Neurocentre Magendie

Arnau BUSQUETS-GARCIA




Post-Doctorant

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14 publication(s) depuis Septembre 2009:


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09/11/2016 | Nature   IF 38.1
A cannabinoid link between mitochondria and memory.
Hebert-Chatelain E, Desprez T, Serrat R, Bellocchio L, Soria-Gomez E, Busquets-Garcia A, Zottola AC, Delamarre A, Cannich A, Vincent P, Varilh M, Robin LM, Terral G, Garcia-Fernandez MD, Colavita M, Mazier W, Drago F, Puente N, Reguero L, Elezgarai I, Dupuy JW, Cota D, Lopez-Rodriguez ML, Barreda-Gomez G, Massa F, Grandes P, Benard G, Marsicano G

Abstract:
Cellular activity in the brain depends on the high energetic support provided by mitochondria, the cell organelles which use energy sources to generate ATP. Acute cannabinoid intoxication induces amnesia in humans and animals, and the activation of type-1 cannabinoid receptors present at brain mitochondria membranes (mtCB1) can directly alter mitochondrial energetic activity. Although the pathological impact of chronic mitochondrial dysfunctions in the brain is well established, the involvement of acute modulation of mitochondrial activity in high brain functions, including learning and memory, is unknown. Here, we show that acute cannabinoid-induced memory impairment in mice requires activation of hippocampal mtCB1 receptors. Genetic exclusion of CB1 receptors from hippocampal mitochondria prevents cannabinoid-induced reduction of mitochondrial mobility, synaptic transmission and memory formation. mtCB1 receptors signal through intra-mitochondrial Galphai protein activation and consequent inhibition of soluble-adenylyl cyclase (sAC). The resulting inhibition of protein kinase A (PKA)-dependent phosphorylation of specific subunits of the mitochondrial electron transport system eventually leads to decreased cellular respiration. Hippocampal inhibition of sAC activity or manipulation of intra-mitochondrial PKA signalling or phosphorylation of the Complex I subunit NDUFS2 inhibit bioenergetic and amnesic effects of cannabinoids. Thus, the G protein-coupled mtCB1 receptors regulate memory processes via modulation of mitochondrial energy metabolism. By directly linking mitochondrial activity to memory formation, these data reveal that bioenergetic processes are primary acute regulators of cognitive functions.




19/08/2016 | oncotarget   IF 5
Glutamatergic stimulation induces GluN2B translation by the nitric oxide-Heme-Regulated eIF2alpha kinase in cortical neurons.
Ramos-Fernandez E, Tajes M, Ill-Raga G, Vargas L, Busquets-Garcia A, Bosch-Morato M, Guivernau B, Valls-Comamala V, Gomis M, Grau C, Fandos C, Rosen MD, Rabinowitz MH, Inestrosa N, Maldonado R, Altafaj X, Ozaita A, Alvarez A, Vicente R, Valverde MA, Munoz FJ

Abstract:
The activation of N-Methyl D-Aspartate Receptor (NMDAR) by glutamate is crucial in the nervous system function, particularly in memory and learning. NMDAR is composed by two GluN1 and two GluN2 subunits. GluN2B has been reported to participate in the prevalent NMDAR subtype at synapses, the GluN1/2A/2B. Here we studied the regulation of GluN2B expression in cortical neurons finding that glutamate up-regulates GluN2B translation through the action of nitric oxide (NO), which induces the phosphorylation of the eukaryotic translation initiation factor 2 alpha (eIF2alpha). It is a process mediated by the NO-heme-regulated eIF2alpha kinase (HRI), as the effect was avoided when a specific HRI inhibitor or a HRI small interfering RNA (siHRI) were used. We found that the expressed GluN2B co-localizes with PSD-95 at the postsynaptic ending, which strengthen the physiological relevance of the proposed mechanism. Moreover the receptors bearing GluN2B subunits upon NO stimulation are functional as high Ca2+ entry was measured and increases the co-localization between GluN2B and GluN1 subunits. In addition, the injection of the specific HRI inhibitor in mice produces a decrease in memory retrieval as tested by the Novel Object Recognition performance. Summarizing our data suggests that glutamatergic stimulation induces HRI activation by NO to trigger GluN2B expression and this process would be relevant to maintain postsynaptic activity in cortical neurons.




