Damaged neuronal energy metabolism and behavior are improved by Ginkgo biloba extract (EGb 761)

The standardized extract EGb 761 from the dried green leaves of Ginkgo bilo ba is a complex mixture of ingredients with an uniquely broad spectrum of p harmacological activities on the central nervous system e.g. in memory enha ncing properties and in the regulation of cerebral glucose/energy metabolis m. To test these effects on both behavioral and metabolic brain parameters, the animal model of intracerebroventricular (icv) streptozotocin (STZ) tre atment was used. To quantify the experimental data more precisely, animals that were good performers were separated from poor performers by means of t he holeboard test before icy administration of STZ. Good performers only we re considered for the study. After a 1-week training period on the holeboar d improvement was seen in all animals in learning, memory and cognition, an d the improvement was maintained over the investigation period of 12 weeks in the control group. In this group, the energy pool in the cerebral pariet otemporal cortex was found to be large and the energy turnover high. After triplicate icy STZ injection, working memory (WM), reference memory (RM), a nd passive avoidance (PA) behavior fell off and continued to deteriorate th roughout the investigation period. Otherwise there were no significant diff erences in locomotor activity, excluding the possibility that activity per se might have contributed to the behavioral abnormalities. These were accom panied by a permanent deficit in cerebral energy metabolism. The ongoing de terioration in behavior and the maintained deficit in cerebral energy metab olism occurring after a triplicate icy STZ injection were significantly slo wed down by EGb761. The deficits in learning, memory and cognition were par tially compensated, and the disturbances in cerebral energy metabolism retu rned to almost completely normal values. These findings underscore the bene ficial effect of EGb761 that had been reported in dementia disorders.