Central alpha adrenergic involvement in the hemodynamic effects of estrogens / by D. Paul Shackelford, Jr.
| Author/creator | Shackelford, D. Paul author. |
| Other author | Iams, Samuel G., degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 1987. |
| Description | [vii], 78 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Estrogen treatment in individuals genetically predisposed to hypertension is known to cause a reduction in systolic blood pressure, while estrogen treatment in normotensive individual will cause a mild elevation or no change depending, on the type of estrogen used. The effects of the estrogens on the cardiovascular system are thought to be mediated in part by estrogen adrenergic interaction in regions of the brain that regulate cardiovascular function. The purpose of this study was to compare the effects of mestranol and estradiol on blood pressure in normotensive as well as hypertensive rats and to correlate observed changes in blood pressure with changes in central alpha adrenoceptors. Female spontaneously hypertensive rats (SHR) and normotensive Sprague Dawley (SD) rats (30 days of age) were were injected S.C. biweekly for 12 weeks with sesame oil vehicle, estradiol or mestranol [50ug/100g body weight]. Animals were sacrificed by decapitation brains were removed and quick frozen. Alpha-1 and alpha-2 adrenoceptors in the frontal cortex (FC), rostral hypothalamus (RH), caudal hypothalamus (CH), the region of the locus coeruleus (LC) and the region of the nucleus tractus solitarius (NTS) were assayed using [3H]-prazosin and [3H]-clonidine. Mestranol and estradiol treatment attenuated the development of hypertension in the SHR by 15% and 30% relative to sesame oil control (170+2:mmHg). Sprague Dawley blood pressure (132+2mm Hg) were not influenced by either estrogen treatment. Estradiol treatment in the SHR had no effect on alpha receptor sub population in any of the brain region examined. Alpha-1 adrenoceptors from the FC of mestranol treated SHR were significantly (p[less-than]0.05) reduced. No other brain regions were effected. Estradiol treatment in the SD resulted in elevated alpha-1 adrenoceptors in the NTS. Alpha-2 adrenoceptors were unaffected by estradiol treatment. Mestranol caused a significant reduction in alpha-1 adrenoceptors in the LC, and a significant reduction in alpha-2 adrenoceptors in the FC, LC and NTS of the SD. Estrogen treatment caused shifts in alpha receptors in several brain regions of the SD with out effecting blood pressure. Conversely estrogen treatment attenuated the development of blood pressure in the SHR while having no effect on alpha receptors in blood pressure regulatory regions. This lack of correlation between estrogen induced changes in blood pressure and alterations in alpha adrenoceptors in blood pressure regulatory sites of the brain suggest that the hemodynamic effects of the estrogens are not mediated by estrogen induced changes in central alpha adrenoceptors. |
| General note | "Presented to the faculty of the Department of Biology ... in partial fulfillment of the requirements for the degree Master of Science." |
| General note | Advisor: S. Gregory Iams |
| Dissertation note | M.S. East Carolina University 1987 |
| Bibliography note | Includes bibliographical references (leaves 64-78). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Joyner | Microforms | MICROFILM* | ✔ Available | |
| Electronic Resources | ✔ Available |