11-deoxycorticosterone, an inducer of a factor stimulating delta 9 desaturase activity in liver microsomes

The effect of 11-deoxycorticosterone on the oxidative desaturation of [14C]palmitic to palmitoleic acid by liver microsomes was studied in the rat. Twenty-four hours after the hormone injection (1 mumol/kg rat) a significant increase in delta 9 desaturase activity was observed in crude microsomes. A similar stimulation was produced in washed microsomes by addition of a factor present in the 110,000 x g supernatant soluble fraction obtained after extracting crude microsomes from deoxycorticosterone-treated rats with a low ionic strength solution. The deoxycorticosterone-induced factor was also present in the cytosol fraction (110,000 x g supernatant) obtained from livers of hormone-treated animals. Since 11-deoxycorticosterone does not have an 11-beta-OH function, this study demonstrates that such a hydroxyl group is not an absolute requirement for the induction of the soluble factor that regulates delta 9 desaturase activity in response to steroid hormones.