| Objective:To investigate the effect of liquirtigenin,a licorice flavonoid,on the behavior deficits and Aβ deposition in ovariectomized APP/PS1 double transgenic AD mice model, as well as to explore the underlying molecular mechanisms. The out come of this study will provide exprimental basis to exploit multi-target-derected and low side effect drugs to the prevention and treatment of AD.Methods:1.40 3-month-old APP/PS1 female double transgenic mice were randomly divided into four groups(10 for each group),One of the groups was sham-operated and the others were ovariectomized. Seven days after the surgery,they were treated with vehicle(0.1% CMC-Na and NS),LG(30mg/kg),E2(0.1mg/kg), vehicle(0.1% CMC-Na and NS),respectively, for 90days.2. After 90-day treatment, Elevated plus-maze test(EPM) was performed to test the anxious emotions;Morris water maze was conducted to observe the effect of liquirtigenin on the spatial learning and memory;IHC was performed to examine the effect of LG on senile plaques,neuron and synaptic changes in the brain of ovariectomized APP/PS1 mice;Western blot was carried out to investigate the effect of LG on the level of APP,BACE1,DCX,NeuN,PSD95,ERβ,beclin1 and LC3 protein in the brain of ovariectomized AD mice;Flow cytometry was performed to detect the apoptosis and mitochondrial membrane potential.Results:1. Behavioral tests:①In the EMP test:Compared with the OVX group,the LQE2 and Sham group showed significantly increased on the open arm entries and open arm duration(P<0.05); ②In the Morris water maze test:Sham,OVX,LG and E2 group was no difference in escape latency, path length and swimming speed(P>0.05) in the visible platform; In the hidden platform experiment, Sham,LG and E2 group had fewer latency (P<0.01) and lesser path length (P<0.01),while there were no significant difference among Sham,LG and E2 group group; In the probe test, platform-passing times in the Sham and E2 group were significantly more than OVX group(P<0.01),while the LG group increased(P<0.05).2. The morphology and weight of uterus in the mice showed:the weight of uterus in the Sham,LG and E2 group were significantly heavior than the OVX group.At the same time, E2 group proliferated with nodule and increased significantly compared with LG and sham group(P<0.01).3. IHC staining showed,the number and area of SP in the cerebral cortex and hippocampus of OVX group were notably increased than the Sham(P<0.05),LG(P<0.01) and E2(P<0.01) group.And the Aβ40 and Aβ42 test consistent with the results of 4G8 test.The neuronal dendrites marked by MAP2 showed long and arranged neatly in the Sham,LG and E2 group,while they were irregular, shorter and segmental in the OVX group. Compared with Sham group, the number of neurons in the OVX group significantly reduced (P＜0.05), while increased after the treatment with liquiritigenin (P<0.05).4. Western blot:Compared with OVX group,the expression of BACE1(P<0.01) and Bax(P<0.01) were dramatically decreased,while DCX(P<0.05),ERP(P<0.01),PSD95(P<0.01),NeuN(P<0.01),GDNF(P<0. 01),BDNF(P<0.05),Bcl-2(P<0.01),Beclin1(P<0.01) and LC3(P<0.05) were significantly increased in the LG group.5. The flow cytometry revealed that the apoptosis significantly decreased and mitochondrial membrane potential increased in the Sham,LG and E2 group, compared with the OVX groupConclusion:1. Liquirtigenin treatment may reduce anxiety and alleviate spatial learning and memory defects on ovariectomized APP/PS1 double transgenic mice.2. Liquirtigenin can inrease a certain amout of uterine weight while the uterine proliferated dramaticlly with nodules in the E2 group.3. Liquirtigenin reduce Aβ deposition and SP formation by inhibiting the activity of Bacel and enhanceng autophagy.4. Liquirtigenin can upregulate the expression of ERβ,BDNF and GDNF.5. Liquiritigenin reduce the vast loss of synapses and neurons via down-regulating neuronal apoptosis and rising mitochondrial membrane potential. |
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