AGE-RELATED-CHANGES OF SULFIDE-SILVER STAINING IN THE RAT HIPPOCAMPUS

The influence of ageing on sulphide-silver positive zinc stores was as sessed in the stratum radiatum of the CA(1)-CA(3) sub fields of the ra t hippocampus and in the molecular layer of the dentate gyrus using a silver amplification histochemical technique associated with microdens itometry. The volume of areas examined for microdensitometry was evalu ated as well by quantitative image analysis. Male Sprague-Dawley rats aged 3 months (considered to be young), 12 months (considered to be ad ult) and 24 months (considered to be old) were used. Microdensitometri c analysis of values of sulphide-silver staining corrected for the vol ume of hippocampal areas investigated revealed no age-dependent change s of staining in the CA(1) sub field of the hippocampus. In the CA(2) sub field a decrease of sulphide-silver staining was noticeable in age d rats in comparison with younger cohorts. A progressive reduction in the intensity of sulphide-silver staining was observed in the CA(3) su b field of the hippocampus. In the molecular layer of the dentate gyru s, the intensity of staining was decreased in adult and old rats in co mparison with young animals. These findings indicate a different sensi tivity to ageing of histochemically detectable zinc stores of rat hipp ocampus. The possibility of a specific sensitivity to senescence of di fferent zinc-containing pathways of the hippocampus is discussed. (C) 1997 Elsevier Science Ireland Ltd.