Browsing by Author "Ardiles, Alvaro O."

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    A centronuclear myopathy-causing mutation in dynamin-2 disrupts neuronal morphology and excitatory synaptic transmission in a murine model of the disease
    (2023) Arriagada-Diaz, Jorge; Flores-Munoz, Carolina; Gomez-Soto, Barbara; Labrana-Allende, Marjorie; Mattar-Araos, Michelle; Prado-Vega, Lorena; Hinostroza, Fernando; Gajardo, Ivana; Guerra-Fernandez, Maria Jose; Bevilacqua, Jorge A.; Cardenas, Ana M.; Bitoun, Marc; Ardiles, Alvaro O.; Gonzalez-Jamett, Arlek M.
    AimsDynamin-2 is a large GTPase, a member of the dynamin superfamily that regulates membrane remodelling and cytoskeleton dynamics. Mutations in the dynamin-2 gene (DNM2) cause autosomal dominant centronuclear myopathy (CNM), a congenital neuromuscular disorder characterised by progressive weakness and atrophy of the skeletal muscles. Cognitive defects have been reported in some DNM2-linked CNM patients suggesting that these mutations can also affect the central nervous system (CNS). Here we studied how a dynamin-2 CNM-causing mutation influences the CNS function. MethodsHeterozygous mice harbouring the p.R465W mutation in the dynamin-2 gene (HTZ), the most common causing autosomal dominant CNM, were used as disease model. We evaluated dendritic arborisation and spine density in hippocampal cultured neurons, analysed excitatory synaptic transmission by electrophysiological field recordings in hippocampal slices, and evaluated cognitive function by performing behavioural tests. ResultsHTZ hippocampal neurons exhibited reduced dendritic arborisation and lower spine density than WT neurons, which was reversed by transfecting an interference RNA against the dynamin-2 mutant allele. Additionally, HTZ mice showed defective hippocampal excitatory synaptic transmission and reduced recognition memory compared to the WT condition. ConclusionOur findings suggest that the dynamin-2 p.R465W mutation perturbs the synaptic and cognitive function in a CNM mouse model and support the idea that this GTPase plays a key role in regulating neuronal morphology and excitatory synaptic transmission in the hippocampus.
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    Age Progression of Neuropathological Markers in the Brain of the Chilean Rodent Octodon degus, a Natural Model of Alzheimer's Disease
    (2015) Inestrosa Cantín, Nibaldo; Rios, Juvenal A.; Cisternas, Pedro; Tapia Rojas, Cheril Cecilia; Rivera, Daniela S.; Braidy, Nady; Zolezzi, Juan M.; Godoy, Juan A.; Carvajal Cachaña, Francisco Javier; Ardiles, Alvaro O.
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    Alzheimer's Disease-Related Protein Expression in the Retina of Octodon degus
    (2015) Du, Lucia Y.; Chang, Lily Y-L.; Ardiles, Alvaro O.; Tapia Rojas, Cheril Cecilia; Araya, Joaquin; Inestrosa Cantín, Nibaldo; Palacios, Adrian G.; Acosta, Monica L.
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    Evidence of Synaptic and Neurochemical Remodeling in the Retina of Aging Degus
    (2020) Chang, Lily Y-L; Ardiles, Alvaro O.; Tapia-Rojas, Cheril; Araya, Joaquin; Inestrosa, Nibaldo C.; Palacios, Adrian G.; Acosta, Monica L.
    Accumulation of amyloid-beta (A beta) peptides is regarded as the hallmark of neurodegenerative alterations in the brain of Alzheimer's disease (AD) patients. In the eye, accumulation of A beta peptides has also been suggested to be a trigger of retinal neurodegenerative mechanisms. Some pathological aspects associated with A beta levels in the brain are synaptic dysfunction, neurochemical remodeling and glial activation, but these changes have not been established in the retina of animals with A beta accumulation. We have employed the Octodon degus in which A beta peptides accumulated in the brain and retina as a function of age. This current study investigated microglial morphology, expression of PSD95, synaptophysin, Iba-1 and choline acetyltransferase (ChAT) in the retina of juvenile, young and adult degus using immunolabeling methods. Neurotransmitters glutamate and gamma-aminobutyric acid (GABA) were detected using immunogold labeling and glutamate receptor subunits were quantified using Western blotting. There was an age-related increase in presynaptic and a decrease in post-synaptic retinal proteins in the retinal plexiform layers. Immunolabeling showed changes in microglial morphology characteristic of intermediate stages of activation around the optic nerve head (ONH) and decreasing activation toward the peripheral retina. Neurotransmitter expression pattern changed at juvenile ages but was similar in adults. Collectively, the results suggest that microglial activation, synaptic remodeling and neurotransmitter changes may be consequent to, or parallel to A beta peptide and phosphorylated tau accumulation in the retina.
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    Octodon degus (Molina 1782): A model in comparative biology and biomedicine
    (2013) Ardiles, Alvaro O.; Ebensperger Pesce, Luis Alberto; Bozinovic Kuscevic, Francisco
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    Pannexin 1 regulates bidirectional hippocampal synaptic plasticity in adult mice
    (2014) Ardiles, Alvaro O.; Flores-Munoz, Carolina; Toro-Ayala, Gabriela; Cardenas, Ana M.; Palacios, Adrian G.; Munoz, Pablo; Fuenzalida, Marco; Saez, Juan C.; Martinez, Agustin D.
    The threshold for bidirectional modification of synaptic plasticity is known to be controlled by several factors, including the balance between protein phosphorylation and dephosphorylation, postsynaptic free Ca2+ concentration and NMDA receptor (NMDAR) composition of GluN2 subunits. Pannexin 1 (Panx1), a member of the integral membrane protein family, has been shown to form non-selective channels and to regulate the induction of synaptic plasticity as well as hippocampal-dependent learning. Although Panx1 channels have been suggested to play a role in excitatory long-term potentiation (LIP), it remains unknown whether these channels also modulate long-term depression (LTD) or the balance between both types of synaptic plasticity. To study how Panx1 contributes to excitatory synaptic efficacy, we examined the age-dependent effects of eliminating or blocking Panx1 channels on excitatory synaptic plasticity within the CA1 region of the mouse hippocampus. By using different protocols to induce bidirectional synaptic plasticity, Panx1 channel blockade or lack of Panx1 were found to enhance LIP whereas both conditions precluded the induction of LTD in adults, but not in young animals. These findings suggest that Panx1 channels restrain the sliding threshold for the induction of synaptic plasticity and underlying brain mechanisms of learning and memory.
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    Pannexin 1 regulates bidirectional hippocampal synaptic plasticity in adult mice.
    (2014) Ardiles, Alvaro O.; Sáez, Juan Carlos
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    Postsynaptic dysfunction is associated with spatial and object recognition memory loss in a natural model of Alzheimer's disease
    (2012) Ardiles, Alvaro O.; Tapia Rojas, Cheril Cecilia; Inestrosa Cantín, Nibaldo