Bipolar-associated miR-499-5p controls neuroplasticity by downregulating the Cav1.2 subunit CACNB2.

Bipolar disorder (BD) is a chronic mood disorder characterized by manic and depressive episodes. Dysregulation of neuroplasticity and calcium homeostasis are frequently observed in BD patients, but the underlying molecular mechanisms are largely unknown. Here, we show that miR-499-5p regulates dendritogenesis and cognitive function by downregulating the BD risk gene CACNB2. miR-499-5p expression is increased in peripheral blood of BD patients, as well as in the hippocampus of rats which underwent juvenile social isolation. In rat hippocampal neurons, miR-499-5p impairs dendritogenesis and reduces surface expression and activity of the L-type calcium channel Cav1.2. We further identified CACNB2, which encodes a regulatory ß-subunit of Cav1.2, as a direct functional target of miR-499-5p in neurons. miR-499-5p overexpression in the hippocampus in vivo induces short-term memory impairments selectively in rats haploinsufficient for the Cav1.2 pore forming subunit Cacna1c. In humans, miR-499-5p expression is negatively associated with gray matter volumes of the left superior temporal gyrus, a region implicated in auditory and emotional processing. We propose that stress-induced miR-499-5p overexpression contributes to dendritic impairments, deregulated calcium homeostasis, and neurocognitive dysfunction in BD.

Mouse and rat ultrasonic vocalizations in neuroscience and neuropharmacology: State of the art and future applications.

Mice and rats emit ultrasonic vocalizations (USVs), which may express their arousal and emotional states, to communicate with each other. There is continued scientific effort to better understand the functions of USVs as a central element of the rodent behavioral repertoire. However, studying USVs is not only important because of their ethological relevance, but also because they are widely applied as a behavioral readout in various fields of biomedical research. In mice and rats, a large number of experimental models of brain disorders exist and studying the emission of USVs in these models can provide valuable information about the health status of the animals and the effectiveness of possible interventions, both environmental and pharmacological. This review (i) provides an updated overview of the contexts in which ultrasonic calling behaviour of mice and rats has particularly high translational value, and (ii) gives some examples of novel approaches and tools used for the analysis of USVs in mice and rats, combining qualitative and quantitative methods. The relevance of age and sex differences as well as the importance of longitudinal evaluations of calling and non-calling behaviour is also discussed. Finally, the importance of assessing the communicative impact of USVs in the receiver, that is, through playback studies, is highlighted.

Calcium Handling Remodeling Underlies Impaired Sympathetic Stress Response in Ventricular Myocardium from Cacna1c Haploinsufficient Rats.

CACNA1C encodes the pore-forming α1C subunit of the L-type Ca2+ channel, Cav1.2. Mutations and polymorphisms of the gene are associated with neuropsychiatric and cardiac disease. Haploinsufficient Cacna1c+/- rats represent a recently developed model with a behavioral phenotype, but its cardiac phenotype is unknown. Here, we unraveled the cardiac phenotype of Cacna1c+/- rats with a main focus on cellular Ca2+ handling mechanisms. Under basal conditions, isolated ventricular Cacna1c+/- myocytes exhibited unaltered L-type Ca2+ current, Ca2+ transients (CaTs), sarcoplasmic reticulum (SR) Ca2+ load, fractional release, and sarcomere shortenings. However, immunoblotting of left ventricular (LV) tissue revealed reduced expression of Cav1.2, increased expression of SERCA2a and NCX, and augmented phosphorylation of RyR2 (at S2808) in Cacna1c+/- rats. The ß-adrenergic agonist isoprenaline increased amplitude and accelerated decay of CaTs and sarcomere shortenings in both Cacna1c+/- and WT myocytes. However, the isoprenaline effect on CaT amplitude and fractional shortening (but not CaT decay) was impaired in Cacna1c+/- myocytes exhibiting both reduced potency and efficacy. Moreover, sarcolemmal Ca2+ influx and fractional SR Ca2+ release after treatment with isoprenaline were smaller in Cacna1c+/- than in WT myocytes. In Langendorff-perfused hearts, the isoprenaline-induced increase in RyR2 phosphorylation at S2808 and S2814 was attenuated in Cacna1c+/- compared to WT hearts. Despite unaltered CaTs and sarcomere shortenings, Cacna1c+/- myocytes display remodeling of Ca2+ handling proteins under basal conditions. Mimicking sympathetic stress with isoprenaline unmasks an impaired ability to stimulate Ca2+ influx, SR Ca2+ release, and CaTs caused, in part, by reduced phosphorylation reserve of RyR2 in Cacna1c+/- cardiomyocytes.

