Modulation of progestin secretion in ovarian cells by 17beta-hydroxy-5alpha-androstan-3-one (dihydrotestosterone): a direct demonstration in monolayer culture.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
R L Stouffer
Publications and source records attributed to R L Stouffer.
In vitro evaluation of corpus luteum function of cycling and pregnant rhesus monkeys: Progesterone Production by dispersed luteal cells.
Corpus luteum function in the cycling and the pregnant rhesus monkey (Macaca mulatta) was evaluated through short term in vitro studies of progesterone production by suspensions of collagenase-dispersed luteal cells in the presence and absence of exogenous gonadotropin (human chorionic gonadotropin, HCG). Cells from mid-luteal phase of the menstrual cycle secreted progesterone, as measured by accumulation of this hormone in the incubation medium, and responded to the addition of 100 ng HCG/ml with a marked increase in progesterone secretion significantly above basal level (63.7 +/- 13.1 versus 24.7 +/- 5.5 ng progesterone/ml/5 x 10(4) cells/3 hr, X +/- S.E., n =6 ; p less than 0.05). However, luteal cells from early pregnancy (23-26 days after fertilization) secreted siginificantly less progesterone than cells of the non-fertile menstrual cycle (3.6 +/- 2.4 versus 24.7 +/- 5.5 ng/ml/5 x 10(4) cells/3 hr, n =3 ; p less than 0.05) and did not respond to HCG with enhanced secretion. By mid-pregnancy (108-118 days gestation ) luteal cells exhibited partially renewed function, and near the time of parturition (163-166 days gestation) basal and HCG-stimulated progesterone secretion (30.2 +/- 5.6 and 63.0 +/- 13.0 ng/ml/5 x 10(4) cells/3 hr, respectively; n = 3) was equivalent to that of cells from the luteal phase of the non-fertile menstrual cycle. The data suggest that following a period around the fourth week of gestation, when steroidogenic activity is markedly diminished, the corpus luteum of pregnancy progressively reacquires its functional capacity and at term exhibits gonadotropin-sensitive steroidogenesis similar to that the corpus luteum of the menstrual cycle.
Animals↗
Changes in (125I) labeled human chorionic gonadotropin (hCG) binding to porcine granulosa cells during follicle development and cell culture.
The specific binding of (125I)iodo human chorionic gonadotropin to porcine granulosa cells isolated at two stages of follicle maturation was quantitated immediately after harvest and following 6-7 days of culture. Both porcine LH (pLH, LER 786-3) and hCG inhibited (125I)iodo hCG binding, while pFSH (ler-1132) did not compete for hCG with granulosa cells for 24-48 hours at 37 C did not alter its subsequent ability to bind to fresh cells. The binding of (125I)iodo hCG was a rapid process which was not readily reversible. Scatchard analysis of the equilibrium binding data resulted in linear plots showing the hCG binding capacity of highly differentiated (HD) cells, harvested from large preovulatory follicles, to be significantly greater than that of moderately differentiated (MD) cells isolated from smaller luteal phase follicles, both before (794 vs 93 pmoles/g; P less than 0.001) and after (157 vs 5 pmoles/g; P less than 0.001) culture. A decline in binding capacity occurred in both cell groups during culture and was associated with a significant decrease in progestin production. In contrast, the hCG binding affinity of the granulosa cell was equivalent at both stages of follicle development and remained unchanged after 6 days of culture (mean apparent Kd = 2.9 x 10-10M; n=27. These data indicate that porcine granulosa cells contain a homogeneous class of LH receptors whose number, but not affinity, increases during follicle maturation in vivo. The loss of receptors in vitro suggests the absence of some factors(s), as yet unidentified, critical to the maintenance and development of the receptor population.
Animals↗
Thermoregulatory ability and the thyroid gland: their development in embryonic Japanese quail (Coturnix c. japonica).
Explore the source record for details and available documents.
Animals↗
Regulation and action of angiogenic factors in the primate ovary.
The ephemerality of the maturing follicle and subsequent corpus luteum as they perform their gametogenic and/or endocrine functions during the ovarian cycle is associated with remarkable changes in local vasculature. Studies on the angiogenic and angiolytic process in the ovary, rare in healthy adult tissues, complement recent efforts to understand vasculogenesis in embryonic tissues and to control angiogenesis in pathologic states such as cancer. Several reports indicate that the newly discovered vascular-specific angiogenic factors are expressed in the ovary, notably members of the vascular endothelial growth factor (VEGF) and angiopoietin (Ang) families plus their receptors (VEGF-Rs, neuropilins, Tie). Unlike in many other tissues, gonadotropic hormones (particularly luteinizing hormone, [LH]) are major stimulators of angiogenesis and VEGF/Ang expression in the ovary. However, local factors such as insulin-like growth factors or oxygen tension likely modulate the angiogenic processes. Recent studies employing systemic or local administration of anti-angiogenic drugs (TNP-470 or fumagillin) or specific VEGF antagonists (VEGF antibody or soluble VEGFR-1) demonstrate a vital role for normal angiogenesis and VEGF action in follicle development, ovulation, or corpus luteum function. Further studies discerning the various angiogenic factors and their roles in controlling the growth, maturation, function, and regression of the vasculature in ovarian compartments during the menstrual cycle could yield novel strategies for manipulating fertility or for alleviating infertility.
Angiogenesis Inhibitors↗
Progesterone as a mediator of gonadotrophin action in the corpus luteum: beyond steroidogenesis.
Studies using newer, potent GnRH antagonists and pure gonadotrophins have clarified the importance of: (i) the strength-duration of the midcycle surge of pituitary gonadotrophins (LH, FSH) in follicle rupture and conversion to the corpus luteum; (ii) the continued requirement for pituitary LH throughout development and the functional lifespan of the primate corpus luteum in the menstrual cycle; and (iii) the exponential secretion of chorionic gonadotrophin (CG) by the developing placenta to extend the functional lifespan of the primate corpus luteum in early pregnancy. Although studies continue to increase current understanding of the cellular and molecular actions of LH/CG to stimulate luteal steroidogenesis, knowledge of the processes whereby these gonadotrophins promote the development and maintenance of the functional corpus luteum remains limited. This review summarizes evidence that the primate ovulatory follicle and corpus luteum is a target for the primary steroid produced by luteinizing/luteal tissue (i.e. progesterone). With evidence for dynamic expression of genomic progesterone receptors (PRA/B), and possibly other progesterone-receptor systems, recent studies addressed the hypothesis that progesterone is a critical 'local luteotrophin' that promotes luteal development and sustains luteal structure-function during the menstrual cycle and early pregnancy. Specific progesterone actions to regulate tissue remodelling (via protease expression), health (anti-apoptotic effects) and sensitivity to other local factors (e.g. via estrogen receptor expression) are discussed. The collective data suggest that there are gonadotrophin-stimulated, progesterone-dependent processes that promote luteotrophic and suppress luteolytic pathways in the primate corpus luteum. However, further studies are needed to verify their role in normal ovarian function and relevance to possible ovarian defects in natural and assisted reproduction technique-related cycles.
Animals↗