Effects of Ginkgo biloba on spatial memory and oxidative metabolism in healthy young rats

Ginkgo biloba (GB) is a yellow-leaved herb used in treating various diseases and cognitive disorders in China since 2000 years. This study investigates the effects of two different doses of GB, in the form of its standardized extract EGb 761, on liver and kidney functions, hippocampal tissue, and recognition and spatial memory in healthy young rats. Twentyone healthy male Sprague-Dawley rats, aged 8 weeks, were utilized. Rats were equally divided into three groups as control group (C) given tap water, experimental groups (GB100 and GB200) given 100 and 200 mg/kg/day GB. Following a 21 days of oral gavage, recognition memory was evaluated using the novel object recognition (NOR) test, while spatial memory were assessed using the Morris water maze (MWM) test. Animals were euthanized 24 h after the completion of the behavioral tests. Tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) levels were assessed in hippocampal tissue, while thiol, disulfide, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), urea, and creatinine levels were measured in serum samples. The recognition index (RI) in the NOR test was higher in 100 mg/kg GB group compared to control, whith no differences in the MWM test parameters among the groups (P > 0.05). GB200 reduced hippocampal TNF-α and IL-1β levels, while both GB100 and GB200 increased serum thiol levels. GB200 decreased disulfide levels but raised liver enzymes, suggesting potential liver impairment. These findings suggest that while 200 mg/kg GB exerts antioxidant effects, only 100 mg/kg improves recognition memory, and neither dose affects spatial memory.