23 February 2018 In vivo measurement of astrocytic endfoot Ca2+ and parenchymal vessel responses during 4-AP induced epilepsy using two-photon fluorescence lifetime microscopy
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Abstract
Neurovascular coupling (NVC) is defined as a local increase in cerebral blood flow in response to neuronal activity, it forms the basis of functional brain imaging and is altered during epilepsy. Because astrocytic calcium signaling (Ca2+) has been involved in the response of parenchymal vessels, this study investigates the role of this pathway during epilepsy. We exploit 4-Aminopyridine (4-AP) induced epileptic seizures to show that absolute Ca2+ concentration in astrocytic endfeet correlates with the changes in diameter of parenchymal vessels during neural activity in vivo. A two-photon laser scanning fluorescence lifetime microscopy was developed to simultaneously monitor free Ca2+ concentration in astrocytic endfeet with the calcium-sensitive indicator Oregon Green 488 BAPTA-1 (OGB-1) and the diameter of parenchymal vessels in the somatosensory cortex of mice following 4-AP injection. Our results reveal that the resting Ca2+ concentration in glial cells was spatially heterogeneous and that resting Ca2+ concentration in somatic regions was significantly higher than in endfoot regions. Moreover, following 4-AP injection in the somatosensory cortex of mice, we observed increases of Ca2+ in astrocytic endfeet associated with vasodilation of parenchymal vessels for each individual ictal event in the epileptic focus. However, vasodilation was seen to be inhibited by increase in absolute resting Ca2+ concentration. Our results suggest a role for baseline astrocytic Ca2+ concentration in vasodilation.
Conference Presentation
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Cong Zhang, Cong Zhang, Maryam Tabatabaei, Maryam Tabatabaei, Samuel Bélanger, Samuel Bélanger, Hélène Girouard, Hélène Girouard, Mohammad Moeini, Mohammad Moeini, Xuecong Lu, Xuecong Lu, Frédéric Lesage, Frédéric Lesage, } "In vivo measurement of astrocytic endfoot Ca2+ and parenchymal vessel responses during 4-AP induced epilepsy using two-photon fluorescence lifetime microscopy", Proc. SPIE 10498, Multiphoton Microscopy in the Biomedical Sciences XVIII, 104980X (23 February 2018); doi: 10.1117/12.2290579; https://doi.org/10.1117/12.2290579
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