression over dopamine transmission, we performed Western blot analysis of dopaminergic proteins and found that EAAT3 ^{g lo} /CMKII mice have higher expression of D2 receptors, suggesting a higher inhibition of the indirect striatal pathway. Together, the data indicate that EAAT3 overexpression impacts on dopamine transmission, making dopamine neurons more sensitive to the effect of amphetamine and leading to a disbalance between the direct and indirect striatal pathways that favors the performance of repetitive behaviors.

Lost in translation: no effect of repeated optogenetic cortico-striatal stimulation on compulsivity in rats

The orbitofrontal cortex-ventromedial striatum (OFC-VMS) circuitry is widely believed to drive compulsive behavior. Hyperactivating this pathway in inbred mice produces excessive and persistent self-grooming, which has been considered a model for human compulsivity. We aimed to replicate these findings in outbred rats, where there are few reliable compulsivity models. Male Long-Evans rats implanted with optical fibers into VMS and with opsins delivered into OFC received optical stimulation at parameters that produce OFC-VMS plasticity and compulsive grooming in mice. We then evaluated rats for compulsive self-grooming at six timepoints: before, during, immediately after, and 1 h after each stimulation, 1 and 2 weeks after the ending of a 6-day stimulation protocol. To further test for effects of OFC-VMS hyperstimulation, we ran animals in three standard compulsivity assays: marble burying, nestlet shredding, and operant attentional set-shifting. OFC-VMS stimulation did not increase self-grooming or induce significant changes in nestlet shredding, marble burying, or set-shifting in rats. Follow-on evoked potential studies verified that the stimulation protocol altered OFC-VMS synaptic weighting. In sum, although we induced physiological changes in the OFC-VMS circuitry, we could not reproduce in a strongly powered study in rats a model of compulsive behavior previously reported in mice. This suggests possible limitations to translation of mouse findings to species higher on the phylogenetic chain.

Differential effects by sex with Kmt5b loss

Lysine methyl transferase 5B (KMT5B) has been recently highlighted as a risk gene in genetic studies of neurodevelopmental disorders (NDDs), specifically, autism spectrum disorder (ASD) and intellectual disability (ID); yet, its role in the brain is not known. The goal of this work was to neurodevelopmentally characterize the effect(s) of KMT5B haploinsufficiency using a mouse model. A Kmt5b gene-trap mouse line was obtained from the Knockout Mouse Project. Wild type (WT) and heterozygous (HET) mice were subjected to a comprehensive neurodevelopmental test battery to assess reflexes, motor behavior, learning/memory, social behavior, repetitive movement, and common ASD comorbidities (obsessive compulsion, depression, and anxiety). Given the strong sex bias observed in the ASD patient population, we tested both a male and female cohort of animals and compared differences between genotypes and sexes. HET mice were significantly smaller than WT littermates starting at postnatal day 10 through young adulthood which was correlated with smaller brain size (i.e., microcephaly). This was more severe in males than females. HET male neonates also had delayed eye opening and significantly weaker reflexes than WT littermates. In young adults, significant differences between genotypes relative to anxiety, depression, fear, and extinction learning were observed. Interestingly, several sexually dimorphic differences were noted including increased repetitive grooming behavior in HET females and an increased latency to hot plate response in HET females versus a decreased latency in HET males. LAY SUMMARY: Lysine methyl transferase 5B (KMT5B) has been recently highlighted as a risk gene in neurodevelopmental disorders (NDDs), specifically, autism spectrum disorder (ASD) and intellectual disability (ID); yet its role in the brain is not known. Our study indicates that mice lacking one genomic copy of Kmt5b show deficits in neonatal reflexes, sociability, repetitive stress-induced grooming, changes in thermal pain sensing, decreased depression and anxiety, increased fear, slower extinction learning, and lower body weight, length, and brain size. Furthermore, several outcomes differed by sex, perhaps mirroring the sex bias in ASD.

Melanins as Sustainable Resources for Advanced Biotechnological Applications

Melanins are a class of biopolymers that are widespread in nature and have diverse origins, chemical compositions, and functions. Their chemical, electrical, optical, and paramagnetic properties offer opportunities for applications in materials science, particularly for medical and technical uses. This review focuses on the application of analytical techniques to study melanins in multidisciplinary contexts with a view to their use as sustainable resources for advanced biotechnological applications, and how these may facilitate the achievement of the United Nations Sustainable Development Goals.

A cross-species assessment of behavioral flexibility in compulsive disorders

Lack of behavioral flexibility has been proposed as one underlying cause of compulsions, defined as repetitive behaviors performed through rigid rituals. However, experimental evidence has proven inconsistent across human and animal models of compulsive-like behavior. In the present study, applying a similarly-designed reversal learning task in two different species, which share a common symptom of compulsivity (human OCD patients and Sapap3 KO mice), we found no consistent link between compulsive behaviors and lack of behavioral flexibility. However, we showed that a distinct subgroup of compulsive individuals of both species exhibit a behavioral flexibility deficit in reversal learning. This deficit was not due to perseverative, rigid behaviors as commonly hypothesized, but rather due to an increase in response lability. These cross-species results highlight the necessity to consider the heterogeneity of cognitive deficits in compulsive disorders and call for reconsidering the role of behavioral flexibility in the aetiology of compulsive behaviors.

Social interaction reward in rats has anti-stress effects

Social interaction in an alternative context can be beneficial against drugs of abuse. Stress is known to be a risk factor that can exacerbate the effects of addictive drugs. In this study, we investigated whether the positive effects of social interaction are mediated through a decrease in stress levels. For that purpose, rats were trained to express cocaine or social interaction conditioned place preference (CPP). Behavioural, hormonal, and molecular stress markers were evaluated. We found that social CPP decreased the percentage of incorrect transitions of grooming and corticosterone to the level of naïve untreated rats. In addition, corticotropin-releasing factor (CRF) was increased in the bed nucleus of stria terminalis after cocaine CPP. In order to study the modulation of social CPP by the CRF system, rats received intracerebroventricular CRF or alpha-helical CRF, a nonselective antagonist of CRF receptors. The subsequent effects on CPP to cocaine or social interaction were observed. CRF injections increased cocaine CPP, whereas alpha-helical CRF injections decreased cocaine CPP. However, alpha-helical CRF injections potentiated social CPP. When social interaction was made available in an alternative context, CRF-induced increase of cocaine preference was reversed completely to the level of rats receiving cocaine paired with alpha-helical CRF. This reversal of cocaine preference was also paralleled by a reversal in CRF-induced increase of p38 MAPK expression in the nucleus accumbens shell. These findings suggest that social interaction could contribute as a valuable component in treatment of substance use disorders by reducing stress levels.

