In VivoDetection of Extracellular Adenosine Triphosphate in a Mouse Model of Traumatic Brain Injury

Abstract

Traumatic brain injury (TBI) is traditionally characterized by primary and secondary injury phases, both contributing to pathological and morphological changes. The mechanisms of damage and chronic consequences of TBI remain to be fully elucidated, but synaptic homeostasis disturbances and impaired energy metabolism are proposed to be a major contributor. It has been proposed that an increase of extracellular (eATP) adenosine triphosphate (ATP) in the area immediately surrounding impact may play a pivotal role in this sequence of events. After tissue injury, rupture of cell membranes allows release of intracellular ATP into the extracellular space, triggering a cascade of toxic events and inflammation. ATP is a ubiquitous messenger; however, simple and reliable techniques to measure its concentration have proven elusive. Here, we integrate a sensitive bioluminescent eATP sensor known as pmeLUC, with a controlled cortical impact mouse model to monitor eATP changes in a living animal after injury. Using the pmeLUC probe, a rapid increase of eATP is observed proximal to the point of impact within minutes of the injury. This event is significantly attenuated when animals are pretreated with an ATP hydrolyzing agent (apyrase) before surgery, confirming the contribution of eATP. This new eATP reporter could be useful for understanding the role of eATP in the pathogenesis in TBI and may identify a window of opportunity for therapeutic intervention.

Blocking P2X7 by intracerebroventricular injection of P2X7-specific nanobodies reduces stroke lesions

“…Some of these endogenous danger signals can induce activation of the inflammasome and the secretion of proinflammatory cytokines by innate immune cells [ 4 , 38 ]. Using transgenic mice that express luciferase on the outer layer of the cell membrane, we showed that similar to traumatic brain injury [ 39 ], eATP is released very early during ischemic tissue damage. In addition, the signal is sustained over 24 h, clearly indicating an ongoing release of eATP in the ischemic tissue.…”

Gut-innervating TRPV1+ Neurons Drive Chronic Visceral Pain via Microglial P2Y12 Receptor

“…Such approach could be done using available sensitive and selective biosensors expressed in microglial cells of the spinal cord. 69 , 70 , 71 Microglia express several subtypes of ionotropic (P2XRs) and metabotropic purinergic receptors (P2YRs), which detect synaptic release of ATP. 34 The nature of purinergic responses is dose-dependent; low concentrations of ATP act via P2YRs, but high concentrations (millimolar range) activate P2XRs.…”

The utilization of small non‐mammals in traumatic brain injury research: A systematic review

“…On the other hand, the mammalian TBI model is more advanced in its robust research background focusing on the mechanism and important biomarkers. 117,[163][164][165][166][167][168] In addition to that, non-mammalian research has not conducted any research on inducing stem cell for brain injury as been conducted previously in this study with mammalian model. 169,170 Indeed, one of the study showed successful xenotransplantation of human iPSC-derived NSCs and isogenic neural cell progenies in a mouse model.…”