Astroglial Plasticity Is Implicated in Hippocampal Remodelling in Adult Rats Exposed to Antenatal Dexamethasone

The long-term effects of antenatal dexamethasone treatment on brain remodelling in 3-months old male Sprague-Dawley rats whose mothers had been treated with dexamethasone were investigated in the present study. Dorsal hippocampus, basolateral amygdala and nucleus accumbens volume, cell numbers and GFAP-immunoreactive astroglial cell morphology were analysed using stereology. Total brain volume as assessed by microCT was not affected by the treatment. The relative volume of the dorsal hippocampus (% of total brain volume) showed a moderate, by 8%, but significant reduction in dexamethasone-treated vs control animals. Dexamethasone had no effect on the total and GFAP-positive cell numbers in the hippocampal sub-regions, basolateral amygdala and nucleus accumbens. Morphological analysis indicated that numbers of astroglial primary processes were not affected in any of the hippocampal sub-regions analysed but significant reductions in the total primary process length were observed in CA1 by 32%, CA3 by 50% and DG by 25%. Mean primary process length values were also significantly decreased in CA1 by 25%, CA3 by 45% and DG by 25%. No significant astroglial morphological changes were found in basolateral amygdala and nucleus accumbens. We propose that the dexamethasone-dependent impoverishment of hippocampal astroglial morphology is the case of maladaptive glial plasticity induced prenatally