Excessive Laughter-like Vocalizations, Microcephaly, and Translational Outcomes in the Ube3a Deletion Rat Model of Angelman Syndrome.

Angelman syndrome (AS) is a rare genetic neurodevelopmental disorder characterized by intellectual disabilities, motor and balance deficits, impaired communication, and a happy, excitable demeanor with frequent laughter. We sought to elucidate a preclinical outcome measure in male and female rats that addressed communication abnormalities of AS and other neurodevelopmental disorders in which communication is atypical and/or lack of speech is a core feature. We discovered, and herein report for the first time, excessive laughter-like 50 kHz ultrasonic emissions in the Ube3amat-/pat+ rat model of AS, which suggests an excitable, playful demeanor and elevated positive affect, similar to the demeanor of individuals with AS. Also in line with the AS phenotype, Ube3amat-/pat+ rats demonstrated aberrant social interactions with a novel partner, distinctive gait abnormalities, impaired cognition, an underlying LTP deficit, and profound reductions in brain volume. These unique, robust phenotypes provide advantages compared with currently available mouse models and will be highly valuable as outcome measures in the evaluation of therapies for AS.SIGNIFICANCE STATEMENT Angelman syndrome (AS) is a severe neurogenetic disorder for which there is no cure, despite decades of research using mouse models. This study used a recently developed rat model of AS to delineate disease-relevant outcome measures to facilitate therapeutic development. We found the rat to be a strong model of AS, offering several advantages over mouse models by exhibiting numerous AS-relevant phenotypes, including overabundant laughter-like vocalizations, reduced hippocampal LTP, and volumetric anomalies across the brain. These findings are unconfounded by detrimental motor abilities and background strain, issues plaguing mouse models. This rat model represents an important advancement in the field of AS, and the outcome metrics reported herein will be central to the therapeutic pipeline.

Early-life seizures modify behavioral response to ultrasonic vocalization playback in adult rats.

Early-life seizures (ELS) are associated with autism spectrum disorder (ASD); however, due to a lack of effective treatments for ELS, it is not clear whether ELS plays a causal role, potentiates the ASD phenotype, or is the result of a common pathophysiology. Deficits in communications are a core feature of ASD. To isolate the impact of ELS on communication, we probed the behavioral consequences of a single episode of kainic acid-induced early-life seizures (KA-ELS) in male and female Sprague-Dawley (CD) rats. Deficits in auditory communication were observed in adult male rats as assessed by behavioral response to ultrasonic vocalization (USV) playback. Ultrasonic vocalizations are classified into two major categories - 50-kHz (positive) calls and 22-kHz (aversive) calls. Behavioral response was assessed via rat preference for different USV playback in a radial arm maze. Response to 22-kHz calls was not impacted by ELS while response to 50-kHz calls was impacted. All rats demonstrated positional preference for the arms adjacent to where 50-kHz calls were playing compared to background noise; however, male ELS rats demonstrated a greater positional preference for the arms adjacent to where 50-kHz calls were playing compared to male control rats. These studies demonstrate that responses to socially relevant auditory cues are chronically altered in adult male rats following a single episode of ELS. We speculate that these changes contribute to previously reported social deficits associated with ELS.

Long-term environmental impact on object recognition, spatial memory and reversal learning capabilities in Cacna1c-haploinsufficient rats.