Corticostriatal dysfunction and social interaction deficits in mice lacking the cystine/glutamate antiporter

The astrocytic cystine/glutamate antiporter system x_c^- represents an important source of extracellular glutamate in the central nervous system, with potential impact on excitatory neurotransmission. Yet, its function and importance in brain physiology remain incompletely understood. Employing slice electrophysiology and mice with a genetic deletion of the specific subunit of system x_c^-, xCT (xCT^-/- mice), we uncovered decreased neurotransmission at corticostriatal synapses. This effect was partly mitigated by replenishing extracellular glutamate levels, indicating a defect linked with decreased extracellular glutamate availability. We observed no changes in the morphology of striatal medium spiny neurons, the density of dendritic spines, or the density or ultrastructure of corticostriatal synapses, indicating that the observed functional defects are not due to morphological or structural abnormalities. By combining electron microscopy with glutamate immunogold labeling, we identified decreased intracellular glutamate density in presynaptic terminals, presynaptic mitochondria, and in dendritic spines of xCT^-/- mice. A proteomic and kinomic screen of the striatum of xCT^-/- mice revealed decreased expression of presynaptic proteins and abnormal kinase network signaling, that may contribute to the observed changes in postsynaptic responses. Finally, these corticostriatal deregulations resulted in a behavioral phenotype suggestive of autism spectrum disorder in the xCT^-/- mice; in tests sensitive to corticostriatal functioning we recorded increased repetitive digging behavior and decreased sociability. To conclude, our findings show that system x_c^- plays a previously unrecognized role in regulating corticostriatal neurotransmission and influences social preference and repetitive behavior.

Further evidence of anxiety- and depression-like behavior for total genetic ablation of cannabinoid receptor type 1

Cannabinoid receptor type 1 (CB1R) is the most abundant cannabinoid receptor in central nervous system. Clinical studies and animal models have shown that the attenuation of endocannabinoid system signaling correlates with the development of psychiatric disorders such as anxiety, depression and schizophrenia. In the present work, multiple behavioral tests were performed to evaluate behaviors related to anxiety and depression in CB1R^+/- and CB1R^-/-. CB1R^+/- mice had anxiety-related behavior similar to wild type (CB1R^+/+) mice, whereas CB1R^-/- mice displayed an anxious-like phenotype, which indicates that lower expression of CB1R is sufficient to maintain the neural circuits modulating anxiety. In addition, CB1R^-/- mice exhibited alterations in risk assessment and less exploration, locomotion, grooming, body weight and appetite. These phenotypic characteristics observed in CB1R^-/- mice could be associated with symptoms observed in human psychiatric disorders such as depression. A better knowledge of the neuromodulatory role of CB1R may contribute to understand scope and limitations of the development of medical treatments.

Parallel ascending spinal pathways for affective touch and pain

The anterolateral pathway consists of ascending spinal tracts that convey pain, temperature and touch information from the spinal cord to the brain^1-4. Projection neurons of the anterolateral pathway are attractive therapeutic targets for pain treatment because nociceptive signals emanating from the periphery are channelled through these spinal projection neurons en route to the brain. However, the organizational logic of the anterolateral pathway remains poorly understood. Here we show that two populations of projection neurons that express the structurally related G-protein-coupled receptors (GPCRs) TACR1 and GPR83 form parallel ascending circuit modules that cooperate to convey thermal, tactile and noxious cutaneous signals from the spinal cord to the lateral parabrachial nucleus of the pons. Within this nucleus, axons of spinoparabrachial (SPB) neurons that express Tacr1 or Gpr83 innervate distinct sets of subnuclei, and strong optogenetic stimulation of the axon terminals induces distinct escape behaviours and autonomic responses. Moreover, SPB neurons that  express Gpr83 are highly sensitive to cutaneous mechanical stimuli and receive strong synaptic inputs from both high- and low-threshold primary mechanosensory neurons. Notably, the valence associated with activation of SPB neurons that express Gpr83 can be either positive or negative, depending on stimulus intensity. These findings reveal anatomically, physiologically and functionally distinct subdivisions of the SPB tract that underlie affective aspects of touch and pain.

The mouse model of fragile X syndrome exhibits deficits in contagious itch behavior

Individuals with autism spectrum disorders (ASDs) imitate observed behavior less than age-matched and typically developing peers, resulting in deterred learning ability and social interaction. However, this deficit lacks preclinical assessment tools. A previous study has shown that mice exhibit contagious itch behavior while viewing a scratching demonstrator mouse, as opposed to an ambulating demonstrator mouse, but whether autism mouse models imitate observed scratching behavior remains unknown. Here, we investigated contagious itch behavior in the mouse model of fragile X syndrome (FXS), a common form of inherited intellectual disabilities with a high risk for ASDs. We found that the mouse model of FXS shows deficits in contagious itch behavior. Our findings can be used as a new preclinical assessment tool for measuring imitative deficits in the study of neurodevelopmental disorders including FXS.

Chronic immobilization stress induces anxiety-related behaviors and affects brain essential minerals in male rats

Alterations of essential elements in the brain are associated with the pathophysiology of many neuropsychiatric disorders. It is known that chronic/overwhelming stress may cause some anxiety and/or depression. We aimed to investigate the effects of two different chronic immobilization stress protocols on anxiety-related behaviors and brain minerals. Adult male Wistar rats were divided into 3 groups as follows (n = 10/group): control, immobilization stress-1 (45 minutes daily for 7-day) and immobilization stress-2 (45 minutes twice a day for 7-day). Stress-related behaviors were evaluated by open field test and forced swimming test. In the immobilization stress-1 and immobilization stress-2 groups, percentage of time spent in the central area (6.38 ± 0.41% and 6.28 ± 1.03% respectively, p < 0.05) and rearing frequency (2.75 ± 0.41 and 3.85 ± 0.46, p < 0.01 and p < 0.05, respectively) were lower, latency to center area (49.11 ± 5.87 s and 44.92 ± 8.04 s, p < 0.01 and p < 0.01, respectively), were higher than the control group (8.65 ± 0.49%, 5.37 ± 0.44 and 15.3 ± 3.32 s, respectively). In the immobilization stress-1 group, zinc (12.65 ± 0.1 ppm, p < 0.001), magnesium (170.4 ± 1.7 ppm, p < 0.005) and phosphate (2.76 ± 0.1 ppm, p < 0.05) levels were lower than the control group (13.87 ± 0.16 ppm, 179.31 ± 1.87 ppm and 3.11 ± 0.06 ppm, respectively). In the immobilization stress-2 group, magnesium (171.56 ± 1.87 ppm, p < 0.05), phosphate (2.44 ± 0.07 ppm, p < 0.001) levels were lower, and manganese (373.68 ± 5.76 ppb, p < 0.001) and copper (2.79 ± 0.15 ppm, p < 0.05) levels were higher than the control group (179.31 ± 1.87 ppm, 3.11 ± 0.06 ppm, 327.25 ± 8.35 ppb and 2.45 ± 0.05 ppm, respectively). Our results indicated that 7-day chronic immobilization stress increased anxiety-related behaviors in both stress groups. Zinc, magnesium, phosphate, copper and manganese levels were affected in the brain.

Bigger doesn't mean bolder: behavioral variation of four wild rodent species to novelty and predation risk following a fast-slow continuum

Background

Understanding how wild species respond to novel situations with associated risk can provide valuable insights for inter-specific behavioral variation and associations with pace-of-life (POL). Rodents, a globally distributed and diverse taxonomic group, have been the subjects of countless studies emulating risky situations. Controlled laboratory experiments with a focus on wild-caught species provide the opportunity to test fine-scale behavioral responses to contexts of risk with ecological implications. For example, assessing the importance of predator cues eliciting antipredator responses, as well as whether wild rodents embody behavioral plasticity and repertoires, illustrated by habituation and variation in behavioral traits, respectively.

