Mechanism of the inhibitory effect of 11 beta-hydroxypregna-1, 4-diene-3, 20-dione (delta HOP) at high concentrations in RNA synthesis.

The strong inhibition of thymocyte-RNA synthesis by 11 beta-hydroxypregna-1, 4-diene-3, 20-dione (delta HOP) reported recently, fulfills the three conditions required for a non-genomic effect, i.e.: no persistence upon washing out, instantaneous action and effect in the presence of inhibitors of RNA synthesis. Injection of (delta HOP) into mice (2 mg/100 g) also causes a 32% inhibition in their thymocyte-RNA synthesis, but the mechanism of this latter inhibition has still not been clarified.