National Neuroinformatics Framework for Canadian Consortium on Neurodegeneration in Aging (CCNA)

The Canadian Institutes for Health Research (CIHR) launched the “International Collaborative Research Strategy for Alzheimer's Disease” as a signature initiative, focusing on Alzheimer's Disease (AD) and related neurodegenerative disorders (NDDs). The Canadian Consortium for Neurodegeneration and Aging (CCNA) was subsequently established to coordinate and strengthen Canadian research on AD and NDDs. To facilitate this research, CCNA uses LORIS, a modular data management system that integrates acquisition, storage, curation, and dissemination across multiple modalities. Through an unprecedented national collaboration studying various groups of dementia-related diagnoses, CCNA aims to investigate and develop proactive treatment strategies to improve disease prognosis and quality of life of those affected. However, this constitutes a unique technical undertaking, as heterogeneous data collected from sites across Canada must be uniformly organized, stored, and processed in a consistent manner. Currently clinical, neuropsychological, imaging, genomic, and biospecimen data for 509 CCNA subjects have been uploaded to LORIS. In addition, data validation is handled through a number of quality control (QC) measures such as double data entry (DDE), conflict flagging and resolution, imaging protocol checks1, and visual imaging quality validation. Site coordinators are also notified of incidental findings found in MRI reads or biosample analyses. Data is then disseminated to CCNA researchers via a web-based Data-Querying Tool (DQT). This paper will detail the wide array of capabilities handled by LORIS for CCNA, aiming to provide the necessary neuroinformatic infrastructure for this nation-wide investigation of healthy and diseased aging

Role of the relaxin-3/RXFP3 system in the mouse: focus on septohippocampal function and memory

