Baseline non-fasting serum leptin concentration to body mass index ratio is predictive of IVF outcomes

BACKGROUND

The present study was designed to determine whether circulating leptin concentrations and/or body mass index (BMI) in women undergoing IVF are predictive of outcomes.

METHODS

IVF cycle outcomes, e.g. fertilization, embryo development, implantation, pregnancy, were analysed relative to baseline (i.e. day gonadotrophin stimulation was initiated) non-fasting serum leptin concentrations and BMI.

RESULTS

Serum leptin concentrations correlated with BMI (r = 0.739, P < 0.0001) as expected. Multiple logistic regression analyses showed correlation between serum leptin and pregnancy success (likelihood ratio = 5.198, P < 0.05), but there was no association between pregnancy and BMI. However, the serum leptin to BMI ratio was more strongly correlated (likelihood ratio = 7.258, P < 0.01) with pregnancy success than was leptin alone. Moreover, women with a low leptin:BMI ratio (< or =0.3) had significantly more superior quality embryos on day 3 post-retrieval (2.5 versus 1.4, P < 0.05, Kruskal-Wallis) and a greater implantation rate (26.7 versus 13.2%, P < 0.025, chi(2)) than women with a high leptin:BMI ratio (> or =0.7).

CONCLUSIONS

The leptin:BMI ratio appears to be highly predictive of IVF success. Elevated leptin concentrations, particularly relative to BMI, may negatively impact fertility by assisted reproduction, possibly through direct ovarian actions resulting in impaired oocyte quality and/or early embryo development.

Chromatin structure in globozoospermia: a case report

Sperm nuclear abnormalities in patients with globozoospermia have not been well characterized and may lead to the high rates of fertilization failure and embryo loss reported in patients with this form of teratozoospermia. This study used transmission electron microscopy (TEM), the sperm chromatin structure assay (SCSA), and single cell gel eletrophoresis assay (COMET) to assess if globozoospermia is associated with sperm chromatin structure abnormalities, DNA fragmentation, or both. The flow cytometric SCSA measures abnormal chromatin structure based on the susceptibility of sperm nuclear DNA to acid-induced denaturation in situ. COMET measures DNA fragmentation in individual sperm nuclei based upon gel electrophoretic patterns. Although sperm concentration (113 million/mL) and motility (66%) were normal in the patient, there was complete acrosome deficiency. TEM and SCSA data confirmed light microscopic examination that showed that sperm populations included a mixture of round and elongated sperm heads. Even though 100% of sperm had abnormal head morphology, only 13% demonstrated DNA denaturation (COMPalpha(t)), which is below our threshold of 15% COMPalpha(t), and consistent with high-fertility patients. Of interest, 13% of the sperm were also positive in the COMET assay, supporting our previous observations that SCSA-positive cells are also positive for DNA fragmentation. It was unexpected but of great interest that a human sperm population with 100% sperm morphology abnormalities had a chromatin integrity at the molecular level that is equivalent to sperm populations shown in previous studies to be highly fertile. These data are the first reported using SCSA and COMET assays to evaluate a patient with globozoospermia and support previous reports that intracytoplasmic sperm injection of globozoospermia may result in fertility/pregnancy. Lower success rates seen in some patients may be due to unrelated factors.

Serum leptin concentrations in women during gonadotropin stimulation cycles

OBJECTIVE

To determine whether elevated follicular steroid levels during gonadotropin stimulation cycles are associated with altered circulating leptin concentrations.

STUDY DESIGN

Sequential serum samples were collected from women (N = 37) undergoing luteal phase GnRH agonist + FSH treatment cycles prior to oocyte retrieval for in vitro fertilization. Leptin concentrations in serum were measured by radioimmunoassay and compared with serum estradiol, testosterone and dehydroepiandrosterone sulfate (DHEAS) levels.

RESULTS

Serum leptin concentrations during stimulated cycles were variable between patients and correlated positively (r = .556, P < .01) with body mass index. Serum leptin levels correlated positively (r = .185, P < .05) with estradiol concentrations across all days. Mean serum leptin concentrations on the day gonadotropin treatment began (baseline, 12.9 +/- 2.0 ng/mL) were lower (P < .0001) than on the day peak estradiol levels were reached (18.4 +/- 2.3 ng/mL). Serum leptin concentrations also correlated with DHEAS levels (r = .214, P < .05) but did not correlate with testosterone or the estradiol:testosterone ratio.

CONCLUSION

Gonadotropin stimulation in women is associated with elevated leptin levels, consistent with an interaction between the reproductive axis and leptin secretion and/or clearance.

Oxidized-low density lipoprotein inhibits cyclic AMP production by porcine luteal cells

Oxidized(OX)-low density lipoprotein (LDL) inhibits steroidogenesis by luteal cells (LC) from regressing porcine CL. The present study was designed to investigate the mechanism of inhibition by determining whether OX-LDL inhibits basal and agonist-stimulated cAMP production in regressing LC. Collagenase-dispersed porcine LC (n = 7 animals, estrous cycle Day 12-15) were cultured (2.5 x 10(5) cells/0.5 ml) in serum-free DMEM/Hams F-12 in duplicate wells at 37 degrees C. Approximately 18 hr after plating, media were replaced and LC were immediately treated with human LDL (0, 25, or 100 microg/ml) or OX-LDL (25 or 100 microg/ml). LC were incubated for 2 hr before addition of isobutylmethylxanthine (IBMX) to inhibit phosphodiesterase activity, immediately followed by hCG (100 ng/ml), cholera toxin (CT; 0.1 microM), forskolin (FS; 50 microM), or no further treatment (controls). LC were incubated for an additional 90 min. After removal of culture media, cells were extracted with 0.1 N HCl. Cell extracts were assayed for cAMP by enzyme immunoassay (EIA). HCG, CT, and FS increased (P < 0.05) cAMP production approximately four-, 10-, and 25-fold, respectively, relative to controls. OX-LDL (25 and 100 microg/ml) inhibited (P < 0.05) cAMP production by unstimulated, hCG-, and CT-stimulated LC, but not that by FS-stimulated LC. The highest concentration of OX-LDL (100 microg/ml) reduced cAMP formation by 39.8 +/- 6.6%, 44.7 +/- 10.5%, and 67.7 +/- 4.5% in unstimulated, hCG-, and CT-stimulated LC, respectively. In contrast, unmodified LDL (25 and 100 microg/ml) did not alter cAMP production. We conclude that OX-LDL can interfere with the cAMP signaling pathway in regressing luteal cells by acting at sites proximal to adenylate cyclase activation.

