The effect "in vivo" of 11 beta-hydroxy-pregna-1,4-diene-3,20-dione (
delta HOP) in acute and chronic treatment was studied in mice compared to those treated with
dexamethasone and vehicle. In acute experiments an injection of 2 mg/100 g
body weight of
delta HOP had a maximal inhibitory effect in 3H-uridine incorporation by thymocytes 18 h after the injection, disappearing 36 h later, meanwhile no change was observed in plasma
corticosterone levels at any time. The dose 0.033 mg/100 g
body weight of
dexamethasone produced a high inhibition 5 h after the injection, and a significant decrease in plasma
corticosterone was produced at this time; the effect disappeared at 24 h. In the chronic treatment
delta HOP produced the maximal inhibition 5 h after the treatment; this effect was maintained until 36 h and disappeared at 48 h without change in
corticosterone levels. Meanwhile
dexamethasone produced the same inhibition as
delta HOP 5 h after the treatment; this effect disappeared after 18 h. In those animals plasma
corticosterone decreased during longer time than in acute treatment, since it continued lower than normal at 18 h and it recovered at 24 h. After 5 h of a chronic treatment
delta HOP did not change thymus and spleen weights, but they decreased with
dexamethasone treatment. These results suggest that the "in vivo" actions of
delta HOP is different from that of
glucocorticoids.