Biology subjects

Stuchlik, A.

Publications and source records attributed to Stuchlik, A..

9 recordsLinked to original sources

bioRxiv2026

Partial lesions of hypocretin neurons of the rat lateral hypothalamus affect wake and sleep regulation under increased sleep pressure

Hypocretin(orexin)-producing neurons in the lateral hypothalamic area are important for sleep and wake regulation in mammals and their damage in humans manifests clinically as narcolepsy. While in previous studies experimentally induced massive loss of these neurons revealed their physiological importance, small lesions and their manifestations can uncover more subtle features of sleep regulation and help understand the delicate processes in early stages of pathogenesis of narcolepsy. We studied the effects of partial lesions (approximately 30%) of hypocretin producing neurons in the lateral hypothalamus on sleep patterns and EEG in rats. The lesions did not change the normal sleep and wake pattern in undisturbed rats. The effects of lesions manifested under increased sleep pressure after six hours of sleep deprivation, when they led to accelerated dynamics of compensatory slow wave sleep. The lesions also led to a slight decrease in theta frequency in wakefulness and in REM sleep, which we observed during undisturbed sleep and wake behavior as well as after sleep deprivation.

neuroscience↗

bioRxiv2024

CA1 ensemble plasticity is coupled to context change and modulated by task familiarity

When should plasticity mechanisms get recruited (stability-plasticity dilemma)? Environments change over time, re/entering a given context increases uncertainty and predicts the need for updating. Hippocampus (HPC) is key to tracking context change but also navigation in relation to moving targets. CA1 ensembles expressing immediate-early genes (IEGs) are contextually specific, while the amount of IEG expression correlates with HPC-dependent task demands. However, task effects on the IEG-expressing ensembles per se remain unclear. In three experiments, we tested the effect of context change and HPC task demands on CA1 IEG+ ensembles in rats. Experiment 1 showed that the IEG+ (Arc, Homer1a RNA) ensemble size drops to baseline level during uninterrupted 30 min exploration, reflecting familiarization and decreasing uncertainty, unless context change is present; the ensemble sizes reflect both context identity and context change. Experiment 2 showed no evidence of task-specificity of IEG+ ensembles during highly HPC-dependent mobile robot avoidance nor HPC-independent stationary robot avoidance. Experiment 3 replicated the findings of Experiment 2 for c-Fos protein. Nonetheless, the data suggest that ensembles shrink with task mastery/familiarity and grow with novelty presented by acquisition of behavioral extinction. Overall, our results shed light on the temporal dynamics, and the context and task control of CA1 IEG+ ensembles. The present results and the relevant literature suggest that context change resets the ensemble of IEG-expressing CA1 neurons and novelty delays the time-dependent ensemble shrinking. HIGHLIGHTSO_LIPlasticity and learning rate should reflect novelty and familiarity, i.e. uncertainty C_LIO_LIChange of context and task requirements increase uncertainty C_LIO_LIFamiliarization with context and task reduces uncertainty C_LIO_LIFor context, this pattern is matched by dynamics of IEG+ ensembles in CA1 C_LIO_LITask demands have modulating influence on CA1 IEG+ ensembles C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/608588v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@12808c0org.highwire.dtl.DTLVardef@156ad3corg.highwire.dtl.DTLVardef@1876f0aorg.highwire.dtl.DTLVardef@8b13f4_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

PV+ optogenetic stimulations at specific frequencies in specific brain regions can restore navigational flexibility in an acute MK801 mouse model of schizophrenia

Impairments of decision-making and behavioral flexibility in schizophrenia (SCZ) are currently the most investigated features. One convincing hypothesis explaining this cognitive impairment is the excitatory/inhibitory (E/I) ratio imbalance in brain regions such as the medial prefrontal cortex (mPFC) and the ventral hippocampus (vHPC). An increased GLUergic excitatory activity and a decreased GABAergic inhibitory activity induces an mPFC-vHPC {gamma}/{theta} band desynchronization in many tasks testing behavioral flexibility. However, these tasks were carried out using "perceptual" decision-making/flexibility but not navigational decision-making/flexibility. Our study addressed the role of frequency-specific optogenetic stimulations of GABAergic parvalbumin-positive (PV+) interneurons in mPFC (50Hz, {gamma}-like) and vHPC (10Hz, {theta}-like) in an acute-MK801 mouse model of navigational inflexibility. We used the active place avoidance task on a rotating arena. Results showed that frequency-specific optogenetic stimulations of mPFC or vHPC acted differently in restoring navigational flexibility, advancing our knowledge of the pivotal role of PV+ activity in SCZ-like navigational decision-making/flexibility.