Results

In this comparative study, we examined multiple behavioral responses of four rodent species in eastern Taiwan (three native species Mus caroli, Apodemus agrarius, Rattus losea, and one invasive, Rattus exulans) exposed to an unfamiliar microenvironment and novel cue from an allopatric predator, the leopard cat (Prionailurus bengalensis). All wild-caught animals were subjected to two consecutive nights of experimental trials in a laboratory setting. Behavioral responses to a novel situation during the first trial differed between species; smaller species investing more time in non-defensive behaviors compared to the larger species. More specifically, the smaller species M. caroli and A. agrarius allocated more time to exploration and foraging, whereas the larger rat species R. exulans and R. losea spent more time motionless or concealing. During the second trial, the addition of leopard cat cues did not elicit antipredator behaviors, but rather, rodents were found to exhibit increased non-defensive behaviors, specifically foraging efforts.

Conclusions

Our results suggest that these four species do largely follow a behavioral fast-slow continuum with the two smaller mice species demonstrating increased boldness in a novel context compared to the larger rat species. Also, the wild populations of rodents in eastern Taiwan may be naïve to leopard cats. Finally, the rodents in our study demonstrated habituation to the microenvironment, indicating they possess adaptive capacity.

Effects of a postnatal Atrx conditional knockout in neurons on autism-like behaviours in male and female mice

BACKGROUND

Alpha-thalassemia/mental retardation, X-linked, or ATRX, is an autism susceptibility gene that encodes a chromatin remodeler. Mutations of ATRX result in the ATR-X intellectual disability syndrome and have been identified in autism spectrum disorder (ASD) patients. The mechanisms by which ATRX mutations lead to autism and autistic-like behaviours are not yet known. To address this question, we generated mice with postnatal Atrx inactivation in excitatory neurons of the forebrain and performed a battery of behavioural assays that assess autistic-like behaviours.

METHODS

Male and female mice with a postnatal conditional ablation of ATRX were generated using the Cre/lox system under the control of the αCaMKII gene promoter. These mice were tested in a battery of behavioural tests that assess autistic-like features. We utilized paradigms that measure social behaviour, repetitive, and stereotyped behaviours, as well as sensory gating. Statistics were calculated by two-way repeated measures ANOVA with Sidak's multiple comparison test or unpaired Student's t tests as indicated.

RESULTS

The behaviour tests revealed no significant differences between Atrx-cKO and control mice. We identified sexually dimorphic changes in odor habituation and discrimination; however, these changes did not correlate with social deficits.

CONCLUSION

The postnatal knockout of Atrx in forebrain excitatory neurons does not lead to autism-related behaviours in male or female mice.

A limbic circuitry involved in emotional stress-induced grooming

Prolonged exposure to negative stressors could be harmful if a subject cannot respond appropriately. Strategies evolved to respond to stress, including repetitive displacement behaviours, are important in maintaining behavioural homoeostasis. In rodents, self-grooming is a frequently observed repetitive behaviour believed to contribute to post-stress de-arousal with adaptive value. Here we identified a rat limbic di-synaptic circuit that regulates stress-induced self-grooming with positive affective valence. This circuit links hippocampal ventral subiculum to ventral lateral septum (LSv) and then lateral hypothalamus tuberal nucleus. Optogenetic activation of this circuit triggers delayed but robust excessive grooming with patterns closely resembling those evoked by emotional stress. Consistently, the neural activity of LSv reaches a peak before emotional stress-induced grooming while inhibition of this circuit significantly suppresses grooming triggered by emotional stress. Our results uncover a previously unknown limbic circuitry involved in regulating stress-induced self-grooming and pinpoint a critical role of LSv in this ethologically important behaviour.

Self-grooming is a frequently observed repetitive behaviour in rodents that is believed to contribute to post-stress de-arousal. The authors identified a previously unknown limbic circuit that includes the ventral lateral septum in rats and is involved in regulating stress-induced self-grooming.

Chronic alcohol disrupts hypothalamic responses to stress by modifying CRF and NMDA receptor function

The chronic inability of alcoholics to effectively cope with relapse-inducing stressors has been linked to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and corticotropin-releasing factor (CRF) signaling. However, the cellular mechanisms responsible for this dysregulation are yet to be identified. After exposure of male Sprague Dawley rats to chronic intermittent ethanol (CIE; 5-6 g/kg orally for 35 doses over 50 days) or water, followed by 40-60 days of protracted withdrawal, we investigated CIE effects on glutamatergic synaptic transmission, stress-induced plasticity, CRF- and ethanol-induced NMDAR inhibition using electrophysiological recordings in parvocellular neurosecretory cells (PNCs) of the paraventricular nucleus. We also assessed CIE effects on hypothalamic mRNA expression of CRF-related genes using real-time polymerase chain reaction, and on HPA axis function by measuring stress-induced increases in plasma adrenocorticotropic hormone, corticosterone, and self-grooming. In control rats, ethanol-mediated inhibition of NMDARs was prevented by CRF1 receptor (CRFR1) blockade with antalarmin, while CRF/CRFR1-mediated NMDAR blockade was prevented by intracellularly-applied inhibitor of phosphatases PP1/PP2A, okadaic acid, but not the selective striatal-enriched tyrosine protein phosphatase inhibitor, TC-2153. CIE exposure increased GluN2B subunit-dependent NMDAR function of PNCs. This was associated with the loss of both ethanol- and CRF-mediated NMDAR inhibition, and loss of stress-induced short-term potentiation of glutamatergic synaptic inputs, which could be reversed by intracellular blockade of NMDARs with MK801. CIE exposure also blunted the hormonal and self-grooming behavioral responses to repeated restraint stress. These findings suggest a cellular mechanism whereby chronic alcohol dysregulates the hormonal and behavioral responses to repetitive stressors by increasing NMDAR function and decreasing CRFR1 function.

Autism-Associated Shank3 Is Essential for Homeostatic Compensation in Rodent V1

Mutations in Shank3 are strongly associated with autism spectrum disorders and neural circuit changes in several brain areas, but the cellular mechanisms that underlie these defects are not understood. Homeostatic forms of plasticity allow central circuits to maintain stable function during experience-dependent development, leading us to ask whether loss of Shank3 might impair homeostatic plasticity and circuit-level compensation to perturbations. We found that Shank3 loss in vitro abolished synaptic scaling and intrinsic homeostatic plasticity, deficits that could be rescued by treatment with lithium. Further, Shank3 knockout severely compromised the in vivo ability of visual cortical circuits to recover from perturbations to sensory drive. Finally, lithium treatment ameliorated a repetitive self-grooming phenotype in Shank3 knockout mice. These findings demonstrate that Shank3 loss severely impairs the ability of central circuits to harness homeostatic mechanisms to compensate for perturbations in drive, which, in turn, may render them more vulnerable to such perturbations.

