Growth hormone and liver mitochondrial protein synthesis effect of cortisol and estradiol

The effect of cortisol and estradiol on the stimulation by growth hormone of liver mitochondrial protein synthesis in hypophysectomized rats has been studied by measuring radioactive leucine incorporation in vivo and in vitro. Estradiol inhibited the stimulatory effect of growth hormone on incorporation into mitochondrial and microsomal proteins. Cortisol blocked the stimulatory effect of growth hormone on mitochondrial protein synthesis. The stimulatory effects of cortisol and growth hormone on microsomal incorporation were not additive. Gain in body weights corresponded with their effects on mitochondrial and microsomal protein synthesis. These results show that steroid hormones may act as regulators of the growth hormone effect.