Moguća uloga metalotioneina i proteina toplotnog stresa u zaštiti glukokokortikoidnog receptora u uslovima trovanja kadmijumom

Abstract

The participation of metallothionein (Mt) and heat shock proteins (Hsps) in protection of glucocorticoid receptor (GR) binding capacity from a toxic metal cadmium (Cd), was investigated. Specific binding of a glucocorticoid to GR in the rat liver cytosol was studied after in vitro and in vivo Cd treatment. Reduction of the GR binding capacity observed after in vitro treatment was proportional to the applied metal concentrations. In animals administered different Cd doses, GR binding capacity was not reduced, except in those that received the highest dose, and a concomitant elevation of Mt, Hsp70 and Hsp90 levels was detected. The results led to the assumption that Cd-induced reduction of the GR binding capacity noticed in vitro, was prevented in intact animals by the elevated levels of Mt and Hsps.

Ispitivano je učešće metalotioneina (Mt) i proteina toplotnog stresa (Hsp)y zapititi glukokortikoidnog receptora (GR) od toksičnog delovanja kadmijuma (Cd). Specifično vezivanje glukokortikoida za GRy citosolu jetre pacova praćeno je posle in vitro i in vivo tretmana kadmijumom. Zapaženo je da je u in vitro uslovima smanjenje sposobnosti GR da vezuje hormon proporcionalno primenjenoj koncentraciji metala. Kod životinja injeciranih različitim dozama Cd, kapacitet GR za vezivanje hormona je nepromenjen osim u prisustvu najveće doze, i istovremeno se uočava povećanje koncentracije Mt, Hsp70 i Hsp90. Dobijeni rezultati ukazuju da je smanjena sposobnost GR za vezivanje hormona zapažena nakon in vitro tretmana kadmijumom, kod životinja injeciranih kadmijumom sprečena povećanom indukcijom Mt i Hsp.