© 2017 Dr. Mouna HaidarAnatomical and functional studies have suggested that the highly conserved neuropeptide relaxin-3 plays an important role in a diverse range of functions, including behavioural arousal, stress responses and cognitive processes. Within rodent brain, relaxin-3 is primarily expressed by γ-aminobutyric acid (GABA) neurons in the pontine nucleus incertus (NI) that project to a number of forebrain areas containing its cognate G-protein-coupled receptor, relaxin-family peptide 3 receptor, RXFP3. Importantly, the relaxin-3/RXFP3 system performs synergistic and complementary roles to monoamine signalling (i.e. noradrenaline (NA)/locus coeruleus (LC) and serotonin (5-HT)/dorsal raphe (DR) systems) within shared downstream target regions. It has previously been established that relaxin-3-containing nerve fibres and RXFP3 mRNA and binding sites are strongly expressed in the main nodes of the septohippocampal system (SHS), including the medial septum/diagonal band of Broca (MS/DB) and hippocampal formation. Indeed, anatomical studies in the rat have demonstrated that relaxin-3-positive nerve fibres terminate on MS/DB GABAergic and cholinergic neurons that project to hippocampus, and functional studies have demonstrated that the relaxin-3/ RXFP3 system within the MS/DB modulates hippocampal theta rhythm and spatial working memory. However, the precise neurochemical and physiological mechanism(s) by which the relaxin-3/RXFP3 system modulates hippocampal activity are largely unknown and there are no studies of this system in mice. Therefore, to address this gap in knowledge, the studies described in this thesis investigated the role of the relaxin-3/RXFP3 system in the mouse in three key areas: (1) hippocampal function and memory; (2) progression of neurodegenerative disease; and (3) affective states and stress responses. Initial anatomical studies revealed that relaxin-3-positive nerve fibres/boutons make close contacts with multiple GABA neuron populations in the hippocampus, including a large population of somatostatin (SST)-positive neurons in the dentate gyrus hilus (DG hilus), and a smaller population of neurons expressing the calcium-binding proteins, parvalbumin (PV) and calretinin (CR). In subsequent functional studies, a ‘floxed’ RXFP3 mouse strain was validated and Cre-recombinase-mediated depletion of RXFP3 from the DG hilus in adult mice produced impairments in spatial reference and working memory. Together, these findings suggest endogenous relaxin-3/RXFP3 signalling is important for normal cognitive function via modulation of inhibitory GABA networks, including effects on the SST neurons that regulate the activity of principal cells and hippocampal oscillatory activity. Determining the role that relaxin-3/RXFP3 signalling plays in hippocampal function and cognition, and any synergistic actions with ascending monoamine systems, is important in relation to potential causative and/or therapeutic roles that relaxin-3/RXFP3 signalling play in disease. Dysfunction of ascending monoamine systems is a feature of several neurological diseases, including tauopathies and related neurodegenerative dementias, but it is not known if damage to the NI relaxin-3 system might contribute to cognitive decline in a similar way to the disruption of brainstem monoamine transmission in the hippocampus and frontal cortex. Therefore, using quantitative histochemical methods, the number and viability of relaxin-3 neurons in the NI was assessed in a cohort of transgenic tau-P301L mice and age- and strain-matched controls. The tau-P301L mouse is a model of human tauopathy and carries the P301L mutation (tau-4R/2N-P301L) in the tau protein, which is critical for binding to microtubules to aid their stabilization, essential for axonal transport, whereas under pathological conditions, phosphorylated tau results in aggregates that are toxic to neurons. A reduced number of relaxin-3-immunoreactive neurons was detected in the NI of 7 – 8 month old tau-P301L mice, relative to age matched controls, suggesting that reduced activity of the relaxin-3/RXFP3 system may contribute to cognitive decline in tauopathies and related disorders. This initial study of relaxin-3 neurons in a preclinical model of neurodegenerative disease indicates that further research in this and other models is warranted, including correlative studies of relaxin-3 mRNA levels and measures of relaxin-3 fibre and RXFP3 densities in key nodes of the septohippocampal system. In a series of functional studies, the relationship between the relaxin-3/RXFP3 system and monoamine signalling in controlling stress responses and affective states was explored by examining the impact of monoamine deficiency on the behavioural profile of normal C57BL/6J mice and mice with a constitutive whole-of-life deletion of the relaxin-3 or RXFP3 genes. Monoamine deficiency was achieved by withdrawal from chronic methamphetamine treatment. It was hypothesized that endogenous relaxin-3/RXFP3 signalling may compensate for the temporary reduction in monoamine signalling and reduce the depressive- and anxiety-like behaviours associated with methamphetamine withdrawal. Depressive- and anxiety-like behaviours were assessed in relaxin-3 and RXFP3 knockout (KO) mice and their wildtype (WT) littermates following withdrawal from escalating doses of methamphetamine. All groups of mice (relaxin-3 and RXFP3 KO, and WT) displayed similar sensitivity to chronic methamphetamine withdrawal in measures of body weight change, behavioural despair and anxiety-like behaviours. These data indicate that a global deficiency in endogenous brain relaxin-3/RXFP3 signalling does not exacerbate depressive- and affective-like behaviours observed during chronic methamphetamine withdrawal. In summary, these studies have demonstrated that relaxin-3/RXFP3 signalling can modulate hippocampal-dependent spatial reference and working memory most likely via modulation of key GABAergic neuron populations in the hippocampus. Furthermore, evidence was obtained that relaxin-3 neurons are dysregulated in a mouse model of tauopathy, further highlighting the importance of this system for healthy cognition. The identification of the contribution of the relaxin-3/RXFP3 system to hippocampal function and cognition encourages further research to identify the potential therapeutic value of RXFP3 targeted drugs to enhance cognitive functioning and improved mental health in a range of neurodegenerative and psychiatric diseases

Sensitivity to chronic methamphetamine administration and withdrawal in mice with relaxin-3/RXFP3 deficiency

