Peculiarities of neoplasms appeared after total body irradiation and homeostasis parameters in rats

Abstract

Background: Tissue damage and disruption of metabolic processes as a result of total body irradiation (TBI) could lead to tumorigenesis.   Methods:  Female rats (25 of 32) were X-irradiated with a 6-Gy dose. On month 12±1 animals   were sacrificed. The alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST),  amylase, lactate dehydrogenase (LDH), Ca 2+, creatinine, glucose, phosphorus, urea, uric acid, total protein, pO2, pCO2, pH, and blood cell count were evaluated in blood. Tumors were examinated histologically. Results:  On 12±1 months after TBI, 76% of rats had visually detected tumors, histologically classified as benign fibro adenomas. Metabolic, hematological changes versus healthy control indicated disturbances in the homeostasis system. The blood lactate level was typically higher in animals with tumors than without. The ratio of tumor weight to lactate (or LDH) level in blood was 1±0.5 in the 63% of rats and histological analysis revealed the signs of biphasic hyperplasia of glandular lobes and connective tissue stroma, associated with secretory and proliferative activities in tumor. In animals with high values of this ratio (≥1.5) neoplasms were represented by fibrous and glandular tissues presenting a predominant stromal fibrous component, associated with the prevalence of high proliferation in tumor. While in 20% of tumor bearing rats with the low ratio (<0.5) predominated an epithelial structure with homogeneous basophilic content in the glandular lumens, suggesting the domination of secretory activity in tumor.  Conclusions: TBI promoted the alterations of hematological and biochemical parameters of homeostasis in rats and provoked the appearance of benign tumors one year after. The ratio of tumor mass to lactate (or LDH) level in blood seems to be an informative indicator of the histological particularities of tumors, suggesting the prevalence of proliferative or secretory activity, or the balance between them.