Environmental enrichment improves metabolic and behavioral health in the BTBR mouse model of autism

BTBR T + Itpr3tf/J (BTBR) mice are an Autism Spectrum Disorder (ASD)-like model that exhibit behavioral and physiological deficits similar to those observed in patients with ASD. While behavioral therapy is a first line of treatment in ASD patients, comparable non-pharmacological treatments are less explored in murine models. Here, we administer a bio-behavioral intervention for BTBR mice by way of environmental enrichment (EE) - an experimental housing paradigm previously shown to improve systemic metabolism, learning/memory, anxious behavior, neurogenesis, locomotion, and immunocompetence in C57BL/6 mice. Juvenile BTBR mice were randomized to standard or EE housing and were subjected to metabolic and behavioral assessments up to 17 weeks. Following EE exposure, we report an EE-induced metabolic and behavioral phenotype. Male BTBR mice responded metabolically to EE, displaying reduced adiposity, increased lean mass, improved glycemic control, and decreased circulating leptin. The gene expressions of brain-derived neurotrophic factor (Bdnf) and its receptor (Ntrk2/TrkB) were upregulated in several brain areas in EE-BTBR males. EE-BTBR females showed modest reduction of adiposity and no changes in glycemic control, circulating leptin, or Bdnf/Ntrk2 gene expression. With regard to behavior, EE resulted in decreased anxiety, and increased social affiliation. Together, these results suggest that EE improves metabolic and behavioral health in BTBR mice.

Effects of DCM Leaf Extract of Gnidia glauca (Fresen) on Locomotor Activity, Anxiety, and Exploration-Like Behaviors in High-Fat Diet-Induced Obese Rats

Obesity is the main component of metabolic syndromes involving distinct etiologies that target different underlying behavioral and physiological functions within the brain structures and neuronal circuits. An alteration in the neuronal circuitry stemming from abdominal or central obesity stimulates a cascade of changes in neurochemical signaling that directly or indirectly mediate spontaneously emitted behaviors such as locomotor activity patterns, anxiety, and exploration. Pharmacological agents available for the treatment of neurologic disorders have been associated with limited potency and intolerable adverse effects. These have necessitated the upsurge in the utilization of herbal prescriptions due to their affordability and easy accessibility and are firmly embedded within wider belief systems of many people. Gnidia glauca has been used in the management of many ailments including obesity and associated symptomatic complications. However, its upsurge in use has not been accompanied by empirical determination of these folkloric claims. The present study, therefore, is aimed at determining the modulatory effects of dichloromethane leaf extract of Gnidia glauca on locomotor activity, exploration, and anxiety-like behaviors in high-fat diet-induced obese rats in an open-field arena. Obesity was experimentally induced by feeding the rats with prepared high-fat diet and water ad libitum for 6 weeks. The in vivo antiobesity effects were determined by oral administration of G. glauca at dosage levels of 200, 250, and 300 mg/kg body weight in high-fat diet-induced obese rats from the 6^th to 12^th week. Phytochemical analysis was done using gas chromatography linked to mass spectroscopy. Results indicated that Gnidia glauca showed anxiolytic effects and significantly increased spontaneous locomotor activity and exploration-like behaviors in HFD-induced obese rats. The plant extract also contained phytocompounds that have been associated with amelioration of the main neurodegenerative mediators, viz., inflammation and oxidative stress. These findings provide “qualified leads” for the synthesis of new alternative therapeutic agents for the management of neurologic disorders. However, there is a need to conduct toxicity studies of Gnidia glauca to establish its safety profiles.

The Steroidogenesis Inhibitor Finasteride Reduces the Response to Both Stressful and Rewarding Stimuli

Finasteride (FIN) is the prototypical inhibitor of steroid 5α-reductase (5αR), the enzyme that catalyzes the rate-limiting step of the conversion of progesterone and testosterone into their main neuroactive metabolites. FIN is clinically approved for the treatment of benign prostatic hyperplasia and male baldness; while often well-tolerated, FIN has also been shown to cause or exacerbate psychological problems in vulnerable subjects. Evidence on the psychological effects of FIN, however, remains controversial, in view of inconsistent clinical reports. Here, we tested the effects of FIN in a battery of tests aimed at capturing complementary aspects of mood regulation and stress reactivity in rats. FIN reduced exploratory, incentive, prosocial, and risk-taking behavior; furthermore, it decreased stress coping, as revealed by increased immobility in the forced-swim test (FST). This last effect was also observed in female and orchiectomized male rats, suggesting that the mechanism of action of FIN does not primarily reflect changes in gonadal steroids. The effects of FIN on FST responses were associated with a dramatic decrease in corticotropin release hormone (CRH) mRNA and adrenocorticotropic hormone (ACTH) levels. These results suggest that FIN impairs stress reactivity and reduces behavioral activation and impulsive behavior by altering the function of the hypothalamus-pituitary-adrenal (HPA) axis.

Identification of a neurocircuit underlying regulation of feeding by stress-related emotional responses

Feeding is known to be profoundly affected by stress-related emotional states and eating disorders are comorbid with psychiatric symptoms and altered emotional responses. The neural basis underlying feeding regulation by stress-related emotional changes is poorly understood. Here, we identify a novel projection from the paraventricular hypothalamus (PVH) to the ventral lateral septum (LSv) that shows a scalable regulation on feeding and behavioral changes related to emotion. Weak photostimulation of glutamatergic PVH→LSv terminals elicits stress-related self-grooming and strong photostimulation causes fear-related escape jumping associated with respective weak and strong inhibition on feeding. In contrast, inhibition of glutamatergic inputs to LSv increases feeding with signs of reduced anxiety. LSv-projecting neurons are concentrated in rostral PVH. LSv and LSv-projecting PVH neurons are activated by stressors in vivo, whereas feeding bouts were associated with reduced activity of these neurons. Thus, PVH→LSv neurotransmission underlies dynamic feeding by orchestrating emotional states, providing a novel neural circuit substrate underlying comorbidity between eating abnormalities and psychiatric disorders.

Human amniotic epithelial cell transplantation promotes neurogenesis and ameliorates social deficits in BTBR mice

Background

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social interactions and communication and stereotypical patterns of behaviors, interests, or activities. Even with the increased prevalence of ASD, there is no defined standard drug treatment for ASD patients. Currently, stem cells, including human amniotic epithelial cell (hAEC) transplantation, seem to be a promising treatment for ASD, but the effectiveness needs to be verified, and the mechanism has not been clarified.

Methods

We intraventricularly transplanted hAECs into a 2-month-old BTBR T+tf/J (BTBR) mouse model of ASD. Behavior tests were detected 1 month later; hippocampal neurogenesis, neuroprogenitor cell (NPC) pool, and microglia activation were analyzed with immunohistochemistry and immunofluorescence; the levels of pro-inflammatory cytokines, brain-derived neurotrophic factor (BDNF), and TrkB in the hippocampus were determined by real-time PCR or western blotting.

Results

After intraventricular injection of hAECs into adult males, social deficits in BTBR mice were significantly ameliorated. In addition, hAEC transplantation restored the decline of neurogenesis and NPCs in the hippocampus of BTBR mice by expanding the stem cell pool, and the decreased levels of BDNF and TrkB were also rescued in the hippocampus of the hAEC-injected BTBR mice. Meanwhile, the transplantation of hAECs did not induce microglial overactivation or excessive production of pro-inflammatory cytokines in the hippocampus of BTBR mice.

