Regeneration, Repair, and Developmental NeuroscienceResearch PaperDexamethasone induces apoptosis in the developing rat amygdala in an age-, region-, and sex-specific manner
Highlights
▶Dexamethasone induces apoptosis in the perinatal amygdala. ▶Effects are timing, sex, and subregion dependent. ▶Dependent on increases in Bax expression.
Section snippets
Animals
Timed-pregnant Sprague–Dawley dams were obtained from Charles River Laboratories (Wilmington, MA, USA) at 7 days' gestation and were handled for 4 days (GD14–17) before treatment. Dams were singly housed in a vivarium with a 14/10-h light/dark cycle, lights on at 0600 h, with food and water available ad libitum. For prenatal treatment, dams were s.c. injected with DEX dissolved in ethanol (2%) and diluted in safflower oil (0.4 mg/kg) or ethanol/safflower oil alone once daily at 1000 h on
Brain and body weights
Separate two-way ANOVAs revealed that both pre- and postnatal DEX treatments decreased brain [prenatal tx: F(1,20)=34.35, P<0.001; postnatal tx: F(1,20)=21.19, P<0.001] and body weights [prenatal tx: F(1,20)=65.57, P<0.001; postnatal tx: F(1,20)=13.9, P<0.01]. No significant sex or interaction effects were found for either treatment period. Post hoc comparisons revealed that body weights taken at the time of euthanasia were significantly decreased in both males and females following both DEX
Discussion
In this series of studies, we examined the effects of both late gestational and postnatal exposure to DEX on neural cell death. The results of these studies show that brain and body weight were decreased in male and female offspring of DEX-treated dams. Postnatal treatment of rats also caused overall decreases in brain and body weight. Of importance, DEX treatment had significant effects on the degree of cleaved caspase-3–positive cells in the amygdala, and these effects occurred in an age-,
Acknowledgments
The authors acknowledge Drs. Stuart Tobet and Jill Goldstein for providing helpful input in the design of these studies and the preparation of the manuscript. Also thanks to Alicia Quihuis and Anthony Lacaganina for their expert technical assistance. Support for these studies was provided by United States Public Health Service grants NS039951 and MH082679 (R.J.H.).
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