Rat liver tyrosine aminotransferase activity and induction by dexamethasone upon cadmium intoxication

This study was focused on Cd effects on basal and dexamethasone-induced tyrosine aminotransferase (TAT) activity in the rat liver cytosol. Cadmium (Cd), applied in the dose of 2 mg/kg b.w., stimulated both TAT activity and its induction by dexamethasone, inducing the most prominent alterations 24 h after administration. Doses lower than 2 mg Cd/kg b.w. were ineffective while the higher ones (3 and 4 mg Cd/kg b.w) led to the changes similar to those reached by 2 mg Cd/kg. The in vitro application of different Cd concentrations to the liver cytosol rendered the enzyme activity unchanged suggesting that the metal acted at the level of TAT gene transcription. Istrazivanja su bila usmerena ka pracenju efekata Cd na osnovnu i deksametazonom indukovanu aktivnost tirozin aminotransferaze (TAT) u citosolu jetre pacova. Kadmijum (Cd) primenjen u dozi od 2 mg/kg telesne tezine, stimulisao je i aktivnost TAT i indukciju enzima deksametazonom. Najizrazenije promene su zapazene 24 h nakon injeciranja metala zivotinjama. Doze nize od 2mg/kg telesne tezine nisu uticale na aktivnost enzima, dok su promene u prisustvu visih doza (3 i 4 mg Cd/kg telesne tezine) bile priblizne onim zapazenim nakon tretiranja zivotinja sa 2 mg Cd/kg. Nepromenjena aktivnost enzima uocena nakon inkubiranja citosola jetre pacova sa razlicitim koncentracija Cd, sugerisala je da se uticaj metala ostvaruje na nivou transkripcije gena za tirozin aminotransferazu.