Conclusions

Based on these results, we found that hAEC transplantation ameliorated social deficits and promoted hippocampal neurogenesis in BTBR mice. Our study indicates a promising therapeutic option that could be applied to ASD patients in the future.

Long-term metabolic cage housing increases anxiety/depression-related behaviours in adult male rats

There are several reports on unfavourable effects of metabolic cage housing on animal welfare mainly due to the characteristic structures of these cages such as single housing and grid flooring. This study was aimed to compare the effects of long-term metabolic cage housing and conventional housing (normal grouped housing in standard cages) on the anxiety/depression-like behaviours in male rats. Anxiety/depression-related behaviours were evaluated by use of forced swimming test and open field test. Swimming and climbing were significantly lower and immobility duration higher in the metabolic cage group. In the open field test, total distance, mean velocity, time spent in the central area, zone transition, grooming, and rearing scores were significantly lower in the metabolic cage. Moreover, serum corticosterone level was higher in the metabolic cage group. The results of the study indicate that long-term metabolic cage housing may cause an increase in the anxiety- and depression-related behaviours in male rats.

The Effect of ASIC3 Knockout on Corticostriatal Circuit and Mouse Self-grooming Behavior

Stereotypic and/or repetitive behavior is one of the major symptoms of autism spectrum disorder (ASD). Increase of self-grooming behavior is a behavioral phenotype commonly observed in the mouse models for ASD. Previously, we have shown that knockout of acid-sensing ion channel 3 (ASIC3) led to the increased self-grooming behavior in resident-intruder test. Given the facts that ASIC3 is mainly expressed in the peripheral dorsal root ganglion (DRG) and conditional knockout of ASIC3 in the proprioceptors induced proprioception deficits. We speculate a hypothesis that stereotypic phenotype related to ASD, pararalled with striatal dysfunction, might be caused by proprioception defect in the peripheral sensory neuron origin. Herein, we investigate in depth whether and how ASIC3 is involved in the regulation of self-grooming behavior. First, we observed that Asic3 null mutant mice exhibited increased self-grooming in social interaction during juvenile stage. Similarly, they displayed increased self-grooming behavior in a novel cage in the absence of cagemate. To further understand the mechanism by which ASIC3 affects grooming behavior, we analyzed neurochemical, neuropathological and electrophysiological features in the dorsal striatum of Asic3 null mutant mice. Knockout of Asic3 increased dopamine (DA) activity and phospho-ERK immunoreactivities in the dorsal striatum. Furthermore, we detected a lower paired-pulse ratio (PPR) and impaired long-term potentiation (LTP) in corticostriatal circuits in Asic3 null mutant mice as compared with wild-type (WT) littermates. Moreover, knockout of Asic3 altered the medial spiny neurons in the striatum with defects in presynaptic function and decrease of dendritic spines. Lastly, genetic ablation of Asic3 specifically in parvalbumin-positive (PV+) cells resulted in the increase of self-grooming behavior in mice. These findings suggest knockout of Asic3 in the PV+ neurons alters grooming behavior by co-opting corticostriatal circuits.

Animal models of major depressive disorder and the implications for drug discovery and development

INTRODUCTION

Depression is a highly debilitating psychiatric disorder that affects the global population and causes severe disabilities and suicide. Depression pathogenesis remains poorly understood, and the disorder is often treatment-resistant and recurrent, necessitating the development of novel therapies, models and concepts in this field. Areas covered: Animal models are indispensable for translational biological psychiatry, and markedly advance the study of depression. Novel approaches continuously emerge that may help untangle the disorder heterogeneity and unclear categories of disease classification systems. Some of these approaches include widening the spectrum of model species used for translational research, using a broader range of test paradigms, exploring new pathogenic pathways and biomarkers, and focusing more closely on processes beyond neural cells (e.g. glial, inflammatory and metabolic deficits). Expert opinion: Dividing the core symptoms into easily translatable, evolutionarily conserved phenotypes is an effective way to reevaluate current depression modeling. Conceptually novel approaches based on the endophenotype paradigm, cross-species trait genetics and 'domain interplay concept', as well as using a wider spectrum of model organisms and target systems will enhance experimental modeling of depression and antidepressant drug discovery.

Camphor, Applied Epidermally to the Back, Causes Snout- and Chest-Grooming in Rats: A Response Mediated by Cutaneous TRP Channels

Thermoregulatory grooming, a behavioral defense against heat, is known to be driven by skin-temperature signals. Because at least some thermal cutaneous signals that drive heat defenses are likely to be generated by transient receptor potential (TRP) channels, we hypothesized that warmth-sensitive TRPs drive thermoregulatory grooming. Adult male Wistar rats were used. We showed that camphor, a nonselective agonist of several TRP channels, including vanilloid (V) 3, when applied epidermally to the back (500 mg/kg), caused a pronounced self-grooming response, including paw-licking and snout- and chest-“washing”. By the percentage of time spent grooming, the response was similar to the thermoregulatory grooming observed during exposure to ambient warmth (32 °C). Ruthenium red (a non-selective antagonist of TRP channels, including TRPV3), when administered intravenously at a dose of 0.1 mg/kg, attenuated the self-grooming behavior induced by either ambient warmth or epidermal camphor. Furthermore, the intravenous administration of AMG8432 (40 mg/kg), a relatively selective TRPV3 antagonist, also attenuated the self-grooming response to epidermal camphor. We conclude that camphor causes the self-grooming behavior by acting on TRP channels in the skin. We propose that cutaneous warmth signals mediated by TRP channels, possibly including TRPV3, drive thermoregulatory self-grooming in rats.

Metformin Administration During Early Postnatal Life Rescues Autistic-Like Behaviors in the BTBR T+ Itpr3tf/J Mouse Model of Autism

Autism spectrum disorder (ASD) is a neurodevelopmental disability characterized by impaired social interactions, stereotypical repetitive behavior and restricted interests. Although the global incidence of ASD has increased over time, the etiology of ASD is poorly understood, and there is no effective pharmacological intervention for treating ASD. Recent studies have suggested that metformin has the potential to treat ASD. Thus, in this study, we assessed the therapeutic effects of early metformin treatment in a BTBR T+ Itpr3tf/J (BTBR) mouse model of ASD. We observed that early metformin administration significantly reversed social approach deficits, attenuated repetitive grooming and reduced marble burying in BTBR mice. Metformin did not change the general locomotor activity or anxiety-like behavior in both BTBR and C57BL/6J (B6) mice. Our findings suggest that early metformin treatment may have beneficial effects on ameliorating behavioral deficits in ASD.

Auto-Reactive Th17-Cells Trigger Obsessive-Compulsive-Disorder Like Behavior in Mice With Experimental Autoimmune Encephalomyelitis

Th17-lymphocytes are well known for their deleterious role in autoimmunity. But does the notoriety of this repertoire extend beyond autoimmunity? In the present study we employed experimental autoimmune encephalomyelitis as model system to study the role auto-reactive Th17 cells in neuropsychiatric disorders. The mice with experimental autoimmune encephalomyelitis exhibited exaggerated grooming activity. The observed behavioral anomaly resembled obsessive compulsive disorder (OCD) upon analysis of grooming microstructure, induced grooming, marble burying and nestlet shredding. The observed OCD like behavior was relieved upon Th17 cell depletion; alternatively, it could alone be induced by adoptive transfer of myelin oligodendrocyte glycoprotein (35-55) reactive Th17 in B6.Rag1^−/− mice. The observed OCD like behavior was also alleviated upon treatment with a selective serotonin reuptake inhibitor, fluoxetine.

