Lipocalin-2 (LCN2), a secreted glycoprotein belonging to the lipocalin superfamily was reported to participate in various biological processes including cell migration, cell survival, inflammatory responses, and insulin sensitivity. LCN2 is expressed in the multiple tissues such as kidney, liver, uterus, and bone marrow. The receptors for LCN2 were additionally found in microglia, astrocytes, epithelial cells, and neurons, but the role of LCN2 in the central nervous system (CNS) has not been fully understood yet. Recently, in vitro, in vivo, and clinical studies reported the association between LCN2 and the risk of Alzheimer's disease (AD). Here, we reviewed the significant evidences showing that LCN2 contributes to the onset and progression of AD. It may suggest that the manipulation of LCN2 in the CNS would be a crucial target for regulation of the pathogenesis and risk of AD.
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The purpose of this study is to investigate whether nicotinic acid (NA) and nicotinamide (NAM) reduce the Alzheimer disease (AD)-related gene expression in brain tissues of amyloid beta (Aβ)-injected mice. Male Crj:CD1 (ICR) mice were divided into 6 treatment groups; 1) control, 2) Aβ control, 3) Aβ + NA 20 mg/kg/day (NA20), 4) Aβ + NA40, 5) Aβ + NAM 200 mg/kg/day (NAM200), and 6) Aβ + NAM400. After 1-week acclimation period, the mice orally received NA or NAM once a day for a total of 7 successive days. On day 7, biotinylated Aβ42 was injected into mouse tail vein. At 5 hours after the injection, blood and tissues were collected. Aβ42 injection was confirmed by Western blot analysis of Aβ42 protein in brain tissue. NAM400 pre-treatment significantly reduced the gene expression of amyloid precursor protein and presenilin 1 in brain tissues. And, NAM200 and NAM400 pre-treatments significantly increased sirtuin 1 expression in brain tissues, which is accompanied by the decreased brain expression of nuclear factor kappa B by 2 doses of NAM. Increased expression of AD-related genes was attenuated by the NAM treatment, which suggests that NAM supplementation may be a potential preventive strategy against AD-related deleterious changes.
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