animal behavior and cognition↗

bioRxiv2024

Genetic Modulation of Protein Expression in Rat Brain

Genetic variations in protein expression are implicated in a broad spectrum of common diseases and complex traits. However, the fundamental genetic architecture and variation of protein expression have received comparatively less attention than either mRNA or classical phenotypes. In this study, we systematically quantified proteins in the brains of a large family of rats using tandem mass tag (TMT)-based quantitative mass-spectrometry (MS) technology. We identified and quantified a comprehensive proteome of 8,119 proteins from Spontaneously Hypertensive (SHR/Olalpcv), Brown Norway with polydactyly-luxate (BN-Lx/Cub), and 29 of their fully inbred HXB/BXH progeny. Differential expression (DE) analysis identified 597 proteins with significant differences in expression between the parental strains (fold change > 2 and FDR < 0.01). We characterized 95 variant peptides by proteogenomics approach and discovered 464 proteins linked to strong cis-acting quantitative trait loci (pQTLs, FDR < 0.05). We also explored the linkage of pQTLs with behavioral phenotypes in rats and examined the sex-specific pQTLs to reveal both distinct and shared cis-pQTLs between sexes. Furthermore, by creating a novel view of the rat pangenome, we improved the ability to pinpoint candidate genes underlying pQTL. Finally, we explored the connection between the pQTLs in rat and human disorders, underscoring the translational potential of our findings. Collectively, this work demonstrates the value of large and systematic proteo-genetic datasets in understanding protein modulation in the brain and its functional linkage to complex central nervous system (CNS) traits.

genetics↗

bioRxiv2023

Internal representation of future interactions in rats

Animals and humans receive the most critical information from parts of the environment that are immediately inaccessible, possibly only visually explored, and highly dynamic. The brain must effectively process potential interactions between elements in such an environment to make appropriate decisions in critical situations. We trained male Long-Evans rats to discriminate static and dynamic visuospatial stimuli displayed on an inaccessible computer screen. We demonstrated that the rats learned to discriminate dynamic visuospatial stimuli faster, with greater accuracy and shorter reaction time than complementary static stimuli. Furthermore, we provide behavioral evidence indicating that rats internally represent dynamic environments as static maps that capture meaningful future interactions. These observations highlight the ecological importance of dynamic stimuli in the outside world and support previous findings in humans that internal static representations can encapsulate relevant spatiotemporal information of dynamic environments. Such a mechanism would allow animals and humans to process complex time-changing situations neatly.

animal behavior and cognition↗

bioRxiv2022

Incidental Temporal Binding in Rats: A Novel Behavioral Task Relevant to Episodic Memory

We designed a behavioral task called One-Trial Trace Escape Reaction (OTTER), in which rats incidentally associate two temporally discontinuous stimuli: a neutral acoustic cue (CS) with an aversive stimulus (US) which occurs two seconds later (CS-2s-US sequence). Rats are first habituated to two similar environmental contexts (A and B), each consisting of an interconnected dark and light chamber. Next, rats experience the CS-2s-US sequence in the dark chamber of one of the contexts (either A or B); the US is terminated immediately after a rat escapes into the light chamber. The CS-2s-US sequence is presented only once to ensure the incidental acquisition of the association. The recall is tested 24 h later when rats are presented with only the CS in the alternate context (B or A), and their behavioral response is observed. Our results show that 59 % of the rats responded to the CS by escaping to the light chamber, although they experienced only one CS-2s-US pairing. The OTTER task offers a flexible high throughput tool to study memory acquired incidentally after a single experience. Incidental acquisition of association between temporally discontinuous events is highly relevant to episodic memory formation.

animal behavior and cognition↗

bioRxiv2022

The role of optogenetic stimulations of parvalbumin-positive interneurons in the prefrontal cortex and the ventral hippocampus on an acute MK801 model of schizophrenia-like cognitive inflexibility

Background and HypothesisSchizophrenia research arose in the last decades, focusing more on its neural basis. Executive functions such as decision making and cognitive flexibility are the main cognitive areas that are impaired and are considered schizophrenia endophenotypes. Recently, cognitive impairment has been connected with the ablation of glutamatergic NMDARs resulting in increased cortical activity. Selective NMDARs antagonists such as dizocilpine have been used to model cognitive inflexibility in schizophrenia. Moreover, a decreased GABAergic inhibitory activity has been shown elsewhere along with the enhanced cortical activity. This NMDARs/GABA unbalanced ratio may reduce the entrainment of prefrontal gamma and hippocampal theta rhythm, resulting in a prefrontal-hippocampal gamma/theta band desynchronization. Study DesignThe study addressed the role of acute administrations of dizocilpine to model schizophrenia-like cognitive inflexibility in rats. We used a new version of the attentional set-shifting task, where rats learned switching/reversing the relevant rule. Moreover, we used the new ASST after dizocilpine systemic injections to test cognitive flexibility. Finally, we used in vivo optogenetic stimulations at specific light pulses of parvalbumin-positive interneurons in the prefrontal cortex and ventral hippocampus. ResultsThe first experiments showed that acute dizocilpine in rats reproduced schizophrenia-like cognitive inflexibility. The second set of experiments demonstrated that appropriate optogenetic light pulses frequencies could rescue the cognitive flexibility previously altered by acute dizocilpine. ConclusionsThese findings advance our knowledge on the pivotal role of parvalbumin interneurons in schizophrenia-like cognitive impairment and may serve as a standpoint for further research of this severe psychiatric disorder.

