Life Sciences Commons^™

Outclimbing Cognitive Decline: Age, Western Diet, Resistance Exercise, And The Brain., Leila Dzinic

Electronic Thesis and Dissertation Repository

Increased age and obesity diminish motivation, perseverance, and spatial memory function. Aerobic exercise interventions have successfully rescued some of these processes. However, in older and heavier populations aerobic exercise is not as sustainable due to high risk of injury. Resistance exercise consists of physical activity where maximum oxygen consumption is not increased and has been proposed as a safe and effective intervention for this population. Here, we used touchscreen-based cognitive testing to elucidate the influence of resistance exercise on motivation and spatial memory in aged, diet-induced obese mice, using a water restriction procedure I develop in Chapter 2. Mice underwent …

Characterizing The Spatial Distribution Of Inhibitory Interneurons Across Early Sensory And Association Areas In Callithrix Jacchus, Nika Khajehdehi

Electronic Thesis and Dissertation Repository

The prefrontal cortex (PFC) is one of the cortical areas responsible for complex cognitive abilities, a function that is believed to arise from increased persistent activity within its microcircuits. Activity within microcircuits is regulated by parvalbumin-containing (PV), calbindin-containing (CB), and calretinin-containing (CR) inhibitory interneurons (INs). It remains unclear how the distribution of activity-regulating INs differs across cortical areas such that persistent activity increases specifically within association areas, allowing for their complex functions. This thesis aims to address this gap by characterizing the spatial distributions and differences in relative proportions of INs across early sensory areas and association areas of the …

Modelling Prenatal Hypoxia As A Risk Factor For Schizophrenia Vulnerability In Patient-Derived Cerebral Organoids, Dana M. Gummerson

Electronic Thesis and Dissertation Repository

Prenatal hypoxia during fetal development is a significant environmental risk factor linked to schizophrenia (SCZ) vulnerability. However, hypoxia’s impact on human brain development at the cellular level remains unclear. Our laboratory has developed human cerebral organoids using induced pluripotent stem cells (iPSCs) derived from healthy control or SCZ patient cell lines to address these questions. This creates a platform that allows for the investigation into the pathophysiology of SCZ and hypoxia in tandem. Organoids were exposed to hypoxic conditions at one month of development, mimicking the early stages of cortical growth in the human fetus. Results reveal innate differences in …

Examining The Emergence Of Mood And Anxiety Molecular Phenotypes Resulting From Chronic Prenatal Nicotine Exposure In Cerebral Organoids, Emma K. Proud

Electronic Thesis and Dissertation Repository

Prenatal nicotine exposure (PNE) from maternal smoking disrupts regulatory processes vital to fetal development. These changes result in long-term behavioural impairments, including mood and anxiety disorders, that manifest later in life. However the relationship underlying PNE, and the underpinnings of mood/anxiety molecular phenotypes remains elusive. To model nicotine exposure during prenatal development, our study used human cerebral organoids that were chronically exposed to nicotine and collected for molecular analyses. Short-term, nicotine altered molecular markers of neural identity, mood/anxiety disorders and those involved in maintaining the excitatory/inhibitory (E/I) balance in the cortex. RNA sequencing further revealed transcriptomic changes in genes pertaining …

Sex Differences In Mood And Anxiety-Related Outcomes In Response To Adolescent Nicotine Exposure, Tsun Hay Jason Ng

Electronic Thesis and Dissertation Repository

Nicotine dependence is causally linked to increased risk of mood/anxiety disorders in later life. Females are reported to experience a higher prevalence of anxiety/depressive disorders and challenges in smoking cessation therapies, suggesting a potential sex-specific response to nicotine exposure and mood/anxiety disorder risk. However, pre-clinical evidence of sex-specific responses to adolescent nicotine exposure is unclear. Thus, to determine any sex differences in anxiety/depressive-related outcomes, adolescent male and female Sprague Dawley rats received nicotine (0.4 mg/kg; 3x daily) or saline injections for 10 consecutive days, followed by behavioural testing, in-vivo electrophysiology and Western Blot analyses. Our results revealed that adolescent nicotine …

