Biology subjects

Ramos-Cabrer, P.

Publications and source records attributed to Ramos-Cabrer, P..

5 recordsLinked to original sources

bioRxiv2026

Mitochondrial pyruvate import in astrocytes links anaplerosis to seizure resistance

Astrocytes are glycolytic cells that convert a substantial fraction of glucose-derived pyruvate into lactate, a metabolite implicated in supporting neuronal energy demand and modulating excitability, plasticity and memory. This view has placed astrocytic lactate production and export at the centre of astrocyte-neuron metabolic coupling, but whether mitochondrial pyruvate utilization in astrocytes is dispensable in vivo or fulfils an essential function in the intact brain remains unknown. Here we show that adult astrocyte-specific deletion of Mpc2, encoding an obligatory mitochondrial pyruvate carrier subunit, causes motor deficits, neuronal hyperexcitability and seizure-associated lethality. Metabolic profiling revealed pyruvate diversion toward alanine as an unsuccessful compensatory bypass, together with impaired tricarboxylic acid-cycle metabolism and an imbalance in neurotransmitter-related pools, including glutamate, glutamine and {gamma}-aminobutyric acid. Thus, astrocytic mitochondrial pyruvate import is not primarily required for bioenergetic purposes but acts as a non-redundant anaplerotic gate that maintains neurotransmitter homeostasis, excitation-inhibition balance and seizure resistance in vivo.

neuroscience↗

bioRxiv2024

SAMson: an automated brain extraction tool for rodents using SAM

Accurate brain extraction is a critical step in the analysis of rodent head magnetic resonance imaging (MRI) data. However, current methods often encounter difficulties in handling the diverse range of imaging setups, resolutions, and experimental conditions that are commonly found in this field. Based on the Segment Anything Model (SAM), we introduce here SAMson (SAM for Segmentation Of Neuroimages), an automated tool for robust rodent brain extraction. SAMson integrates a bounding box generator and a mask prediction pipeline, offering fully automated and semi-automated modes to address varying experimental complexities. The performance of SAMson was evaluated using three multi-centre rodent MRI datasets annotated at the pixel level, which differed in terms of acquisition parameters, resolution, and animal age groups. SAMson demonstrates superior performance to existing methods, including BET, RBM, and BEN, in terms of segmentation accuracy, with Jaccard indices exceeding 90% across datasets. The semi-automated mode demonstrates particular efficacy in challenging scenarios, including low-resolution images and cases requiring refined mask precision. In contrast to conventional volumetric techniques, SAMson identifies errors at the level of individual slices, thereby enabling rapid and targeted correction when needed. By providing open-source access, SAMson aims to support large-scale research workflows and advance translational neuroscience. The curated data can be downloaded from https://doi.org/10.20350/digitalCSIC/17000, and the code is available at https://github.com/CanalsLab/SAMson.

neuroscience↗

bioRxiv2023

Widespread drastic reduction of brain myelin content upon prolonged endurance exercise

Recent evidence suggests that myelin lipids may act as glial energy reserves when glucose is lacking, a hypothesis yet to be solidly proven. Hereby, we examined the effects of running a marathon on the myelin content by MRI. Our findings show that marathon runners undergo widespread robust myelin decrease at completion of the effort. This reduction involves white and gray matter, and includes primary motor and sensory cortical areas and pathways, as well as the entire corpus callosum and internal capsule. Notably, myelin levels partially recover within two weeks after the marathon. These results reveal that myelin use and replenishment is an unprecedented form of metabolic plasticity aimed to maintain brain function during extreme conditions. One-Sentence SummaryBrain myelin usage during strenuous exercise and recovery thereafter

neuroscience↗

bioRxiv2023

Weak neuronal glycolysis sustains cognition and organismal fitness

The energy cost of neuronal activity is mainly sustained by glucose1,2. However, in an apparent paradox, neurons only weakly metabolize glucose through glycolysis3,4,5,6, a circumstance that can be accounted for by the constant degradation of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (Pfkfb3)3,7,8, a key glycolysis-promoting enzyme. To evaluate the in vivo physiological significance of this hypo-glycolytic metabolism, here we genetically engineered mice with their neurons transformed into active glycolytic cells through Pfkfb3 expression. In vivo molecular, biochemical, and metabolic flux analyses of these neurons revealed an accumulation of anomalous mitochondria, complex I disassembly, bioenergetic deficiency and mitochondrial redox stress. Notably, glycolysis-mediated NAD+ reduction impaired sirtuin-dependent autophagy. Furthermore, these mice displayed cognitive decline and a metabolic syndrome that was mimicked by confining Pfkfb3 expression to hypothalamic neurons. Neuron-specific genetic ablation of mitochondrial redox stress corrected these alterations. Thus, the weak glycolytic nature of neurons is required to sustain higher-order organismal functions.

cell biology↗

bioRxiv2020

Monitoring the collective behavior of enzymatic nanomotors in vitro and in vivo by PET-CT

Enzyme powered nanomotors hold great potential for biomedical applications, as they show improved diffusion and navigation within biological environments using endogenous fuels. Yet, understanding their collective behavior and tracking them in vivo is paramount for their clinical translation. Here, we report on the in vitro and in vivo study of swarms of self-propelled enzyme-nanomotors and the effect of collective behavior on the nanomotors distribution within the bladder. For that purpose, mesoporous silica nanomotors were functionalized with urease enzymes and gold nanoparticles. Two radiolabeling strategies, i.e. absorption of 124I on gold nanoparticles and covalent attachment of an 18F-labeled prosthetic group to urease, were assayed. In vitro experiments using optical microscopy and positron emission tomography (PET) showed enhanced fluid mixing and collective migration of nanomotors in phantoms containing complex paths. Biodistribution studies after intravenous administration in mice confirmed the biocompatibility of the nanomotors at the administered dose, the suitability of PET to quantitatively track nanomotors in vivo, and the convenience of the 18F-labeling strategy. Furthermore, intravesical instillation of nanomotors within the bladder in the presence of urea resulted in a homogenous distribution after the entrance of fresh urine. Control experiments using BSA-coated nanoparticles or nanomotors in water resulted in sustained phase separation inside the bladder, demonstrating that the catalytic decomposition of urea can provide urease-nanomotors with active motion, convection and mixing capabilities in living reservoirs. This active collective dynamics, together with the medical imaging tracking, constitutes a key milestone and a step forward in the field of biomedical nanorobotics, paving the way towards their use in theranostic applications.Competing Interest StatementThe authors have declared no competing interest.View Full Text

bioengineering↗