Reducing Astrocyte Calcium Signaling In Vivo Alters Striatal Microcircuits and Causes Repetitive Behavior

Astrocytes tile the central nervous system, but their functions in neural microcircuits in vivo and their roles in mammalian behavior remain incompletely defined. We used two-photon laser scanning microscopy, electrophysiology, MINIscopes, RNA-seq, and a genetic approach to explore the effects of reduced striatal astrocyte Ca²⁺ signaling in vivo. In wild-type mice, reducing striatal astrocyte Ca²⁺-dependent signaling increased repetitive self-grooming behaviors by altering medium spiny neuron (MSN) activity. The mechanism involved astrocyte-mediated neuromodulation facilitated by ambient GABA and was corrected by blocking astrocyte GABA transporter 3 (GAT-3). Furthermore, in a mouse model of Huntington's disease, dysregulation of GABA and astrocyte Ca²⁺ signaling accompanied excessive self-grooming, which was relieved by blocking GAT-3. Assessments with RNA-seq revealed astrocyte genes and pathways regulated by Ca²⁺ signaling in a cell-autonomous and non-cell-autonomous manner, including Rab11a, a regulator of GAT-3 functional expression. Thus, striatal astrocytes contribute to neuromodulation controlling mouse obsessive-compulsive-like behavior.

Long-Term Stress and Concomitant Marijuana Smoke Exposure Affect Physiology, Behavior and Adult Hippocampal Neurogenesis

Marijuana is a widely used recreational drug with increasing legalization worldwide for medical purposes. Most experimental studies use either synthetic or plant-derived cannabinoids to investigate the effect of cannabinoids on anxiety and cognitive functions. The aim of this study was to mimic real life situations where young people smoke cannabis regularly to relax from everyday stress. Therefore, we exposed young adult male NMRI mice to daily stress and concomitant marijuana smoke for 2 months and investigated the consequences on physiology, behavior and adult hippocampal neurogenesis. Animals were restrained for 6-h/day for 5-days a week. During the stress, mice were exposed to cannabis smoke for 2 × 30 min/day. We burned 2 “joints” (2 × 0.8 g marijuana) per occasion in a whole body smoking chamber. Cannabinoid content of the smoke and urine samples was measured by HPLC and SFC-MS/MS. Body weight gain was recorded daily and we did unrestrained, whole body plethysmography to investigate pulmonary functions. The cognitive performance of the animals was evaluated by the novel object recognition and Y maze tests. Anxietyrelated spontaneous locomotor activity and self-grooming were assessed in the open field test (OFT). Adult neurogenesis was quantified post mortem in the hippocampal dentate gyrus. The proliferative activity of the precursor cells was detected by the use of the exogenous marker 5-bromo-20-deoxyuridine. Treatment effects on maturing neurons were studied by the examination of doublecortin-positive neurons. Both stress and cannabis exposure significantly reduced body weight gain. Cannabis smoke had no effect on pulmonary functions, but stress delayed the maturation of several lung functions. Neither stress, nor cannabis smoke affected the cognitive functioning of the animals. Results of the OFT revealed that cannabis had a mild anxiolytic effect and markedly increased self-grooming behavior. Stress blocked cell proliferation in the dentate gyrus, but cannabis had no effect on this parameter. Marijuana smoke however had a pronounced impact on doublecortin-positive neurons influencing their number, morphology and migration. In summary, we report here that long-term stress in combination with cannabis smoke exposure can alter several health-related measures, but the present experimental design could not reveal any interaction between these two treatment factors except for body weight gain.

Anxiolytic effects of ascorbic acid and ketamine in mice

Some studies have demonstrated that ascorbic acid, similarly to ketamine, exhibits antidepressant-like effects mediated, at least in part, by modulation of the glutamatergic system. Despite the involvement of glutamatergic system in the pathophysiology of anxiety disorders, the ability of ascorbic acid and ketamine to elicit anxiolytic effects in animal models remains to be established. Therefore, this study investigated the effects of a single administration of ascorbic acid, ketamine or diazepam (positive control) in different animal models of anxiety. Mice were treated with ascorbic acid (1, 3 and 10 mg∕kg, p.o.), ketamine (1 and 10 mg∕kg, i.p.) or diazepam (2 mg∕kg, p.o) and their behavioral responses were assessed in the elevated plus maze, open field test (OFT), ligh∕dark preference test and marble burying test. Ascorbic acid increased total time spent in the open arms of elevated plus maze, increased total time in the center of the OFT, decreased rearing responses, increased the latency to grooming, decreased the rostral grooming, but did not affect body grooming. Furthermore, ascorbic acid increased the latency time and total time in light area in the ligh∕dark preference test, but did not affect the performance of mice in the marble burying test. Ketamine demonstrated an anxiolytic-like effect in elevated plus maze, OFT, and ligh∕dark preference test. Diazepam exhibited an anxiolytic-like effect in all the behavioral tests. Altogether, the results indicate the potential anxiolytic effect of ascorbic acid and ketamine, providing a possible new avenue for the management of anxiety-related disorders.

Altered dopaminergic regulation of the dorsal striatum is able to induce tic-like movements in juvenile rats

Motor tics are sudden, repetitive, involuntary movements representing the hallmark behaviors of the neurodevelopmental disease Tourette’s syndrome (TS). The primary cause of TS remains unclear. The initial observation that dopaminergic antagonists alleviate tics led to the development of a dopaminergic theory of TS etiology which is supported by post mortem and in vivo studies indicating that non-physiological activation of the striatum could generate tics. The striatum controls movement execution through the balanced activity of dopamine receptor D1 and D2-expressing medium spiny neurons of the direct and indirect pathway, respectively. Different neurotransmitters can activate or repress striatal activity and among them, dopamine plays a major role. In this study we introduced a chronic dopaminergic alteration in juvenile rats, in order to modify the delicate balance between direct and indirect pathway. This manipulation was done in the dorsal striatum, that had been associated with tic-like movements generation in animal models. The results were movements resembling tics, which were categorized and scored according to a newly developed rating scale and were reduced by clonidine and riluzole treatment. Finally, post mortem analyses revealed altered RNA expression of dopaminergic receptors D1 and D2, suggesting an imbalanced dopaminergic regulation of medium spiny neuron activity as being causally related to the observed phenotype.