The Combined Effects Of Physical Exercise And Cognitive Training On Gait Speed And Primary Motor Cortex Metabolism In Individuals With Mild Cognitive Impairment: A 1h-Mrs Analysis, Jack Thomas Emsey Elkas

Electronic Thesis and Dissertation Repository

Mild cognitive impairment (MCI) is a transitional stage before dementia. Altered gait in MCI has been associated with progression to dementia. Using magnetic resonance spectroscopy, a relationship between primary motor cortex (M1) neurochemistry and dual task gait speed has been reported in MCI. Interventional research suggests exercise, cognitive training, and vitamin D supplementation may benefit MCI, yet the combined effect of these treatments on gait speed and M1 metabolism is unknown. Participants with MCI (N=75) were assigned to one of five intervention arms and dual task cost on gait speed and M1 metabolism was assessed before and five months after …

The Effects Of Prenatal Cannabis Exposure On The Basolateral Amygdala, Karen Kw Wong

Undergraduate Student Research Internships Conference

Clinical and preclinical studies indicate prenatal cannabis exposure (PCE) pathologically affects fetal brain development and may increase vulnerability to neuropsychiatric disorders, including schizophrenia and mood/anxiety disorders. In review research from our lab suggests that fetal exposure to Δ9-THC sex-selectively impairs mesocorticolimbic (MCL) circuit function. However, there is a distinct lack of focus on PCE models on the BLA. The BLA plays a central role within the MCL where it directly interacts with the VTA, PFC and HIPP. Importantly, our model exhibits significant VTA hyperdopaminergic activity, and sex-specific alterations to PFC/HIPP glutamate firing, alongside region- and sex-specific changes in dopamine (DA), …

Neural Circuitry Of The Midbrain Pedunculopontine Tegmental Nucleus Regarding Its Role In Sensorimotor Gating, Niveen Fulcher

Electronic Thesis and Dissertation Repository

The brain is a complicated structure that receives copious amounts of information at any given time. The pedunculopontine tegmental nucleus (PPTg) is involved in many innate functions like arousal, rapid eye-movement (REM) sleep, reward association and sensorimotor gating. Although commonly referred to as a cholinergic structure, it also contains glutamatergic and GABAergic neurons. Based on chronic PPTg lesions that disrupted PPI, cholinergic PPTg neurons were long assumed to mediate prepulse inhibition (PPI) of startle, a measure of sensorimotor gating. Deficits of PPI are observed in a variety of neurological disorders, including Autism Spectrum Disorder (ASD), Obsessive-Compulsive Disorder (OCD), and is …

Illuminating Transfer Rna Variants As Genetic Modifiers In Models Of Human Disease, Jeremy T. Lant

Electronic Thesis and Dissertation Repository

Transfer RNAs (tRNAs) physically link the genetic code to an amino acid sequence, by recruiting amino acids to three-nucleotide codons in messenger RNAs. To ensure that the genetic code is translated as intended, tRNAs must be accurately aminoacylated and faithfully recognize codons in the ribosome during protein synthesis. Given the critical function of tRNAs, it has often been assumed that mutations in human tRNA genes would be either lethal to cells or not significantly impair tRNA function. My goal was to rigorously test this assumption in mammalian cell models, prompted by the recent discovery of unprecedented variation in human tRNA …

Exercise As A Treatment For Cognitive Decline In Older Adults: The Role Of Growth Factors And Inflammatory Cytokines, Joshua A. Titus

Electronic Thesis and Dissertation Repository

The purpose of this thesis was to investigate the effects that exercise modalities have on neurotrophic and inflammatory blood markers and cognitive outcomes in older adults. A systematic review and meta-analysis were completed. The included studies illustrated that most of the literature evaluated the effect of aerobic exercise interventions on systemic concentrations of the blood marker brain-derived neurotrophic factor (BDNF). The review found that aerobic exercise increases BDNF and resistance training increases insulin-like growth factor 1 (IGF-1). Interventions with sex-specific cohorts presented advantages in males for blood marker and cognitive outcomes compared to females. One of three included interventions decreased …

