Biology subjects

Sperlagh, B.

Publications and source records attributed to Sperlagh, B..

6 recordsLinked to original sources

bioRxiv2026

Targeting microglial P2Y12-receptor signalling attenuates neurodegeneration in experimental Parkinsons disease

Neuroinflammation is increasingly recognized as a determinant of dopaminergic neuron vulnerability in Parkinson's disease, yet the receptor-level mechanisms linking microglia to disease progression remain incompletely defined. We investigated whether microglial P2Y12 receptor (P2Y12R) signalling drives neurodegeneration in experimental Parkinsonism and assessed its pharmacological tractability. Tamoxifen-inducible microglia-specific P2ry12 deletion was examined in acute and subchronic MPTP models, with receptor deletion induced before or during disease progression. Neurodegeneration, neuroinflammation, neurochemistry, and motor function were evaluated, and novel P2Y12R antagonists identified by structure-based virtual screening were characterized in vitro and following central administration in vivo. Inducible microglia-specific P2Y12R deletion reduced nigrostriatal dopaminergic neuron loss, preserved dopamine synthesis, attenuated acute and sustained neuroinflammatory responses, and improved parkinsonian motor deficits without affecting survival. Importantly, delayed receptor deletion during ongoing neurodegeneration remained protective, indicating that P2Y12R contributes to disease progression. Two novel antagonists exhibited functional P2Y12R inhibition in vitro, and central administration of the most promising candidate recapitulated the neuroprotective phenotype observed following genetic receptor deletion. These findings identify microglial P2Y12R as a therapeutically relevant regulator of neuroinflammation and dopaminergic vulnerability and provide complementary genetic and pharmacological proof-of-concept for targeting central P2Y12R in Parkinsonism.

neuroscience↗

bioRxiv2026

P2X7 receptor-mediated astrocytic atrophy in the hippocampus of mice after status epilepticus

Genetic deletion or pharmacological blockade of P2X7 receptors (Rs) counteract status epilepticus (SE) in animal models of epilepsy. It is, however, unclear whether P2X7Rs are localized at astrocytes or neurons, and the reason for astrocytic atrophy arising in consequence of SE is also ambiguous. We conducted a combined morphological/electrophysiological study in order to investigate these issues. It has been shown that kainic acid (KA)-induced SE in mice led to the atrophy of hippocampal astrocytes and at the same time to the decrease of ezrin immunoreactivity and its co-expression with mCherry, whose synthesis has been initiated by the injection of a virus complex. mCherry expression in astrocytes enabled us to study changes in cell somata and processes brought about by KA-injection. Ezrin is a plasmalemmal-cytoskeleton linker; its grade of expression indicates changes in the existence/function of small peripheral astrocytic processes. Pretreatment of mice with the blood-brain barrier-permeable P2X7R antagonist JNJ-47965567 prevented the SE-induced damage of astrocytes. KA caused a potentiation of dibenzoyl-ATP (Bz-ATP) currents in astrocytes but not neurons of the hippocampus. This effect was also abolished by pre-treatment of mice with JNJ-47965567 before applying KA, although no similar changes occurred in hippocampal CA1 neurons. The measurement of spontaneous postsynaptic currents (sPSCs) and spontaneous excitatory postsynaptic currents (sEPSCs) indicated a presynaptic facilitation of neurotransmitter release by Bz-ATP. In conclusion, we suggest that astrocytic P2X7Rs are the primary target of ATP release from damaged CNS cells in the hippocampus which simultaneously causes damage to astrocytic somata and processes.

neuroscience↗

bioRxiv2021

Microglia control cerebral blood flow and neurovascular coupling via P2Y12R-mediated actions

Microglia, the main immunocompetent cells of the brain regulate neuronal function in health and disease, but their contribution to cerebral blood flow (CBF) remained elusive. Here we identify microglia as important modulators of CBF both under physiological conditions and during hypoperfusion. We show that microglia establish direct purinergic contacts with cells in the neurovascular unit that shape cerebral perfusion in both mice and humans. Surprisingly, the absence of microglia or blockade of microglial P2Y12 receptor (P2Y12R) substantially impairs neurovascular coupling in the barrel cortex after whisker stimulation. We also reveal that hypercapnia, which is associated with acidification, induces microglial adenosine production, while depletion of microglia reduces brain pH and impairs hypercapnia-induced vasodilation. Furthermore, the absence or dysfunction of microglia markedly impairs adaptation to hypoperfusion via P2Y12R after transient unilateral common carotid artery occlusion, which is also influenced by CX3CR1-mediated actions. Thus, our data reveal a previously unrecognized role for microglia in CBF regulation with broad implications for common neurological diseases.

