Participation of blood valine and L-arginine-NO system in the development of hyperthermia, the formation of thyroid status and prooxidant-antioxidant state under stress due to bacterial endotoxin

Abstract

The importance of free amino acids in the processes of vital activity in normal and pathological conditions is well known. At the same time, there are no data on the role of blood plasma valine in the formation of thyroid status, prooxidant-antioxidant state, and in the development of hyperthermia caused by bacterial endotoxin, although its participation in these processes is quite natural, since valine is an inhibitor of arginase, the activity of which affects the level of arginine amino acid and nitric monoxide (NO). This is important in the regulation of body temperature, lipidperoxidation processes, and the level of iodine-containing hormones. The aim of the study was to elucidate the significance of blood plasma valine and the L-arginine-NO system in the formation of thyroid status, prooxidant-antioxidant state and the maintenance of body temperature during stress caused by bacterial endotoxin. In experiments on rats and rabbits, it was found that under the conditions of E. сoli lipopolysaccharide action in the body of animals, the pituitary-thyroid gland system, lipid peroxidation (LPO) processes in the blood and liver activate, the nitrate/nitrite (NO3–/NO2–) content increases, the level of valine and arginine in the blood plasma decreases, and body temperature increases . Under the conditions of depression of liver arginase with L- valine (100 mg / kg intraperitoneally 30 minutes before endotoxin injection ), the LPS action is not accompanied by an increase in body temperature , leads to less pronounced changes in lipid peroxidation processes , as well as to a more significant decrease in the triiodothyronine content and to an increase in the NO3–/NO2– level in blood plasma in rats . Preliminary administration of the NO synthesis inhibitor L-NAME (25 mg / kg intraperitoneally 30 minutes before endotoxin injection ) into the animal body not only reduces body temperature rise and NO3–/NO2– level increase in the blood plasma when acted upon by endotoxin , but also exacerbates changes in the LPO processes in the blood plasma and liver , and prevents the activation of the pituitary-thyroid gland system .