Biology subjects

Gobbo, D.

Publications and source records attributed to Gobbo, D..

7 recordsLinked to original sources

bioRxiv2024

Cannabidiol reverses microglia activation and loss of parvalbumin interneurons and perineuronal nets in a mouse model of schizophrenia

Cannabidiol (CBD) has shown potential for treating schizophrenia (SCZ) by targeting its positive, negative, and cognitive symptoms. In this study, we investigated if CBD could reverse the memory impairment observed after chronic administration of the NMDA receptor antagonist. MK-801 treatment (0.5 mg/kg i.p., twice a day, for 14 days) resulted in short- and long-term memory deficits and decreased relative power of {gamma} oscillation in freely moving animals. CBD administration (60 mg/kg i.p. daily for seven days after the MK-801 treatment period) reversed these changes. The positive cognitive effects of CBD were prevented by a 5-HT1A, but not a CB2, receptor antagonist. On the cellular level, CBD reversed MK-801-induced reduced number of parvalbumin-positive neurons and their associated perineuronal nets in the prelimbic medial prefrontal cortex (mPFC) and ventral hippocampus (vHip). This neuroprotective effect was mediated by 5-HT1A and CB2 receptors in the vHip but was independent of these receptors in the mPFC. Additionally, CBD reversed MK-801-induced microglial activation in both mPFC and vHip, again through 5-HT1A and CB2 receptors. These findings suggest that CBD modulates multiple pathways affected in SCZ-like conditions, offering a promising therapeutic avenue for SCZ treatment. Chemical compounds studied in this articleCBD (PubChem CID: 644019), MK-801 (PubChem CID: 180081), AM630 (PubChem CID: 4302963), WAY100635 (PubChem CID: 11957721).

neuroscience↗

bioRxiv2024

Genetic ablation of GABAB receptors from oligodendrocyte precursor cells protects against demyelination in the mouse spinal cord

GABAergic signaling and GABAB receptors play crucial roles in regulating the physiology of oligodendrocyte-lineage cells, including their proliferation, differentiation, and myelination. Therefore, they are promising targets for studying how spinal oligodendrocyte precursor cells (OPCs) respond to injuries and neurodegenerative diseases like multiple sclerosis. Taking advantage of the temporally controlled and cell-specific genetic removal of GABAB receptors from OPCs, our investigation addresses their specific influence on OPC behavior in the gray and white matter of the mouse spinal cord. Our results show that while GABAB receptors do not significantly alter OPC cell proliferation and differentiation under physiological conditions, they distinctly regulate the Ca2+ signaling of OPCs. In addition, we investigate the impact of OPC-GABAB receptors in two models of toxic demyelination, namely the cuprizone and the lysolecithin models. The genetic removal of OPC-GABAB receptors protects against demyelination and oligodendrocyte loss. Additionally, we observe enhanced resilience to cuprizone-induced pathological alterations in OPC Ca2+ signaling. Our results provide valuable insights into the potential therapeutic implications of manipulating GABAB receptors in spinal cord OPCs and deepen our understanding of the interplay between GABAergic signaling and spinal cord OPCs, providing a basis for future research.

neuroscience↗

bioRxiv2024

Neuronal lysosome transfer to oligodendrocyte precursor cells: a novel mechanism of neuron-glia communication and its role in neurodegenerative disease

Oligodendrocyte precursor cells (OPCs) shape brain function through intricate regulatory mechanisms. Here, we observed that OPC processes establish connections with neuronal somata, with smaller lysosomes positioned near these contact sites. Tracking lysosomes demonstrated neuronal lysosomes were attracted to and released at these contact points, eventually becoming incorporated into OPC processes, suggesting a selective, OPC-evoked release of lysosomes from neuronal soma and their ingestion by OPCs, highlighting a unique lysosome-mediated communication between neurons and OPCs. Diminished branching of OPC processes resulted in fewer neuron-OPC contacts, fostering larger lysosome accumulation in neurons, altered neuronal activity and escalated prevalence of senescent neurons during aging. A similar reduction in OPC branching and neuronal lysosome accumulation was evident in an early-stage Alzheimers disease mouse model. Together, these findings underscore the pivotal role of OPC processes in modulating neuronal activity through direct somatic contact and lysosome ingestion, presenting a prospective therapeutic avenue for addressing neurodegenerative diseases.

neuroscience↗

bioRxiv2023

Adenosine triggers astrocyte reactivity to drive the pathogenesis of sepsis-associated encephalopathy

Molecular pathways mediating systemic inflammation entering the brain parenchyma to induce sepsis-associated encephalopathy (SAE) remain elusive. Here, we report that in mice during the first 6 hours of peripheral lipopolysaccharide (LPS)-evoked systemic inflammation (6 hpi), the plasma level of adenosine quickly increased and enhanced the tone of central extracellular adenosine which then provoked neuroinflammation by triggering early astrocyte reactivity. Specific ablation of astrocytic A1 adenosine receptors (A1ARs) prevented this early reactivity and reduced the levels of inflammatory factors (e.g., CCL2, CCL5, and CXCL1) in astrocytes, thereby alleviating microglial activation, ameliorating blood-brain barrier disruption, neuronal dysfunction, and depression-like behaviour in the mice. Chemogenetic stimulation of Gi signaling in A1AR-deficent astrocytes at 2 and 4 hpi of LPS injection could restore neuroinflammation and depression-like behaviour, highlighting astrocytes rather than microglia as early drivers of neuroinflammation. Our results identify early astrocyte reactivity towards peripheral and central levels of adenosine as a novel pathway driving SAE.

