Cargando…
Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS
BACKGROUND: Obstructive sleep apnea (OSA) imposes vascular and metabolic risks through chronic intermittent hypoxia (CIH) and impairs skeletal muscle performance. As studies addressing limb muscles are rare, the reasons for the lower exercise capacity are unknown. We hypothesize that CIH-related mor...
Autores principales: | , , , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2022
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8841105/ https://www.ncbi.nlm.nih.gov/pubmed/35151349 http://dx.doi.org/10.1186/s13395-022-00288-7 |
_version_ | 1784650764125208576 |
---|---|
author | Bannow, L. I. Bonaterra, G. A. Bertoune, M. Maus, S. Schulz, R. Weissmann, N. Kraut, S. Kinscherf, R. Hildebrandt, W. |
author_facet | Bannow, L. I. Bonaterra, G. A. Bertoune, M. Maus, S. Schulz, R. Weissmann, N. Kraut, S. Kinscherf, R. Hildebrandt, W. |
author_sort | Bannow, L. I. |
collection | PubMed |
description | BACKGROUND: Obstructive sleep apnea (OSA) imposes vascular and metabolic risks through chronic intermittent hypoxia (CIH) and impairs skeletal muscle performance. As studies addressing limb muscles are rare, the reasons for the lower exercise capacity are unknown. We hypothesize that CIH-related morphological alterations in neuromuscular junctions (NMJ) and mitochondrial integrity might be the cause of functional disorders in skeletal muscles. METHODS: Mice were kept under 6 weeks of CIH (alternating 7% and 21% O(2) fractions every 30 s, 8 h/day, 5 days/week) compared to normoxia (NOX). Analyses included neuromuscular junctions (NMJ) postsynaptic morphology and integrity, fiber cross-sectional area (CSA) and composition (ATPase), mitochondrial ultrastructure (transmission-electron-microscopy), and relevant transcripts (RT-qPCR). Besides wildtype (WT), we included inducible nitric oxide synthase knockout mice (iNOS(−/−)) to evaluate whether iNOS is protective or risk-mediating. RESULTS: In WT soleus muscle, CIH vs. NOX reduced NMJ size (− 37.0%, p < 0.001) and length (− 25.0%, p < 0.05) together with fiber CSA of type IIa fibers (− 14%, p < 0.05) and increased centronucleated fiber fraction (p < 0.001). Moreover, CIH vs. NOX increased the fraction of damaged mitochondria (1.8-fold, p < 0.001). Compared to WT, iNOS(−/−) similarly decreased NMJ area and length with NOX (− 55%, p < 0.001 and − 33%, p < 0.05, respectively) or with CIH (− 37%, p < 0.05 and − 29%, p < 0.05), however, prompted no fiber atrophy. Moreover, increased fractions of damaged (2.1-fold, p < 0.001) or swollen (> 6-fold, p < 0.001) mitochondria were observed with iNOS(−/−) vs. WT under NOX and similarly under CIH. Both, CIH- and iNOS(−/−) massively upregulated suppressor-of-cytokine-signaling-3 (SOCS3) > 10-fold without changes in IL6 mRNA expression. Furthermore, inflammatory markers like CD68 (macrophages) and IL1β were significantly lower in CIH vs. NOX. None of these morphological alterations with CIH- or iNOS(−/−) were detected in the gastrocnemius muscle. Notably, iNOS expression was undetectable in WT muscle, unlike the liver, where it was massively decreased with CIH. CONCLUSION: CIH leads to NMJ and mitochondrial damage associated with fiber atrophy/centronucleation selectively in slow-twitch muscle of WT. This effect is largely mimicked by iNOS(−/−) at NOX (except for atrophy). Both conditions involve massive SOCS3 upregulation likely through denervation without Il6 upregulation but accompanied by a decrease of macrophage density especially next to denervated endplates. In the absence of muscular iNOS expression in WT, this damage may arise from extramuscular, e.g., motoneuronal iNOS deficiency (through CIH or knockout) awaiting functional evaluation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13395-022-00288-7. |
format | Online Article Text |
