The effect of aerobic and resistance exercise on the progression of colorectal cancer in an animal model

Purpose: The aim of this study was to assess the effects of resistance and aerobic exercise on colorectal cancer (CRC) development in mice induced by azoxymethane (AOM) coupled with colitis. Methods: Forty animals induced with CRC were used, divided into five groups of eight animals each: sedentary; continuous aerobics; continuous anaerobic; aerobic PI; and anaerobic PI. AOM was administered to the animals in two doses of 10 mg/kg each over the course of two weeks, the first dose administered in the third week and the second administered in the fourth. For the colitis, three cycles of dextran sodium sulfate were administered for five days, separated by two weeks of water. The 14th week of the experiment saw the euthanasia, the removal of their colons, and the creation of microscopy slides for histological analysis. Results: Preneoplastic lesions developed in all five groups; there were no significant differences between them. However, in terms of inflammatory symptoms, mucosal ulceration was much more frequently in the exercise groups than in the sedentary group (p = 0.016). The number of polyps overall (p = 0.002), the distal region's polyp development (p = 0.003), and the proximal region's polyp development (p = 0.04) were all statistically different than sedentary group. Conclusions: The study discovered no significant difference in disease activity index scores between groups, but there was a significant difference in the number of polyps and the presence of mucosal ulceration in the colon.

Repercussão hepática da carcinogênese colorretal induzida pelo azoximetano / Hepatic repercussions of azoxymethane-induced colorectal carcinogenesis

OBJETIVO: Avaliar as repercussões hepáticas da carcinogênese colônica induzida por diferentes doses e tempos de exposição ao azoximetano em ratos Wistar. MÉTODOS: Quarenta e quatro ratos foram distribuídos em quatro grupos. Os animais tinham oito semanas no início do experimento. No grupo 1, receberam 1.0mL de solução salina intraperitonealmente uma vez por semana por duas semanas. No grupo 2, receberam 15 mg/kg de azoximetano intraperitonealmente uma vez por semana por duas semanas. Esses animais foram mortos na 15ª semana do experimento. Os animais do grupo 3 receberam solução salina intraperitonealmente uma vez por semana por duas semanas. Os animais do grupo 4 receberam 20mg/kg de azoximetano intraperitonealmente uma vez por semana por duas semanas. Esses animais foram mortos na 26ª semana do experimento. Os fragmentos de tecido hepático foram corados pela hematoxilina e eosina e avaliadas microscopicamente. RESULTADOS: Grupo 1 e grupo 2 diferiram significantemente em relação a esteatose, mas não houve diferença entre o grupo 3 e o grupo 4. No entanto, no grupo 4 foram observadas lesões pré-neoplásicas (focos de células alteradas, claras, vacuoladas, basofílicas, anfofílicas, tigróides, oncocíticas, pequenas ou acidófilas, espongioses e pelioses) e lesões neoplásicas (colangiomas e adenomas) contendo hepatócitos atípicos de permeio, não identificados no grupo 3. CONCLUSÃO: No modelo de carcinogênese colorretal, lesões hepáticas pré-neoplásicas e neoplásicas aparecem e evoluem na proporção do tempo e dose de exposição ao azoximetano.

OBJECTIVE: To evaluate the hepatic effects of colonic carcinogenesis induced by azoxymethane at different doses and times of exposure in rats. METHODS: Forty-four Wistar rats were divided into four groups. The animals were eight weeks at the beginning of the experiment. group 1 received 1.0ml of saline intraperitoneally once a week for two weeks. Group 2 received 15 mg/kg of azoxymethane intraperitoneally once a week for two weeks. These animals were killed at the 15th week of the experiment. The animals of group 3 received saline intraperitoneally once a week for two weeks. Group 4 animals received 20mg/kg of azoxymethane intraperitoneally once a week for two weeks. These animals were killed at the 26th week of the experiment. The fragments of liver tissue were stained with hematoxylin and eosin and evaluated microscopically. RESULTS: Groups 1 and 2 differed significantly in relation to steatosis, no difference having been found between group 3 and group 4. However, in group 4 we observed pre-neoplastic lesions (foci of altered, clear, vacuolated, basophilic, amphophilic tigroid, oncocytic, small or acidophilus cells, spongiosis and peliosis) and neoplastic lesions (adenomas and colangiomas) containing atypical hepatocytes in between, not identified in group 3. CONCLUSION: In the model of colorectal carcinogenesis, preneoplastic and neoplastic hepatic lesions appear and evolve in proportion to the time of exposure and dose of azoxymethane.

Antioxidative and modifying effects of a tropical plant Azadirachta indica (Neem) on azoxymethane-induced preneoplastic lesions in the rat colon.

The purpose of the present study was to examine whether Neem leaf (Azadirachta indica) has short-term chemopreventive effects on endpoint preneoplastic lesions involved in rat colon carcinogenesis and might also exert antioxidative activity. Forty- two male F344 rats were randomly divided into 6 experimental groups. Groups 1 to 4 were given a subcutaneous injection of azoxymethane (AOM, 20 mg/kg body weight) once a week for 2 weeks. Starting one week before the first injection of AOM, rats in groups 2 to 4 received an aqueous extract of Neem leaf (20, 100, and 250 mg/kg, respectively) by gavage 3 times per week, for 5 weeks. Rats in group 5 also were given the Neem extract by gavage feeding 3 times per week for 5 weeks, while group 6 served as untreated controls. The experiment was terminated 5 weeks after the start. Dietary feeding of the Neem extract at all dose levels significantly inhibited the induction of aberrant crypt foci (ACF) (P<0.0002), when compared to the AOM-treated group (group 1). In groups 2 to 4, treatment of rats with the Neem extract also significantly decreased the proliferating cell nuclear antigen (PCNA) labeling indices (P<0.0006) of colon epithelium and ACF. Moreover, the Neem extract also showed antioxidative activity. The finding that dietary Neem has possible chemopreventive effects in the present short-term colon carcinogenesis bioassay suggests that longer-term exposure may cause suppression of tumor development.

Inhibition of azoxymethane-induced colon carcinogenesis in rats due to JTE-522, a selective cyclooxygenase-2 inhibitor.

Prostaglandin E2, which is produced by cyclooxygenase (COX) during arachidonic acid metabolism, is considered to be related to colon carcinogenesis and selective COX-2 inhibitors may be effective for chemoprevention without the adverse side effects of non-selective, nonsteroid anti-inflammatory drugs. Therefore, the influence of JTE-522 (4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzensulfonamide), a selective COX-2 inhibitor, was examined in azoxymethane(AOM)-induced rat colon carcinogenesis. A total of 40 male F344 rats were randomly divided into two groups. Group 1 received diet containing 0.015% JTE-522 and group 2 the normal diet without supplement as a control group; one week later, all rats were administered axozymethane (AOM) s.c. at a dose of 15 mg/kg body weight once a week for 3 successive weeks. At the termination of the experiment (30 weeks after the start), the multiplicity of colon cancer in group 1 was significantly less than that of group 2. The proliferating cell nuclear antigen (PCNA) indices for non-neoplastic cells of the colon mucosa in group 1 were also lower. These data thus suggest that JTE-522 has chemopreventive potential against colon carcinogenesis with decrease of mucosal cell proliferation in rats.