No description available.

Not available / text

published_or_final_version / abstract / Obstetrics and Gynaecology / Master / Master of Philosophy

No description available.

Two experiments were conducted to determine whether in ewes uterine concentrations of estrogen and progesterone receptors are affected by the presence of a conceptus or by the hormonal milieu associated with extremes in photoperiod to which ewes are exposed. In Exp.1, nine mature ewes were unilaterally ovariectomized by removing an ovary bearing the corpus luteum (CL). The ipsilateral uterine horn was ligated at the external bifurcation and a portion of the anterior ipsilateral uterine horn was removed and assayed for endometrial nuclear and cytosolic concentrations of estrogen receptor (ER) and progesterone receptor (PR) by exchange assays. After a recovery estrous cycle, ewes were bred to a fertile ram. On day 18 of gestation a 10 ml jugular blood sample was collected for measurement of serum concentrations of estradiol -17β (E₂) and progesterone by radioimmunoassay. Ewes were relaparotomized on day 18 and the remaining uterine tissue was removed. Endometrium from both the pregnant and nonpregnant uterine horn was assayed for nuclear and cytosolic ER and PR concentrations. Nuclear and cytosolic ER concentrations on day 10 of the cycle were greater than in endometrium of gravid and nongravid uterine horns on day 18 of gestation (p<.01). Endometrial nuclear PR levels were also greater on day 10 of the cycle than in the pregnant (p<.05) and nonpregnant horn (p<.01) on day 18 of gestation. There were no differences in nuclear and cytosolic ER and PR concentrations between the pregnant and nonpregnant uterine horn on day 18. Serum levels of E₂ and progesterone on day 18 of gestation were 16.56 ± 2.43 pg/ml and 1.74 ± 0.57 ng/ml, respectively. These data suggest that duration of exposure of the uterus to progesterone and(or) the presence of the conceptus causes a reduction in uterine concentrations of ER and PR. Further, an effect of the conceptus, if any, is exerted via a systemic route. In Exp. 2, ten mature ewes were bilaterally ovariectomized in early October. During the onset of the winter solstice (late December), a 10 ml blood sample was collected from five ewes for analysis of serum levels of E₂ and progesterone. Ewes were then laparotomized and approximately one-third to one-half of a uterine horn was removed and assayed for endometrial nuclear and cytosolic ER. The contralateral horn was ligated at the external bifurcation and 10 μg of E₂ in 3 ml of physiological saline was injected into the uterine lumen of the ligated horn. After 48 h, a jugular blood sample was collected for steroid analysis and a section of the E₂ treated horn was removed and assayed for endometrial cytosolic and nuclear ER. This procedure was repeated on the remaining five ewes during the height of the summer solstice (late June). Endometrial nuclear and cytosolic concentrations of ER prior to and after exogenous E₂ stimulation were similar during the winter and summer solstice (p>.05). However, treatment with E₂ increased endometrial nuclear and cytosolic concentrations of ER compared with those of the nonstimulated uterine horn during the winter and summer solstice (p<.05 for each). Serum levels of E₂ prior to luminal treatment of ewes with E₂ during the winter and summer solstice did not differ (16.55 ± 4.05 vs 16.00 ± 3.0 pg/ml, respectively, p>.05). Serum levels of E₂ 48 h after administration of E₂ did not differ among ewes at the winter and summer solstice (18.75 ± 2.4 vs 18.65 ± 1.65 pg/ml, respectively, p>.05). Serum levels of progesterone were basal (<0.10 ng/ml) and did not differ in ewes prior to and after E₂ treatment at the winter and summer solstice (p>.05). These data indicate that physiological factors and(or) hormones such as prolactin and melatonin secreted in response to extremes in photoperiod do not appear to influence uterine concentrations of ER in ovariectomized ewes. / Graduation date: 1991

No description available.

Bisphenol A (BPA) is an estrogen receptor binding chemical, widely used in the plastics industry, and as such commonly encountered from plastic containers etc. Even at very low doses, BPA is believed to induce obesity and to have various endocrine disruptive effects. The purpose of this study was to determine possible gene expression changes in gonadal and inguinal adipose tissue from rats perinatally exposed to BPA. The method used was quantitative real-time PCR, and genes found to be up-regulated were PLZF, adiponectin, RXRa and Tcf21, while down-regulated genes were PPARγ, Tmem26, EsR1, Resistin, LPL, Chemerin, Serpina6, TFAM and Ahr. This is so far largely unsupported by other studies, and more research is needed.

published_or_final_version / abstract / Medicine / Master / Master of Philosophy

published_or_final_version / Medicine / Master / Master of Research in Medicine

Both estradiol and progeterone are proposed autocrine or paracrine regulators of ovarian function in primate species. However, specific receptors for these steroids have not been localized to individual compartments of the primate ovary. Using immunocytochemical techniques, estradiol receptors were detected in the germinal epithelium, but not other structures, of ovaries obtained from rhesus or cynomolgus monkeys during the follicular and luteal phases of the menstrual cycle. In contrast, progesterone receptors were present in stromal and interstitial tissue, the thecal layers of healthy and atretic follicles, as well as the functional corpus luteum. These results are consistent with the concept of a receptor-mediated role for progesterone, but not estrogen, within the predominant gametogenic and endocrine structures, e.g., the follicle and corpus luteum, of the primate ovary. The recent discovery of distinct cell types in the corpus luteum of domestic ungulates has revised concepts on the control of luteal function in these species. Studies were designed to test the hypothesis that the primate corpus luteum consists of cell subpopulations that differ in physical characteristics, function and regulation. Cells enzymatically-dispersed from the monkey corpus luteum at mid-luteal phase of the menstrual cycle differed in size (diameter) and the presence of the steroidogenic enzyme, 3β-hydroxysteroid dehydrogenase (3β-HSD). Analysis of dispersed cells for forward and 90° light scatter properties by flow cytometry revealed two distinct continua (Cα and Cβ). These continua were isolated using the sorting capabilities of the flow cytometer. Cα contained single cells of ≤ 15 μm and cell clusters; the cells were typically 3β-HSD-negative nonsteroidogenic. Cβ consisted of single cells that increased in size up to 40 μm and were 3β-HSD-positive. Cβ was divided into two regions (R₁ and R₃) and the cells isolated. R₁ cells were ≤ 15 μm whereas R₃ cells were ≥ 20 μm. Basal progesterone and estrogen production by R₃ cells was greater than that produced by R₁ cells (as determined by radioimmunoassay of the incubation media). Relative stimulation of progesterone production by hCG, cAMP or PGE₂ was not different between R₁ and R₃ luteal cells. These results support the hypothesis that the primate corpus luteum consists of distinct cell subpopulations which differ in size and steroidogenic capacity. However, the cell types which secrete progesterone are typically responsive to gonadotropin and PGE₂, possibly via a cAMP-mediated pathway.