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Information transfer within neuronal circuits depends on the balance and recurrent activity of excitatory and inhibitory neurotransmission. Chloride (Cl−) is the major central nervous system (CNS) anion mediating inhibitory neurotransmission. Astrocytes are key homoeostatic glial cells populating the CNS, although the role of these cells in regulating excitatory-inhibitory balance remains unexplored. Here we show that astrocytes act as a dynamic Cl− reservoir regulating Cl− homoeostasis in the CNS. We found that intracellular chloride concentration ([Cl−]i) in astrocytes is high and stable during sleep. In awake mice astrocytic [Cl−]i is lower and exhibits large fluctuation in response to both sensory input and motor activity. Optogenetic manipulation of astrocytic [Cl−]i directly modulates neuronal activity during locomotion or whisker stimulation. Astrocytes thus serve as a dynamic source of extracellular Cl− available for GABAergic transmission in awake mice, which represents a mechanism for modulation of the inhibitory tone during sustained neuronal activity. Astrocytes act as a dynamic Cl− reservoir regulating Cl− homeostasis in the CNS. Astrocytic Cl− is high and stable during sleep, it is lower during wakefulness and fluctuates in response to sensory input and motor activity. Efflux of Cl− from astrocytes supports inhibitory transmission in the CNS. [ABSTRACT FROM AUTHOR]

It is now well accepted that astrocytes are essential in all major nervous system functions of the rodent brain, including neurotransmission, energy metabolism, modulation of blood flow, ion and water homeostasis, and, indeed, higher cognitive functions, although the contribution of astrocytes in cognition is still in early stages of study. Here we review the most current research findings on human astrocytes, including their structure, molecular characterization, and functional properties. We also highlight novel tools that have been established for translational approaches to the comparative study of astrocytes from humans and experimental animals. Understanding the differences in astrocytes is essential to elucidate the contribution of astrocytes to normal physiology, cognitive processing and diverse pathologies of the central nervous system. [ABSTRACT FROM AUTHOR]

Focuses on the study published in the 'Proceedings of the National Academy of Science USA,' that suggests erythropoietin (EPO), recognized as a potent neuroprotective cytokine, as a potential treatment for spinal cord injury. Functional improvement made under the EPO treatment; Neuroprotective effects of EPO; Features of EPO.