The effect of corticosteroids on amyloid beta precursor protein/amyloid precursor-like protein expression and processing in vivo

In this study, we have investigated the effect of altered corticosteroid le vels on the expression and processing of the amyloid beta precursor protein (A beta PP) and its a myloid precursor-like protein (APLP) homologue in ra t brain. Four groups of animals were used in the study: sham operated, adre nalectomised, and adrenalectomised treated with either dexamethasone or ald osterone, with the A beta PP/APLP expression being determined by western bl ot analysis. While there were no changes in the levels of A beta PP/APLP fo llowing adrenalectomy, treatment with dexamethasone, but not aldosterone, r esulted in a marked increase in protein expression levels with the level of increase varying between the brain regions examined. Corticosteroids had a more marked effect on the particulate rather than the soluble form of the protein, thus suggesting that elevated glucocorticoids may also be adversel y influencing A beta PP/APLP processing. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.