The effects of repeated corticosteroid administration on the neurogenesis in the neonatal rat.

Objective: The purpose of this study is to clarify the effects on the brain including neurogenesis pretreated with repeated doses of dexamethasone in the neonatal rat.

Study Design: The 4-day-old Sprague Dawley rats were pretreated with 4 different regimens, namely, single administration of dexamethasone, 2-dose administration, 3-dose administration, and saline administration as a control. Concurrently, bromodeoxyuridine (BrdU), which was incorporated into the dividing cells, was administered. We examined body weight, brain weight, and the number of BrdU-labeled cells in the subventricular zone (SVZ), the subgranular zone (SGZ), and the cortex.

Results: Both the body and brain weight of the rats pretreated with dexamethasone were significantly decreased compared with those given saline. Quantitative analysis of BrdU-labeled cells revealed the significant dose-dependent decreases in the SVZ, the SGZ, and the cortex with the dexamethasone treatment.

Conclusion: We concluded that the decreases in neurogenesis caused by repeated antenatal corticosteroid therapy might result in the adverse effects on the size of the head at birth.