Overexpression of Sirt6 ameliorates sleep deprivation induced-cognitive impairment by modulating glutamatergic neuron function

Sleep benefits the restoration of energy metabolism and thereby supports neuronal plasticity and cognitive behaviors. Sirt6 is a NAD⁺-dependent protein deacetylase that has been recognized as an essential regulator of energy metabolism because it modulates various transcriptional regulators and metabolic enzymes. The aim of this study was to investigate the influence of Sirt6 on cerebral function after chronic sleep deprivation (CSD). We assigned C57BL/6J mice to control or two CSD groups and subjected them to AAV2/9-CMV-EGFP or AAV2/9-CMV-Sirt6-EGFP infection in the prelimbic cortex (PrL). We then assessed cerebral functional connectivity (FC) using resting-state functional MRI, neuron/astrocyte metabolism using a metabolic kinetics analysis; dendritic spine densities using sparse-labeling; and miniature excitatory postsynaptic currents (mEPSCs) and action potential (AP) firing rates using whole-cell patch-clamp recordings. In addition, we evaluated cognition via a comprehensive set of behavioral tests. Compared with controls, Sirt6 was significantly decreased (P < 0.05) in the PrL after CSD, accompanied by cognitive deficits and decreased FC between the PrL and accumbens nucleus, piriform cortex, motor cortex, somatosensory cortex, olfactory tubercle, insular cortex, and cerebellum. Sirt6 overexpression reversed CSD-induced cognitive impairment and reduced FC. Our analysis of metabolic kinetics using [1-¹³C] glucose and [2-¹³C] acetate showed that CSD reduced neuronal Glu₄ and GABA₂ synthesis, which could be fully restored via forced Sirt6 expression. Furthermore, Sirt6 overexpression reversed CSD-induced decreases in AP firing rates as well as the frequency and amplitude of mEPSCs in PrL pyramidal neurons. These data indicate that Sirt6 can improve cognitive impairment after CSD by regulating the PrL-associated FC network, neuronal glucose metabolism, and glutamatergic neurotransmission. Thus, Sirt6 activation may have potential as a novel strategy for treating sleep disorder-related diseases.