A Review of Three Commonly Used Herbs Which Enhance Memory and New Evidences Which Show Their Combination Could Improve Memory in Young Animals

This review looks into the herbs gingko biloba, polygala tenuifolia, and lycii fructus for their widely studied neuroprotective properties. Effects of the interaction between the herbs are studied by behavior tests to evaluate memory, and examination of signal transduction enzyme, major neurotransmitters, cell death and antioxidation. For 6-month treated mice, behavior showed shorter escape latency in the water maze and faster arrival time in a consolidated memory task. Immunochemistry showed evident increase in superoxide dismutase (SOD) activities in the prefrontal cortex, which implies protection against harmful free radicals during aging. Discrete increase of catecholaminergic neurons was found in the prefrontal area, hippocampus, corpus striatum, and midbrain. This hints better memory and better control on mood and behavior. Necrotic cells in the brain decreased as indicated by immunocytochemistry of lactic dehydrogenase (LDH). TUNEL showed no apoptotic cells in most brain areas in high dose treated animals. Biochemistry revealed increase of dopaminergic cells in all treatment groups for the prefrontal area, and in the hippocampus and cerebellum of the high dose group. Most 6-month groups had an increase of serotonin in all three areas. For the high dose group, GABA increased in the hippocampus but not prefrontal, which would help induce sleep at night. Protein kinase C was increased in most groups in the prefrontal, hippocampus and cerebellum, signifying increase of possible signal transduction pathways for memory or other nervous activations. Our results intimate that the interaction of the three herbs exerts beneficial effects in memory, associated cognitive function, and necrosis.