ABSTRACT
BACKGROUND: In brain insulin does its work through the insulin receptor substrate (IRS). Amyloid beta protein precursor 17 (APP17) peptide has the neurotrophic function, which may improve diabetic encephalopathy resulted from insulin deficiency by affecting insulin receptor substrate.OBJECTIVE: The mouse diabetic model was produced to observe the effect of APP17 peptide on the distribution of IRS-1 in brain tissues.DESIGN: Randomized control animal experiment.SETTING: Staff Room of Pathology, College of Basic Medical Sciences,Capital University of Medical Sciences; Beijing Research Laboratory for Brain Aging of Xuanwu Hospital.MATERIALS: The experiment was performed in Staff Room of Pathology,College of Basic Medical Sciences, Capital University of Medical Sciences and Beijing Research Laboratory for Brain Aging of Xuanwu Hospital from September to October 2003. Totally 18 male kunming mice were employed,and randomly assigned into control group, diabetic group and APP17 peptide treatment group with 6 mice in each group.METHODS: ①The mice were subjected to intraperitoneal injection of streptozotocin (STZ, Sigma) by 200 mg/kg, and 3 days later, the tail blood was sampled to examine non-fasting blood glucose, and the blood glucose over 15 mmol/L was set as the criteria for successful diabetic model establishment. ②In APP17 + diabetes mellitus group, the mice received subcutaneous injection of 0.35 μg APP17 peptide once daily for 2 weeks. The mice in the normal control group were not interfered. ③Then brain was removed and crystat sections were prepared. Immunohistochemical staining was done for IRS-1 at four weeks after giving streptozotocin.MAIN OUTCOME MEASURES: Pattern and distribution of IRS-1 positive cells of mice in each group.RESULTS: Totally 18 mice were involved in the result analysis. ①In the brains of diabetic mice the IRS-1 immunohistochemical positive cells distributed at cortex, hippocampus, thalamus, hypothalamus and so on, while the positive cells distributed only at cortex and hippocampus in the normal control group and APP17 peptide treatment group, lightly stained. ②Numbers of immunohistochemical positive cells of IRS-1 of cerebral hippocampus in the diabetic group, normal control group and APP17 peptide treatment group were (28.7±1.5), (9.2±1.5), (10.1±1.4) piece per 10 power object lens, and that in the diabetic group was higher than that in the other two groups (P ＜ 0. 001 ). CONCLUSION: Neurons in many regions of brains of diabetic mice have plenty of IRS-1 positive cells. APP17 peptide can make part and quantity of IRS-1 positive cells normality so as to ameliorate the degeneration of hippocampal neurons of diabetic mice.
ABSTRACT
BACKGROUND: D-galactose-induced aging animal model is similar tohuman natural aging. Whether the expression of protein phosphatase-1(PP-1) in the brain of D-galactose-induced aging mice is related to cerebralaging process or not should be researched further. OBJECTIVE: To investigate the effect of the APP17 peptide and theliquid extract ofjiunao yizhi capsule on regulating the expression of PP-1 inhippocampal neurons of the aging mice induced by the D-galactose (D-gal). DESIGN: A random controlled study. SETTING: Department of Pathology, College of Basic Medical Sciences, Capital University of Medical Sciences and Beijing Research Laboratory forBrain Aging, Xuanwu Hospital of Capital University of Medical Sciences. MATERIALS: The study was completed between July 2003 and July2004 in the Experimental Center of Capital University of Medical Sciences. Forty male Kunming mice (SPF grade) with a body mass fron 28 g to 32 gwere purchased from Chinese Academy of Medical Sciences Institute ofMaterial Medical.METHODS: Kunming mice were randomly divided into 5 groups: control group, D-gal group, APP17 peptide treatment group, low dose herb treatment group, and high dose herb treatment group with 8 mice in each group. In Dgal group, APP17 peptide treatment group, low dose herb treatment group and high dose herb treatment group, galactose was injected subcutaneously (50 nmg/kg). Meanwhile, 0.1 mL normal saline containing 0.35 μg of APP17 peptide was injected subcutaneously into the mice in APP17 peptide treatment group, once a day for 3 months; liquid extract of jiunao yizhi capsule (provided by Beijing Chaoyangmen Hospital and Shanxi Quwo Traditional Medical Institute; the main component: dangshen, baizhu, guijia and chuanshanjia, etc.) was perfused by stomach (0.3 g/kg and 1.0 g/kg respectively) in low dose herb treatment group and high dose herb treatment group, once a day. And equivalent normal saline was injected and perfused in the two control groups. After 3 months of survival, the mice were killed and their brains were cut into sections. The immunohistochemical staining of these sections was then performed with PP-1 antibody.MAIN OUTCOME MEASURES: The results of immunohistochemical staining analysis of PP-1.RESULTS: Forty mice entered the final analysis without any loss. PP-1 positive cells in the hippocampus were poorly stained in the D-gal mice. In contrast, PP-1 positive neurons were widely distributed in the hippocampus of those normal mice, the APP17 peptide-treated D-gal mice and the high liquid extract of raw herb-treated D-gal mice. These cells were darkly stained in cytoplasm. The unexpected result was that in the low liquid extract of raw herb-treated D-gal mice the number of PP-1 positive neurons did not increase to normal.CONCLUSION: The results demonstrated that the expression of PP-1 decreased in the hippocampus of D-gal mice. The APP17 and low dose liquid extract of raw herbs can regulate the distribution of PP-1 in the brain of D-gal mice and make them recover to normal situation.
ABSTRACT
Objective To investigate the effect of insulin signaling pathway on neuronal survival and the effect of the peptide App17 on regulating the expression of some apoptosis-related proteins in neurons of the hippocampus through intracerebrorentricular injection of streptozotocin in rats. Methods The rats were injected with App17 peptide subcutaneously three weeks after the model group was established by intracerebrorentricular injection of streptozotocin.After the four-week treament,the expressions of the apoptosis-related proteins,such as Bcl-2,Bax,CytoC in neurons of the hippocampus were tested with immunohistochemical staining and Western blotting.Results Bax,CytoC positive neurons were widely distributed in the hippocampus of the model group,and the cytoplasm was darkly stained.In contrast,the positive neurons for Bax,CytoC in hippocampus were poorly stained in the control group and the treated group,and appeared significant difference in cell counting as compared with model group.Bcl-2 positive neurons were widely distributed in the hippocampus in the control group and the treated group,and the cytoplasm was darkly stained while its positive neurons were poorly stained in the model group,and appeared significant difference in cell counting as compared with the model group.From the Western blotting clear bars could be seen in the three groups and there was a significant difference between them.Conclusions The expression of Bax,CytoC increased in the hippocampus in the rats with intracerebrorentricular injection of streptozotocin while the expression of Bcl-2 decreased.The App17 peptide could promote the rehabilitation of the abnormal expression of the three proteins to some extent.The insulin signaling pathway could affect the survival of the neurons in rats' hippocampus.