Influence of selected parenteral drugs on tightness and morphological parameters of enteroanastomosis in rats

Abstract

During the past few years many scientific investigations regarding the status of enteroanastomoses after surgical resections have been performed all over the world. General surgery wards perform intestinal resections on patients with neoplastic processes or with advanced nonspecific intestinal inflammation. Partial resections of the intestines are also performed on patients with necrotic changes caused by intestinal torsion or embolism of the branches of the mesenteric artery. These types of surgeries often require additional treatment which should cause a minimal strain for the patient in the postoperative period in order to obtain the highest percentage of recoveries. In proliferative diseases chemo- and radiotherapy are the most commonly used methods of treatment whereas general and local steroid therapy are used in inflammatory diseases. Additionally, immunomodulating agents are used with conventional therapy to improve the therapeutic effect. In a few studies, the influence of drugs on the local status of the intestine and wound healing status after surgeries was examined. The influence of selected agents on the status of experimental enteroanastomoses performed on the large intestine of rats was evaluated based on physical and morphometric tests. The study was performed on 60 Wistar rats, all of whom were male, of a similar body weight (250-350 grams) and the same age (2 months old). The rats were operated on to create an experimental anastomosis of the ascending colon. Then we administered selected drugs to evaluate their effect on the status of the newly created intestinal anastomosis. Selected parameters were evaluated after 4, 7 and 14 days after the surgery. In our experimental cycle animals were divided into 4 groups with 15 individuals in each group. The first group (I) was given physiological saline intraperitoneally (control group). Animals in the second group (II) were given the immuno-modulating drug interferon (Intron A) (45.000 IU/kg of b.w./day) after the surgery. Animals in the third group (III) were given the steroid Dexaven (0.5 mg/day) after the surgery. Animals in the fourth group (IV) were given a cytostatic agent (5-fluoroauracil) after the surgery (20 mg/kg/day). All of the drugs were administered in the same form as intra-peritoneal injections with the same amount of fluid. The study was planned for 5 cycles. 12 animals participated in one experimental cycle: 3 animals each from groups I, II, III and IV were operated on. The drugs were given for 5 days starting from the second day after the surgery. The rats were dissected after the 4th, 7th and 14th days of the experimental cycle to evaluate the status of the enteroanastomosis and the skin, according to previously mentioned parameters. Macroscopic changes of the enteroanastomosis were examined. Swabs were taken from all individuals with features of inflammation around this location. Next, the tightness of the anastomosis was evaluated by examining the appearance of air in the area of the anastomosis. The most important and last part of the experiment was amorphometric analysis of the large intestine with the anastomosis. In preparations stained with hematoxylin and eosin the following parameters were evaluated: amount of active intestinal crypts/mm, amount of non-active intestinal crypts/mm, total amount of intestinal crypts/mm, thickness of the mucous membrane, thickness of the submucous membrane, thickness of the muscular layer, fractal dimension of the mucosal membrane, fractal dimension of conjunctive tissue. Under the influence of steroid agents tightness disorders of the anastomosis were observed. Evaluation of the influence of the used substances on the morphometry of the enteroanastomosis revealed evident changes in the later days of the trial. In the days following the dissection of the animals from the control group histological changes were also observed that can suggest that the surgical intervention in itself influenced the morphometric parameters and caused disorders in the activity of intestinal crypts, decreased the dimension of the submucous membrane and altered the regeneration of the mucous membrane of the large intestine. Generally, agents used in the study caused disorders in the healing of the anastomosis, which significantly decreased particular dimensions of analyzed parameters. The substances examined influenced the thickness of the submucous membrane by making it thinner. Steroid and immunotherapy changed the reconstruction of conjunctive tissue which significantly affected the status and the resistance of the anastomosis. Intraperitoneal administration of selected therapeutical substances, especially Dexaven and Intron A have influenced the complete healing process of the anastomosis by disturbing the regenerative processes.