HIPPOCAMPAL DENTATE GRANULE CELL DEGENERATION AFTER ADRENALECTOMY IN THE RAT IS NOT REVERSED BY DEXAMETHASONE

Although adrenalectomy has been reported to induce a selective and som etimes nearly complete degeneration of hippocampal dentate granule cel ls, Azmitia and colleagues recently reported (Mol. Brain Res., 19 (199 3) 328-332) that normal hippocampal structure can nonetheless be resto red within a matter of days by dexamethasone in the drinking water. We have attempted to confirm this remarkable finding. Four months after adrenalectomy, rats were given vehicle or dexamethasone for 5 days and then sacrificed. Histological analysis revealed that vehicle-treated adrenalectomized rats exhibited a full spectrum of granule cell loss, which spanned mild to nearly complete cell loss. Dexamethasone-treated adrenalectomized rats did not differ from vehicle-treated adrenalecto mized rats and, in fact, exhibited a virtually identical spectrum of g ranule cell loss. These results confirm that adrenalectomy reliably in duces hippocampal granule cell degeneration in a majority of animals a nd indicate that dexamethasone does not restore normal hippocampal str ucture once granule cell loss has occurred.