Regional Lipid Expression Abnormalities Identified Using Maldi Ims Correspond To Mri-Defined White Matter Hyperintensities Within Post-Mortem Human Brain Tissue., William J. Pinsky

Electronic Thesis and Dissertation Repository

Periventricular white matter hyperintensities (pvWMHs) are a neurological feature detected with magnetic resonance imaging (MRI) and are clinically associated with an increased risk of stroke and dementia. pvWMHs are characterized by white matter lesions with myelin and axon rarefaction, and as such likely involve changes in lipid composition, however these alterations remain unknown. Lipids are critical in determining cell function and survival, although their detection within tissue, until recently has been challenging. Perturbations in lipid expression have previously been associated with neurological disorders. Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) is an emerging technique for untargeted, high-throughput investigation of …

The Functional And Structural Consequences Of Aberrant Microglial Activity In Major Depressive Disorder, Jasmine D. Cakmak

Electronic Thesis and Dissertation Repository

Major depressive disorder (MDD) is a highly debilitating neuropsychiatric illness which has been linked with increases in both peripheral and central inflammation, as well as with changes in connectivity. Although countless studies have investigated these two topics, the relationship between neuroinflammation and functional/structural connectivity has not been explored. Using [¹⁸F]FEPPA PET imaging, we measured translocator protein-related (TSPO) microglial activity in the subgenual anterior cingulate cortex (sgACC) and insula and confirmed significantly increased [¹⁸F]FEPPA uptake in depressed patients (N=12) compared to healthy controls (N=23). Using a seed-based ROI analysis of fMRI data, we found that patients show …

Examining The Role Of Chloride Homeostasis And Pge2 Signaling In The Neuroendocrine Stress Response To Inflammation, Samuel A. Mestern

Electronic Thesis and Dissertation Repository

The brain senses inflammatory signals and drives the release of glucocorticoids (GCs) — potent immunosuppressants — via the activation of the hypothalamic-pituitary-adrenal (HPA) axis. This inflammation-induced HPA axis activation is largely mediated by prostaglandin E2 (PGE2), acting on two subtypes of the PGE2 receptor, EP1 and EP3. Recently, our group revealed EP3 signaling mechanisms that excite HPA axis regulatory neurons. This thesis sought to tease out the remaining EP1 signaling mechanisms. Considering that the excitability of HPA axis regulatory neurons is constrained by GABA_A receptor-mediated synaptic inhibition that relies on low-level intracellular Cl^-. We hypothesized that PGE2-EP1 …

Investigating The Effects Of Maternal Immune Activation On Sensory Processing: Timing, Immune Mechanisms, And Gene-Environment Interactions, Faraj Haddad

Electronic Thesis and Dissertation Repository

Maternal infection during the first or second trimester of pregnancy poses a risk factor for the child to have neurodevelopmental disorders like autism spectrum disorder (ASD) and schizophrenia. Various clinical and preclinical studies have shown that the maternal immune response to infection, also known as maternal immune activation (MIA), can disrupt fetal brain development.

Over the past two decades, MIA has been studied in rodents using the Polyinosinic Polycytidylic acid (Poly I:C) rodent model. Poly I:C has a molecular pattern resembling viruses that can induce a robust immune response. Following exposure to Poly I:C MIA, rodent offspring exhibit many brain …

Investigation Of The Hsp90 Co-Chaperone, Sti1, In Cellular Resilience And Neurodegenerative Diseases, Rachel E. Lackie

Electronic Thesis and Dissertation Repository

In neurodegenerative diseases, certain proteins misfold and form toxic aggregates that cause brain matter atrophy, leading to decline in motor and/or cognitive functions. To maintain cellular proteostasis and survival, molecular chaperones regulate protein maturation and help to prevent aberrant protein aggregation. The molecular chaperone Hsp90 regulates hundreds of proteins and interestingly, several of those are misfolded in neurodegenerative diseases. Stress inducible-phosphoprotein-1 (STI1, STIP1), an Hsp90 co-chaperone, orchestrates client protein transfer between chaperones Hsp70 and Hsp90 through physical interactions with both chaperones. Notably, previous work in yeast, worms, and mouse neurons all showed that STI1 protects organisms against stressors and amyloid-like …

