The studies of Ginkgo biloba extract in animals with damage and degeneration of brain tissue

• Main Authors: Shu-Ying Chung, 鐘淑英
• Other Authors: Ming-fu Wang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/13750239006538697948

博士 === 靜宜大學 === 食品營養研究所 === 95 === Abstract The dissertation has narrated the effects of Ginkgo biloba leaf extract (EGb 761) or combined with neuroprotective agents (MgSO4, FK506 and MK-801) on cerebral infarct volumes, energy and dopamine metabolites in the animal (gerbil) subjected to cerebral ischemia, and the other effects of Ginkgo biloba leaf extract on the learning abilities and memory and brain pathology in the animal (SAM P8) with brain aging. Prior to ligature for one week gerbils were fed EGb 761 (100 mg/kg/day, ig.) then combined with single dose MgSO4 (90 mg/kg), FK506 (0.5 mg/kg), or MK-801 (1 mg/kg) treatment by intraperitoneal injection. The infarct volumes of permanent cerebral ischemia were assessed by TTC (2,3,5-triphenyl-tetrazolium chloride) staining. And in the temporary cerebral ischemia two microdialysis probes were used for collecting the in vivo samples to measure the levels of extracelluar glucose, pyruvate, lactate as well as dopamine and its metabolites, including 3,4-dihydroxy-phenylacetate (DOPAC), 3-methoxytyramine (3-MT) and homovanillic acid (HVA) during cerebral ischemia and reperfusion periods. The results of the studies showed that in the permanent cerebral ischemic model EGb761 alone or in combination with MgSO4, FK506 or MK-801 reduced the total infarct volumes by 36%, 40.3%, 35.3%, and 56.4%, respectively (P<0.01). In the temporary cerebral ischemia EGb761 combined with FK506 injected after ligature reduced the total infarct volumes by 57%. EGb761 alone or in combination with FK506 injected prior to ligature significantly preserved glucose (50% of the baseline) and pyruvate (60% of the baseline) levels during ischemia and increased glucose (150% of the baseline) and maintained pyruvate (65% of the baseline) during reperfusion, but EGb761 combined with FK506 group showed that the dopamine peak significantly increased approximately 2 folds at the onset of ligature, when compared with the control group (P<0.05). And the significant elevation of the dopamine level persisted for 120 minutes in reperfusion period. The supplementation of 0.06% (100 mg/kg), 0.12% or 0.3% Ginkgo biloba leaf extract was extra used in the 20% casein diet. All the aged SAM P8 (aged 6 months) were fed for four months, tested their learning abilities and memory and observed the changes of brain pathology. It was found that the supplemen- tation of different percent Ginkgo biloba leaf extract could not improve learning abilities and memory of aged SAM P8, but significantly reduced the variations of β-amyloid deposits by mean area percentage in the hypothalamus (P<0.05), and the numbers of multiple vacuoles in the cortex, hippocampus, and thalamus (P<0.01). The results of the studies indicated that the long-term administration of EGb761 alone or in combination with neuroprotective agents could efficiently have neurological protection in the infarct volumes of gerbils’ brain and the treatment of EGb761 in combination with FK506 owned the reserve effect of cellular energy metabolism during cerebral ischemia and reperfusion. However, cerebral ischemia induced a large part of dopamine may be catabolited through alternative pathway to form more reactive metabolites other than 3-MT. On the contrary it is harmful to neuron. The long-term supplementation of Ginkgo biloba leaf extract could influence in the variations of β-amyloid deposits and spongy form of aged SAM P8 brain, but not in the learning abilities and memory of aged SAM P8.