Search

Objective To investigate the potential signal transduction mechanism of β-amyloid protein 1-42 (Aβ1-42) induced up-regulation of ATP sensitive potassium channel KATP subunit SUR1/Kir6.2 proteins expression. Methods The primary cultured cortical and hippocampal neurons of rats were identified by immunocytochemistry. The experimental groups were added with 0.50 μmol/L nuclear factor - kB (NF-kB) inhibitor SN50, 2 μmol/L p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 or 2 μmol/L protein kinease C (PKC) inhibitor CTC, 2 μmol/L Aβ1-42 (30 min later), respectively. Western blotting was used to detect the protein expression of KATP subunit SUR1/Kir6.2 after 72 h of culture. Results 1) NF-kB inhibitor SN50: SUR1/Kir6.2 proteins of KATP subunit in SN50 + Aβ1-42 group were lower than that in control group (t = 6.237, P = 0.010; t = 7.136, P = 0.004) and Aβ1-42 group (t = 12.620, P = 0.000; t = 18.580, P = 0.000), but the SUR1 protein expression of KATP subunit in SN50 + Aβ1-42 group was higher than that in SN50 group (t = 6.002, P = 0.012). SUR1/Kir6.2 proteins of KATP subunit in SN50 group were lower than that in control group (t = 12.240, P = 0.000; t = 4.906, P = 0.034) and Aβ1-42 group (t = 18.620, P = 0.000; t = 16.350, P = 0.000). 2) p38 MAPK inhibitor SB203580: the proteins expression of KATP subunit SUR1/Kir6.2 in SB203580 + Aβ1-42 group were lower than that in Aβ1-42 group (t = 13.010, P = 0.000; t = 8.506, P = 0.001), but higher than that in SB203580 group (t = 5.869, P = 0.014; t = 26.920, P = 0.000), but the expression of KATP subunit Kir6.2 protein in SB203580 + Aβ1-42 group was higher than that in control group (t = 7.537, P = 0.003). The SUR1/Kir6.2 proteins expression of KATP subunit in SB203580 group were lower than that in control group (t = 8.089, P = 0.002; t = 19.380, P = 0.003) and Aβ1-42 group (t = 18.870, P = 0.000; t = 35.430, P = 0.000). 3) PKC inhibitor CTC: the SUR1 protein expression of KATP subunit in CTC + Aβ1-42 group was higher than that in control group (t = 4.756, P = 0.040) and in CTC group (t = 28.760, P = 0.000), but lower than that in Aβ1-42 group (t = 15.170, P = 0.000). The SUR1 protein expression of KATP subunit in CTC group was lower than that in control group (t = 24.000, P = 0.000), Aβ1-42 group (t = 43.930, P = 0.000) and CTC + Aβ1-42 group. The protein expression of KATP subunit Kir6.2 in CTC + Aβ1-42 group was lower than that in control group (t = 15.000, P = 0.000), Aβ1-42 group (t = 24.140, P = 0.000) and CTC group (t = 5.571, P = 0.018). The expression of KATP subunit Kir6.2 protein in CTC group was lower than that in control group (t = 9.429, P = 0.001) and in Aβ1-42 group (t = 18.570, P = 0.000). Conclusions NF-kB, p38 MAPK and PKC signaling pathways are involved in Aβ1-42 up-regulation of SUR1/Kir6.2 proteins expression of KATP subunit in cortical and hippocampal neurons of rats. [ABSTRACT FROM AUTHOR]

Study Question: Does metformin inhibit excessive androgen-induced endoplasmic reticulum (ER) stress in mouse granulosa cells (GCs) in vivo and in vitro?, Summary Answer: Metformin inhibits testosterone-induced ER stress and unfolded protein response (UPR) activation by suppressing p38 MAPK phosphorylation in ovarian GCs., What Is Known Already: Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism. Excessive testosterone induces ER stress and UPR activation in human cumulus cells, leading to cell apoptosis. Metformin has potential inhibitory effects on ER stress and UPR activation, as demonstrated in human pancreatic beta cells and obese mice., Study Design, Size, Duration: Cumulus cells and follicular fluid were collected from 25 women with PCOS and 25 controls at our IVF centre. A dihydrotestosterone (DHT)-induced PCOS mouse model was constructed and treated with or without metformin. Primary mouse GCs and cumulus-oocyte complexes (COCs) were cultured with testosterone, metformin, a p38 MAPK inhibitor, or p38 MAPK small interfering RNA., Participants/materials, Setting, Methods: The levels of UPR sensor proteins and UPR-related genes were measured in cumulus cells from PCOS and control patients by real-time quantitative PCR (qPCR) and western blot. The ovaries, oocytes, GCs and COCs were collected from PCOS mice treated with metformin and controls. The expressions of ER stress markers and p38 MAPK phosphorylation were assessed by qPCR, western blot and immunofluorescence. A subsequent in vitro analysis with primary cultured GCs and COCs was used to confirm the influence of metformin on ER stress activation by qPCR and western blot. Finally, the effects of ER stress activation on GCs and COCs in relation to LH responsiveness were examined by qPCR and COC expansion., Main Results and the Role of Chance: The expression of the ER stress markers GRP78, CHOP and XBP1s in the cumulus cells was higher in PCOS patients than in control patients, as were the levels of the UPR sensor proteins p-IRE1α, p-EIF2α and GRP78. Compared to those of control mice, the ovaries, GCs and COCs of DHT-treated PCOS mice showed increased levels of ER stress marker genes and proteins. Hyperandrogenism in PCOS mouse ovaries also induced p38 MAPK phosphorylation in COCs and GCs. Metformin inhibited ER stress activation was associated with decreased p-p38 MAPK levels. In vitro experiments, testosterone-induced ER stress was mitigated by metformin or p38 MAPK inhibition in primary cultured GCs and COCs. COCs expanded rapidly in the presence of testosterone during LH administration, and ovulation-related genes, namely, Areg, Ereg, Ptgs2, Sult1e1, Ptx3 and Tnfaip6, were strongly expressed in the COCs and GCs. These effects were reversed by treatment with metformin, an ER stress inhibitor or by knockdown of p38 MAPK., Limitations, Reasons for Caution: The number of PCOS patients in this study was small., Wider Implications of the Findings: This study provides further evidence for metformin as a PCOS treatment., Study Funding/competing Interest(s): This study was funded by the National Key Research and Developmental Program of China (2018YFC1004800), the Key Research and Development Program of Zhejiang Province (2017C03022), the Zhejiang Province Medical Science and Technology Plan Project (2017KY085, 2018KY457), the National Natural Science Foundation of China (31701260, 81401264, 81701514), and the Special Funds for Clinical Medical Research of the Chinese Medical Association (16020320648). The authors report no conflict of interest in this work and have nothing to disclose., Trial Registration Number: N/A., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.)

Investigation into the chemical diversity of Artemisia argyi led to the discovery of four new (1-4) and one known (5) guaianolide sesquitenpenoid dimers linked via ester bond, and five other known mono-sesquiterpenoids (6-10). Their structures were determined via extensive spectroscopic data, and the absolute configurations of these compounds were elucidated by calculated ECD analysis and chemical method. The dimeric sesquiterpenoids exhibited NO production inhibitory activity with IC 50 values ranging from 7.02 to 32.1 μM. The studies further suggested that compound 2 inhibited inflammatory responses via suppression of the expression of iNOS, resulting from activation of nuclear factor-kappaB (NF-κB) and phosphorylation of MAPKs (ERK and p38)., (Copyright © 2018 Elsevier B.V. All rights reserved.)