RESUMO
This study aimed to investigate the changes in oxidative stress, adenosine monophosphate-activated protein kinase (AMPK), connexin43 (Cx43), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) expression, and extracellular matrix (ECM) in the gastric smooth muscle tissues of rats with diabetic gastroparesis (DGP) and high glucose-cultured gastric smooth muscle cells, determine the existence of oxidative stress-AMPK-Cx43-NLRP3 pathway under high glucose condition, and the involvement of this pathway in ECM remodeling in DGP rats. The results showed that with increasing duration of diabetes, oxidation stress levels gradually increased, the AMPK activity decreased first and then increased, NLRP3, CX43 expression, and membrane/cytoplasm ratio of Cx43 expression were increased in the gastric smooth muscle tissues of diabetic rats. Changes in ECM of gastric smooth muscle cells were observed in DGP rats. The DGP group showed higher collagen type I content, increased expression of Caspase-1, transforming growth factor-beta 3 (TGF-ß3), and matrix metalloproteinase-2 (MMP-2), decreased tissue inhibitor of metalloproteinase-1 (TIMP-1) expression, and higher interleukin-1 beta content when compared with the control group. For gastric smooth muscle cells cultured under higher glucose, the MMP-2 and TGF-ß3 expression was decreased, TGF-ß1 and TIMP-1 expression was increased, the interleukin-1 beta content was decreased in cells after inhibition of NLRP3 expression; the NLRP3 and Caspase-1 expression was decreased, and adenosine triphosphate content was lower after inhibition of Cx43; the expression of NLRP3, Caspase-1, P2X7, and the membrane/cytoplasm ratio of CX43 expression was decreased in cells after inhibition of AMPK and oxidative stress, the phospho-AMPK expression was also decreased after suppressing oxidative stress. Our findings suggest that high glucose induced the activation of the AMPK-Cx43-NLRP3 pathway through oxidative stress, and this pathway was involved in the ECM remodeling of gastric smooth muscles in DGP rats by regulating the biological functions of TGF-ß3, TGF-ß1, MMP-2, and TIMP-1.
RESUMO
Amino acids are an important constituent in organic nitrogen deposition, and changes in the content of their components have a direct impact on the nitrogen input to the ecosystem. From December 2018 to November 2019, 176 precipitation samples were collected at Danjiangkou Reservoir, the source of the middle line of the South-to-North Water Diversion Project, and the variation characteristics of dissolved free amino acids (DFAA) and dissolved combined amino acids (DCAA) were analyzed. The volume-weighted value concentration ranges of DFAA and DCAA were 0.159-1.136 µmol/L and 1.603-7.044 µmol/L, respectively, and amino acids were dominated by DCAA in wet deposition. Our results showed that glutamic acid (Glu), glycine (Gly), and aspartic acid (Asp) were the dominant amino acids in both DFAA and DCAA. The concentration of DFAA was highest in winter, while the concentration of DCAA was in autumn. Dissolved total amino acids (DTAA) were insignificantly correlated with DFAA, whereas they were linearly correlated with DCAA, indicating a significant influence of agricultural activities on DTAA. The analysis of the backward trajectory of air masses showed that amino acids were mainly influenced by proximity inputs around the reservoir. The bioavailability of organic matter was higher in the southeastern of the reservoir than in the northwestern. The wet deposition flux of TDN was 14.096 kg N/ha/year, and the potential ecological impact on water bodies cannot be ignored. This study was conducted to clarify the variation characteristics of amino acids fractions in wet deposition and to provide parameters for regional assessment of amino acids wet deposition. The ecological impact of nitrogen wet deposition on water bodies will be explored to provide a basis for nitrogen pollution control and water quality protection in the middle line of the South-to-North Water Diversion Project.
