REGULATORY EFFECT OF VARIOUS STEROID-HORMONES ON THE INCORPORATION AND METABOLISM OF [C-14] STEARATE IN RAT HEPATOMA-CELLS IN CULTURE

We have examined the incorporation and metabolism of [C-14] stearic ac id within the total lipids of HTC rat-hepatoma cells in suspension cul ture in presence and in absence of steroidal hormone stimulation. Both , glucocorticoids (dexamethasone, cortisol and corticosterone) and min eralocorticoids (deoxycorticosterone and aldosterone) as well as the e strogen beta-estradiol and the androgen testosterone enhanced the exte nt of Delta 9 desaturation to oleic acid of the saturated precursors, whereas only the two mineralocorticoids affected the incorporation rat e of the exogenous acid into total cellular lipids, thus promoting a l ittle stimulation. Furthermore, all the hormones tested increased the radiolabelling of the total cellular phospholipids except deoxycortico sterone and testosterone, the former having no effect and the latter e xerting a moderate inhibition. On the other hand, the incorporation of C-14 into neutral lipids was stimulated by testosterone, in contrast to the inhibition of this parameter observed exclusively with either t he mineralocorticoids or the estrogen, Within the phospholipid subclas ses, the radiolabelling of phosphatidylcholine was augmented by means of all the steroids tested save deoxycorticosterone and testosterone, whereas phosphatidylethanolamine exhibited a decrease only in the pres ence of testosterone. In a similar fashion, within the neutral lipids, the predominating triglyceride fraction was preferentially labelled - at the expense of other subclasses of lesser abundance - upon treatme nt with the steroids except aldosterone, which exerted no effect. The results obtained were correlated with those changes observed in the ma ss distribution of the different lipid subclasses either with or witho ut prior hormonal stimulation.