id | pubmed-8841105 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-88411052022-02-16 Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS Bannow, L. I. Bonaterra, G. A. Bertoune, M. Maus, S. Schulz, R. Weissmann, N. Kraut, S. Kinscherf, R. Hildebrandt, W. Skelet Muscle Research BACKGROUND: Obstructive sleep apnea (OSA) imposes vascular and metabolic risks through chronic intermittent hypoxia (CIH) and impairs skeletal muscle performance. As studies addressing limb muscles are rare, the reasons for the lower exercise capacity are unknown. We hypothesize that CIH-related morphological alterations in neuromuscular junctions (NMJ) and mitochondrial integrity might be the cause of functional disorders in skeletal muscles. METHODS: Mice were kept under 6 weeks of CIH (alternating 7% and 21% O(2) fractions every 30 s, 8 h/day, 5 days/week) compared to normoxia (NOX). Analyses included neuromuscular junctions (NMJ) postsynaptic morphology and integrity, fiber cross-sectional area (CSA) and composition (ATPase), mitochondrial ultrastructure (transmission-electron-microscopy), and relevant transcripts (RT-qPCR). Besides wildtype (WT), we included inducible nitric oxide synthase knockout mice (iNOS(−/−)) to evaluate whether iNOS is protective or risk-mediating. RESULTS: In WT soleus muscle, CIH vs. NOX reduced NMJ size (− 37.0%, p < 0.001) and length (− 25.0%, p < 0.05) together with fiber CSA of type IIa fibers (− 14%, p < 0.05) and increased centronucleated fiber fraction (p < 0.001). Moreover, CIH vs. NOX increased the fraction of damaged mitochondria (1.8-fold, p < 0.001). Compared to WT, iNOS(−/−) similarly decreased NMJ area and length with NOX (− 55%, p < 0.001 and − 33%, p < 0.05, respectively) or with CIH (− 37%, p < 0.05 and − 29%, p < 0.05), however, prompted no fiber atrophy. Moreover, increased fractions of damaged (2.1-fold, p < 0.001) or swollen (> 6-fold, p < 0.001) mitochondria were observed with iNOS(−/−) vs. WT under NOX and similarly under CIH. Both, CIH- and iNOS(−/−) massively upregulated suppressor-of-cytokine-signaling-3 (SOCS3) > 10-fold without changes in IL6 mRNA expression. Furthermore, inflammatory markers like CD68 (macrophages) and IL1β were significantly lower in CIH vs. NOX. None of these morphological alterations with CIH- or iNOS(−/−) were detected in the gastrocnemius muscle. Notably, iNOS expression was undetectable in WT muscle, unlike the liver, where it was massively decreased with CIH. CONCLUSION: CIH leads to NMJ and mitochondrial damage associated with fiber atrophy/centronucleation selectively in slow-twitch muscle of WT. This effect is largely mimicked by iNOS(−/−) at NOX (except for atrophy). Both conditions involve massive SOCS3 upregulation likely through denervation without Il6 upregulation but accompanied by a decrease of macrophage density especially next to denervated endplates. In the absence of muscular iNOS expression in WT, this damage may arise from extramuscular, e.g., motoneuronal iNOS deficiency (through CIH or knockout) awaiting functional evaluation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13395-022-00288-7. BioMed Central 2022-02-12 /pmc/articles/PMC8841105/ /pubmed/35151349 http://dx.doi.org/10.1186/s13395-022-00288-7 Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data. |
spellingShingle | Research Bannow, L. I. Bonaterra, G. A. Bertoune, M. Maus, S. Schulz, R. Weissmann, N. Kraut, S. Kinscherf, R. Hildebrandt, W. Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS |
title | Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS |
title_full | Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS |
title_fullStr | Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS |
title_full_unstemmed | Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS |
title_short | Effect of chronic intermittent hypoxia (CIH) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of iNOS |
title_sort | effect of chronic intermittent hypoxia (cih) on neuromuscular junctions and mitochondria in slow- and fast-twitch skeletal muscles of mice—the role of inos |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8841105/ https://www.ncbi.nlm.nih.gov/pubmed/35151349 http://dx.doi.org/10.1186/s13395-022-00288-7 |
work_keys_str_mv | AT bannowli effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT bonaterraga effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT bertounem effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT mauss effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT schulzr effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT weissmannn effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT krauts effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT kinscherfr effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos AT hildebrandtw effectofchronicintermittenthypoxiacihonneuromuscularjunctionsandmitochondriainslowandfasttwitchskeletalmusclesofmicetheroleofinos |