A neural basis for antagonistic control of feeding and compulsive behaviors

Abnormal feeding often co-exists with compulsive behaviors, but the underlying neural basis remains unknown. Excessive self-grooming in rodents is associated with compulsivity. Here, we show that optogenetically manipulating the activity of lateral hypothalamus (LH) projections targeting the paraventricular hypothalamus (PVH) differentially promotes either feeding or repetitive self-grooming. Whereas selective activation of GABAergic LH→PVH inputs induces feeding, activation of glutamatergic inputs promotes self-grooming. Strikingly, targeted stimulation of GABAergic LH→PVH leads to rapid and reversible transitions to feeding from induced intense self-grooming, while activating glutamatergic LH→PVH or PVH neurons causes rapid and reversible transitions to self-grooming from voracious feeding induced by fasting. Further, specific inhibition of either LH→PVH GABAergic action or PVH neurons reduces self-grooming induced by stress. Thus, we have uncovered a parallel LH→PVH projection circuit for antagonistic control of feeding and self-grooming through dynamic modulation of PVH neuron activity, revealing a common neural pathway that underlies feeding and compulsive behaviors.

Metformin Administration During Early Postnatal Life Rescues Autistic-Like Behaviors in the BTBR T+ Itpr3tf/J Mouse Model of Autism

Autism spectrum disorder (ASD) is a neurodevelopmental disability characterized by impaired social interactions, stereotypical repetitive behavior and restricted interests. Although the global incidence of ASD has increased over time, the etiology of ASD is poorly understood, and there is no effective pharmacological intervention for treating ASD. Recent studies have suggested that metformin has the potential to treat ASD. Thus, in this study, we assessed the therapeutic effects of early metformin treatment in a BTBR T+ Itpr3tf/J (BTBR) mouse model of ASD. We observed that early metformin administration significantly reversed social approach deficits, attenuated repetitive grooming and reduced marble burying in BTBR mice. Metformin did not change the general locomotor activity or anxiety-like behavior in both BTBR and C57BL/6J (B6) mice. Our findings suggest that early metformin treatment may have beneficial effects on ameliorating behavioral deficits in ASD.

Npas4 deficiency and prenatal stress interact to affect social recognition in mice

Neurodevelopmental disorders such as autism spectrum disorders and schizophrenia have an expansive array of reported genetic and environmental contributing factors. However, none of these factors alone can account for a substantial proportion of cases of either disorder. Instead, many gene-by-environment interactions are responsible for neurodevelopmental disturbances that lead to these disorders. The current experiment used heterozygous knock-out mice to examine a potential interaction between 2 factors commonly linked to neurodevelopmental disorders and cognitive deficit: imbalanced excitatory/inhibitory signaling in the cortex and prenatal stress (PNS) exposure. Both of these factors have been linked to disrupt GABAergic signaling in the prefrontal cortex (PFC), a common feature of neurodevelopmental disorders. The neuronal PAS domain protein 4 (Npas4) gene is instrumental in regulation of the excitatory/inhibitory balance in the cortex and hippocampus in response to activation. Npas4 heterozygous and wild-type male and female mice were exposed to either PNS or standard gestation, then evaluated during adulthood in social and anxiety behavioral measures. The combination of PNS and Npas4 deficiency in male mice impaired social recognition. This behavioral deficit was associated with decreased parvalbumin and cFos protein expression in the infralimbic region of the PFC following social stimulation in Npas4 heterozygous males. In contrast, females displayed fewer behavioral effects and molecular changes in PFC in response to PNS and decreased Npas4.

Neuronal Glutamate Transporters Control Dopaminergic Signaling and Compulsive Behaviors

There is an ongoing debate on the contribution of the neuronal glutamate transporter EAAC1 to the onset of compulsive behaviors. Here, we used behavioral, electrophysiological, molecular, and viral approaches in male and female mice to identify the molecular and cellular mechanisms by which EAAC1 controls the execution of repeated motor behaviors. Our findings show that, in the striatum, a brain region implicated with movement execution, EAAC1 limits group I metabotropic glutamate receptor (mGluRI) activation, facilitates D1 dopamine receptor (D1R) expression, and ensures long-term synaptic plasticity. Blocking mGluRI in slices from mice lacking EAAC1 restores D1R expression and synaptic plasticity. Conversely, activation of intracellular signaling pathways coupled to mGluRI in D1R-containing striatal neurons of mice expressing EAAC1 leads to reduced D1R protein level and increased stereotyped movement execution. These findings identify new molecular mechanisms by which EAAC1 can shape glutamatergic and dopaminergic signals and control repeated movement execution.SIGNIFICANCE STATEMENT Genetic studies implicate Slc1a1, a gene encoding the neuronal glutamate transporter EAAC1, with obsessive-compulsive disorder (OCD). EAAC1 is abundantly expressed in the striatum, a brain region that is hyperactive in OCD. What remains unknown is how EAAC1 shapes synaptic function in the striatum. Our findings show that EAAC1 limits activation of metabotropic glutamate receptors (mGluRIs) in the striatum and, by doing so, promotes D1 dopamine receptor (D1R) expression. Targeted activation of signaling cascades coupled to mGluRIs in mice expressing EAAC1 reduces D1R expression and triggers repeated motor behaviors. These findings provide new information on the molecular basis of OCD and suggest new avenues for its treatment.

The behavioral and molecular evaluation of effects of social instability stress as a model of stress-related disorders in adult female rats

The study aimed to test the hypotheses that chronic social instability stress (CSIS) alters behavioral and physiological parameters and expression of selected genes important for stress response and social behaviors. Adult female Sprague-Dawley rats were subjected to the 4-week CSIS procedure, which involves unpredictable rotation between phases of isolation and overcrowding. Behavioral analyses (Experiment 1) were performed on the same rats before and after CSIS (n = 16) and physiological and biochemical measurements (Experiment 2) were made on further control (CON; n = 7) and stressed groups (CSIS; n = 8). Behaviors in the open field test (locomotor and exploratory activities) and elevated-plus maze (anxiety-related behaviors) indicated anxiety after CSIS. CSIS did not alter the physiological parameters measured, i.e. body weight gain, regularity of estrous cycles, and circulating concentrations of stress hormones and sex steroids. QRT-PCR analysis of mRNA expression levels was performed on amygdala, hippocampus, prefrontal cortex (PFC), and hypothalamus. The main finding is that CSIS alters the mRNA levels for the studied genes in a region-specific manner. Hence, expression of POMC (pro-opiomelanocortin), AVPR1a (arginine vasopressin receptor), and OXTR (oxytocin receptor) significantly increased in the amygdala following CSIS, while in PFC and/or hypothalamus, POMC, AVPR1a, AVPR1b, OXTR, and ERβ (estrogen receptor beta) expression decreased. CSIS significantly reduced expression of CRH-R1 (corticotropin-releasing hormone receptor type 1) in the hippocampus. The directions of change in gene expression and the genes and regions affected indicate a molecular basis for the behavior changes. In conclusion, CSIS may be valuable for further analyzing the neurobiology of stress-related disorders in females.