Methamphetamine (METH) is a highly addictivepsychostimulant, and cessation of use is associatedwith reduced monoamine signalling, and increased anxiety/depressive states. Neurons expressing the neuropeptide,relaxin-3 (RLN3), and its cognate receptor, RXFP3, constitutea putative ‘ascending arousal system’, which sharesneuroanatomical and functional similarities with serotonin(5-HT)/dorsal raphe and noradrenaline (NA)/locus coeruleusmonoamine systems. In light of possible synergisticroles of RLN3 and 5-HT/NA, endogenous RLN3/RXFP3signalling may compensate for the temporary reduction inmonoamine signalling associated with chronic METHwithdrawal, which could alter the profile of ‘behaviouraldespair’, bodyweight reductions, and increases in anhedoniaand anxiety-like behaviours observed following chronicMETH administration. In studies to test this theory, Rln3and Rxfp3 knockout (KO) mice and their wildtype (WT)littermates were injected once daily with saline or escalatingdoses of METH (2 mg/kg, i.p. on day 1, 4 mg/kg,i.p. on day 2 and 6 mg/kg, i.p. on day 3–10). WT and Rln3and Rxfp3 KO mice displayed an equivalent sensitivity tobehavioural despair (Porsolt swim) during the 2-dayMETH withdrawal and similar bodyweight reductions onday 3 of METH treatment. Furthermore, during a 3-weekperiod after the cessation of chronic METH exposure, Rln3KO, Rxfp3 KO and corresponding WT mice displayedsimilar behavioural responses in paradigms that measuredanxiety (light/dark box, elevated plus maze), anhedonia(saccharin preference), and social interaction. These findingsindicate that a whole-of-life deficiency in endogenousRLN3/RXFP3 signalling does not markedly alter behaviouralsensitivity to chronic METH treatment or withdrawal,but leave open the possibility of a more significantinteraction with global or localised manipulations of thispeptide system in the adult brain

Relaxin-3/RXFP3 networks: an emerging target for the treatment of depression and other neuropsychiatric diseases?

Animal and clinical studies of gene-environment interactions have helped elucidate the mechanisms involved in the pathophysiology of several mental illnesses including anxiety, depression, and schizophrenia; and have led to the discovery of improved treatments. The study of neuropeptides and their receptors is a parallel frontier of neuropsychopharmacology research and has revealed the involvement of several peptide systems in mental illnesses and identified novel targets for their treatment. Relaxin-3 is a newly discovered neuropeptide that binds, and activates the G-protein coupled receptor, RXFP3. Existing anatomical and functional evidence suggests relaxin-3 is an arousal transmitter which is highly responsive to environmental stimuli, particularly neurogenic stressors, and in turn modulates behavioral responses to these stressors and alters key neural processes, including hippocampal theta rhythm and associated learning and memory. Here, we review published experimental data on relaxin-3/RXFP3 systems in rodents, and attempt to highlight aspects that are relevant and/or potentially translatable to the etiology and treatment of major depression and anxiety. Evidence pertinent to autism spectrum and metabolism/eating disorders, or related psychiatric conditions, is also discussed. We also nominate some key experimental studies required to better establish the therapeutic potential of this intriguing neuromodulatory signaling system, including an examination of the impact of RXFP3 agonists and antagonists on the overall activity of distinct or common neural substrates and circuitry that are identified as dysfunctional in these debilitating brain diseases

A Novel Ultra-Stable, Monomeric Green Fluorescent Protein for Direct Volumetric Imaging of Whole Organs Using CLARITY

Abstract Recent advances in thick tissue clearing are enabling high resolution, volumetric fluorescence imaging of complex cellular networks. Fluorescent proteins (FPs) such as GFP, however, can be inactivated by the denaturing chemicals used to remove lipids in some tissue clearing methods. Here, we solved the crystal structure of a recently engineered ultra-stable GFP (usGFP) and propose that the two stabilising mutations, Q69L and N164Y, act to improve hydrophobic packing in the core of the protein and facilitate hydrogen bonding networks at the surface, respectively. usGFP was found to dimerise strongly, which is not desirable for some applications. A point mutation at the dimer interface, F223D, generated monomeric usGFP (muGFP). Neurons in whole mouse brains were virally transduced with either EGFP or muGFP and subjected to Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging/Immunostaining/In situ hybridization-compatible Tissue-hYdrogel (CLARITY) clearing. muGFP fluorescence was retained after CLARITY whereas EGFP fluorescence was highly attenuated, thus demonstrating muGFP is a novel FP suitable for applications where high fluorescence stability and minimal self-association are required

Central injection of relaxin-3 receptor (RXFP3) antagonist peptides reduces motivated food seeking and consumption in C57BL/6J mice

