Effect of isoflavone genistein on insulin receptors in perfused liver of ovariectomized rats

The experiments were carried out on ovariectomized Wistar rats. Their liver s were perfused with basic perfusion medium (BPM) or BPM supplemented with isoflavone genistein, insulin or combination of the two factors. The obtain ed results support the hypothesis that genistein influences the kinetics of insulin binding to cell membranes changing the number of insulin receptors and dissociation constant (K-d) BPM supplementation with genistein decreas ed number of high affinity insulin receptors (HAIR) both in livers treated and untreated with insulin. The amount of HAIR diminished significantly fro m 610+/-77 x 10(-15) (no genistein) to 238+/-72 x 10(-15) mol/mg of membran e protein (supplement of genistein). Similarly, genistein reduced slightly the amount of HAIR even when added together with insulin (372+/-59 x 10(-15 ) mol/mg) in comparison to rats perfused with medium containing insulin but not the isoflavone (421+/-46 x 10(-15) mol/mg). Simultaneously, genistein decreased significantly K-d for HAIR (perfusion with BPM - 1.44+/-0.18 x 10 (-9) mol/l; (perfusion with BMP + genistein 0.83+/-0.20 x 10(-9) mol/l). Su ch effects of genistein during liver perfision did not 0.83+/-0.20 x 10(-9) mol/l). Such effects of genistein during liver perfision did not take plac e when the liver membranes were in vitro incubated with this xenobiotic.