P2X7 Receptor-Dependent Layer-Specific Changes in Neuron-Microglia Reactivity in the Prefrontal Cortex of a Phencyclidine Induced Mouse Model of Schizophrenia

Abstract

Background : It has been consistently reported that the deficiency of the adenosine triphosphate (ATP) sensitive purinergic receptor P2X7 (P2X7R) ameliorates symptoms in animal models of brain diseases. Objective : This study aimed to investigate the role of P2X7R in rodent models of acute and subchronic schizophrenia based on phencyclidine (PCP) delivery in animals lacking or overexpressing P2X7R, and to identify the underlying mechanisms involved. Methods : The psychotomimetic effects of acute i.p. PCP administration in C57Bl/6J wild-type, P2X7R knockout (P2rx7 −/− ) and overexpressing (P2X7-EGFP) young adult mice were quantified. The medial prefrontal cortex (mPFC) of P2rx7 −/− and heterozygous P2X7-EGFP acutely treated animals was characterized through immunohistochemical staining. The prefrontal cortices of young adult P2rx7 −/− and P2rx7 tg/+ mice were examined with tritiated dopamine release experiments and the functional properties of the mPFC pyramidal neurons in layer V from P2rx7 −/− mice were assessed by patch-clamp recordings. P2rx7 −/− animals were subjected to a 7 days subchronic systemic PCP treatment. The animals working memory performance and PFC cytokine levels were assessed. Results : Our data strengthen the hypothesis that P2X7R modulates schizophrenia-like positive and cognitive symptoms in NMDA receptor antagonist models in a receptor expression level-dependent manner. P2X7R expression leads to higher medial PFC susceptibility to PCP-induced circuit hyperactivity. The mPFC of P2X7R knockout animals displayed distinct alterations in the neuronal activation pattern, microglial organization, specifically around hyperactive neurons, and were associated with lower intrinsic excitability of mPFC neurons. Conclusions : P2X7R expression exacerbated PCP-related effects in C57Bl/6J mice. Our findings suggest a pleiotropic role of P2X7R in the mPFC, consistent with the observed behavioral phenotype, regulating basal dopamine concentration, layer-specific neuronal activation, intrinsic excitability of neurons in the mPFC, and the interaction of microglia with hyperactive neurons. Direct measurements of P2X7R activity concerning microglial ramifications and dynamics could help to further elucidate the molecular mechanisms involved.

Detection and Functional Evaluation of the P2X7 Receptor in hiPSC Derived Neurons and Microglia-Like Cells

“…This ATP serves as a damage-associated molecular pattern (DAMP) which is detected by microglial cells via their purinergic receptors. From amongst both ionotropic (P2X) and metabotropic (P2Y) ATP-gated purinergic receptors ( Huang et al, 2019 ), the P2X7R has attracted most attention due to its unique characteristics such as its low affinity to ATP ( Surprenant et al, 1996 ) and the suggested involvement in a broad range of neurodegenerative diseases such as AD ( Martin et al, 2019 ; Francistiová et al, 2020 ), epilepsy ( Engel et al, 2012 ; Conte et al, 2020 ; Morgan et al, 2020 ), schizophrenia ( Calovi et al, 2020 ), Huntington’s disease ( Ollà et al, 2020 ) and many others. Moreover, another property of the P2X7R is its ability to induce macropore formation upon exposure to high concentrations of ATP ( Di Virgilio et al, 2018 ).…”

Interneuron Heterotopia in the Lis1 Mutant Mouse Cortex Underlies a Structural and Functional Schizophrenia-Like Phenotype

“…Proteins coded by immediate-early genes such as cFOS , are considered markers of neuronal activity in the central nervous system ( Sagar et al, 1988 ; Herdegen et al, 1995 ; Kontkanen et al, 2002 ). Moreover, it has been established that the number of cFOS-expressing neurons increases in animal models of schizophrenia ( Celada et al, 2013 ; Hervig et al, 2016 ; Calovi et al, 2020 ). Here, we analyzed the distribution pattern of cFOS immunopositive cells in the hippocampal areas, mPFC, PERI, ECT, and ENT of both control and Lis1/sLis1 mutant mice.…”

“…For the last three decades, the cFOS protein has been used as a marker for transcriptional activity ( Sagar et al, 1988 ), and cFOS immunohistochemistry allows the labeling of stimulated neurons. Previous studies using pharmacological mouse models for SZ have shown that phencyclidine (PCP) and related drugs increased cFOS expression levels in the mPFC and hippocampus ( Näkki et al, 1996 ; Sato et al, 1997 ; Kargieman et al, 2007 ; Santana et al, 2011 ; Castañé et al, 2015 ; Calovi et al, 2020 ). Moreover, it has been reported that cFOS expression induced by PCP occurs in GAD67+ interneurons, specifically in the hippocampus, RSC, amygdala, and somatosensory cortex ( Santana et al, 2011 ).…”

Beyond Seizure Control: Treating Comorbidities in Epilepsy via Targeting of the P2X7 Receptor

“…Similar to anti-depressants, several drugs used to treat schizophrenia (e.g., prochlorperazine, trifluoperazine) have been shown to alter P2X7R function [174]. While no association between schizophrenia and several P2X7R polymorphisms has been reported [175], recent studies in a mouse model using the chemical phencyclidine (PCP) have provided encouraging data showing that P2X7R knockout and treatment with specific P2X7R antagonists alleviated several schizophrenic-like parameters at the molecular and behavioural levels [27,176,177].…”