The Primary Study On The Relationship Between Central VGLUT1 Expression And The Function Of Learning And Memory

Alzheimer's disease (AD) is a progressive neurological disorder characterized by progressive impairment in cognitive function. Its pathomechanism is too complicated, which blocks the therapeutic effect, so cares for AD is remain a very difficult problem. Deeply investigate on relationship between gene function and AD also could contribute to developing new therapeutic drugs and effective motheds.Recent years several vesicular glutamate transporters have been identified and characterized. These include VGLUT1-3(vesicular glutamate transporter1-3), VGLUT1 was predominantly localized to synaptic vesicles and loading the vesicle with glutamate. It is directly concerned with glutamateric exocytosis. Expression of VGLUT1 determine the level of synaptic vesicle filling and glutamate quantal size. It is a special marker for glutamatargic neurons and directly concerned with glutamatergic neurons condition and the homeostasis of glutamate transmitter. But it is unclear about VGLUT1 physiological function involving in learning and memory, let alone the relationship between VGLUT1 expression and it's role in mechanism of disease.The senescence-accelerated mouse (SAM) was established as a murine model of accelerated aging provided by Dr Takeda of Kyoto University, Japan. SAMP8 especially shows a dysfunction in learning and memory. SAMR1 following a normal process of development. The SAMP8 exhibit a short life span with many signs of senile aging. In particular, SAMP8 has been known to show age-related deterioration of learning ability and memory, which begins to progress as early as 2 months after birth. On the contrary, the SAMR1 show normal aging characteristics without brain dysfunction. SAMP8 can appear glutamate mediated excitotoxicity, neurodegeneration and the obnormal expressions of other glumatic transports with aging. Meanwhile SAMP8 showed abnormal metabolism of APP and high concentration of Aβ. It is used to as a nice animal model of AD. Our lab previous study suggested that the expression of VGLUT1 were significantly changed in hippocampus of 12-month-old SAMP8 after administrated Hup A and LW for 4 weeks. The results implied there are important links between drugs effects and VGLUT1.1. The expression and distribution of VGLUT1 in the brain of SAMP8 with agingSAMP8 is characterized with deficit of cognition with aging. To study relationship between VGLUT1 and impairment of cognition functions, we observed the expression and distribution of VLGUT1 in hippocampus and cortex of SAMP8 with aging by Real-time PCR, Western-blot and immunohistochemistry techniques.1.1 The expression of APP in hippocampus and cortex of SAMP8β-amyloid (Aβ) derived from amyloid precursor protein (APP), The brain of AD known as senile plaques that contain Aβ. A lot of research showed that transgenes mice possessed the characteristic of disfunction of learning and memory. Thus, We observed the expression of APP gene and protein in hippocampus and cortex of SAMP8 with aging. The results showed that the expression of APP gene and protein kept unchangeable in the brain of SAMR1 with aging. But we found any markly up-regulated change about VGLUT1 in hippocampus and cortex of 6, 12 months old SAMP8 when compared with age-macthed SAMR1.1.2 The expression and distribution of VGLUT1 in the brain of SAMP8The results showed that a markly down-regulated expression of VGLUT1 existed in hippocampus and cortex of 6 month old SAMP8 when compared with age-matched SAMRL, and the expression of VGLUT1 gene and protein have appeared a 'V' curve in 2, 6, 12month old SAMP8 brain. No any difference found in SAMR1 brain with aging. Meanwhile, we study the distribution of VGLUT1 to the brain of SAMP8 and SAMR1 The results demonstrated that VGLUT1 staining in the hippocampus and granule cells of the dentate gyrus and full-thickness cortex. It stained in cytoplasm and membrane of neurons, no in nuclei. It is intriguing that there are a markly decrease in VGLUT1 staining of hippocampus, dentate gyrus and cortex of 6-month-old SAMP8 when compare with age-matched SAMR1 and 2, 12-month-old SAMP8. VLGUT1 staining no any difference observed in SMAR1 with aging.2. Relationship between leaning and memory and VLGUT1We explored shuttle box test to study relationship between VGLUT1 and learning and memory. We choose male mice as test subjects, one trial session was composed of 60 trials/mice/days. Avoidance response number is an important date for our study. The testing trial was given total to 6 days. We divided mice into groups depend on their performanc at sixth trial days.The results demonstrated that the level of VGLUT1 gene and protein were increased following acquired ability of learning and memory. It implied VGLUT1 could involve in physiological functions of learning and memory.3. Drug effects on VGLUT1 of aged SAMP8 brainThis paper employs real-time PCR and western-blot technique to study the effect of HupA and six traditional Chinese medicinal prescriptions including Huperzine A (HupA) Liuwei Dihuang decoction (LW) Bawei Dihuang decoction (BW), Danggui Shaoyao San decoction (DSS), Huang Lian Jiedu decoction (HL) Tiao Xin Fang (TXF) on expression of VGLUT1 and APP in the hippocampus and cortex of 12-month-old male SAMP8. The results showed that almost of these drugs could exert down-regulated effects on VGLUT1 and APP. SAMP8 possessed glutamate system dysfunction begins to progress as early as 2 months, and can appear glutamate mediated excitotoxicity, neurodegeneration and the obnormal expressions of other glumatic transports with aging. Our results showed a markly down-regulatled of VGLUT1 in 6-month-old SAMP8 brain can be a feedback mechanism, which against high gluatamate concentration.