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Role of oxidative stress in oxaliplatin ‐ induced enteric neuropathy and colonic dysmotility in mice

View Article: PubMed Central - PubMed

ABSTRACT

Background and purpose: Oxaliplatin is a platinum‐based chemotherapeutic drug used as a first‐line therapy for colorectal cancer. However, its use is associated with severe gastrointestinal side‐effects resulting in dose limitations and/or cessation of treatment. In this study, we tested whether oxidative stress, caused by chronic oxaliplatin treatment, induces enteric neuronal damage and colonic dysmotility.

Experimental approach: Oxaliplatin (3 mg·kg−1 per day) was administered in vivo to Balb/c mice intraperitoneally three times a week. The distal colon was collected at day 14 of treatment. Immunohistochemistry was performed in wholemount preparations of submucosal and myenteric ganglia. Neuromuscular transmission was studied by intracellular electrophysiology. Circular muscle tone was studied by force transducers. Colon propulsive activity studied in organ bath experiments and faeces were collected to measure water content.

Key results: Chronic in vivo oxaliplatin treatment resulted in increased formation of reactive oxygen species (O2ˉ), nitration of proteins, mitochondrial membrane depolarisation resulting in the release of cytochrome c, loss of neurons, increased inducible NOS expression and apoptosis in both the submucosal and myenteric plexuses of the colon. Oxaliplatin treatment enhanced NO‐mediated inhibitory junction potentials and altered the response of circular muscles to the NO donor, sodium nitroprusside. It also reduced the frequency of colonic migrating motor complexes and decreased circular muscle tone, effects reversed by the NO synthase inhibitor, Nω‐Nitro‐L‐arginine.

Conclusion and implications: Our study is the first to provide evidence that oxidative stress is a key player in enteric neuropathy and colonic dysmotility leading to symptoms of chronic constipation observed in oxaliplatin‐treated mice.

No MeSH data available.


Related in: MedlinePlus

Mitochondrial superoxide in the colonic submucosal and myenteric ganglia and iNOS protein expression. Fluorescent and binary images of wholemount preparations of submucosal (A,AI and B,BI) and myenteric (C,CI and D,DI) ganglia labelled with MitoSOX™ Red in the colons from day 14 sham and oxaliplatin‐treated mice. Scale bar = 50 μm. (E) Quantification of the levels of mitochondrial superoxide production visualized by fluorescent probe in submucosal and myenteric ganglia in colonic preparations from day 14 sham and oxaliplatin‐treated animals. *P < 0.05, significantly different as indicated; n = 6 mice per group. (F) Representative images and quantification of the Western blot analysis for iNOS in LMMP tissue from day 14 sham and oxaliplatin‐treated mice. iNOS protein was normalized to total protein values obtained from the Coomassie Blue membrane staining (see Methods section). All values are expressed as a percentage of the values obtained from sham‐treated mice. Data presented as mean ± SEM. *P < 0.05, significantly different as indicated; n = 5 mice per group.
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bph13646-fig-0003: Mitochondrial superoxide in the colonic submucosal and myenteric ganglia and iNOS protein expression. Fluorescent and binary images of wholemount preparations of submucosal (A,AI and B,BI) and myenteric (C,CI and D,DI) ganglia labelled with MitoSOX™ Red in the colons from day 14 sham and oxaliplatin‐treated mice. Scale bar = 50 μm. (E) Quantification of the levels of mitochondrial superoxide production visualized by fluorescent probe in submucosal and myenteric ganglia in colonic preparations from day 14 sham and oxaliplatin‐treated animals. *P < 0.05, significantly different as indicated; n = 6 mice per group. (F) Representative images and quantification of the Western blot analysis for iNOS in LMMP tissue from day 14 sham and oxaliplatin‐treated mice. iNOS protein was normalized to total protein values obtained from the Coomassie Blue membrane staining (see Methods section). All values are expressed as a percentage of the values obtained from sham‐treated mice. Data presented as mean ± SEM. *P < 0.05, significantly different as indicated; n = 5 mice per group.

Mentions: To evaluate production of ROS following long‐term oxaliplatin treatment, distal colon samples were probed with a fluorescent mitochondrial superoxide marker MitoSOX™ Red M36008. Increased MitoSOX fluorescence was found in both the submucosal (Figure 3A,AI and B,BI) and myenteric (Figure 3C,CI and D,DI) plexuses of the distal colon from oxaliplatin‐treated mice compared to sham‐treated animals (Figure 3E).


