Temporal effects of fescue toxicosis and heat stress on rat physiology and hepatic gene expression

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Temporal effects of fescue toxicosis and heat stress on rat physiology and hepatic gene expression

Please use this identifier to cite or link to this item: http://hdl.handle.net/10355/4751

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dc.contributor.advisor Spiers, Donald E. en
dc.contributor.author Settivari, Raja Sekhar, 1977- en_US
dc.date.accessioned 2010-01-12T18:41:42Z
dc.date.available 2010-01-12T18:41:42Z
dc.date.issued 2007 en_US
dc.date.submitted 2007 Fall en
dc.identifier.other SettivariR-102307-D8438 en_US
dc.identifier.uri http://hdl.handle.net/10355/4751
dc.description The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. en_US
dc.description Title from title screen of research.pdf file (viewed on February 29, 2008) en_US
dc.description Includes bibliographical references. en_US
dc.description Vita. en_US
dc.description Thesis (Ph. D.) University of Missouri-Columbia 2007. en_US
dc.description Dissertations, Academic -- University of Missouri--Columbia -- Animal sciences. en_US
dc.description.abstract Fescue toxicosis results from intake of toxins in fescue containing an endophytic fungus, Neotyphodium coenophialum. Time-related changes in rats associated with intake of an endophyte-infected fescue diet (E+) were evaluated under thermoneutral (TN), and both short- and long-term heat stress (HS) conditions. Short-term E+ intake decreased feed intake and growth rate under both conditions, whereas rats exhibited signs of adaptation during long-term exposure with better recovery occurring under TN conditions. Rats fed an E+ diet did not change core temperature during TN, but under HS conditions they exhibited a short-term increase in core temperature above control level. However, there was adaptive return of this temperature to TN level with long-term exposure. Short-term E+ intake at TN decreased serum glucose, urea nitrogen, alkaline phosphatase, and cholesterol; whereas long-term E+ intake under these conditions resulted in complete adaptation. In contrast, short-term E+ intake at HS did not affect serum biochemistry, while long-term intake decreased all the above mentioned serum parameters. Serum prolactin level was decreased during both short- or long-term TN and HS conditions. The E+ diet decreased hepatic antioxidant gene expression, with even greater reduction as a result of HS. Long-term E+ intake and HS increased expression of cytochrome P450 and detoxification pathways, respectively. Genes associated with immune response increased with long-term E+ at TN, but decreased with E+ diet at HS. Similarly, genes coding for chaperone and DNA repair decreased with long-term E+ at TN, but increased with E+ and HS. Recovery observed in E+ rats at TN could be attributed to increased gene expression for detoxification and immune response, whereas decreased antioxidant and immune response associated genes could contribute to distress associated with E+ at HS. Fescue toxicosis results from intake of toxins in fescue containing an endophytic fungus, Neotyphodium coenophialum. Time-related changes in rats associated with intake of an endophyte-infected fescue diet (E+) were evaluated under thermoneutral (TN), and both short- and long-term heat stress (HS) conditions. Short-term E+ intake decreased feed intake and growth rate under both conditions, whereas rats exhibited signs of adaptation during long-term exposure with better recovery occurring under TN conditions. Rats fed an E+ diet did not change core temperature during TN, but under HS conditions they exhibited a short-term increase in core temperature above control level. However, there was adaptive return of this temperature to TN level with long-term exposure. Short-term E+ intake at TN decreased serum glucose, urea nitrogen, alkaline phosphatase, and cholesterol; whereas long-term E+ intake under these conditions resulted in complete adaptation. In contrast, short-term E+ intake at HS did not affect serum biochemistry, while long-term intake decreased all the above mentioned serum parameters. Serum prolactin level was decreased during both short- or long-term TN and HS conditions. The E+ diet decreased hepatic antioxidant gene expression, with even greater reduction as a result of HS. Long-term E+ intake and HS increased expression of cytochrome P450 and detoxification pathways, respectively. Genes associated with immune response increased with long-term E+ at TN, but decreased with E+ diet at HS. Similarly, genes coding for chaperone and DNA repair decreased with long-term E+ at TN, but increased with E+ and HS. Recovery observed in E+ rats at TN could be attributed to increased gene expression for detoxification and immune response, whereas decreased antioxidant and immune response associated genes could contribute to distress associated with E+ at HS. en_US
dc.language.iso en_US en_US
dc.publisher University of Missouri--Columbia en_US
dc.subject.lcsh Fescue -- Toxicology en_US
dc.subject.lcsh Rats -- Effect of stress on en_US
dc.subject.lcsh Gene expression en_US
dc.subject.lcsh Liver cells -- Effect of heat on en_US
dc.title Temporal effects of fescue toxicosis and heat stress on rat physiology and hepatic gene expression en_US
dc.type Thesis en_US
thesis.degree.discipline Animal sciences en_US
thesis.degree.grantor University of Missouri--Columbia en_US
thesis.degree.name Ph. D. en_US
thesis.degree.level Doctoral en_US
dc.identifier.merlin .b62225674 en_US
dc.identifier.oclc 212408915 en_US
dc.relation.ispartofcommunity University of Missouri-Columbia. Graduate School. Theses and Dissertations. Dissertations. 2007 Dissertations
dc.relation.ispartofcollection 2007 Freely available dissertations (MU)


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