Genetic and environmental influences are thought to interact in their contribution to the etiology of major neuropsychiatric disorders. One of the best replicated findings obtained in genome-wide association studies are genetic variants in the CACNA1C gene. Here, we used our constitutive heterozygous Cacna1c rat model in combination with a 4-week exposure to either post-weaning social isolation, standard housing or social and physical environmental enrichment during the critical juvenile developmental period to observe their long-term interactive effects with Cacna1c haploinsufficiency. Our study provides evidence for a gene × environment interaction, i.e. an interplay between Cacna1c haploinsufficiency and environment during juvenile development, on object recognition, spatial memory and reversal learning capabilities. Social and physical enrichment had a positive influence on Cacna1c+/- rats and Cacna1c+/+ littermate controls on spatial and reversal learning, while post-weaning social isolation negatively affected novel object recognition in both genotypes. Despite intact spatial learning and re-learning abilities in all groups, slight but consistent deficits were evident in Cacna1c+/- rats previously housed under standard conditions particularly during reversal learning but not Cacna1c+/- rats previously exposed to social and physical enrichment. Together, this supports the notion that Cacna1c interacts with the environment to shape disease vulnerability and associated alterations in cognitive functioning.

A placental mammal-specific microRNA cluster acts as a natural brake for sociability in mice.

Aberrant synaptic function is thought to underlie social deficits in neurodevelopmental disorders such as autism and schizophrenia. Although microRNAs have been shown to regulate synapse development and plasticity, their potential involvement in the control of social behaviour in mammals remains unexplored. Here, we show that deletion of the placental mammal-specific miR379-410 cluster in mice leads to hypersocial behaviour, which is accompanied by increased excitatory synaptic transmission, and exaggerated expression of ionotropic glutamate receptor complexes in the hippocampus. Bioinformatic analyses further allowed us to identify five "hub" microRNAs whose deletion accounts largely for the upregulation of excitatory synaptic genes observed, including Cnih2, Dlgap3, Prr7 and Src. Thus, the miR379-410 cluster acts a natural brake for sociability, and interfering with specific members of this cluster could represent a therapeutic strategy for the treatment of social deficits in neurodevelopmental disorders.

Sex differences in the acoustic features of social play-induced 50-kHz ultrasonic vocalizations: A detailed spectrographic analysis in wild-type Sprague-Dawley and Cacna1c haploinsufficient rats.

Sexual dimorphisms are widespread in the animal kingdom. At the behavioral level, there is evidence for sex differences in social play behavior. In rats, males typically engage more in rough-and-tumble play than females. One prominent component of the rough-and-tumble play repertoire in rats is the emission of 50-kHz ultrasonic vocalizations (USV). Such 50-kHz USV reflect the rewarding nature of play and serve as socioaffective signals. Here, we provide evidence for sexual dimorphisms within rough-and-tumble play-induced 50-kHz USV in juvenile rats. Specifically, females displayed reduced 50-kHz USV emission during playful interactions. This reduction was associated with changes in 50-kHz USV emission rates and subtype profiles during specific rough-and-tumble components, i.e., pinning, wrestling, and chasing, as well as differences in acoustic parameters. Interestingly, sex differences were modulated by Cacna1c, a gene strongly implicated in major neuropsychiatric disorders, often characterized by prominent sex biases, most notably autism. Specifically, Cacna1c haploinsufficiency affected the emission of 50-kHz USV during rough-and-tumble play in female rats and we provide evidence supporting the notion that such effects of Cacna1c haploinsufficiency are driven by male-typical features of 50-kHz USV emission. This is in line with the hypermasculinized social play repertoire previously observed in juvenile Cacna1c haploinsufficient females.

Fear Extinction and Predictive Trait-Like Inter-Individual Differences in Rats Lacking the Serotonin Transporter.

