Dissociation of glucocorticoid effects of C-21 steroids at high concentrations in thymocytes

Influence of calf serum on glucocorticoid-responses of certain progesterone derivatives

The following in vitro glucocorticoid (GC) parameters of progesterone (P), 1-ene progesterone (deltaP), 11beta-hydroxyprogesterone (HOP), 11beta-1-ene progesterone (deltaHOP) and dexamethasone (Dexa) were assayed in the presence or absence of bovine calf serum (BCS): binding to thymus cytosol, dissociation of the glucocorticoid receptor (GR)-heat shock protein 90 (hsp90) complex (diss.), tyrosine aminotransferase (TAT) induction in hepatocytes and the inhibition of 3H-uridine and 35S-methionine uptake by thymocytes. Without BCS, steroids were in most cases active in this general order: Dex > deltaHOP > HOP > deltaP > P. BCS abolished all activities in P and deltaP, but left them unaltered in all other steroids, except diss. in HOP, which diminished intermediately. Binding of P, deltaP, HOP and deltaHOP to GR and CBG paralleled their in vivo activating effects on glycogen deposition.

CONCLUSIONS

in this steroid series, BCS, but not CBG, inhibits GC responses of P and deltaP. 11-Beta hydroxylation frees those molecules from the inhibitory effects of BCS.

Electron impact induced fragmentations of the 1,4-diene analogues of steroid hormones and related steroids

The electron impact induced fragmentations observed in the mass spectra of eight 1,4-diene-3-ketopregnane steroids are described. The effect of hydroxyl substituents in positions 11 beta, 17 alpha and 21, on the typical fragmentation pattern is analysed; in particular the 'long range' effect of the 17 alpha-hydroxy group on the relative abundance of the ions m/z 121 and 122 is confirmed using specific deuterium labelling.