The influence of ovarian hormones and aging on cognition and neuronal morphology.
Item
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Title
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The influence of ovarian hormones and aging on cognition and neuronal morphology.
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Identifier
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AAI3245083
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identifier
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3245083
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Creator
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Wallace, Maureen E.
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Contributor
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Adviser: Victoria N. Luine
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Date
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2007
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Language
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English
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Publisher
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City University of New York.
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Subject
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Psychology, Psychobiology | Psychology, Cognitive | Biology, Neuroscience | Biology, Physiology
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Abstract
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Current research indicates gonadal hormones influence cognition. Understanding the effects of ovarian hormones on cognitive function is especially important because, as life expectancy is continually increasing, and hormone production declines with age, individuals, especially females, will spend a larger portion of their lives in a state of hormone deficiency. Therefore, to assess the effects of ovarian hormones on cognitive function, young, gonadally intact and ovariectomized (OVX) female rats were compared on tasks of non-spatial (Object Recognition) and spatial (Object Placement) memory. OVX rats were impaired on both tasks relative to intact rats. To determine possible mechanisms for memory loss, golgi impregnation was used to compare dendritic spine density of pyramidal cell neurons in two brain areas known to influence memory, the prefrontal cortex and hippocampus. OVX rats had significantly lower dendritic spine density for apical and basal dendritic branches in both areas compared to intact. As aging is accompanied by hormone loss, intact young and aged female rats were compared on the same tasks as the intact and ovariectomized rats in order to assess the effects of the aging process on cognitive function and morphology. Young rats demonstrated better performance on both tasks compared to aged rats. Golgi impregnation was then completed and showed significantly lower dendritic spine density for aged rats compared to young rats on tertiary, apical dendritic branches of neurons in both the prefrontal cortex and hippocampus. To examine whether hormone replacement would be effective at reversing the observed effects of aging, aged female rats were compared on the Object Recognition and Object Placement tasks while treated subchronically with estradiol benzoate (EB) and while treated with vehicle. Results indicated that performance on both tasks was best while receiving the highest dose of EB. Prior to sacrifice, rats received either vehicle or EB treatment. Golgi impregnation assessed morphological changes associated with hormone replacement. Results demonstrated a small, though insignificant, increase in dendritic spine density for secondary, basal dendritic branches of neurons in the prefrontal cortex with EB treatment. Thus, these findings have important implications for designing treatment paradigms for women during the perimenopausal and post menopausal period.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