Anxiety disorders are associated with a failure to sufficiently extinguish fear memories. The serotonergic system (5-hydroxytryptamine, 5-HT) with the 5-HT transporter (5-HTT, SERT) is strongly implicated in the regulation of anxiety and fear. In the present study, we examined the effects of SERT deficiency on fear extinction in a differential fear conditioning paradigm in male and female rats. Fear-related behavior displayed during acquisition, extinction, and recovery, was measured through quantification of immobility and alarm 22-kHz ultrasonic vocalizations (USV). Trait-like inter-individual differences in novelty-seeking, anxiety-related behavior, habituation learning, cognitive performance, and pain sensitivity were examined for their predictive value in forecasting fear extinction. Our results show that SERT deficiency strongly affected the emission of 22-kHz USV during differential fear conditioning. During acquisition, extinction, and recovery, SERT deficiency consistently led to a reduction in 22-kHz USV emission. While SERT deficiency did not affect immobility during acquisition, genotype differences started to emerge during extinction, and during recovery rats lacking SERT showed higher levels of immobility than wildtype littermate controls. Recovery was reflected in increased levels of immobility but not 22-kHz USV emission. Prominent sex differences were evident. Among several measures for trait-like inter-individual differences, anxiety-related behavior had the best predictive quality.

Origins of scale invariance in vocalization sequences and speech.

To communicate effectively animals need to detect temporal vocalization cues that vary over several orders of magnitude in their amplitude and frequency content. This large range of temporal cues is evident in the power-law scale-invariant relationship between the power of temporal fluctuations in sounds and the sound modulation frequency (f). Though various forms of scale invariance have been described for natural sounds, the origins and implications of scale invariant phenomenon remain unknown. Using animal vocalization sequences, including continuous human speech, and a stochastic model of temporal amplitude fluctuations we demonstrate that temporal acoustic edges are the primary acoustic cue accounting for the scale invariant phenomenon. The modulation spectrum of vocalization sequences and the model both exhibit a dual regime lowpass structure with a flat region at low modulation frequencies and scale invariant 1/f2 trend for high modulation frequencies. Moreover, we find a time-frequency tradeoff between the average vocalization duration of each vocalization sequence and the cutoff frequency beyond which scale invariant behavior is observed. These results indicate that temporal edges are universal features responsible for scale invariance in vocalized sounds. This is significant since temporal acoustic edges are salient perceptually and the auditory system could exploit such statistical regularities to minimize redundancies and generate compact neural representations of vocalized sounds.

Neurobiology of the major psychoses: a translational perspective on brain structure and function-the FOR2107 consortium.

Genetic (G) and environmental (E) factors are involved in the etiology and course of the major psychoses (MP), i.e. major depressive disorder (MDD), bipolar disorder (BD), schizoaffective disorder (SZA) and schizophrenia (SZ). The neurobiological correlates by which these predispositions exert their influence on brain structure, function and course of illness are poorly understood. In the FOR2107 consortium, animal models and humans are investigated. A human cohort of MP patients, healthy subjects at genetic and/or environmental risk, and control subjects (N = 2500) has been established. Participants are followed up after 2 years and twice underwent extensive deep phenotyping (MR imaging, clinical course, neuropsychology, personality, risk/protective factors, biomaterials: blood, stool, urine, hair, saliva). Methods for data reduction, quality assurance for longitudinal MRI data, and (deep) machine learning techniques are employed. In the parallelised animal cluster, genetic risk was introduced by a rodent model (Cacna1c deficiency) and its interactions with environmental risk and protective factors are studied. The animals are deeply phenotyped regarding cognition, emotion, and social function, paralleling the variables assessed in humans. A set of innovative experimental projects connect and integrate data from the human and animal parts, investigating the role of microRNA, neuroplasticity, immune signatures, (epi-)genetics and gene expression. Biomaterial from humans and animals are analyzed in parallel. The FOR2107 consortium will delineate pathophysiological entities with common neurobiological underpinnings ("biotypes") and pave the way for an etiologic understanding of the MP, potentially leading to their prevention, the prediction of individual disease courses, and novel therapies in the future.

Sex-specific effects of Cacna1c haploinsufficiency on object recognition, spatial memory, and reversal learning capabilities in rats.