15/08/2016 | Proc Natl Acad Sci U S A   IF 9.6
Peripheral and central CB1 cannabinoid receptors control stress-induced impairment of memory consolidation.
Busquets-Garcia A, Gomis-Gonzalez M, Srivastava RK, Cutando L, Ortega-Alvaro A, Ruehle S, Remmers F, Bindila L, Bellocchio L, Marsicano G, Lutz B, Maldonado R, Ozaita A

Abstract:
Stressful events can generate emotional memories linked to the traumatic incident, but they also can impair the formation of nonemotional memories. Although the impact of stress on emotional memories is well studied, much less is known about the influence of the emotional state on the formation of nonemotional memories. We used the novel object-recognition task as a model of nonemotional memory in mice to investigate the underlying mechanism of the deleterious effect of stress on memory consolidation. Systemic, hippocampal, and peripheral blockade of cannabinoid type-1 (CB1) receptors abolished the stress-induced memory impairment. Genetic deletion and rescue of CB1 receptors in specific cell types revealed that the CB1 receptor population specifically in dopamine beta-hydroxylase (DBH)-expressing cells is both necessary and sufficient for stress-induced impairment of memory consolidation, but CB1 receptors present in other neuronal populations are not involved. Strikingly, pharmacological manipulations in mice expressing CB1 receptors exclusively in DBH+ cells revealed that both hippocampal and peripheral receptors mediate the impact of stress on memory consolidation. Thus, CB1 receptors on adrenergic and noradrenergic cells provide previously unrecognized cross-talk between central and peripheral mechanisms in the stress-dependent regulation of nonemotional memory consolidation, suggesting new potential avenues for the treatment of cognitive aspects on stress-related disorders.




23/09/2015 | Neuron   IF 14
Habenular CB Receptors Control the Expression of Aversive Memories.
Soria-Gomez E, Busquets-Garcia A, Hu F, Mehidi A, Cannich A, Roux L, Louit I, Alonso L, Wiesner T, Georges F, Verrier D, Vincent P, Ferreira G, Luo M, Marsicano G

Abstract:
Expression of aversive memories is key for survival, but the underlying brain mechanisms are not fully understood. Medial habenular (MHb) axons corelease glutamate and acetylcholine onto target postsynaptic interpeduncular (IPN) neurons, but their role in aversive memories has not been addressed so far. We found that cannabinoid type 1 receptors (CB1R), key regulators of aversive responses, are present at presynaptic terminals of MHb neurons in the IPN. Conditional deletion of CB1R from MHb neurons reduces fear-conditioned freezing and abolishes conditioned odor aversion in mice, without affecting neutral or appetitively motivated memories. Interestingly, local inhibition of nicotinic, but not glutamatergic receptors in the target region IPN before retrieval, rescues these phenotypes. Finally, optogenetic electrophysiological recordings of MHb-to-IPN circuitry revealed that blockade of CB1R specifically enhances cholinergic, but not glutamatergic, neurotransmission. Thus, presynaptic CB1R control expression of aversive memories by selectively modulating cholinergic transmission at MHb synapses in the IPN.




11/08/2015 | bioessays   IF 4.7
Dissecting the cannabinergic control of behavior: The where matters.
Busquets-Garcia A, Desprez T, Metna-Laurent M, Bellocchio L, Marsicano G, Soria-Gomez E

Abstract:
The endocannabinoid system is the target of the main psychoactive component of the plant Cannabis sativa, the Delta9 -tetrahydrocannabinol (THC). This system is composed by the cannabinoid receptors, the endogenous ligands, and the enzymes involved in their metabolic processes, which works both centrally and peripherally to regulate a plethora of physiological functions. This review aims at explaining how the site-specific actions of the endocannabinoid system impact on memory and feeding behavior through the cannabinoid receptors 1 (CB1 R). Centrally, CB1 R is widely distributed in many brain regions, different cell types (e.g. neuronal or glial cells) and intracellular compartments (e.g. mitochondria). Interestingly, cellular and molecular effects are differentially mediated by CB1 R according to their cell-type localization (e.g. glutamatergic or GABAergic neurons). Thus, understanding the cellular and subcellular function of CB1 R will provide new insights and aid the design of new compounds in cannabinoid-based medicine. Also watch the Video Abstract.




