Open Access

Effects of norepinephrine on colonic tight junction protein expression during heat stress

  • Authors:
    • Yan Luo
    • Huiming Ma
    • Shibo Niu
    • Xu Li
    • Lihong Nie
    • Guanghua Li
  • View Affiliations

  • Published online on: February 25, 2021     https://doi.org/10.3892/etm.2021.9865
  • Article Number: 421
  • Copyright: © Luo et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Stress induced by changes in the internal or external environment in humans and animals leads to intestinal epithelial damage, in a manner that is associated with impaired intestinal barrier function. However, the role of the stress hormone norepinephrine (NE) in impairments in barrier function remains poorly understood. In the present study, a rat heat‑exposed model was used to observe changes in the tight junction proteins Occludin and zonula occludens‑1 (ZO‑1), in addition to those in protease‑activated receptor 2 (PAR‑2) and transient receptor potential ankyrin 1 channel (TRPA1) in colon. The levels of plasma NE were detected using an ELISA kit. Different concentrations of NE were used to culture the human colon cell line Caco‑2 for 6 and 24 h to investigate the cell viability using Cell Counting Kit‑8 assay, whilst the expression levels of Occludin, ZO‑1, PAR‑2 and TRPA1 were examined using western blotting and immunofluorescence in Caco‑2 cells and immunohistrochemistry in rat colon tissues. Although there was no clear histological damage to the rat colonic mucosa, there were decreased expression levels of tight junction proteins Occludin and ZO‑1 after heat exposure. In addition, PAR‑2 expression was increased by heat exposure. It was found that TRPA1 expression was concentrated to the luminal surface of the colon in the heat exposed group compared with that in the control group. After the administration of increasing concentrations of NE for 6 h, treatment did not affect cell viability. Furthermore, after application of NE for 24 h, cell viability gradually increased as the NE concentration was elevated from 10 to 100 µM. However, no significant increase in viability was observed when the cells were treated with 120 and 160 µM NE. Occludin expression was decreased when 10 µM NE was applied for 6 or 24 h. By contrast, 60 µM NE significantly downregulated Occludin expression in the 6 h group, but caused an insignificant decrease in the 24 h group. It was found that ZO‑1 expression was upregulated after treatment with 10 µM NE for 6 h, whilst downregulation was observed after treatment with 10 µM NE for 24 h. PAR‑2 protein expression was increased after application of NE for both 6 and 24 h, but not after treatment with 60 µM NE. In addition, TRPA1 expression was not affected by the treatment of NE, but increased positive staining was observed on the luminal side of the mucosa, which appeared to be concentrated in the cells of the luminal side in the rat colon after heat exposure. Collectively, the present results suggested that expression of tight junction proteins Occludin and ZO‑1, in addition to that of PAR‑2, can be regulated by NE, which may contribute to impairments in barrier function observed during heat stress.
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May-2021
Volume 21 Issue 5

Print ISSN: 1792-0981
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Copy and paste a formatted citation
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Spandidos Publications style
Luo Y, Ma H, Niu S, Li X, Nie L and Li G: Effects of norepinephrine on colonic tight junction protein expression during heat stress. Exp Ther Med 21: 421, 2021
APA
Luo, Y., Ma, H., Niu, S., Li, X., Nie, L., & Li, G. (2021). Effects of norepinephrine on colonic tight junction protein expression during heat stress. Experimental and Therapeutic Medicine, 21, 421. https://doi.org/10.3892/etm.2021.9865
MLA
Luo, Y., Ma, H., Niu, S., Li, X., Nie, L., Li, G."Effects of norepinephrine on colonic tight junction protein expression during heat stress". Experimental and Therapeutic Medicine 21.5 (2021): 421.
Chicago
Luo, Y., Ma, H., Niu, S., Li, X., Nie, L., Li, G."Effects of norepinephrine on colonic tight junction protein expression during heat stress". Experimental and Therapeutic Medicine 21, no. 5 (2021): 421. https://doi.org/10.3892/etm.2021.9865