Binge-pattern cocaine administration causes long-lasting behavioral hyperarousal but does not enhance vulnerability to single prolonged stress in rats

Cocaine use disorder and post-traumatic stress disorder (PTSD) commonly co-occur. This could be due to vulnerability to post-traumatic symptoms conferred by previous exposure to cocaine. Therefore, we combined chronic binge-pattern cocaine with a model of psychological trauma (single prolonged stress) to determine whether the behavioral effects of psychological trauma are enhanced in cocaine-sensitized individuals. Adult male Sprague Dawley rats received 14 days of cocaine (15mg/kg/injection) or saline in a binge pattern (3 injections per day, 1h apart). Seven days after the last injection animals were exposed to traumatic stress or a control procedure. Seven days after stress, activity and anxiety-like behaviors were measured. Binge-pattern cocaine increased locomotor activity in the open field and elevated plus maze, and both cocaine and SPS exposure increased the rapidity with which rats moved through grooming sequences. Neither binge-pattern cocaine nor SPS increased anxiety-like behaviors, and no interactions were found between binge-pattern cocaine exposure and SPS exposure. A behavioral phenotype categorization approach demonstrated that cocaine-exposed groups expressed a high incidence of hyperactivity-like symptoms. These results suggest that binge-pattern cocaine exposure causes a long-lasting hyper-exploratory phenotype but does not make individuals more vulnerable to a later traumatic stress exposure.

Mental Misrepresentation in Non-human Psychopathology

In this paper, we defend a representational approach to at least some kinds of non-human psychopathology. Mentally-ill non-human minds, in particular in delusions, obsessive-compulsive disorders and similar cognitive states, are traditionally understood in purely behavioral terms. In contrast, we argue that non-human mental psychopathology should be at least sometimes not only ascribed contentful mental representation but also understood as really having these states. To defend this view, we appeal to the interactivist account of mental representation, which is a kind of a constructive approach to meaning. We follow Mark Bickhard in assuming that only an organism - either human or non-human - capable of detecting its own misrepresentations is representational. However, under his autonomy-based account of biological function these minds are incapable of misrepresentations because these minds are, ex hypothesi, unable to detect error in such representations. To solve this problem, we argue that adding a historical dimension - as in Millikan's view on mental representations - to Bickhard's account of function makes mental misrepresentation of mentally-ill minds possible. Using Bickhard's dynamic account of function, it is possible to explain why delusions and other mental disorders can be seen as locally functional. However, an etiological dimension can further explain why misrepresentations seem to be globally dysfunctional. Even if representational or biosemiotic hypotheses about non-human psychopathology are difficult to confirm empirically, we defend the view that they can enrich our understanding of the causes and development of such pathologies, and may constitute a new progressive research programme.

Automated classification of self-grooming in mice using open-source software

BACKGROUND

Manual analysis of behavior is labor intensive and subject to inter-rater variability. Although considerable progress in automation of analysis has been made, complex behavior such as grooming still lacks satisfactory automated quantification.

NEW METHOD

We trained a freely available, automated classifier, Janelia Automatic Animal Behavior Annotator (JAABA), to quantify self-grooming duration and number of bouts based on video recordings of SAPAP3 knockout mice (a mouse line that self-grooms excessively) and wild-type animals.

RESULTS

We compared the JAABA classifier with human expert observers to test its ability to measure self-grooming in three scenarios: mice in an open field, mice on an elevated plus-maze, and tethered mice in an open field. In each scenario, the classifier identified both grooming and non-grooming with great accuracy and correlated highly with results obtained by human observers. Consistently, the JAABA classifier confirmed previous reports of excessive grooming in SAPAP3 knockout mice.

COMPARISON WITH EXISTING METHODS

Thus far, manual analysis was regarded as the only valid quantification method for self-grooming. We demonstrate that the JAABA classifier is a valid and reliable scoring tool, more cost-efficient than manual scoring, easy to use, requires minimal effort, provides high throughput, and prevents inter-rater variability.

CONCLUSION

We introduce the JAABA classifier as an efficient analysis tool for the assessment of rodent self-grooming with expert quality. In our "how-to" instructions, we provide all information necessary to implement behavioral classification with JAABA.

Prenatal lipopolysaccharide induces hypothalamic dopaminergic hypoactivity and autistic-like behaviors: Repetitive self-grooming and stereotypies

Previous investigations by our group have shown that prenatal exposure to lipopolysaccharide (LPS), which mimics infection by gram-negative bacteria, induces social, cognitive, and communication deficits. For a complete screening of autistic-like behaviors, the objective of this study was to evaluate if our rat model also induces restricted and repetitive stereotyped behaviors. Thus, we studied the self-grooming microstructure. We also studied the neurochemistry of hypothalamus and frontal cortex, which are brain areas related to autism to better understand central mechanisms involved in our model. Prenatal LPS exposure on gestational day 9.5 increased the head washing episodes (frequency and time), as well as the total self-grooming. However, body grooming, paw/leg licking, tail/genital grooming, and circling behavior/tail chasing did not vary significantly among the groups. Moreover, prenatal LPS induced dopaminergic hypoactivity (HVA metabolite and turnover) in the hypothalamus. Therefore, our rat model induced restricted and repetitive stereotyped behaviors and the other main symptoms of autism experimentally studied in rodent models and also found in patients. The hypothalamic dopaminergic impairments seem to be associated with the autistic-like behaviors.

Highly palatable food access during adolescence increased anxiety-/depression-like behaviors in male, but not in female, rats

OBJECTIVES

This study was conducted to examine the sexual dimorphic effects of highly palatable food (HPF) access during adolescence on the neurochemistry and depression-/anxiety-like behaviors of rats.

METHODS

Male and female Sprague-Dawley pups had free access to chocolate cookie rich in fat (HPF) from postnatal day 28 in addition to ad libitum chow, and the control groups received only chow. The food conditions were continued throughout the entire experimental period, and the neurochemical and behavioral measurements were performed during young adulthood. Rats were subjected to the ambulatory activity, elevated plus maze, and forced swim tests. Corticosterone levels during 2 h of restraint stress were analyzed with radioimmunoassay, and ΔFosB and brain-derived neurotrophic factor (BDNF) expression in the nucleus accumbens (NAc) with Western blot analysis.

RESULTS

Cookie access did not affect body weight gain and total caloric intake in both sexes; however, it increased retroperitoneal fat depot only in males. The time spent in open arms during elevated plus maze test was decreased and immobility during forced swim test was increased in cookie-fed males, but not in cookie-fed females. Main effect of food condition on the stress-induced corticosterone increase was observed in males, but not in females, and cookie access increased BDNF expression in the NAc only in males.

CONCLUSIONS

Increased BDNF expression in the NAc and fat depot, in addition to the stress axis dysfunction, may play roles in the pathophysiology of depression- and/or anxiety-like behaviors induced by cookie access.

Autism-like behavior in the BTBR mouse model of autism is improved by propofol

Autism spectrum disorder (ASD) is a developmental disorder that is characterized by symptoms of impaired social interactions, restricted interests and repetitive behaviors. Recent studies in humans and animal-models suggest that reduced GABAergic neurotransmission in the brain may underlie autism-related behavioral symptoms. It has been shown that propofol, a commonly used anesthetic, facilitates γ-aminobutyric acid-mediated inhibitory synaptic transmission. The present study investigated whether propofol improved autistic phenotypes in BTBR T + Itpr3tf/J (BTBR) mice, a model of idiopathic autism. We found that i.p. injection of propofol in BTBR mice significantly improved aspects of social approach and repetitive behaviors without affecting reciprocal social interactions and without any detrimental effects in C57BL/6J mice. The ability of propofol to improve autistic phenotypes in BTBR mice through GABAergic neurotransmission suggests a potential pharmacological target for interventions to treat symptoms of autism.