23/02/2015 | Antioxid Redox Signal   IF 7.6
Physiological Control of Nitric Oxide on neuronal BACE1 Translation by Heme-Regulated Eif2-alpha Kinase HRI Induces Synaptogenesis.
Ill-Raga G, Tajes M, Busquets-Garcia A, Ramos-Fernandez E, Vargas LM, Bosch-Morato M, Guivernau B, Valls-Comamala V, Eraso-Pichot A, Guix FX, Fandos C, Rosen MD, Rabinowitz MH, Maldonado R, Alvarez AR, Ozaita A, Munoz FJ

Abstract:
Aims: Hippocampus is the brain center for memory formation, a process that requires synaptogenesis. However hippocampus is dramatically compromised in Alzheimer's disease due to the accumulation of amyloid alpha-peptide, whose production is initiated by BACE1. It is known that pathological stressors activate BACE1 translation through the phosphorylation of the eukaryotic initiation factor-2alpha (eIF2alpha) by GCN2, PERK or PKR kinases leading to amyloidogenesis. However BACE1 physiological regulation is still unclear. Since nitric oxide (NO) participates directly in hippocampal glutamatergic signaling we investigated the neuronal role of the eIF2alpha kinase HRI, which can bind NO by a heme group, in BACE1 translation and its physiological consequences. Results: We found that BACE1 is expressed upon glutamate activation being NO the downstream effector by triggering eIF2alpha phosphorylation, as it was obtained by western blot and luciferase assay. It is due to the activation of HRI by NO as assayed by western blot and immunofluorescence with a HRI inhibitor and HRI siRNA. BACE1 expression was early detected at synaptic spines contributing to spine growth and consolidating the hippocampal memory as assayed with mice treated with HRI or neuronal NO synthase inhibitors. Innovation: We provide the first description that HRI and eIF2alpha are working in physiological conditions in brain under the control of nitric oxide and glutamate signaling, and also that BACE1 has a physiological role in hippocampal function. Conclusion: We conclude BACE1 translation is controlled by NO through HRI in glutamatergic hippocampal synapses where it plays physiological functions allowing the spine growth and memory consolidation.




14/05/2014 | Int J Biochem Cell Biol   IF 4.9
New insights into the molecular pathophysiology of fragile X syndrome and therapeutic perspectives from the animal model.
Busquets-Garcia A, Maldonado R, Ozaita A

Abstract:
Fragile X syndrome is the most common monogenetic form of intellectual disability and is a leading cause of autism. This syndrome is produced by the reduced transcription of the fragile X mental retardation (FMR1) gene, and it is characterized by a range of symptoms heterogeneously expressed in patients such as cognitive impairment, seizure susceptibility, altered pain sensitivity and anxiety. The recent advances in the understanding of the pathophysiological mechanisms involved have opened novel potential therapeutic approaches identified in preclinical rodent models as a necessary preliminary step for the subsequent evaluation in patients. Among those possible therapeutic approaches, the modulation of the metabotropic glutamate receptor signaling or the GABA receptor signaling have focused most of the attention. New findings in the animal models open other possible therapeutic approaches such as the mammalian target of rapamycin signaling pathway or the endocannabinoid system. This review summarizes the emerging data recently obtained in preclinical models of fragile X syndrome supporting these new therapeutic perspectives.




10/2013 | Neuropharmacology   IF 4.9
Synaptic plasticity alterations associated with memory impairment induced by deletion of CB2 cannabinoid receptors.
Garcia-Gutierrez MS, Ortega-Alvaro A, Busquets-Garcia A, Perez-Ortiz JM, Caltana L, Ricatti MJ, Brusco A, Maldonado R, Manzanares J

Abstract:
In this study, the role of CB(2)r on aversive memory consolidation was further evaluated. Mice lacking CB(2)r (CB2KO) and their corresponding littermates (WT) were exposed to the step-down inhibitory avoidance test (SDIA). MAP2, NF200 and synaptophysin (SYN)-immunoreactive fibers were studied in the hippocampus (HIP) of both genotypes. The number of synapses, postsynaptic density thickness and the relation between the synaptic length across the synaptic cleft and the distance between the synaptic ends were evaluated in the HIP (dentate gyrus (DG) and CA1 fields) by electron microscopy. Brain-derived neurotrophic factor (BDNF), glucocorticoid receptor (NR3C1) gene expressions and mTOR/p70S6K signaling cascade were evaluated in the HIP and prefrontal cortex (PFC). Finally, the effects of acute administration of CB(2)r-agonist JWH133 or CB2r-antagonist AM630 on memory consolidation were evaluated in WT mice by using the SDIA. The lack of CB(2)r impaired aversive memory consolidation, reduced MAP2, NF200 and SYN-immunoreactive fibers and also reduced the number of synapses in DG of CB2KO mice. BDNF and NR3C1 gene expression were reduced in the HIP of CB2KO mice. An increase of p-p70S6K (T389 and S424) and p-AKT protein expression was observed in the HIP and PFC of CB2KO mice. Interestingly, administration of AM630 impaired aversive memory consolidation, whereas JWH133 enhanced it. Further functional and molecular assessments would have been helpful to further support our conclusions. These results revealed that CB(2)r are involved in memory consolidation, suggesting that this receptor could be a promising target for developing novel treatments for different cognitive impairment-related disorders.




