Key gene and protein changes in the beta-amyloid pathway following Longyanshen polysaccharides treatment in a mouse model of Alzheimer's disease

BACKGROUND： During onset and development of Alzheimer＇s disease, β-amyloid （Aβ） precursor protein （APP）, β-site amyloid precursor protein cleaving enzyme （BACE）, and β-amyloid are key genes and proteins in the Aβ pathway, and over-expression of these genes can lead to Aβ deposit/on in the brain. OBJECTIVE： To observe the influence of Longyanshen polysaccharides on expression of BACE, APP, and Aβ in the senescence-accelerated mouse prone/8 （SAMP8） brain, and to compare these effects with huperzine A treatment. DESIGN, TIME AND SETTING： A randomized, controlled, neurobiochemical experiment was performed at the Department of Pharmacology and Scientific Experimental Center of Guangxi Medical University from September 2005 to January 2008. MATERIALS： Longyanshen polysaccharfdes powder was extracted from the dried slices of the medicinal plant Longyanshen. The active component, Longyanshen polysaccharides, was provided by the Department of Pharmacology, Guangxi Medical University; huperzine A was purchased from Yuzhong Drug Manufactory, China. METHODS： Healthy SAMP8 mice were used to establish a model of Alzheimer＇s disease. A total of 50 SAMP8 mice were randomly assigned to 5 groups （n = 10）： SAMP8, huperzine A, low-, middle-, and high-dose polysaccharides. In addition, 10 senescence-accelerated mouse resistant 1 （SAMR1） mice were selected as normal controls. SAMP8 and SAMR1 mice were administered 30 mL/kg normal saline; the huperzine A group was administered 0.02 mg/kg huperzine A; the low-, middle-, and high-dose polysaccharides groups were respectively administered 45, 90, and 180 mg/kg Longyanshen polysaccharides. Each group was treated by intragastric administration, once per day, for 50 consecutive days. MAIN OUTCOME MEASURES： One hour after the final administration, immunohistochemical analysis was used to determine Aβ expression in the cortex and hippocampus of SAMP8 mice. Reverse-transcription polymerase chain reaction was used to determine mRNA levels of BACE and APP in SAMP8 brain tissue. RESULTS： Compared with the SAMR1 group, Aβ expression in the cerebral cortex and hippocampus, as well as expression of BACE, APP mRNA in the brain was significantly increased in the SAMP8 group （P 〈 0.05-0.01）. Compared with the SAMP8 group, Aβ expression, as well as BACE and APP mRNA expression, were significantly decreased in the cerebral cortex and hippocampus of huperzine A and low-, middle-, and high-dose polysaccharides groups （P 〈 0.05-0.01）. In particular, the effect of high-dose polysaccharides was the most significant （P 〈 0.05-0.01 ）. CONCLUSION： Longyanshen polysaccharides reduced or inhibited over-expression of BACE, APP, and Aβ in SAMP8 mice in a dose-dependent manner, and the effect was not worse than huperzine A.

Protective Effect of Ethanol Extract from Sweet Potato Leaves on CCL_(4)-Induced Liver Injury in Mice

[Objectives]To investigate the protective effect of ethanol extract from sweet potato leaves on liver injury induced by CCl_(4)in mice.[Methods]25 ICR mice were randomly divided into blank group,model group,high-dose extract group(200 mg/kg),low-dose extract group(100 mg/kg)and positive control group(2 mg/kg colchicine),with 5 mice in each group.All groups except the blank group were given intraperitoneal injection of 20%CCl 4 olive oil solution(2 mL/kg),and the blank group was given the same dose of olive oil solution three times a week.After 4 weeks,each administration group was given the corresponding dose of drugs(10 mL/kg),and the blank group and model group were given the corresponding amount of normal saline for 2 weeks.After the last intragastric administration,fasting was required,but water was allowed,blood was taken from eyeballs,and upper serum was taken by static centrifugation.Serum AST,ALT,CRP,IL-6 and SOD levels were detected by the kit.[Results]Compared with the blank group,the serum AST and ALT levels in the model group were significantly increased;compared with the model group,the ethanol extract of sweet potato leaves could decrease the levels of ALT,AST,CRP,IL-6 and increase the level of SOD in serum.[Conclusions]The ethanol extract of sweet potato leaves had protective effect on the mice with liver injury induced by CCl_(4),and its mechanism may be to protect the liver by lowering enzymes,inhibiting inflammation and antioxidant stress.