Blocking Pirb Function Increases Dendritic Spine Density In The Prefrontal Cortex Of Adult Rats, Hannah J. Macneil

Electronic Thesis and Dissertation Repository

Schizophrenia is a psychotic disorder consisting of positive, negative, and cognitive symptoms. While patients currently have access to treatments for the positive and negative symptoms, no satisfactory treatment exists to alleviate the cognitive deficits, which cause severe impairments to the quality of life of patients and their families. Although the mechanisms underlying the cognitive deficits of schizophrenia are not clear, a decreased dendritic spine density on layer 3 pyramidal neurons in the dorsolateral prefrontal cortex has been strongly implicated. Generally, the adult brain is not permissive to the formation of new dendritic spines. Recently, an immune receptor called paired immunoglobulin-like …

Expression And Subcellular Localization Of Circrnas Dysregulated Als That Are Encoded In Cytoskeletal Protein Genes, Asieh Alikhah

Electronic Thesis and Dissertation Repository

Amyotrophic lateral sclerosis (ALS) is a fatal and progressive neurodegenerative disorder that causes the death of motor neurons. While alterations in the metabolism of RNA, including RNA-binding proteins have been linked to the pathogenesis of ALS, our understanding of the role of non-coding RNAs including circRNAs is less well developed. In this study, using a combination of fluorescence in situ hybridization (FISH) and immunofluorescence (IF) with markers of RNP granules, I investigated the effect of osmotic stress on the localization and expression of a selection of circRNAs whose expression is dysregulated in ALS. Alteration in the number of granules for …

Modulation Of Gabaa Receptor By Neurosteroids And Protein Kinases In Health And Disease, Jaymin Jeong

Electronic Thesis and Dissertation Repository

γ-aminobutyric acid type A receptors (GABA_A receptors) underlie the majority of inhibitory synaptic transmission in the brain. Modulation of GABAergic activity occurs in development and normal physiological functioning of the brain, and changes to GABAergic function has been implicated in numerous neurological disorders including epilepsy. Neurosteroids, metabolites of steroid hormones, and kinases are known to modulate GABA_A receptor mediated currents in health and disease. This thesis aims to investigate the effects of kinases and neurosteroids on modulating GABA_A receptor-mediated currents in cortical pyramidal cells and their effects on the piriform cortex (PCtx) circuit in naïve rats and …

Protein Misfolding Toxicity And Inclusion Formation In Cellular Models Of Neurodegeneration, Sonja E. Di Gregorio

Electronic Thesis and Dissertation Repository

Protein misfolding characterizes most neurodegenerative diseases. Protein misfolding is the conversion of specific proteins from their normal, often soluble, and native three-dimensional conformation into an aberrant, often insoluble, non-functional conformation. Protein inclusions and aggregates are among the major pathological hallmarks of protein misfolding associated with many neurodegenerative diseases. Yet, the role of aggregates and inclusions is not clearly defined and heavily debated. This study utilizes powerful genetic approaches in yeast and verification in mammalian neuronal cell lines to address the misfolding and toxicity of three proteins, the Rho Guanine Nucleotide Exchange Factor (RGNEF), Matrin3, which are involved in amyotrophic lateral …

Imaging Of Neurotransmitters And Small Molecules In Brain Tissues Using Laser Desorption/Ionization Mass Spectrometry Assisted With Zinc Oxide Nanoparticles., Chaochao Chen, Steven R Laviolette, Shawn N Whitehead, Justin B Renaud, Ken K-C Yeung

Chemistry Publications

Inorganic nanostructured materials such as silicon, carbon, metals, and metal oxides have been explored as matrices of low-background signals to assist the laser desorption/ionization (LDI) mass spectrometric (MS) analysis of small molecules, but their applications for imaging of small molecules in biological tissues remain limited in the literature. Titanium dioxide is one of the known nanoparticles (NP) that can effectively assist LDI MS imaging of low molecular weight molecules (LMWM). TiO₂ NP is commercially available as dispersions, which can be applied using a chemical solution sprayer. However, aggregation of NP can occur in the dispersions and the aggregated NP …

