Morphological aspects of small intestinal mucosal injury and repair after electron irradiation

Morphological evaluation of the small intestine mucosa and apoptosis activity (caspase-3) is necessary to assessthe severity of damage to the small intestine. At the same time, proliferative index based on Ki-67 can be used to assess theregenerative potential of the small intestine. Fragments of small intestine of Wistar rats (n=60) of three groups: I) control(n=20); II) experimental group (n=20; local single electron irradiation at a dose of 2 Gy), III) experimental group (n=20; localsingle electron irradiation at a dose of 8 Gy) were studied by light microscopy using hematoxylin and eosin staining andimmunohistochemical reactions with antibodies to Ki-67 and caspase-3. In all samples of the experimental groups, a decreasein all morphometric indices was observed on day 1 with a tendency to recover on day 3. Small intestinal electron irradiationled to disturbances in the histoarchitecture of varying severity, and an increase in cell apoptosis was observed (increasedexpression of caspase-3 and decrease in Ki-67). In addition, modulation of the PI3K/AKT and MAPK/ERK signalingpathways was detected. The most pronounced destructive changes were observed in the group of 8 Gy single electronirradiation. Local irradiation of the small intestine with electrons at a dose of 2 and 8 Gy results in a decrease in the numberof enterocytes, mainly stem cells of the intestinal crypts.