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70
placed on the rotating drum which was set to gradually accelerate from 4 to 40 rpm over a 300s interval. Mice were forced to move at increasing speeds to avoid the 16.5 cm fall to the platform. Each mouse received 3 trials, with a 15-min inter-trial interval. Latencies before falling were measured and averaged for each group.
Water Maze
The water maze apparatus consisted of a white circular plastic tank (100 cm diameter and 70 cm high) which was filled with water (24±1 ◦C) made opaque by the addition of white DryTemp® paint powder (Palmer Paint Products Inc.,Troy, MI, USA). Visual cues of objects varying in geometric shape and color and were affixed to a clear, plastic cylinder inserted adjacent to the interior wall of the tank and extending approximately 30 cm above the water surface. A clear, circular (10 cm diameter) escape platform was submerged a few millimeters below the water surface.
Mice were trained to locate the hidden platform with 4 trials per day for 6 days. Each trial was started by placing the mouse in the water, adjacent to and facing the wall of the tank. The location of entry of the mouse changed for every trial such that mice entered the maze from each of 4 different start positions each day, with the order of start position randomly set each day. During trials, mice were given 60s to find the submerged platform. If a mouse did not find the platform, it was gently led to the platform. After either finding or being led to the platform, mice were left on the platform for 30s allowing it time to familiarize itself of the platform’s location with respect to the visual
Object Description
| Title | Roles of SIRT1 in neuronal oxidative damage and brain function |
| Author | Li, Ying |
| Author email | lying@usc.edu; yingraceli@yahoo.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Neuroscience |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-09-12 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-30 |
| Advisor (committee chair) | Longo, Valter D. |
| Advisor (committee member) |
Baudry, Michel Pike, Christian J. Madigan, Stephen A. |
| Abstract | Aging is a common phenomenon of multiple organisms. In humans aging is frequently accompanied by cognitive decline and occurrence of neurodegenerative diseases which reduce the quality of life and impose financial stress on society. Delaying the aging process, extending life span and decreasing the occurrence of age-related brain function deficit have always been aspirations of human kind. Extensive research has advanced our understanding of the mechanisms underlying aging, among which is the ability of calorie restriction to increase longevity, and the pivotal regulatory roles of insulin/IGF-1 signaling pathway. Some recent studies identified silent information regulator 2 (Sir2; SIRT1 is the mammalian homolog) as a key mediator of the beneficial effects of calorie restriction and this prompted development of SIRT1 activators for human consumption to delay aging and accompanying cognitive decline. However, our laboratory previously showed in yeast that Sir2 can increase stress sensitivity and limit life span extension under certain conditions, calling for more detailed characterization of SIRT1. In the research described in this dissertation I extended this study to the mammalian system and focused on the role of SIRT1 on the health of neurons and brain functions, especially learning and memory.; This dissertation consists of three chapters. In chapter 1 I briefly review some recent progress on aging, oxidative stress, insulin/IGF-1 signaling pathway and learning and memory with emphasis on the involvement of SIRT1 in these processes. In chapter 2 I focused on the role of SIRT1 in oxidative stress in neurons and its mechanisms. I found that SIRT1 inhibition increased resistance to oxidative damage and this effect is partially mediated by a reduction in IGF-I/IRS-2/Ras/ERK1/2 signaling. In chapter 3 I studied the functions of SIRT1 in learning and memory. The experiments showed that deletion of SIRT1 impairs a certain form of synaptic plasticity and reduce performance in several different learning and memory tasks while overexpressing SIRT1 did not substantially affect learning and memory.; Together, my studies reveal that SIRT1 exacerbates neuronal oxidative damage but is essential in learning and memory, indicating that SIRT1 plays multiple roles in aging and brain functions and that caution should be exercised in designing anti-aging or therapeutic approaches that involve targeting SIRT1. |
| Keyword | SIRT1; neurons; brain; oxidative damage; learning and memory |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1723 |
| Contributing entity | University of Southern California |
| Rights | Li, Ying |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-LI-2405 |
| Archival file | uscthesesreloadpub_Volume44/etd-LI-2405.pdf |
Description
| Title | Page 80 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 70 placed on the rotating drum which was set to gradually accelerate from 4 to 40 rpm over a 300s interval. Mice were forced to move at increasing speeds to avoid the 16.5 cm fall to the platform. Each mouse received 3 trials, with a 15-min inter-trial interval. Latencies before falling were measured and averaged for each group. Water Maze The water maze apparatus consisted of a white circular plastic tank (100 cm diameter and 70 cm high) which was filled with water (24±1 ◦C) made opaque by the addition of white DryTemp® paint powder (Palmer Paint Products Inc.,Troy, MI, USA). Visual cues of objects varying in geometric shape and color and were affixed to a clear, plastic cylinder inserted adjacent to the interior wall of the tank and extending approximately 30 cm above the water surface. A clear, circular (10 cm diameter) escape platform was submerged a few millimeters below the water surface. Mice were trained to locate the hidden platform with 4 trials per day for 6 days. Each trial was started by placing the mouse in the water, adjacent to and facing the wall of the tank. The location of entry of the mouse changed for every trial such that mice entered the maze from each of 4 different start positions each day, with the order of start position randomly set each day. During trials, mice were given 60s to find the submerged platform. If a mouse did not find the platform, it was gently led to the platform. After either finding or being led to the platform, mice were left on the platform for 30s allowing it time to familiarize itself of the platform’s location with respect to the visual |
