The Anaesthetics Isoflurane and Xenon Reverse the Synaptotoxic Effects of Aβ1-42 on Megf10-Dependent Astrocytic Synapse Elimination and Spine Density in Ex Vivo Hippocampal Brain Slices

General anesthetic agents induce neurotoxicity through astrocytes

ABSTRACT

Neuroscientists have recognized the importance of astrocytes in regulating neurological function and their influence on the release of glial transmitters. Few studies, however, have focused on the effects of general anesthetic agents on neuroglia or astrocytes. Astrocytes can also be an important target of general anesthetic agents as they exert not only sedative, analgesic, and amnesic effects but also mediate general anesthetic-induced neurotoxicity and postoperative cognitive dysfunction. Here, we analyzed recent advances in understanding the mechanism of general anesthetic agents on astrocytes, and found that exposure to general anesthetic agents will destroy the morphology and proliferation of astrocytes, in addition to acting on the receptors on their surface, which not only affect Ca2+ signaling, inhibit the release of brain-derived neurotrophic factor and lactate from astrocytes, but are even involved in the regulation of the pro- and anti-inflammatory processes of astrocytes. These would obviously affect the communication between astrocytes as well as between astrocytes and neighboring neurons, other neuroglia, and vascular cells. In this review, we summarize how general anesthetic agents act on neurons via astrocytes, and explore potential mechanisms of action of general anesthetic agents on the nervous system. We hope that this review will provide a new direction for mitigating the neurotoxicity of general anesthetic agents.

Astrocytes Excessively Engulf Synapses in a Mouse Model of Alzheimer's Disease

Synapse loss is one of the most critical features in Alzheimer's disease (AD) and correlates with cognitive decline. Astrocytes mediate synapse elimination through multiple EGF-like domains 10 (MEGF10) pathways in the developing and adult brain to build the precise neural connectivity. However, whether and how astrocytes mediate synapse loss in AD remains unknown. We here find that the phagocytic receptor MEGF10 of astrocytes is significantly increased in vivo and in vitro, which results in excessive engulfment of synapses by astrocytes in APP/PS1 mice. We also observe that the astrocytic lysosomal-associated membrane protein 1 (LAMP1) is significantly elevated, colocalized with the engulfed synaptic puncta in APP/PS1 mice, and astrocytic lysosomes contain more engulfed synaptic puncta in APP/PS1 mice relative to wild type mice. Together, our data provide evidence that astrocytes excessively engulf synapses in APP/PS1 mice, which is mediated by increased MEGF10 and activated lysosomes. The approach targeting synapse engulfment pathway in astrocytes would be a potent therapy for AD.

Molecular Mechanism of Alzheimer's Disease

Neurodegenerative disorders are a major public health concern [...].

Absolute CO2 /Xenon Separation in Ultramicropore MOF for Anesthetic Gases Regeneration

Xe is an ideal anesthetic gas, but it has not been widely used in practice due to its high cost and low output. Closed-circuit Xe recovery and recycling is an economically viable method to ensure adequate supply in medical use. Herein, we design an innovative way to recover Xe by using a stable fluorinated metal-organic framework (MOF) NbOFFIVE-1-Ni to eliminate CO2 from moist exhaled anesthetic gases. Unlike other Xe recovery MOFs with low Xe/CO2 selectivity (less than 10), NbOFFIVE-1-Ni could achieve absolute molecular sieve separation of CO2 /Xe with excellent CO2 selectivity (825). Mixed-gas breakthrough experiments assert the potential of NbOFFIVE-1-Ni as a molecular sieve adsorbent for the effective and energy-efficient removal of carbon dioxide with 99.16 % Xe recovery. Absolute CO2 /Xe separation in NbOFFIVE-1-Ni makes closed-circuit Xe recovery and recycling can be easily realized, demonstrating the potential of NbOFFIVE-1-Ni for important anesthetic gas regeneration under ambient conditions.