A Study On The Effects And Mechanism Of Icariin On Learning And Memory In Senescence Aecelerated Mouse Prone/10(SAMP10)

Alzheimer’s disease (AD) is a degenerative disease in the central nervous system. It is characteristic of long-term memory loss, cognitive deficits, dystropy and the general withdrawal of the sufferer as their senses decline. The typical pathologic change of AD is cerebral atrophy, amyloid plaques, neuro fibrillary tangles and formation of senile plaque in brain. The loss of neurons in cerebral cortex and certain subcortical regions is also observed. So it has been among the top4killers worldwide. There is a great difference in the incidence of AD between male and female. Usually the morbidity of AD in woman is2or3times higher than man. Icariin(ICA) is a flavonoid extracted from Epimedium. Recent studies show the ICA has an obvious effect of estrogen. Reported that ICA can improve the aluminum poisoning induced learning and memory impairment in rats, suggested that ICA may be potential drug candidates in the treatment of senile dementia.The study takes the senescence-accelerated mouse prone10as a model, mainly containing two steps. The first step:the rapid aging of the detection of changes associated with aging in mice SAMP10. Detection indicators include:the Morris water maze, ski jumping, the level of acetylcholine in the cerebral cortex, acetylcholine transferase, acetylcholinesterase activity and cholinergic receptor binding, monoamine neurotransmitters and amino acid neurotransmitter quality.The The second step explores the effects of icariin on the improvement of learning and memory dysfunction in senescence accelerated mice SAMP10research. Morris water maze and experimental platform are used to test the effects of ICA on learning and memory in SAMP10groups. The colorimetric determination of AChE activity in the cortex are used to enzyme-linked immunosorbent assay detection of ACh, ChAT, MCBC of the cerebral cortex to study ICA on the cholinergic system of SAMP10. HPLC-electrochemical is used to test the effects of ICA on monoamine neurotransmitters and amino acid neurotransmitters of SAMP10, and immunohistochemical methods are employed to study Aβ on ICA of SAMP10.To sum up the results of the experiment， the first step of the experimental results show that:l)In place navigation trail, compared with the the control group, the latency of3-month-old and6-month-old SAMP10mice have no significant difference (p>0.O5), the latency of9-month-old SAMP10mice become longer (p<O.O5);2)in space exploration experiment, compared with the the control group SAMR1, there is no significant difference between periods of staying in the time of platform quadrant and the number of times across the platform in3-month-old and6-month-old SAMP10mice (p>0.05).9-month-old SAMP10mice stay in platform quadrant for a shorter time and the number of times across the platform are fewers. The difference is statistically significant (p<0.05);3) in the step down test, reactive ability of the3-month-old and6-month-old SAMP10mice have no significant difference (p>0.05). while the reactive capacity of the9-month-old SAMP10mice decreases significantly, showing that the period of jumping off the platform is shorter (p<0.05), and the number of a shock increases (p<0.05);4) compared with SAMRl of the same age, the activity of AChE, ChAT activity, MCBC, of ACh content in3-month and6-month-old SAMP10mice have no significant difference (p>0.05), with the AChE activity of the9-month-old SAMP10mice decreasing (p<0.05), the ChAT activity and ACh reduced (p<0.05), and MCBC lower (p<0.05);5) compared with the SAMRl of same age, monoamine neurotransmitters of3month and6-month-old SAMP10mice are not significantly different (p>0.05); the monoamine neurotransmitters of9-month-old SAMP10mice was decreased (p<0.05);6) compared with the same age SAMRl, amino acid neurotransmitters of3month and6-month-old SAMP10mice was no significant difference (p>0.05); Glu and Gln content in9-month-old SAMP10decreases and the content of tau and GAB A increases (p<O.O5). The second step of the experimental results show that:1) the ICA100mg· kg-1and ICA200mg·kg-1can reduce latency of SAMP10in positioning navigation (P<0.05) and increase the residence time in the platform quadrant and the number of times across the platform(p<O.O5); the period of jumping out in space exploration of the mice is prolonged (p<0.05) and the number of electric shock is reduced (P<0.05);2) the dose of ICA100mg·kg-1and the ICA200mg·kg-1increase ChAT activity (p<O.O5), increase the ACh content and improve the MCBC(p<O.05);3) the ICA100mg·kg-1and the ICA of200mg·kg-1you can increase monoaminergic neurotransmitter content (P<0.05);4) the dose of ICA100mg·kg-1and ICA200mg·kg-1can increase asp, tau, reduced Glu, Gln, GABA.These results indicate that:1) with the month growing, learning and memory of SAMP10mice gradually diminishes;9-month-old SAMP10mice showe significant learning and memory dysfunction;2) in behavioral experiments, ICA can improve learning and memory ability of SAMP10;3) ICA may improve cholinergic function and monoaminergic neurotransmitter content, and regulate excitatory amino acids and inhibitory amino acid neurotransmitters and metabolic balance to improve learning and memory of SAMP10.