Background
Adolescent methamphetamine exposure causes a broad range of neurobiological deficits in adulthood. Glycogen synthase kinase-3β is involved in various cognitive and behavioral processes associated with methamphetamine exposure. This study aims to investigate the protective effects of the glycogen synthase kinase-3β inhibitor lithium chloride on adolescent methamphetamine exposure-induced long-term alterations in emotion, cognition, behavior, and molecule and hippocampal ultrastructure in adulthood.
Methods
A behavioral test battery was used to investigate the protective effects of lithium chloride on adolescent methamphetamine exposure-induced long-term emotional, cognitive, and behavioral impairments in mice. Western blotting and immunohistochemistry were used to detect glycogen synthase kinase-3β activity levels in the medial prefrontal cortex and dorsal hippocampus. Electron microscopy was used to analyze changes in synaptic ultrastructure in the dorsal hippocampus. Locomotor sensitization with a methamphetamine (1 mg/kg) challenge was examined 80 days after adolescent methamphetamine exposure.
Results
Adolescent methamphetamine exposure induced long-term alterations in locomotor activity, novel spatial exploration, and social recognition memory; increases in glycogen synthase kinase-3β activity in dorsal hippocampus; and decreases in excitatory synapse density and postsynaptic density thickness in CA1. These changes were ameliorated by lithium chloride pretreatment. Adolescent methamphetamine exposure-induced working memory deficits in Y-maze spontaneous alternation test and anxiety-like behavior in elevated-plus maze test spontaneously recovered after long-term methamphetamine abstinence. No significant locomotor sensitization was observed after long-term methamphetamine abstinence.
Conclusions
Hyperactive glycogen synthase kinase-3β contributes to adolescent chronic methamphetamine exposure-induced behavioral and hippocampal impairments in adulthood. Our results suggest glycogen synthase kinase-3β may be a potential target for the treatment of deficits in adulthood associated with adolescent methamphetamine abuse.
Abstract:It is believed that amyloid-β peptide (Aβ) plays a central role in the pathogenesis of Alzheimer's disease (AD). Thus, the process of amyloid precursor protein (APP) cleavage is a key event and has raised much attention in the field of AD research. It is proposed that APP, β-and γ-secretases are all located on the lipid raft, and the meeting of them is an indispensable step for Aβ generation. Endocytosis can lead to clustering of APP, β-and γ-secretases from separate smaller lipid rafts into a larger one. On the other hand, for myristoylated alanine-rich C kinase substrate (MARCKS), phosphorylation by protein kinase C (PKC) or interaction with Ca 2+ can lead to its release from membrane into cytoplasm. This process induces the release of actins and phosphatidylinositol 4, 5-bisphosphate (PIP 2 ), which are important factors for endocytosis. Thus, the present review proposes that MARCKS may be implicated in Aβ generation, by modulating free PIP 2 level and actin movement, causing endocytosis.
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