Functional and structural development of bovine and porcine steroidogenic tissue and the expression of the steroidogenic acute regulatory protein (StAR) /
Steroidogenic Acute Regulatory (StAR) protein was recently identified as the rate limiting factor in steroidogenesis. This project represents the initial investigation of the ontogeny of the expression of StAR protein in fetal bovine and porcine steroidogenic tissues. Whether fetal age or breed affe...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733671391&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Steroidogenic Acute Regulatory (StAR) protein was recently identified as the rate limiting factor in steroidogenesis. This project represents the initial investigation of the ontogeny of the expression of StAR protein in fetal bovine and porcine steroidogenic tissues. Whether fetal age or breed affects expression of StAR protein and other steroidogenic enzymes (cytochrome P450 cholesterol side chain cleavage, P450 SCC; 3-beta-hydroxysteroid dehydrogenase, 3β-HSD) was studied. Study I examined structure-function relationships of the hypothalamic-pituitary-adrenal axis in fetal Angus (n=18) and Brahman (n=18) calves during the last trimester of gestation. Fetal body weight (wt.), pituitary gland wt., paired adrenal gland wt., plasma ACTH, adrenocortical area and plasma cortical increased with fetal age. StAR protein was localized to the adrenocortical cells by immunohistochemistry. StAR protein and the steroidogenic enzymes P450 SCC and 3β-HSD were detected in adrenocortical tissue by western blot analysis and only StAR protein increased with fetal age. Adrenal gland wt. and adrenocortical area was lower for Brahman calves. Plasma cortical was positively correlated with paired adrenal wt., cortical area, and StAR protein. Study II focused on the presence of StAR, P450 SCC and 3β-HSD in fetal bovine gonads and perinatal porcine gonads. Fetal bovine gonads were obtained during the last trimester of gestation. Porcine gonads were obtained at 113 day of gestation, l-hour-old, 2 weeks-of-age, and 3 weeks-of-age. Fetal bovine gonadal wt. increased with fetal age. By Western blot analysis StAR protein, P450 SCC and 3β-HSD were detected in fetal bovine testes but only P450 SCC and 3β-HSD were detected in fetal bovine ovaries. Immunohistochemical analysis detected the presence of StAR in fetal bovine testes and fetal ovaries. By Western blot analysis StAR, P450 SCC and 3β- HSD were detected in perinatal porcine testes. Perinatal porcine ovaries did not contain StAR and had lower concentrations of P450 SCC and 3β-HSD than age-matched perinatal testes. This dissertation project 1) characterized morphological and functional changes in the fetal bovine adrenal axis and 2) identified ontogenic changes in the acquisition and maintenance of gonadal steroid producing capacity in fetal and perinatal pigs and cattle. |
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| Item Description: | Vita. "Major Subject: Physiology of Reproduction". |
| Physical Description: | xv, 181 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 150-172). |