IVDevelopment of a new model of actinic enteritis in rats using a cobalt-60 open source and a protection device as a collimator 1
7-Technical SkillActa Cir Bras. 2017;32(3):319-324
AbstractPurpose: To describe a new model of actinic enteritis that does not use radiotherapy machines. Methods: Sixteen Wistar rats were divided into four groups, consisting of four animals each: control (group A), two weeks after irradiation (group B), five weeks after irradiation (group C) and eight weeks after irradiation (group D). Animals were given a 10Gy radiation from a Cobalt-60 natural source in a nuclear technology research center. Protections of the surrounding tissues were obtained through the usage of plumb devices with a hole in the center, which served as a collimator. We obtained irradiated and non-irradiated colons from each animal.Results: In group B we found an important inflammatory response in the irradiated colon, which appeared in a reduced way in group C and was minimal in group D, in which we found a relevant collagen submucosal deposition/fibrosis. In all groups, the non-irradiated colon had a lower pathological damage in comparison with the irradiated colon. Conclusion: We thus described an efficient and feasible technique for obtaining an animal model of actinic enteritis. around 220-280g and aged 2-3 months were used in this study, obtained from the Universidade Federal de Minas Gerais (UFMG). The rats were housed in polycarbonate cages (49×34×16cm), with n= 4/cage, under controlled conditions (temperature, humidity, air flux). Throughout the experimental period, all mice had access to food (Purina Lab Chow, Curitiba, Brazil) and filtered water ad libitum.The rats were randomly distributed into four groups of four animals each: group A (control without irradiation); group B (single dose 10Gy irradiation and euthanized after two weeks); group C (single dose 10Gy irradiation and euthanized after five weeks); group D (single dose 10Gy irradiation and euthanized after eight weeks).All experimental procedures were performed on anesthetized rats. Anesthesia was maintained with ketamine and xylazine (60mg/Kg and 8mg/Kg i.p.). After properly anesthetized, the rats were set in an acrylic cylindrical compartment (Figure 1). They were transferred into a protected room which has the MDS Nordion Cobalt-60 source in the center. This room has a complex protection mechanism that rises the source from an enclosed cage from under the ground only when it is fully locked and safe. We developed a covering device (15cm-thick plumb bricks with a 32mm round opening in the center to provide a collimator) to protect the rest of the animal's body from the radiation shade (Figure 2). This protective plumb device did not cover the back of the animal, in order to allow radiation to disperse after collimation and prevent it from reflecting and spreading in the surrounding tissues (Figure 3). A TLD dosimetry system was used in the pilot experiment so as to check the proper radiation dose in the irradiated field and it also proved that ...
