EFFECT OF LONG-TERM TREATMENT WITH EGB-761 ON AGE-DEPENDENT STRUCTURAL-CHANGES IN THE HIPPOCAMPI OF 3 INBRED MOUSE STRAINS

Female mice of the inbred strains C57BL/6J, BALB/cJ and DBA/2J were us ed to determine the possible existence of a genetically-based differen tial susceptibility to the effects of treatment with an extract of Gin kgo biloba (EGb 761). Timm's silver-sulphide staining method was used to visualize and determine changes in the areas of the hippocampal str uctures of aged subjects, and more specifically on the projection fiel ds of the messy fibers which appear to decrease as a function of agein g. Experiments were begun when the animals were 15 months old. Treated animals received EGb 761 (50 mg/kg/day, p.o.) for 7 months in their d rinking water. Inter-strain differences existed for the areas of the w hole regio inferior, stratum pyramidale, stratum lacunosum moleculare and hilus (CA4) and for the projection field of intra- and infrapyrami dal mossy fibers (iipMF) in the CA3 region of the hippocampus. Chronic treatment with EGb 761 significantly increased the projection field o f iipMF and significantly reduced the area of the stratum radiatum, as compared with control mice. No differential sensitivity to EGb 761 ex isted among the mouse strains tested. Antioxydant properties of EGb 76 1 may explain its neuroprotective and neurotrophic actions on the hipp ocampus, and might explain certain improvements in memory and other co gnitive functions in both humans and experimental animals.