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Jujuboside A prevents sleep loss-induced disturbance of hippocampal neuronal excitability and memory impairment in young APP/PS1 mice.

ABSTRACT: Sleep deprivation (SD) is the hallmark of modern society and may increase risk of Alzheimer's disease (AD). However, it is unclear how SD facilitates early cognitive impairments observed in AD models, as the underlying molecular mechanism is largely unknown. Here, we aim to investigate SD-induced cellular and molecular alterations in hippocampus of young APP/PS1 mice and whether jujuboside A (JuA) treatment could negate these alterations. Our results reveal that although SD causes spatial memory impairments in both genotypes, SD decreases frequency and amplitude of mEPSCs and pCREB levels in WT, but increases frequency and amplitude of mEPSCs, NMDAR, GluR1, pCaMKII (?, ?) and decreases CREB levels in APP/PS1 mice, implicating that SD may facilitate abnormalities in young APP/PS1 mice via enhancing neuronal excitability. Moreover, JuA suppresses SD-induced enhancement of mEPSCs and prevents memory impairment in APP/PS1 mice. Further, whole-cell puff experiment suggests that JuA may function to activate GABAergic inhibition to reduce SD-induced enhancement of excitatory synaptic transmission in APP/PS1 mice. The present study reveals that sleep loss induces spatial memory impairment in an AD mouse model by disrupting the excitatory signaling pathway, and JuA prevents this via GABAergic mechanism.

SUBMITTER: Tabassum S

PROVIDER: S-EPMC6418242 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Project description:In Alzheimer's disease (AD), the severity of cognitive symptoms is better correlated with the levels of soluble amyloid-beta (A?) rather than with the deposition of fibrillar A? in amyloid plaques. In APP/PS1 mice, a murine model of AD, at 8 months of age the cerebellum is devoid of fibrillar A?, but dosage of soluble A?(1-42), the form which is more prone to aggregation, showed higher levels in this structure than in the forebrain. Aim of this study was to investigate the alterations of intrinsic membrane properties and of synaptic inputs in Purkinje cells (PCs) of the cerebellum, where only soluble A? is present. PCs were recorded by whole-cell patch-clamp in cerebellar slices from wild-type and APP/PS1 mice. In APP/PS1 PCs, evoked action potential discharge showed enhanced frequency adaptation and larger afterhyperpolarizations, indicating a reduction of the intrinsic membrane excitability. In the miniature GABAergic postsynaptic currents, the largest events were absent in APP/PS1 mice and the interspike intervals distribution was shifted to the left, but the mean amplitude and frequency were normal. The ryanodine-sensitive multivescicular release was not altered and the postsynaptic responsiveness to a GABA(A) agonist was intact. Climbing fiber postsynaptic currents were normal but their short-term plasticity was reduced in a time window of 100-800 ms. Parallel fiber postsynaptic currents and their short-term plasticity were normal. These results indicate that, in the cerebellar cortex, chronically elevated levels of soluble A?(1-42) are associated with alterations of the intrinsic excitability of PCs and with alterations of the release of GABA from interneurons and of glutamate from climbing fibers, while the release of glutamate from parallel fibers and all postsynaptic mechanisms are preserved. Thus, soluble A?(1-42) causes, in PCs, multiple functional alterations, including an impairment of intrinsic membrane properties and synapse-specific deficits, with differential consequences even in different subtypes of glutamatergic synapses.

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Jujuboside A prevents sleep loss-induced disturbance of hippocampal neuronal excitability and memory impairment in young APP/PS1 mice.

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