neuroscience↗

bioRxiv2021

Central inhibition of P2Y12R differentially regulates survival and neuronal loss in MPTP-induced Parkinsonism in mice

Parkinsons disease (PD) is a chronic, progressive neurodegenerative condition; characterized with the degeneration of the nigrostriatal dopaminergic pathway and neuroinflammation. During PD progression, microglia, the resident immune cells in the central nervous system (CNS) display altered activity, but their role in maintaining PD development has remained unclear to date. The purinergic P2Y12 receptor (P2Y12R), which is exclusively expressed on the microglia in the CNS has been shown to regulate microglial activity and responses; however, the function of the P2Y12R in PD is unknown. Here we show that while pharmacological or genetic targeting of P2Y12R previous to disease onset augments acute mortality, these interventions protect against neurodegenerative cell loss and the development of neuroinflammation in vivo. Pharmacological inhibition of receptors during disease development reverses the symptoms of PD and halts disease progression. We found that P2Y12R regulate ROCK and p38 MAPK activity and control cytokine production. Understanding protective and detrimental P2Y12 receptor-mediated actions in the CNS may reveal novel approaches to control neuroinflammation and modify disease progression in PD.

neuroscience↗

bioRxiv2019

Microglia actively remodels adult hippocampal neurogenesis through the phagocytosis secretome

During adult hippocampal neurogenesis, the majority of newborn cells undergo apoptosis and are rapidly phagocytosed by resident microglia to prevent the spillover of their intracellular contents. Here, we propose that phagocytosis is not merely a passive process of corpse removal but has an active role in maintaining adult hippocampal neurogenesis. First, we found that neurogenesis was disrupted in mice chronically deficient for two microglial phagocytosis pathways (P2Y12 and MerTK/Axl), but was transiently increased in mice in which MerTK expression was conditionally downregulated. Next, we performed a transcriptomic analysis of microglial phagocytosis in vitro and identified genes involved in metabolism, chromatin remodeling, and neurogenesis-related functions. Finally, we discovered that the secretome of phagocytic microglia limits the production of new neurons both in vivo and in vitro. Our data suggest that reprogrammed phagocytic microglia act as a sensor of local cell death, modulating the balance between cell proliferation and cell survival in the neurogenic niche, thereby supporting the long-term maintenance of adult hippocampal neurogenesis.\n\nGRAPHICAL ABSTRACT

cell biology↗

bioRxiv2017

Non-blocking modulation as the major mechanism of sodium channel inhibition by riluzole

Modulated- or guarded receptor hypothesis; Channel block or modulation; \"Voltage-sensor block\" or \"lipophilic block\" are some of the questions that arise when drug effects on sodium channels are investigated. Understanding the exact mechanism of action for individual drugs is essential, because it is one of the major factors that determine their therapeutic applicability.\n\nIn this study we created a kinetic model of sodium channels, which can help us understand the modes of action for individual drugs in the context of these hypotheses. The model was constructed so that it could integrate the above hypotheses.\n\nIn particular we aimed to understand the mode of action of riluzole, a neuroprotective drug with a peculiar state-dependent inhibition. In experiments the inhibition by 100M riluzole was full within the first two milliseconds, but it was almost completely removed between 2 and 20 ms post-depolarization. This abrupt loss of inhibition could not be explained by dissociation, which was proceeding with a time constant of ~300 ms. We propose that for sodium channel inhibitors binding without blocking is possible, and riluzole predominantly inhibits by non-blocking modulation. We used lidocaine as a reference compound, and found that non-blocking modulation, although less prominent, also may play a role in its mechanism of inhibition. Non-blocking modulation may selectively inhibit cells with pathological activity patterns, therefore this property may be a good trait to investigate in the development of sodium channel inhibitor drugs.\n\nSUMMARYAlthough never actually proven, presence of sodium channel inhibitors at their binding site is assumed to prevent ion conduction. Authors provide evidence from experiments and kinetic simulations that bound riluzole permits conduction and exerts its inhibitory effect almost entirely by modulation.

pharmacology and toxicology↗