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Abstract To explore the effect of Ginkgo biloba extract on the advanced functional activities of the central nervous system, and to provide an experimental basis for the clinical application of Ginkgo biloba extract in the treatment of cognitive dysfunction, an animal model of Alzheimer's disease with learning and memory impairment induced by scopolamine in aged rats. Learning memory behavior training and biochemical detection methods such as water maze and darkness test were used to observe the changes of animal learning and memory behavior and hippocampal acetylcholine and protein content before and after treatment.
Experimental Study on Ginkgo Biloba Extract Improving Learning and Memory Disorder
Experimental Study on Ginkgo Biloba Extract Improving Learning and Memory Disorder
The results showed that Ginkgo biloba extract significantly improved the learning and memory ability of experimental animals in a dose-dependent manner (P < 0105 or P < 0101) and significantly increased the acetylcholine content in hippocampus (P < 0105 or P < 0101). The results showed that Ginkgo biloba extract could improve learning and memory dysfunction in dementia rats.
Key words Ginkgo biloba extract, acetylcholine, learning and memory impairment
Ginkgo biloba is a traditional Chinese medicine with various pharmacological effects. The main medicinal ingredients extracted from Ginkgo biloba leaves are total flavonoids and ginkgolides. Abbreviated as ginkgo leaf extract (ex t ract s of ginkgo b iloba leaves, EGB) ). Recent studies have shown that EGB is a natural free radical scavenger that protects the body from free radical damage, improves cerebral circulation disorders and neuronal function. EGB has been widely used in the treatment of coronary heart disease and brain at home and abroad. Ischemia, and experimental or clinical studies on the effects of EGB on advanced neurological activities such as cognitive function are rarely reported. The aim of this study was to investigate the effect of EGB on learning and memory in rats with Alzheimer's disease, and to explore its possible mechanism to provide a basis for clinical application of EGB.
1 Materials and methods
1.1 Experimental materials
1.1.1 Experimental animals: Old male W istar rats, aged from 20 to 24 months, weighing 650-820 g (feeding young to old age), animal model of senile dementia was established with reference to [1].
1.1.2 Drugs: Ginkgo biloba extract EGB (containing 24% total flavonoids, 60% total lactone); scopolamine.
1.2 Experimental methods
1.2.1 Experimental grouping: Rats were randomly divided into 5 groups: normal old control group, model group, EGB low dose group (75m gö kg), EGB medium dose group (150 m gö kg), EGB high dose group (500) m gökg) , 8 rats in each group were administered by intragastric administration. The normal old control group and the model group were intragastrically administered with the same volume of normal saline. The single-dose administration was 5 days, and the water maze and darkness were tested on the 6th day. Test, stop the medicine during the test. The experimental animals were kept at (22 ± 3) °C, free to drink water, and naturally illuminated.
1.2.2 Learning and memory behavior training and learning and memory ability evaluation: 1 Distinguishing learning and memory training and evaluation: The effect of drugs on learning and memory ability of dementia rats was tested by water maze method. The number of times the dementia rats traveled from the beginning of the water maze to the end point safety station and the number of errors entering the blind end on the way was used as an indicator to measure the ability of learning acquisition and memory consolidation. 2 avoidance reaction: The effect of drugs on learning and memory ability of dementia rats was tested by avoiding dark test. The time required for the rats to reach the dark environment passive avoidance test and the number of shocks were used as indicators for learning and memory enhancement in rats.
1.2.3 Determination of acetylcholine and protein in hippocampus
An improved method for determining the acetylcholine content of the hippocampus by alkaline hydroxylamine colorimetry. The method for determination of hippocampus protein content was as follows: After completing each experimental step, the rats in each group were quickly decapitated, and the hippocampus were weighed separately, and the homogenate was ground by adding T r is2 HCl buffer (pH 712), centrifuged, and filtered. The protein content of the hippocampus was determined by the Low ry method.
1.3 Statistical processing
All experimental data were expressed as xq±s, and data were processed using t test and analysis of variance. The significance level was P < 0105 or P <0101.
2 results
2.1 Effect of EGB on learning and memory ability of old mice with learning and memory impairment caused by scopolamine (Scop)
The 7-day water maze test showed that the time required for the rats in the EGB group to travel to the labyrinth and the number of errors in the middle of the group were significantly lower than those in the model group (P < 0105 or P < 0101), EGB large, medium and small dose groups. The differences were significant (P < 0105 or P < 0101). Compared with the normal elderly control group, the model group had significantly higher time and number of errors in the labyrinth than the latter (P <0101).