The CACNA1C gene is strongly implicated in the etiology of multiple major neuropsychiatric disorders, such as bipolar disorder, major depression, and schizophrenia, with cognitive deficits being a common feature. It is unclear, however, by which mechanisms CACNA1C variants advance the risk of developing neuropsychiatric disorders. This study set out to investigate cognitive functioning in a newly developed genetic Cacna1c rat model. Specifically, spatial and reversal learning, as well as object recognition memory were assessed in heterozygous Cacna1c+/- rats and compared to wildtype Cacna1c+/+ littermate controls in both sexes. Our results show that both Cacna1c+/+ and Cacna1c+/- animals were able to learn the rewarded arm configuration of a radial maze over the course of seven days. Both groups also showed reversal learning patterns indicative of intact abilities. In females, genotype differences were evident in the initial spatial learning phase, with Cacna1c+/- females showing hypo-activity and fewer mixed errors. In males, a difference was found during probe trials for both learning phases, with Cacna1c+/- rats displaying better distinction between previously baited and non-baited arms; and regarding cognitive flexibility in favor of the Cacna1c+/+ animals. All experimental groups proved to be sensitive to reward magnitude and fully able to distinguish between novel and familiar objects in the novel object recognition task. Taken together, these results indicate that Cacna1c haploinsufficiency has a minor, but positive impact on (spatial) memory functions in rats.

Isolation-induced ultrasonic vocalizations in pups: A comparison between Long-Evans, Sprague-Dawley, and Wistar rats.

Rat pup ultrasonic vocalizations (USV) are usually studied in outbred rats belonging to either Long-Evans, Sprague-Dawley, or Wistar stocks, but these were not compared so far. We therefore performed a stock comparison and analyzed USV of male pups (postnatal day 11) belonging to these three stocks. Pups of all three stocks showed substantial isolation-induced USV, but differed in various call features, like call numbers, peak frequency, and frequency modulation. Also, three different call types were identified by means of a quantitative approach based on peak frequency and frequency modulation, and it was found that their proportions differed between stocks. These results are discussed with respect to functional aspects of pup USV.

Aberrant cognitive phenotypes and altered hippocampal BDNF expression related to epigenetic modifications in mice lacking the post-synaptic scaffolding protein SHANK1: Implications for autism spectrum disorder.

Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders characterized by persistent deficits in social communication/interaction, together with restricted/repetitive patterns of behavior. ASD is among the most heritable neuropsychiatric conditions, and while available evidence points to a complex set of genetic factors, the SHANK gene family has emerged as one of the most promising candidates. Here, we assessed ASD-related phenotypes with particular emphasis on social behavior and cognition in Shank1 mouse mutants in comparison to heterozygous and wildtype littermate controls across development in both sexes. While social approach behavior was evident in all experimental conditions and social recognition was only mildly affected by genotype, Shank1-/- null mutant mice were severely impaired in object recognition memory. This effect was particularly prominent in juveniles, not due to impairments in object discrimination, and replicated in independent mouse cohorts. At the neurobiological level, object recognition deficits were paralleled by increased brain-derived neurotrophic factor (BDNF) protein expression in the hippocampus of Shank1-/- mice; yet BDNF levels did not differ under baseline conditions. We therefore investigated changes in the epigenetic regulation of hippocampal BDNF expression and detected an enrichment of histone H3 acetylation at the Bdnf promoter1 in Shank1-/- mice, consistent with increased learning-associated BDNF. Together, our findings indicate that Shank1 deletions lead to an aberrant cognitive phenotype characterized by severe impairments in object recognition memory and increased hippocampal BDNF levels, possibly due to epigenetic modifications. This result supports the link between ASD and intellectual disability, and suggests epigenetic regulation as a potential therapeutic target.

Phasic dopamine release in the nucleus accumbens in response to pro-social 50 kHz ultrasonic vocalizations in rats.

