Improving Effects of FG-7080, a Serotonin Reuptake Inhibitor, on Scopolamine-Induced Performance Deficits of Memory Tasks in Rats

Abstract

Effect of an extract of Ginkgo biloba leaves (EGb) on oxidative metabolism was studied using rat brain neurons and 2',7'-dichlorofluorescin fluorescence. lonomycin (100 nM to 1 ƒÊM), a Ca2+-iono phore, dose-dependently augmented the 2',7'-dichlorofluorescin fluorescence in the presence of external Ca2+, but not under the external Ca2+-free condition. Preincubation of neurons with EGb (3 ƒÊg/ml) greatly reduced the ionomycin-induced increase in 2',7'-dichlorofluorescin fluorescence. Results suggest that EGb may reduce the Ca2+-induced increase in the oxidative metabolism of brain neurons.

Oxidative Stress-Induced Increase in Intracellular Ca2+ and Ca2+-Induced Increase in Oxidative Stress: An Experimental Model Using Dissociated Rat Brain Neurons

“…Ionomycin also augmented the intensity of DCF fluorescence significantly as shown previously (1,13). However, the potency of ionomycin in augmenting DCF fluorescence (the potency of oxidative effect of ionomycin) was unknown.…”

“…In fact, ionomycin that greatly increases the [Ca 2+]; of neurons augmented DCF fluorescence (Fig. 3A), suggesting an oxidation of cellular DCFH, depending on the [Ca 2+], increased by ionomycin (1). The potency of ionomycin in increasing the intensity of DCF fluorescence was almost equivalent to that of hydrogen peroxide at concentrations of 100-300 pM (Fig.…”

“…We have shown that the calcium ionophore ionomycin increases the oxidation of intracellular 2',7'-dichlorofluorescin which is considered to be oxidized by cellular peroxidants including hydrogen peroxide, in mammalian brain neurons; this is associated with an increase in the intracellular concentration of Ca2+ ([Ca 2+];) (1). Thus, excessive influx of Ca 2+ into brain neurons may result in an increased formation of reactive oxygen species that are involved in ischemic brain damages (2)(3)(4).…”

Extract of Ginkgo biloba Leaves Attenuates Kainate-Induced Increase in Intracellular Ca2+ Concentration of Rat Cerebellar Granule Neurons

“…We have shown that EGBL protects neurons suffering from oxidative stress induced by hydrogen peroxide 7) and decreases oxidative metabolism in resting and Ca 2ϩ -loaded neurons. 12,16) Oxidative stress is also induced by abnormally increasing [Ca 2ϩ ]i in neurons. 20,21) Therefore, if EGBL prevents increasing [Ca 2ϩ ]i of neurons by excessive activation of glutamate receptor, it would contribute to the neuroprotective action of EGBL.…”

“…9,10) The extract exerts protective action (or antioxidant action) on neurons suffering from oxidative stress induced by hydrogen peroxide, one of ROS, and by overload of intracellular Ca 2ϩ . 7,11,12) EGBL and its constituents inhibit the response mediated by activation of NMDA receptor. 13,14) However, there is limited information concerning the effect of EGBL on response induced by activation of non-NMDA glutamate receptor.…”