Effect of dexamethasone on mitochondrial maturation in the fetal rat brain

OBJECTIVE: The objective of the present study was to explore whether prenatal dexamethasone treatment influences mitochondrial maturation in the fetal rat brain. STUDY DESIGN: Mitochondrial respiration was measured polarographically with homogenates of fetal cerebral cortical tissues on day 16 (with saline solution, N = 8; with dexamethasone, N = 8), day 18 (with saline solution, N = 8; with dexamethasone, N = 8), and day 20 (with saline solution, N = 8; with dexamethasone,n = 8) of gestation. Four doses of dexamethasone (0.1 mg • kg) or vehicle (saline solution) were given, withan interval of 12 hours, until 12 hours before each measurement. RESULTS: In the vehicle-treated animals, mitochondrial respiratory activity was increased significantly after day 18 of gestation. Dexamethasone-treated animals showed a significant increase in mitochondrial activity at day 16 of gestation compared with vehicle-treated animals. CONCLUSION: The results indicate that prenatal dexamethasone treatment contributes to the precocious maturation of mitochondrial activity in the fetal rat brain. Because acceleration in cerebral mitochondrial activities is required immediately after birth to maintain high-energy phosphate levels, the precocious maturation may be crucial for the successful outcome of the preterm infant. (Am J Obstet Gynecol 2002;186:574-8.)