Research Article Immunohistochemical Expression of Ornithine Decarboxylase, Diamine Oxidase, Putrescine, and Spermine in Normal Canine Enterocolic Mucosa, in Chronic Colitis, and in Colorectal Cancer Giacomo Rossi, 1 Matteo Cerquetella, 1 Graziano Pengo, 2 Subeide Mari, 1 Emilia Balint, 3 Gabrio Bassotti, 4 and Nicolae Manolescu 3 1 School of Biosciences and Veterinary Medicine, University of Camerino, Via Circonvallazione 93/95, 62024 Matelica, Italy 2 S. Antonio Clinic, 26020 Madignano, Italy 3 Faculty of Veterinary Medicine, 050097 Bucharest, Romania 4 Gastroenterology and Hepatology Section, Department of Medicine, Santa Maria della Misericordia Hospital, Piazzale Menghini 1, San Sisto, 06153 Perugia, Italy Correspondence should be addressed to Giacomo Rossi; giacomo.rossi@unicam.it Received 29 May 2015; Revised 3 August 2015; Accepted 10 September 2015 Academic Editor: Atsushi Sakuraba Copyright © 2015 Giacomo Rossi et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We compared the immunohistochemical expression of putrescine (PUT), spermine (SPM), ornithine decarboxylase (ODC), and diamine oxidase (DAO) in bioptic samples of canine colonic mucosa with chronic inflammation (i.e., granulomatous colitis and lymphoplasmacytic colitis) or neoplasia. Single and total polyamines levels were significantly higher in neoplastic tissue than in normal samples. Samples with different degrees of inflammation showed a general decrease expression of ODC if compared to controls; SPM was practically not expressed in control samples and very low in samples with chronic-granulomatous inflammation. In carcinomatous samples, the ODC activity was higher with respect to controls and samples with inflammation. is is the first description of polyamines expression in dog colonic mucosa in normal and in different pathological conditions, suggesting that the balance between polyamine degradation and biosynthesis is evidently disengaged during neoplasia. 1. Introduction e polyamines (PAs) spermine (SPM) and putrescine (PUT) are intimately involved in regulation of DNA, RNA, and protein synthesis; therefore, they are essential for prolifera- tion of both normal and neoplastic cells. Dysregulation of cellular polyamines is associated with various pathological conditions, including inflammation, and cancer; for this latter association, polyamine pathways have been explored as targets for cancer chemotherapy and chemoprevention [1, 2]. Fujiwara et al. [3] reported the first immunohistochemical demonstration of PAs distribution in different portions of healthy gut mucosa of rats and mice using specific mono- clonal antibodies and observed that PAs are well expressed in gastrointestinal tract according to the rapid turnover of gastrointestinal epithelium. e intracellular amount of PAs is the result of the biosynthetic activity of the key-enzyme ornithine decarboxylase (ODC) and of the uptaking from extracellular environment. In human beings several studies reported an increased expression of ODC in neoplastic colorectal tissue versus normal-appearing mucosa [4, 5]. e enzyme diamine oxidase (DAO) inactivates his- tamine and other biogenic amines, such as PAs by a reaction of oxidative deamination. DAO is mainly expressed in the intestine, located almost exclusively in the villus tip entero- cytes of mammals [6]. Decreased levels of DAO were found in various bowel diseases both in dogs and in humans [6, 7]. Although polyamines are critical for optimal cell growth, excessive accumulation may interfere directly with normal cell function, and they have been implicated recently in the control of the apoptotic response, inflammation, and cancerogenesis [8, 9]. Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 172756, 8 pages http://dx.doi.org/10.1155/2015/172756