Role of oxidative stress in oxaliplatin ‐ induced enteric neuropathy and colonic dysmotility in mice
Mitochondrial superoxide in the colonic submucosal and myenteric ganglia and iNOS protein expression. Fluorescent and binary images of wholemount preparations of submucosal (A,AI and B,BI) and myenteric (C,CI and D,DI) ganglia labelled with MitoSOX™ Red in the colons from day 14 sham and oxaliplatin‐treated mice. Scale bar = 50 μm. (E) Quantification of the levels of mitochondrial superoxide production visualized by fluorescent probe in submucosal and myenteric ganglia in colonic preparations from day 14 sham and oxaliplatin‐treated animals. *P < 0.05, significantly different as indicated; n = 6 mice per group. (F) Representative images and quantification of the Western blot analysis for iNOS in LMMP tissue from day 14 sham and oxaliplatin‐treated mice. iNOS protein was normalized to total protein values obtained from the Coomassie Blue membrane staining (see Methods section). All values are expressed as a percentage of the values obtained from sham‐treated mice. Data presented as mean ± SEM. *P < 0.05, significantly different as indicated; n = 5 mice per group.
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bph13646-fig-0003: Mitochondrial superoxide in the colonic submucosal and myenteric ganglia and iNOS protein expression. Fluorescent and binary images of wholemount preparations of submucosal (A,AI and B,BI) and myenteric (C,CI and D,DI) ganglia labelled with MitoSOX™ Red in the colons from day 14 sham and oxaliplatin‐treated mice. Scale bar = 50 μm. (E) Quantification of the levels of mitochondrial superoxide production visualized by fluorescent probe in submucosal and myenteric ganglia in colonic preparations from day 14 sham and oxaliplatin‐treated animals. *P < 0.05, significantly different as indicated; n = 6 mice per group. (F) Representative images and quantification of the Western blot analysis for iNOS in LMMP tissue from day 14 sham and oxaliplatin‐treated mice. iNOS protein was normalized to total protein values obtained from the Coomassie Blue membrane staining (see Methods section). All values are expressed as a percentage of the values obtained from sham‐treated mice. Data presented as mean ± SEM. *P < 0.05, significantly different as indicated; n = 5 mice per group.
Mentions: To evaluate production of ROS following long‐term oxaliplatin treatment, distal colon samples were probed with a fluorescent mitochondrial superoxide marker MitoSOX™ Red M36008. Increased MitoSOX fluorescence was found in both the submucosal (Figure 3A,AI and B,BI) and myenteric (Figure 3C,CI and D,DI) plexuses of the distal colon from oxaliplatin‐treated mice compared to sham‐treated animals (Figure 3E).

View Article: PubMed Central - PubMed

ABSTRACT

Background and purpose: Oxaliplatin is a platinum&#8208;based chemotherapeutic drug used as a first&#8208;line therapy for colorectal cancer. However, its use is associated with severe gastrointestinal side&#8208;effects resulting in dose limitations and/or cessation of treatment. In this study, we tested whether oxidative stress, caused by chronic oxaliplatin treatment, induces enteric neuronal damage and colonic dysmotility.

Experimental approach: Oxaliplatin (3&nbsp;mg&middot;kg&minus;1 per day) was administered in vivo to Balb/c mice intraperitoneally three times a week. The distal colon was collected at day 14 of treatment. Immunohistochemistry was performed in wholemount preparations of submucosal and myenteric ganglia. Neuromuscular transmission was studied by intracellular electrophysiology. Circular muscle tone was studied by force transducers. Colon propulsive activity studied in organ bath experiments and faeces were collected to measure water content.

Key results: Chronic in vivo oxaliplatin treatment resulted in increased formation of reactive oxygen species (O2&#713;), nitration of proteins, mitochondrial membrane depolarisation resulting in the release of cytochrome c, loss of neurons, increased inducible NOS expression and apoptosis in both the submucosal and myenteric plexuses of the colon. Oxaliplatin treatment enhanced NO&#8208;mediated inhibitory junction potentials and altered the response of circular muscles to the NO donor, sodium nitroprusside. It also reduced the frequency of colonic migrating motor complexes and decreased circular muscle tone, effects reversed by the NO synthase inhibitor, N&omega;&#8208;Nitro&#8208;L&#8208;arginine.

Conclusion and implications: Our study is the first to provide evidence that oxidative stress is a key player in enteric neuropathy and colonic dysmotility leading to symptoms of chronic constipation observed in oxaliplatin&#8208;treated mice.

No MeSH data available.


Related in: MedlinePlus