The Effects Of Malnutrition On The Brain Development And Learning Of Rats

Author : Ling Wang
Publisher : Open Dissertation Press
ISBN 13 : 9781374674431
Total Pages : pages
Book Rating : 4.6/5 (744 download)

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Download or read book Effects of Perinatal Malnutrition on Brain Development in Rats written by Ling Wang and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Effects of Perinatal Malnutrition on Brain Development in Rats" by Ling, Wang, 王玲, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of the thesis entitled EFFECTS OF PERINATAL MALNUTRITION ON BRAIN DEVELOPMENT IN RATS submitted by Wang Ling for the degree of Doctor of Philosophy at The University of Hong Kong in August 2006 The perinatal period, the period around the time of birth, is critical for brain development in most mammalian species. Numerous studies reported in the literature have shown that nutritional insults during this period can cause life-long impairment in various brain functions, including learning and memory function. How perinatal malnutrition leads to impairment in brain learning and memory function is still unclear. An emerging theory suggests that nutritional factors may modulate critical gene expression and subsequently lead to the functional alteration. More resent studies have shown that brain-derived neurotrophic factor (BDNF) plays a crucial role in brain learning and memory function. The objective of the present study was to investigate the effects of perinatal malnutrition on BDNF gene expression in the brain and the effects on spatial learning and memory function. Laboratory rats (Wistar and Sprague-Dawley strains) were used as an animal model. Pregnant or lactating rats were subjected to various types of nutritional insults, including calorie restriction, protein malnutrition or n-3 fatty acid deficiency, and their offspring were evaluated for the spatial learning and memory performance using the Morris water maze test. The concentrations of BDNF and BDNF mRNA in various regions of the brain were determined using enzyme-linked immunosorbent assay (ELISA) and real-time reverse transcription polymerase chain reaction (RT-PCR) respectively. It was found that prenatal 50% calorie restriction significantly reduced the levels of BDNF and its mRNA in hippocampus. Calorie restriction also caused significant impairment in spatial learning ability in the rats. The effects appeared to be proportionate to the duration of prenatal calorie restriction. The effects of perinatal protein malnutrition on spatial learning and memory performance and BDNF gene expression varied in rats depending on the time and duration of the dietary insults. Rats fed with a low protein diet (6% vs. 20% in control) during the four weeks period after birth showed poor spatial learning and memory performance at ten weeks of age accompanied with significant decrease in BDNF and its mRNA concentrations in hippocampus. Rats subjected to the low protein diet two weeks before and four weeks after birth also showed a significantly poor learning and memory performance at four but not ten weeks of age. Moderate decrease in BDNF concentration was observed in the cerebral cortex and hippocampus. Dietary n-3 fatty acid deficiency for three generations led to significant depletion of decosahexaenoic acid (DHA) in the brain tissue. Rats with depleted brain DHA showed dramatic impairment in learning and memory ability at four and ten weeks of age. BDNF mRNA concentration was also significantly reduced in the cerebral cortex and hippocampus in DHA depleted rat pups at four weeks of age. In conclusion, results of the present study indicate that perinatal malnutrition generally reduces BDNF gene expression in the brain and causes impairment in spatial learning and memory performance. Severity of the effect increases with an increased duration of the nu