Rats emit ultrasonic vocalizations (USVs) that are thought to serve as situation-dependent affective signals and accomplish important communicative functions. In appetitive situations, rats produce 50 kHz USVs, whereas 22 kHz USVs occur in aversive situations. Reception of 50 kHz USVs induces social approach behavior, while 22 kHz USVs lead to freezing behavior. These opposite behavioral responses are paralleled by distinct brain activation patterns, with 50 kHz USVs, but not 22 kHz USVs, activating neurons in the nucleus accumbens (NAcc). The NAcc mediates appetitive behavior and is critically modulated by dopaminergic afferents that are known to encode the value of reward. Therefore, we hypothesized that 50 kHz USVs, but not 22 kHz USVs, elicit NAcc dopamine release. While recording dopamine signaling with fast-scan cyclic voltammetry, freely moving rats were exposed to playback of four acoustic stimuli via an ultrasonic speaker in random order: (1) 50 kHz USVs, (2) 22 kHz USVs, (3) time- and amplitude-matched white noise, and (4) background noise. Only presentation of 50 kHz USVs induced phasic dopamine release and elicited approach behavior toward the speaker. Both of these effects, neurochemical and behavioral, were most pronounced during initial playback, but then declined rapidly with subsequent presentations, indicating a close temporal relationship between the two measures. Moreover, the magnitudes of these effects during initial playback were significantly correlated. Collectively, our findings show that NAcc dopamine release encodes pro-social 50 kHz USVs, but not alarming 22 kHz USVs. Thus, our results support the hypothesis that these call types are processed in distinct neuroanatomical regions and establish a functional link between pro-social communicative signals and reward-related neurotransmission.

Affective communication in rodents: serotonin and its modulating role in ultrasonic vocalizations.

Serotonin (5-hydroxytryptamine, 5-HT) is an important modulatory neurotransmitter and functions as a key neurodevelopmental signal in the mammalian brain. 5-HT plays a prominent role in regulating various types of psychological processes and functions, including mood and emotion, particularly anxiety, but also in regulating social behavior. Consequently, the 5-HT system is implicated in various neuropsychiatric disorders, such as anxiety disorders and depression or autism spectrum disorders (ASD), with selective 5-HT reuptake inhibitors being the frontline medication. Mice and rats perceive and emit ultrasonic vocalizations (USV). It is widely believed that the various distinct USV types reflect the animal's affective state, such as anxiety or pleasure. Furthermore, they serve communicative functions, for instance, as alarm calls or social contact calls. Manipulations targeting the 5-HT system alter affective ultrasonic communication in rodents throughout life, probably because of its important role in regulating anxiety and social behavior. Ample evidence indicates the involvement of the 5-HT system in modulating isolation-induced USV in pups. Later in life, the 5-HT system plays a strong modulatory role in the emission of aversive 22-kHz USV in rats. So far, little is known about the role of 5-HT in the production of interaction-induced USV in mice and appetitive 50-kHz USV in rats, although recent findings also suggest a modulatory effect of the 5-HT system. Assessment of rodent USV is a valuable method to investigate mood and emotion, and to enhance our understanding of, and develop novel pharmacological therapies for neuropsychiatric disorders, such as anxiety disorders and depression or ASD.

Behaviorally conditioned effects of psychoactive drugs in experimental animals: What we have learned from nearly a century of research and what remains to be learned.

Continuous treatment with drugs is a crucial requirement for managing various clinical conditions, including chronic pain and neuropsychiatric disorders such as depression or schizophrenia. Associative learning processes, i.e. Pavlovian conditioning, can play an important role for the effects of drugs and could open new avenues for optimizing patient treatment. In this narrative literature review, we summarize available data in experimental animals regarding the behaviorally conditioned effects of psychostimulants such as d-amphetamine and cocaine, the dopamine receptor agonist apomorphine, the dopamine receptor antagonist haloperidol, morphine and antidepressant drugs. In each section, the drug under discussion is briefly introduced, followed by a detailed examination of conditioning features, including doses and dosing regimens, characteristics of the conditioning process such as test environments or specific conditioned stimuli, testing and conditioned response characteristics, possible extinction or reconditioning or reversal training, neural mechanisms, and finally, the potential clinical relevance of the research area related to the drug. We focus on key outcomes, delve into methodical issues, identify gaps in current knowledge, and suggest future research directions.

Altered socio-affective communication and amygdala development in mice with protocadherin10-deficient interneurons.

