REGION-SPECIFIC ALTERATIONS OF CALBINDIN-D28K IMMUNOREACTIVITY IN THERAT HIPPOCAMPUS FOLLOWING ADRENALECTOMY AND CORTICOSTERONE TREATMENT

The aim of this study was (i) to compare the immunocytochemical distri bution of the calcium-binding protein calbindin-D28k (CB) in the hippo campus of rats with the pattern of neurodegeneration following adrenal ectomy (ADX) using silver impregnation, and (ii) to investigate the CB -immunoreactivity in the hippocampus following 3 weeks corticosterone treatment. 24 h following ADX no degenerative changes, nor alterations in CB-immunoreactivity were found in the hippocampus. Both 3 and 21 d ays following ADX neurodegeneration in the dentate gyrus could be obse rved which was accompanied with a loss of CB-immunoreactive (CB-ir) ce lls in that parts of the dentate gyrus suffering neuronal degeneration . Additionally we observed a marked loss of CB-ir in the CA1 area both 3 and 21 days following ADX. Three weeks daily corticosterone treatme nt (10 mg/day) induced a marked increase of CB-ir exclusively in the C A1 pyramidal cell layer. We conclude that (i) there is a close relatio nship between the loss of CB-immunoreactive cells in the DG and the ne uronal degeneration in the dentate gyrus following ADX, and (ii) corti costerone appears to be involved in the regulation of calbindin-D28k i n the CA1 pyramidal cell layer.