Elucidating The Consequence And Cause Of Microrna Dysregulation In Amyotrophic Lateral Sclerosis (Als), Zachary C. E. Hawley

Electronic Thesis and Dissertation Repository

Amyotrophic Lateral Sclerosis (ALS) is a progressive motor neurodegenerative disorder with an average life expectancy of 2-5 years post-diagnosis. Common pathological features associated with ALS are the formation of cytoplasmic inclusions of intermediate filaments and RNA-binding proteins within motor neurons. The formation of intermediate filament cytoplasmic inclusions is believed to be driven by a loss of stochiometric expression between five neuronal intermediate filament proteins—NFL, NFM, NFH, INA and PRPH—where there is a selective suppression of the steady-state levels of NEFL, INA and PRPH mRNA. Further, three RNA-binding proteins—TDP-43, FUS and RGNEF—have been shown to co-aggregate with each other in …

Dnajc7, A Molecular Chaperone Protein That Modulates Protein Misfolding In Amyotrophic Lateral Sclerosis (Als), Meaghan Kathleen Stoltz

Electronic Thesis and Dissertation Repository

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease associated with protein misfolding and dysregulated cellular protein quality control mechanisms. Molecular chaperones, and heat shock proteins (Hsp), are key players in maintaining cellular protein quality control. DNAJC7 is an understudied cytosolic Hsp40 that works together with Hsp70 and Hsp90 to regulate proper protein folding or degradation. Of note, mutations in the gene encoding DNAJC7 were discovered to cause familial ALS. We asked whether ALS-associated mutations in DNAJC7 compromise its function as a chaperone, which may cause the toxic accumulation of misfolded proteins. This study attempts to uncover the functions of DNAJC7 …

The Role Of The Leucine-Rich (Leur) Domain Of Rho Guanine Nucleotide Exchange Factor (Rgnef) In The Regulation Of Amyotrophic Lateral Sclerosis (Als) Associated Protein Tar Dna-Binding Protein Of 43 Kda (Tdp-43), Hind Amzil

Electronic Thesis and Dissertation Repository

The presence of neuronal cytoplasmic inclusions (NCIs) composed of RNA-binding proteins (RBPs) and neurofilaments is considered to be ALS’s neuropathological hallmark. RGNEF has been previously shown to interact with TDP-43 and to have a regulatory effect on the expression levels of NEFL mRNA and NFL protein in vitro. Here, I examined the mechanism of the RGNEF N-terminus, leucine-rich domain (LeuR) domain’s interaction with TDP-43. I observed that the minimal domain required is 110 amino acids (LeuR110), that the Ankyrin domain adjacent to LeuR110 does not participate, and that LeuR110 forms of a high molecular weight complex with TDP-43 in …

The Effect Of Nitric Oxide On Microglia Function And Activity: Implications On Transient Receptor Potential Channels, Matthew J-E. Maksoud

Electronic Thesis and Dissertation Repository

Microglia proliferation and phagocytosis is critical for proper development and maintenance of the central nervous system (CNS), whereas dysregulated proliferation and phagocytosis contributes to various CNS pathologies. Specifically, in response to pathology or tissue injury, microglia transform to an activated state characterized by elevated inducible nitric oxide synthase (iNOS) expression, increased nitric oxide (NO) production, active phagocytosis, and decreased proliferation. Importantly, microglial phagocytosis and proliferation are tightly regulated by intracellular calcium levels. As non-excitable cells, microglia rely on calcium entry through transient receptor potential (TRP) channels to carry out phagocytosis and proliferation. However, the role of iNOS/NO signaling in regulating …

Mushroom Body-Specific Gene Regulation By The Swi/Snf Chromatin Remodeling Complex, Kevin Cj Nixon

Electronic Thesis and Dissertation Repository

Over the lifetime of an organism, neurons must establish, remodel, and maintain precise connections in order to form neural circuits that are required for proper nervous system functioning. Disruptions in these processes can lead to neurodevelopmental disorders such as intellectual disability (ID) and autism spectrum disorder. Mutations in genes encoding subunits of the SWI/SNF chromatin remodeling complex have been implicated in ID, yet the role of this complex in neurons is poorly understood. In this project, I established cell-type specific methods to examine the effect of SWI/SNF subunit knockdowns on gene transcription and chromatin structure in the memory-forming neurons of …