Autism spectrum disorder (ASD) is a group of neurodevelopmental conditions associated with deficits in social interaction and communication, together with repetitive behaviours. The cell adhesion molecule protocadherin10 (PCDH10) is linked to ASD in humans. Pcdh10 is expressed in the nervous system during embryonic and early postnatal development and is important for neural circuit formation. In mice, strong expression of Pcdh10 in the ganglionic eminences and in the basolateral complex (BLC) of the amygdala was observed at mid and late embryonic stages, respectively. Both inhibitory and excitatory neurons expressed Pcdh10 in the BLC at perinatal stages and vocalization-related genes were enriched in Pcdh10-expressing neurons in adult mice. An epitope-tagged Pcdh10-HAV5 mouse line revealed endogenous interactions of PCDH10 with synaptic proteins in the young postnatal telencephalon. Nuanced socio-affective communication changes in call emission rates, acoustic features and call subtype clustering were primarily observed in heterozygous pups of a conditional knockout (cKO) with selective deletion of Pcdh10 in Gsh2-lineage interneurons. These changes were less prominent in heterozygous ubiquitous Pcdh10 KO pups, suggesting that altered anxiety levels associated with Gsh2-lineage interneuron functioning might drive the behavioural effects. Together, loss of Pcdh10 specifically in interneurons contributes to behavioural alterations in socio-affective communication with relevance to ASD.

Reduced excitatory neurotransmission and mild autism-relevant phenotypes in adolescent Shank3 null mutant mice.

Mutations in the synaptic scaffolding protein gene SHANK3 are strongly implicated in autism and Phelan-McDermid 22q13 deletion syndrome. The precise location of the mutation within the Shank3 gene is key to its phenotypic outcomes. Here, we report the physiological and behavioral consequences of null and heterozygous mutations in the ankyrin repeat domain in Shank3 mice. Both homozygous and heterozygous mice showed reduced glutamatergic transmission and long-term potentiation in the hippocampus with more severe deficits detected in the homozygous mice. Three independent cohorts were evaluated for magnitude and replicability of behavioral endophenotypes relevant to autism and Phelan-McDermid syndrome. Mild social impairments were detected, primarily in juveniles during reciprocal interactions, while all genotypes displayed normal adult sociability on the three-chambered task. Impaired novel object recognition and rotarod performance were consistent across cohorts of null mutants. Repetitive self-grooming, reduced ultrasonic vocalizations, and deficits in reversal of water maze learning were detected only in some cohorts, emphasizing the importance of replication analyses. These results demonstrate the exquisite specificity of deletions in discrete domains within the Shank3 gene in determining severity of symptoms.

Affective communication in rodents: ultrasonic vocalizations as a tool for research on emotion and motivation.

Mice and rats emit and perceive calls in the ultrasonic range, i.e., above the human hearing threshold of about 20 kHz: so-called ultrasonic vocalizations (USV). Juvenile and adult rats emit 22-kHz USV in aversive situations, such as predator exposure and fighting or during drug withdrawal, whereas 50-kHz USV occur in appetitive situations, such as rough-and-tumble play and mating or in response to drugs of abuse, e.g., amphetamine. Aversive 22-kHz USV and appetitive 50-kHz USV serve distinct communicative functions. Whereas 22-kHz USV induce freezing behavior in the receiver, 50-kHz USV lead to social approach behavior. These opposite behavioral responses are paralleled by distinct patterns of brain activation. Freezing behavior in response to 22-kHz USV is paralleled by increased neuronal activity in brain areas regulating fear and anxiety, such as the amygdala and periaqueductal gray, whereas social approach behavior elicited by 50-kHz USV is accompanied by reduced activity levels in the amygdala but enhanced activity in the nucleus accumbens, a brain area implicated in reward processing. These opposing behavioral responses, together with distinct patterns of brain activation, particularly the bidirectional tonic activation or deactivation of the amygdala elicited by 22-kHz and 50-kHz USV, respectively, concur with a wealth of behavioral and neuroimaging studies in humans involving emotionally salient stimuli, such as fearful and happy facial expressions. Affective ultrasonic communication therefore offers a translational tool for studying the neurobiology underlying socio-affective communication. This is particularly relevant for rodent models of neurodevelopmental disorders characterized by social and communication deficits, such as autism and schizophrenia.