ИСТИНА

Introduction: Due to its high metabolic activity, the human brain consumes up to 20% of the total oxygen uptake of the body while at rest. However, various cell types of the brain are characterized by different profiles of energy metabolism and spatial organization of electron transport chain (ETC) complexes in the inner mitochondrial membrane. Rapid response of these cells to the changes in oxygen supply (e.g. locomotion, hypoxia, brain activity etc) underlies the normal functional activity of the brain. Therefore, the goal of the present study was to assess the redox state of the ETC complexes in astrocytes and neurons together with monitoring of the blood oxygenation in vessels in cortex of awake mice under locomotion. Methods: Astrocytes and neurons in the somatosensory cortex (S1) of C57Bl/6 mice were identified by the expression of green fluorescent protein and near infrared fluorescent protein respectively, following the AAVs injection. The redox state of the ETC complexes and blood oxygenation was assessed using Raman microspectroscopy with excitation wavelength of 532 nm. In addition, we used the mitochondrial form of genetically encoded sensor HyPer7 to monitor H 2 O 2 production in the mitochondria matrix. Results and discussion: The blood oxygenation level during locomotion increased in both arterioles and venules of the somatosensory cortex, wherein the relative amount of reduced cytochromes B and C reversibly decreased in neurons and increased in astrocytes in response to animals’ activity (running on the treadmill or grooming). Apart from ETC overloading in astrocytes we observed H 2 O 2 production in their mitochondria with no significant changes of H2O2 level in neurons. We suggest that H 2 O 2 produced in astrocytes’ mitochondria plays significant role in the intercellular signaling, contributing to synaptic plasticity. Research support: The work is supported by the Russian Science Foundation (grant 23-44-00015).