Behavioural And Molecular Consequences Of Postnatal Stress In A Mouse Model Of Fetal Alcohol Spectrum Disorder, Bonnie Alberry

Electronic Thesis and Dissertation Repository

Fetal alcohol spectrum disorders (FASD) are caused by prenatal alcohol exposure (PAE) and affect 1‑5% of the North American population. Children born with FASD often face maternal separation throughout childhood. How this early life stress (ELS) affects the severity of FASD-related deficits is poorly understood. Using a mouse model, this dissertation establishes that behavioural deficits accumulate following prenatal alcohol exposure and early life stress, assessed using tests for activity, anxiety-like behaviour as well as learning and memory. Hippocampal gene expression was evaluated using RNA-seq followed by clustering of expression profiles through weighted gene co-expression network analysis (WGCNA). A set of …

Lysosomes Mediate Rab27b-Dependent Secretion Of Beta-Amyloid, Shany Lahan

Electronic Thesis and Dissertation Repository

Extracellular deposition of beta-Amyloid (Aβ) is an early event in Alzheimer’s disease development. However, it is not known how Aβ is secreted. Lysosomes readily undergo calcium-dependent exocytosis, a process that relies on small GTPase Rab27b. In addition, lysosomal enzymes have been found within extracellular amyloid plaques. We hypothesized that lysosomes mediate Rab27b-dependent exocytosis of Aβ. Neuro-2a cells were transfected with wild-type or mutant Rab27b constructs and/or a lysosomal marker. Cells were incubated with Aβ monomers and imaged using a confocal microscope before and after stimulation of calcium-dependent exocytosis. We observed a significant decrease in lysosome and Aβ co-localization post-treatment in …

Assessing The Role Of Drosophila Melanogaster Neuroligin 3 On Social Spacing And Climbing Behaviour, J. Wesley Robinson

Electronic Thesis and Dissertation Repository

Autism spectrum disorders can be clinically defined in part by impairments of social interactions. Social interactions can be modeled in Drosophila melanogaster with behaviours such as social spacing. Here, I examined the effects of autism-related gene neuroligin 3 on fly social spacing. I hypothesized if neuroligin 3 is mutated or gene expression is targeted for knockdown, then flies will have altered social space in males and females at different ages. Using the social space assay, I found that different mutations to neuroligin 3 change the fly’s behavior, in a mutation and sex-specific manner. Using an antibody against Nlg3, I localized …

Brain-Specific And Systemic Inflammatory Response Following Repetitive Concussive Impact In A Mouse Model, So Young Eo

Electronic Thesis and Dissertation Repository

Concussion is the most common form of mild traumatic brain injury (mTBI). TBI resolution is modulated by neuroinflammation, which is augmented by the infiltration of innate immune cells from the circulation. Peripheral, myeloid immune cells not only invade neural tissues but other organs as well causing local inflammation and tissue damage, known as systemic inflammatory response syndrome. Here, I assessed the temporal and anatomical nature of the neural and systemic cellular inflammatory response to repetitive, mTBI in a 3-hit mouse model of concussion. The results showed significant microglial activity, accumulation of peripheral myeloid cells and prominent axonal damage post-injury. The …

Psychological Stress Modulates Synaptic Mechanisms For Prostaglandin E2-Mediated Hpa Axis Activation, Meagan Wiederman

Electronic Thesis and Dissertation Repository

Immune-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis elevates glucocorticoids, anti-inflammatory hormones, promoting the effective resolution of inflammation. Psychological stress can modulate this anti-inflammatory mechanism, but the mechanisms underlying this modulation remain largely unknown. The immune-induced HPA axis activation is, in large part, mediated by prostaglandin E₂ (PGE₂), an inflammatory mediator. In the brain, PGE₂ attenuates GABAergic synaptic transmission onto corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN) that act as the apex of the HPA axis. The removal of GABA-mediated inhibition (i.e. disinhibition) excites CRH neurons and, consequently, activates the HPA axis. …