neuroscience↗

bioRxiv2021

System genetics in the rat HXB/BXH family identifies Tti2 as a pleiotropic quantitative trait gene for adult hippocampal neurogenesis and serum glucose

Neurogenesis in the adult hippocampus contributes to learning and memory in the healthy brain but is dysregulated in metabolic and neurodegenerative diseases. The molecular relationships between neural stem cell activity, adult neurogenesis, and global metabolism are largely unknown. Here we applied unbiased systems genetic methods to quantify genetic covariation among adult neurogenesis and metabolic phenotypes in peripheral tissues of a genetically diverse family of rat strains, derived from a cross between the spontaneously hypertensive (SHR/OlaIpcv) strain and Brown Norway (BN-Lx/Cub). The HXB/BXH family is a very well established model to dissect genetic variants that modulate metabolic and cardiovascular disease and we have accumulated deep phenome and transcriptome data in a FAIR-compliant resource for systematic and integrative analyses. Here we measured rates of precursor cell proliferation, survival of new neurons, and gene expression in the hippocampus of the entire HXB/BXH family, including both parents. These data were combined with published metabolic phenotypes to detect a neurometabolic quantitative trait locus (QTL) for serum glucose and neuronal survival. We subsequently fine-mapped a key phenotype to a locus that includes the telo2-interacting protein 2 gene (Tti2)--a chaperone that modulates the activity and stability of PIKK kinases. To validate variants in or near Tti2 as a cause for differences in neurogenesis and glucose levels, we generated a targeted frameshift mutation on the SHR/OlaIpcv background. Heterozygous SHR-Tti2+/- mutants had lower rates of hippocampal neurogenesis and hallmarks of dysglycemia compared to wild-type littermates. Our findings highlight Tti2 as a causal genetic and molecular link between glucose metabolism and structural brain plasticity. In humans, more than 800 genomic variants are linked to TTI2 expression, seven of which have associations to protein and blood stem cell factor concentrations, blood pressure and frontotemporal dementia. Author summaryMetabolic and neurological disorders are often comorbid, suggesting that biological pathways which orchestrate peripheral homeostasis and the integrity of the nervous system intersect. The genetic architecture behind these relationships is still poorly described, in part because molecular processes in the human brain are very difficult to study. We thus used a rodent genetic reference population to investigate links between adult hippocampal neurogenesis-- a cellular plasticity mechanism important for learning flexibility--and metabolism. We measured adult neurogenesis in the family of 30 HXB/BXH rat recombinant inbred strains, who are characterised by stable differences in metabolism, behaviour, and gene expression levels. Because gene variants affecting distinct traits segregated into different members of the family, we discovered that previously published phenotypes correlated to adult neurogenesis due to shared genomic sequence. We found that expression levels of Tti2--a part of a specialised protein chaperone complex regulating stability of PIKK kinases--were concomitantly influencing adult neurogenesis and serum glucose levels. In human populations hundreds of genomic variants regulate TTI2 expression, potentially affecting brain function and glucose homeostasis.

neuroscience↗

bioRxiv2019

CRMP2 mediates Sema3F-dependent axon pruning and dendritic spine remodeling

Regulation of axon guidance and pruning of inappropriate synapses by class 3 semaphorins is key to development of neural circuits. Collapsin response mediator protein 2 (CRMP2) has been shown to regulate axon guidance by mediating Semaphorin 3A (Sema3A) signaling and its dysfunction has been linked to schizophrenia, however, nothing is known about its role in the synapse pruning. Here, using newly generated crmp2-/- mice we demonstrate that while CRMP2 has only a moderate effect on Sema3A-dependent axon guidance in vivo, it is essential for Sema3F-dependent axon pruning and dendritic spine remodeling. We first demonstrate that CRMP2 deficiency interferes with Sema3A signaling in compartmentalized neuron cultures and leads to a mild defect in axon guidance in peripheral nerves and corpus callosum. Strikingly, we show that crmp2-/- mice display more prominent defects in dendritic spine pruning and stereotyped axon pruning in hippocampus and visual cortex consistent with impaired Sema3F signaling and with autism spectrum disorder (ASD)-rather than schizophrenia-like phenotype. Indeed, we demonstrate that CRMP2 mediates Sema3F-induced axon retraction in primary neurons and that crmp2-/- mice display early postnatal behavioral changes linked to ASD. In conclusion, we demonstrate that CRMP2 is an essential mediator of Sema3F-dependent synapse pruning and its dysfunction in early postnatal stages shares histological and behavioral features of ASD.

neuroscience↗