neuroscience↗

bioRxiv2022

Novel algorithms for improved detection and analysis of fluorescent signal fluctuations

Fluorescent dyes and genetically encoded fluorescence indicators (GEFI) are common tools for visualizing concentration changes of specific ions and messenger molecules during intra-as well as intercellular communication. Using advanced imaging technologies, fluorescence indicators are a prerequisite for the analysis of physiological molecular signaling. Automated detection and avnalysis of fluorescence signals requires to overcome several challenges, including correct estimation of fluorescence fluctuations at basal concentrations of messenger molecules, detection and extraction of events themselves as well as proper segmentation of neighboring events. Moreover, event detection algorithms need to be sensitive enough to accurately capture localized and low amplitude events exhibiting a limited spatial extent. Here, we present two algorithms (PBasE and CoRoDe) for accurate baseline estimation of fluorescent detection of messenger molecules and automated detection of fluorescence fluctuations. Author summaryAnalyzing molecular signalling is crucial in understanding intra- and intercellular communication. These signals are visualized using fluorescent dyes or genetically encoded fluorescence indicators. In the brain, Ca2+ signals of glial cells are essential in deciphering complex regulatory functions in health and disease. Due to signal heterogeneity, detection and analysis are highly challenging. They can be stationary, with low amplitude and localized in cell processes, occur as prominent somatic signals or propagate as waves across cellular networks. We have developed two algorithms to analyze fluorescence transients, each tackling a specific problem. PBasE performs automatic and adaptive background correction, removing basal fluorescence fluctuations. CoRoDe automatically extracts regions of interest, explicitly including temporal information to obtain a precise segmentation, which is essential for accurate transient extraction. Combined, these algorithms are able to detect regions exhibiting low amplitude transients with small spatial extent as well as large, high amplitude signals. Extracted transients are categorized based on their peak amplitude, allowing detailed analyses by comparing changes of specific properties. In order to make these algorithms accessible, an interactive application, called Msparkles, has been designed.

neuroscience↗

bioRxiv2022

Architecture of the MKK6-p38α complex defines the basis of MAPK specificity and activation

The MAP kinase p38 is a central component of signalling in inflammation and the immune response and is, therefore, an important drug target. Little is known about the molecular mechanism of its activation by double-phosphorylation from MAP2Ks, due to the challenge of trapping a transient and dynamic hetero-kinase complex. Here, we applied a multidisciplinary approach to generate the first structure of p38 in complex with its MAP2K MKK6 and understand the activation mechanism. Integrating cryo-EM with MD simulations, HDX-MS and in cellulo experiments, we demonstrate a dynamic, multi-step, phosphorylation mechanism, reveal new catalytically relevant interactions, and show that MAP2K disordered N-termini determine pathway specificity. Our work captures, for the first time, a fundamental step of cell signalling: a kinase phosphorylating its downstream target kinase. One-Sentence SummaryIntegrative Cryo-EM and MD analysis of an active hetero-kinase complex reveals details of cellular signal transmission

biophysics↗

bioRxiv2022

Time-lapse Imaging of Microglial Activity and Astrocytic Calcium Signaling Reveals a Neuroprotective Effect of Cannabidiol in the Subacute Phase of Stroke

Pharmacological agents that limit secondary tissue loss and/or improve functional outcomes after stroke are still limited. Cannabidiol, the major non-psychoactive component of Cannabis sativa, has been proposed as a neuroprotective agent against experimental focal cerebral ischemia. The effects of cannabidiol have generally been related to the modulation of neuroinflammation, including the control of glial activation and the toxicity exerted by pro-inflammatory mediators. However, so far, most information concerning cannabidiol neuroprotective effects was obtained from histological and biochemical post-mortem assays. To test whether the effects of cannabidiol on glial cells could be also detected in vivo, we performed time-lapse imaging of microglial activity and astrocytic calcium signaling in the subacute phase of stroke using two-photon laser-scanning microscopy. First, C57BL/6N wild-type mice underwent either sham or transient middle cerebral artery occlusion surgery. The animals received intraperitoneal injection of vehicle or cannabidiol (10 mg/kg) 30 min, 24 h, and 48 h after surgery. One day later the neurological score test was performed. Brain tissue was processed to evaluate the neuronal loss and microglial activation. Transgenic mice with microglial expression of the enhanced green fluorescent protein and astrocyte-specific expression of the calcium sensor GCaMP3 were used to access in vivo microglial activity and astrocytic calcium signaling, respectively. The animals were submitted to the same experimental design described above and to imaging sessions before, 30 min, 24 h and, 48 h after surgery. Astrocytic calcium signaling was also assessed in acutely isolated slices 5 h after transient middle cerebral artery occlusion surgery in the presence of perfusion or cannabidiol solution. Cannabidiol prevented ischemia-induced neurological impairments as well as protected against neuronal loss in ischemic mice. Cannabidiol also reduced ischemia-induced microglial activation, as demonstrated in fixed tissue as well in in vivo conditions. No difference in the amplitude and duration of astrocytic calcium signals was detected before and after the middle cerebral artery occlusion in vivo. Similarly, no significant difference was found in the astrocytic calcium signals between contra and ipsilateral side of acutely isolated brain slices. The present results suggest that the neuroprotective effects of cannabidiol after stroke may occur in the subacute phase of ischemia and reinforce the strong anti-inflammatory property of this compound.

neuroscience↗