Тhe alarm-stage of stress reaction (аn hour after the stress of swimming of rats in a cage during an hour) is characterized by the stimulation of trypsinе-like activity (TLA) in the liver, and especially in the blood. At the resistance stage (48 hours after the stress) there is normalization of TLA in the blood and limitation of its growth in the liver. At the stage of exhaustion (an hour of stress during 10 days) the most significant increase of TLA in the liver and blood develops. Experimental hypothyroidism (25 mg/kg merkazolil within 20 days) per se causes a reduction of TLA, defines more pronounced stimulation of proteolysis in the alarm-stage, prevents its normalization at the resistance-stage, and promotes its excessive activation at the stage of exhaustion. Introduction of small doses of L-thyroxine (1.5-3.0 g/kg during 28 days) does not affect the system of proteolysis, limitis the increase of TLA at the alarm- and exhaustion stages, prevents its stimulation at the resistance-stage. The dependence of the changes in the proteases/inhibitors system under stress from the level of iodine-containing thyroid hormones in the blood is due to their influence on the activity of endogenous proteinase inhibitors (a1-antitrypsin and a2-macroglobulin) and on the permeability of lysosomes membranes.
Stadiia trevogi stress-reaktsii (cherez 1 ch posle stressa, modeliruemogo plavaniem krys v kletke v techenie 1 ch) kharakterizuetsia stimuliatsieĭ tripsinopodobnoĭ aktivnosti (TpA) v pecheni i, osobenno, v krovi. V stadiiu rezistentnosti (cherez 48 ch posle stressa) proiskhodit normalizatsiia TpA v krovi i ogranichenie ee vozrastaniia v pecheni. V stadiiu istoshcheniia stress-reaktsii (stressirovanie po 1 ch v techenie 10 sut.) razvivaetsia naibolee znachitel'noe uvelichenie TpA v pecheni i v krovi. Éksperimental'nyĭ gipotireoz (25 mg/kg merkazolila, 20 sut.), per se vyzyvaiushchiĭ umen'shenie TpA, opredeliaet bolee vyrazhennuiu stimuliatsiiu proteoliza v stadiiu trevogi, prepiatstvuet ego nivelirovaniiu v stadiiu rezistentnosti, a v stadiiu istoshcheniia sposobstvuet ego izbytochnoĭ aktivatsii. Vvedenie L–tiroksina v “malykh” dozakh (1,5-3,0 mkg/kg, 28 sut.) samo po sebe ne vliiaet na sistemu proteoliza, v stadii trevogi i istoshcheniia – limitiruet uvelichenie TpA, v stadiiu ustoĭchivosti – preduprezhdaet ee stimuliatsiiu. Zavisimost' izmeneniĭ v sisteme proteinazy/ingibitory pri stresse ot urovnia ĭodsoderzhashchikh tireoidnykh gormonov v krovi sviazana s ikh vliianiem na aktivnost' éndogennykh ingibitorov proteinaz (a1-antitripsina i a2-makroglobulina) i pronitsaemost' lizosomal'nykh membran.
Keywords: iodine-containing thyroid hormones; proteolysis; stress.