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. 2020 Sep 10;17(16):2505-2510.
doi: 10.7150/ijms.48231. eCollection 2020.

Experimental Model of Rectal Carcinogenesis Induced by N-Methyl-N-Nitrosoguanidine in Mice with Endoscopic Evaluation

Vanessa Foresto Machado  1 , Rogerio Serafim Parra  1 , Caio Abner Leite  2 , Stefania Bovo Minto  3 , Thiago Mattar Cunha  2 , Fernando de Queiroz Cunha  2 , Sergio Britto Garcia  3 , Marley Ribeiro Feitosa  1 , Jose Joaquim Ribeiro da Rocha  1 , Omar Feres  1
Affiliations

Experimental Model of Rectal Carcinogenesis Induced by N-Methyl-N-Nitrosoguanidine in Mice with Endoscopic Evaluation

Vanessa Foresto Machado et al. Int J Med Sci. .

Abstract

Background and purpose: The discovery of chemical substances with carcinogenic properties has allowed the development of several experimental models of colorectal cancer (CRC). Classically, experimental models of CRC in mice have been evaluated through clinical or serial euthanasia. The present study aims to investigate the role of low endoscopy in the analysis of carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Methods: Thirty C57BL6 mice were divided into two groups: a control group with fifteen animals that underwent rectal instillation of saline solution on day 0 and a carcinogen group with fifteen animals that underwent a 100 mg/kg MNNG rectal instillation on day 0. In both groups, low endoscopies were performed on weeks 4 and 8. We used a validated endoscopic scoring system to evaluate the severity of colitis and colorectal tumor. Euthanasia was carried out at week 12. Results: We observed higher inflammation scores (p <0.001) and a higher number of tumors (p <0.05) in the MNNG group than the control group, both at weeks 4 and 8. A worsening of inflammation scores from the first to the second endoscopy was also noticeable in the MNNG group. There were no bowel perforations related to the procedure, and there was one death in the control group. Conclusion: Low endoscopy in experimental animals allows safe macroscopic evaluation of colorectal carcinogenesis without the need for euthanasia.

Keywords: colorectal carcinogenesis; experimental model.; low endoscopy.

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Conflict of interest statement

COMPETING INTERESTS: The authors have declared that no competing interest exists.

Figures

Figure 1
Figure 1
Endoscopic visualization of the normal rectum (A) and of a rectal tumor (B).
Figure 2
Figure 2
Comparison of mean endoscopic inflammatory scores between groups at weeks 4 and 8.
Figure 3
Figure 3
Comparison of the mean number of tumors between groups at weeks 4 and 8.
Figure 4
Figure 4
Histological findings of dysplastic crypt in control and MNNG groups.
See this image and copyright information in PMC

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