EGb 761® is a special extract from leaves of Ginkgo biloba L. and is one of the most
popular herbal medicines in the world. Its therapeutic use includes the treatment
of cognitive impairment and neuropsychiatric symptoms in dementia. Alzheimer's disease
(AD) is a neurodegenerative disorder that accounts for 50 – 70% of all cases of dementia.
Although the etiology of the disease is still unknown considerable evidence suggests
the involvement of mitochondrial damage. Reduction of mitochondrial complex IV activity
mimics pathological processes involved in AD and can be evoked in rats by chronic
administration of sodium azide (NaN3). In fact, chronic infusion of NaN3 for one month
via subcutaneously implanted osmotic minipumps induced deficits in learning performance
of rats in the passive avoidance paradigm (PA). In comparison to control rats, animals
receiving NaN3 showed a significantly shorter latency time indicating a diminished
potential to remember previous aversive stimuli. Daily concomitant oral administration
of EGb 761® (25, 50 or 100 mg/kg) reversed the NaN3-induced learning deficit in the
PA model which was statistically significant already for the lowest dose and was comparable
to that of the acetylcholinesterase inhibitor donepezil (0.3 mg/kg/day).
Tab. 1: Effect of EGb 761® and donepezil on NaN3-induced cognitive impairment in rats as
measured by the latency time (seconds) in the passive avoidance model
|
Dose
(mg/kg, p.o.)
|
Vehicle +
NaCl
|
Vehicle +
NaN3
|
EGb 761® +
NaN3
|
Donepezil +
NaN3
|
|
0
|
180 ± 0
|
44 ± 29 *
|
|
|
|
0.3
|
|
|
|
145 ± 61 #
|
|
25
|
|
|
160 ± 56 #
|
|
|
50
|
|
|
147 ± 64 #
|
|
|
100
|
|
|
177 ± 7 #
|
|
|
* p < 0.05 vs. control group without NaN3; # p < 0.01 vs. vehicle group with NaN3
|
These results substantiate earlier experimental findings demonstrating neuroprotective
activity of EGb 761® and support its therapeutic use in the prevention and treatment
of AD.
