BASIC FIBROBLAST GROWTH-FACTOR AND STEROID-RECEPTORS IN THE AGING HIPPOCAMPUS OF THE BROWN-NORWAY RAT - IMMUNOCYTOCHEMICAL ANALYSIS IN COMBINATION WITH STEREOLOGY

The effect of aging on the hippocampal formation of the male Brown Nor way rat was studied by immunohistochemistry and measurements of the im munoreactive hippocampal cells using stereological techniques. The tot al estimated number of glucocorticoid receptor (GR) immunoreactive neu rons of the CA1-CA2 area did not differ in the 3- and the 36-month-old rat. However, the intensity of the GR immunoreactivity was decreased in the aged animals. A gradual decrease of the immunoreactivity for th e mineralocorticoid receptor was also observed in the CA1-CA2 area. In the stratum oriens and the stratum radiatum of the CA1-CA2 area the i mmunoreactivity for basic fibroblast growth factor (bFGF) present in t he glia was found to be reduced [20,000 +/- 2100 (n = 6)] in the 36-mo nth-old rat vs the 3-month-old rat [28,500 +/- 4500 (n = 4) (P = 0.05 )]. However, there was no difference in the number of glial fibrillary acidic protein immunoreactive cells of this area in these two age gro ups. The present findings give evidence that in the Brown Norway rat t here is no loss of the neuronal population containing glucocorlicoid r eceptors of the CA1-CA2 area during aging but suggest that aging is ch aracterized by deficits of glially derived growth factors, such as bFG F.