[DHEA: another hormonal modulator of bone blood flow in rats]

Dehydroepiandrosterone (DHEA) is a steroid with important effects on the bone tissue. We tried to check up if it influenced also the bone blood flow (similarly as estradiol and testosterone). We administered DHEA (Sigma) dissolved in dimethylsulphoxide s.c. three times weekly for four weeks in the doses of 15-20 mg per rat on 125 mg/kg body weight to female rats--sham-operated or oophorectomized (OOX). In two experiments (A and B) we ascertained the uptake of 85Sr-microspheres, local blood flow, cardiac output, density and ash weight of the burned tibia, in the third experiment (C) 24 hour incorporation of 45Ca and 3H-proline into the bone. The 85Sr-microsphere uptake in the tibia was elevated after OOX in both experiments A and B; this increase was inhibited completely (and statistically significantly versus the OOX group) by the administration of DHEA. Similar and also significant reactions were found in the microsphere uptake values in the distal end of femur. No significant changes could be demonstrated in the diaphysis of femur and calvaria as well as in the cardiac output, output, blood pressure and heart rate. The incorporation of 45Ca and 3H-proline into the tibia (experiment C) was significantly increased after OOX. The administration of DHEA inhibited this increase significantly in the values of 3H-proline. The density of tibia in both experiments A and B and ash weight of tibia in experiment A, suppressed after OOX, were significantly increased after the administration of DHEA to OOX females. The results show that also DHEA--in the experimental conditions used--has similar effect on the bone blood flow as estradiol and testosterone.