Behavioural arousal in mammals is regulated by various interacting central monoamine- and peptide-neurotransmitter/receptor systems, which function to maintain awake, alert and active states required for performance of goal-directed activities essential for survival, including food seeking. Existing anatomical and functional evidence suggests the highly-conserved neuropeptide, relaxin-3, which signals via its cognate G(i/o)-protein coupled receptor, RXFP3, contributes to behavioural arousal and feeding behaviour in rodents. In studies to investigate this possibility further, adult male C57BL/6J mice were treated with the selective RXFP3 antagonist peptides, R3(B1-22)R/I5(A) and R3(B1-22)R, and motivated food seeking and consumption was assessed as a reflective output of behavioural arousal. Compared to vehicle treatment, intracerebroventricular (icv) injection of RXFP3 antagonists reduced: (i) food anticipatory activity before meal time during food restriction; (ii) consumption of highly palatable food; (iii) consumption of regular chow during the initial dark phase, and; (iv) consumption of regular chow after mild (similar to 4-h) food deprivation. Effects were not due to sedation and appeared to be specifically mediated via antagonism of relaxin-3/RXFP3 signalling, as RXFP3 antagonist treatment did not alter locomotor activity in wild-type mice or reduce palatable food intake in relaxin-3 deficient (knock-out) mice. Notably, in contrast to similar studies in the rat, icy injection of RXFP3 agonists and infusion into the paraventricular hypothalamic nucleus did not increase food consumption in mice, suggesting species differences in relaxin-3/RXFP3-related signalling networks. Together, our data provide evidence that endogenous relaxin-3/RXFP3 signalling promotes motivated food seeking and consumption, and in light of the established biological and translational importance of other arousal systems, relaxin-3/RXFP3 networks warrant further experimental investigation. (C) 2014 Elsevier B.V. All rights reserved

Synaptopathies: synaptic dysfunction in neurological disorders - A review from students to students

Synapses are essential components of neurons and allow information to travel coordinately throughout the nervous system to adjust behavior to environmental stimuli and to control body functions, memories, and emotions. Thus, optimal synaptic communication is required for proper brain physiology, and slight perturbations of synapse function can lead to brain disorders. In fact, increasing evidence has demonstrated the relevance of synapse dysfunction as a major determinant of many neurological diseases. This notion has led to the concept of synaptopathies as brain diseases with synapse defects as shared pathogenic features. In this review, which was initiated at the 13th International Society for Neurochemistry Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental disorders (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer and Parkinson disease). We finally discuss the appropriateness and potential implications of gathering synapse diseases under a single term. Understanding common causes and intrinsic differences in disease-associated synaptic dysfunction could offer novel clues toward synapse-based therapeutic intervention for neurological and neuropsychiatric disorders. In this Review, which was initiated at the 13th International Society for Neurochemistry (ISN) Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer's and Parkinson's diseases), gathered together under the term of synaptopathies

Perturbed BMP signaling and denervation promote muscle wasting in cancer cachexia

Most patients with advanced solid cancers exhibit features of cachexia, a debilitating syndrome characterized by progressive loss of skeletal muscle mass and strength. Because the underlying mechanisms of this multifactorial syndrome are incompletely defined, effective therapeutics have yet to be developed. Here, we show that diminished bone morphogenetic protein (BMP) signaling is observed early in the onset of skeletal muscle wasting associated with cancer cachexia in mouse models and in patients with cancer. Cancer-mediated factors including Activin A and IL-6 trigger the expression of the BMP inhibitor Noggin in muscle, which blocks the actions of BMPs on muscle fibers and motor nerves, subsequently causing disruption of the neuromuscular junction (NMJ), denervation, and muscle wasting. Increasing BMP signaling in the muscles of tumor-bearing mice by gene delivery or pharmacological means can prevent muscle wasting and preserve measures of NMJ function. The data identify perturbed BMP signaling and denervation of muscle fibers as important pathogenic mechanisms of muscle wasting associated with tumor growth. Collectively, these findings present interventions that promote BMP-mediated signaling as an attractive strategy to counteract the loss of functional musculature in patients with cancer