ABSTRACT
AIM: To evaluate the prevalent topical therapeutic modalities available for the treatment of acute radiation proctitis compared to formalin. METHODS: A total of 120 rats were used. Four groups (n = 30) were analyzed with one group for each of the following applied therapy modalities: control, mesalazine, formalin, betamethasone, and misoprostol. A single fraction of 17.5 Gy was delivered to each rat. The rats in control group rats were given saline, and the rats in the other three groups received appropriate enemas twice a day beginning on the first day after the irradiation until the day of euthanasia. On d 5, 10, and 15, ten rats from each group were euthanized and a pathologist who was unaware of treatment assignment examined the rectums using a scoring system. RESULTS: The histopathologic scores for surface epithelium, glands (crypts) and lamina propria stroma of the rectums reached their maximum level on d 10. The control and formalin groups had the highest and mesalazine had the lowest, respectively on d 10. On the 15th d, mesalazine, betamethasone, and misoprostol had the lowest scores of betamethasone. CONCLUSION: Mesalazine, betamethasone, and misoprostol are the best topical agents for radiation proctitis and formalin has an inflammatory effect and should not be used.
Subject(s)
Proctitis , Rectum/pathology , Rectum/radiation effects , Administration, Topical , Animals , Anti-Inflammatory Agents/therapeutic use , Anti-Ulcer Agents/therapeutic use , Betamethasone/therapeutic use , Disease Models, Animal , Female , Formaldehyde/therapeutic use , Gamma Rays , Humans , Mesalamine/therapeutic use , Misoprostol/therapeutic use , Proctitis/drug therapy , Proctitis/pathology , Random Allocation , Rats , Rats, Sprague-Dawley , Rectum/anatomy & histologyABSTRACT
BACKGROUND: Radiation rectitis is a major problem associated with high-doseirradiation used for pelvic malignancies. OBJECTIVE: The aim of this study was to investigate the possible protectiveeffect of mesalamine against irradiation-induced oxidative tissue damage in an experimental model. METHODS: THREE GROUPS OF FEMALE SPRAGUE DAWLEY RATS WERE ASSIGNED TO RECEIVE TREATMENT AS FOLLOWS: mesalamine enema (60 mg/mL) BID + irradiation (IR) was given to the mesalamine + IR group, and isotonic saline enema BID + irradiation to the control group. Treatments were given from the day before irradiation until euthanization (72 hours after the irradiation). Sham control rats received isotonic saline enema BID but no irradiation. On the third day of treatment, all animals were euthanized, and reduced glutathione (GSH) level, malondialdehyde (MDA) level, and myeloperoxidase (MPO) activity were measured in the rectal, intestinal, and hepatic tissue of the rats. RESULTS: The sham group comprised 7 rats; the control and mesalamine + IRgroups, 16 rats each. The median GSH levels of rectal and intestinal specimens were lower in the control group compared with the sham group. The rectal and intestinal MDA levels were higher in the control group compared with the sham group. The rectal and intestinal MPO activities were higher in the control group compared with the sham group. All of these differences were statistically significant (P < 0.001) and indicated oxidative stress. With the topical application of mesalamine, the GSH and MDA levels and MPO activities were similar to those of the sham group. CONCLUSION: The pelvic irradiation of rats caused oxidative rectal, intestinal,and hepatic tissue damage, which was ameliorated with the use of mesalamine.