In the EGB large, medium and small dose group, the model was established to achieve the dark environment passive avoidance test, and the learning process was significantly shorter than the model group (P <0105 or P < 0101). The time required for the EGB large, medium and small dose groups was significantly different (P<0101), and the learning time of the model group was significantly longer than that of the normal elderly control group (P < 0101); the number of electric shocks in each EGB dose group It was also significantly less than the model group (P < 0101). The number of shocks in the EGB high-dose group was significantly less than that in the middle-dose group (P < 0101). The middle-dose group was significantly less than the low-dose group (P < 0105).
2.2 Effects of EGB on acetylcholine (Ach) and protein content in hippocampus of aged rats with learning and memory impairment induced by Scop
The A ch content in the hippocampus of EGB rats in the large, medium and small dose groups was significantly higher than that in the model group (P < 0105 or P < 0101), while the A ch content in the hippocampus of the EGB high dose group was significantly higher than that in the EGB medium and low dose groups. (P < 0101). In addition, compared with the normal elderly control group, the protein content in the hippocampus of the rats in the learning and memory impairment model group was significantly decreased (P < 0101). After the administration of EGB, the protein content in the hippocampus of the experimental rats after modeling was Increased, but not statistically significant (P > 0105),
3 Discussion
Ginkgo biloba is one of the longest-lived plants on the earth. Ginkgo biloba leaves are contained in the Essentials of Herbal Medicine. It has been used for thousands of years as a traditional Chinese medicine in the motherland. Since the active ingredients of Ginkgo biloba have been basically confirmed, some clinical pharmacology and application studies on Ginkgo biloba have appeared in recent years. There are indications [4] that Ginkgo biloba extract EGB may improve the function of learning and memory, but its specific mechanism needs to be further explored. In particular, the mechanism of EGB prevention and treatment of senile dementia learning and memory dysfunction is rarely reported.
The ideal animal model for making human senile dementia is directly related to the reliability and practical value of the experiment. In recent years, although many animal models of senile dementia have been established, most of them can only simulate the biochemistry and pathology of senile dementia. In terms of changes, the in-depth study on the pathogenesis and prevention measures of Alzheimer's disease is still waiting to develop a more ideal animal model. According to reports [5], the rat learning and memory impairment model established by the anticholinergic drug scopolamine can be used as one of the effective animal models for studying the mental retardation of Alzheimer's disease. This experiment uses old rats to model, more in line with the aging characteristics of the senile dementia animals, but also closer to the functional state of human senile dementia patients. Our experimental results showed that the learning and memory ability of the model group was significantly lower than that of the normal old control group, suggesting that the modeling method is stable and reliable, and is suitable for the study of advanced neurological activities such as learning and memory. In this study, we found through water maze and avoidance test: EGB can effectively improve the learning and memory ability of dementia rats, suggesting that EGB can alleviate the mental retardation of dementia aged rats to a certain extent, in the range of 75-500 m gö kg, EGB The pharmacological effects were dose-dependently enhanced. Chop in et al [6] in the mouse model of memory dysfunction caused by A lzheim er disease, giving EGB 150 ~ 500 m gö kg, can significantly reduce the forgetting effect. A similar study showed that EGB dose-dependently improved learning and memory in normal rats [7]. In recent years, the clinical efficacy of EGB has also found that EGB can significantly improve the mental retardation of patients with vascular dementia. This effect may be related to EGB's acceleration of nerve impulse conduction, facilitating synaptic transmission, thus facilitating information acquisition, memory consolidation and reproduction. Related to [4,8]. It can be seen that EGB is a kind of nootropic drug with a wide range of effects and a positive effect, and it has a good clinical application prospect.
Studies have shown that the level of protein synthesis in hippocampus is closely related to learning and memory [9], and another study found that the mechanism of learning and memory impairment caused by scopolamine may be due to scopolamine inhibiting the synthesis of synaptosome proteins in the brain, especially in the hippocampus. The synaptic transmission affecting neural information leads to the influence of learning and memory ability in rats [1]. The protein in the hippocampus of the experimental model group was significantly lower than that of the normal old control group, which was consistent with the above conclusions, and further proved that the modeling method was stable and reliable after improvement. This experiment also showed that EGB, unlike other nootropics, did not significantly increase the reduced protein content in the hippocampus of dementia rats, so the promotion of protein synthesis may not be the mechanism of EGB.
The hippocampal cholinergic projection fibers of the central cholinergic system and the dysfunction of basal forebrain cholinergic cells are important causes of the decline in learning and memory ability of various types of dementia animals. The results of this study are to explore the pathophysiological mechanisms of animal learning and memory. Established a certain morphological and material basis. Our experiments found that EGB can significantly increase the A ch content in the hippocampus of senile dementia rats, and this promotion is also dose-dependent. It is speculated that EGB may improve by increasing the A ch content in the brain region of learning and memory function. Intelligent barriers to dementia animals. In order to understand the mechanism of EGB in senile dementia more deeply and comprehensively, systematic research on multi-model, multi-dose, multi-time and multi-index has yet to be carried out.
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