[Hydrocortisone decreases blood flow in bones in sham-operated and oophorectomized female rats]

In an experiment on 38 75-day-old female rats--sham-operated or oophorectomized (OOX)--the authors assessed the effect of hydrocortisone administration (0.01% in the diet for four weeks) on the blood flow in the tibia and distal end of the femur (uptake of 85Sr microparticles). In the tibia they assessed also the density (according to the Archimed principle) and the weight of ashes per volume unit of bone. OOX increases significantly local circulation in both bones. After hydrocortisone these values are significantly lower in sham-operated and OOX rats as compared with controls and also significantly lower in the group OOX+hydrocortisone, as compared with group OOX. The density and weight of ashes from the tibia are not affected by hydrocortisone; the minute volume of the heart per 100 g body weight of rats is not altered in any group. The mechanism of the described hydrocortisone effects on circulation is not known. In the discussion the authors indicate possible associations of blood flow and the osteoblast and prostaglandin function in bony tissue.