01/07/2013 | J Clin Invest   IF 12.6
Microglial activation underlies cerebellar deficits produced by repeated cannabis exposure.
Cutando L, Busquets-Garcia A, Puighermanal E, Gomis-Gonzalez M, Delgado-Garcia JM, Gruart A, Maldonado R, Ozaita A

Abstract:
Chronic cannabis exposure can lead to cerebellar dysfunction in humans, but the neurobiological mechanisms involved remain incompletely understood. Here, we found that in mice, subchronic administration of the psychoactive component of cannabis, delta9-tetrahydrocannabinol (THC), activated cerebellar microglia and increased the expression of neuroinflammatory markers, including IL-1beta. This neuroinflammatory phenotype correlated with deficits in cerebellar conditioned learning and fine motor coordination. The neuroinflammatory phenotype was readily detectable in the cerebellum of mice with global loss of the CB1 cannabinoid receptor (CB1R, Cb1(-/-) mice) and in mice lacking CB1R in the cerebellar parallel fibers, suggesting that CB1R downregulation in the cerebellar molecular layer plays a key role in THC-induced cerebellar deficits. Expression of CB2 cannabinoid receptor (CB2R) and Il1b mRNA was increased under neuroinflammatory conditions in activated CD11b-positive microglial cells. Furthermore, administration of the immunosuppressant minocycline or an inhibitor of IL-1beta receptor signaling prevented the deficits in cerebellar function in Cb1(-/-) and THC-withdrawn mice. Our results suggest that cerebellar microglial activation plays a crucial role in the cerebellar deficits induced by repeated cannabis exposure.




06/2013 | Neuropsychopharmacology   IF 7.8
Dissociation of the pharmacological effects of THC by mTOR blockade.
Puighermanal E, Busquets-Garcia A, Gomis-Gonzalez M, Marsicano G, Maldonado R, Ozaita A

Abstract:
The potential therapeutic benefits of cannabinoid compounds have raised interest in understanding the molecular mechanisms that underlie cannabinoid-mediated effects. We previously showed that the acute amnesic-like effects of delta9-tetrahydrocannabinol (THC) were prevented by the subchronic inhibition of the mammalian target of rapamycin (mTOR) pathway. In the present study, we assess the relevance of the mTOR pathway in other acute and chronic pharmacological effects of THC. The rapamycin derivative temsirolimus, an inhibitor of the mTOR pathway approved by the Food and Drug Administration, prevents both the anxiogenic- and the amnesic-like effects produced by acute THC. In contrast, THC-induced anxiolysis, hypothermia, hypolocomotion, and antinociception are not sensitive to the mTOR inhibition. In addition, a clear tolerance to THC-induced anxiolysis, hypothermia, hypolocomotion, and antinociception was observed after chronic treatment, but not to its anxiogenic- and amnesic-like effects. Temsirolimus pre-treatment prevented the amnesic-like effects of chronic THC without affecting the downregulation of CB1 receptors (CB1R) induced by this chronic treatment. Instead, temsirolimus blockade after chronic THC cessation did not prevent the residual cognitive deficit produced by chronic THC. Using conditional knockout mice lacking CB1R in GABAergic or glutamatergic neurons, we found that GABAergic CB1Rs are mainly downregulated under chronic THC treatment conditions, and CB1-GABA-KO mice did not develop cognitive deficits after chronic THC exposure. Therefore, mTOR inhibition by temsirolimus allows the segregation of the potentially beneficial effects of cannabinoid agonists, such as the anxiolytic and antinociceptive effects, from the negative effects, such as anxiogenic- and amnesic-like responses. Altogether, these results provide new insights for targeting the endocannabinoid system in order to prevent possible side effects.