Density gradient centrifugation and glass wool filtration of semen remove spermatozoa with damaged chromatin structure

The ability of double-layered density gradient centrifugation (DGC) or glass wool filtration (GWF) of semen to remove spermatozoa with damaged chromatin structure was assessed by the flow cytometric sperm chromatin structure assay (SCSA), which measures the susceptibility to sperm nuclear denaturation in situ. Ejaculates from 26 men attending a university-affiliated assisted reproduction laboratory were processed by DGC and GWF. Unprocessed, DGC- and GWF-processed specimens were assessed by the SCSA and by conventional semen parameters. Changes in chromatin structure were compared with conventional semen parameters. Both sperm preparation techniques yielded sperm suspensions with improved sperm chromatin structure as well as motility (%), forward progression (1-4) and viability (%). DGC was superior to GWF in the efficiency of recovering motile, morphologically normal, mature sperm suspensions. However, GWF produced improved chromatin integrity (SDalpha(t)) and viability. Moderate correlations between SCSA and conventional sperm parameters were observed. Nevertheless, the SCSA provides additional information about the biochemical integrity of sperm DNA and may be used in future studies to provide insight into assisted reproduction technology outcomes not explained by conventional sperm parameters.

Leptin inhibits gonadotrophin-stimulated granulosa cell progesterone production by antagonizing insulin action

Recent evidence has demonstrated that expression of leptin and leptin receptors is expected in the human ovary, and that leptin alters ovarian steroidogenesis in animal models. This study was designed to determine whether leptin modulates basal, gonadotrophin-, and insulin-stimulated progesterone production by human luteinized granulosa cells (GC). GC were recovered from follicular aspirates obtained during transvaginal ultrasound-guided oocyte retrieval for in-vitro fertilization-embryo transfer, and cultured in defined medium with various combinations of chorionic gonadotrophin (HCG; 0 or 100 ng/ml), insulin (0-30 microg/ml), and leptin (0-100 ng/ml). Progesterone concentrations in media were determined at various time points (2 h to 6 days). Leptin time- and dose-dependently inhibited (P < 0.05) HCG-stimulated progesterone production by human luteinized GC, but did not alter basal steroidogenesis. Moreover, the inhibitory effect of leptin on gonadotrophin-stimulated progesterone production was only manifested in the presence of insulin. Leptin suppression of insulin-supported steroidogenesis was also time- and dose-dependent. We conclude that leptin inhibits gonadotrophin-stimulated GC progesterone production apparently by antagonizing insulin action. Leptin suppression of progesterone production by human luteinized GC is consistent with recent data from animal models, and supports the possible role of leptin as a regulator of human ovarian function.

Macrophages are the major source of tumor necrosis factor alpha in the porcine corpus luteum

This study was designed to determine the source of tumor necrosis factor (TNF) alpha within the porcine corpus luteum (CL). 1) Sections of frozen or paraffin-embedded CL from various stages of the estrous cycle were incubated with the following primary antibodies: anti-human recombinant TNFalpha, anti-porcine macrophage-specific antigen, or anti-alpha-actin (marker of pericyte and smooth muscle cells). Dolichos biflorus lectin-peroxidase was used as an endothelial cell label. Positive immunostaining for TNFalpha was apparent in porcine CL throughout the estrous cycle. TNFalpha immunoreactivity was primarily localized in cells along septal/vascular tracts, and exhibited spatial and temporal distribution similar to that of cells labeled with anti-macrophage antibodies. Large luteal cells exhibited weak staining for TNFalpha in paraffin sections, whereas microvascular endothelial cells were consistently negative in both frozen and paraffin sections. 2) Enriched subpopulations of macrophages, endothelial cells, and large and small luteal cells were isolated by density gradient and immunomagnetic bead separation techniques. TNFalpha secretion by each subpopulation was determined by measuring bioactive TNFalpha in incubation media using a specific in vitro bioassay. Macrophage subpopulations secreted up to 100-fold greater quantities of bioactive TNFalpha (up to 400 pg/10(6) cells) than did other subpopulations. In contrast, endothelial cell and small luteal cell subpopulations released very small amounts (< 8 pg/10(6) cells) of bioactive TNFalpha. Large luteal cells secreted slightly greater amounts of TNFalpha (10-15 pg/10(6) cells). Local macrophages appear to be the primary source of TNFalpha in the porcine CL.

Is the free androgen index a useful clinical marker in male patients?

The clinical relevance of the free androgen index (FAI), a ratio of total testosterone (T) to sex-hormone binding globulin (SHBG), was investigated in a regional population of men (n = 40) and women (n = 30). The FAI correlated well with free testosterone (T) in both men (r = 0.551, p < 0.001) and women (r = 0.454, p < 0.01). However, there was considerable variability among individual patients. Moreover, the FAI showed no association with sperm parameters in male patients, although total T and free T showed weak associations. The FAI may be a cost-effective alternative to free T measurement in the diagnosis of oligomenorrhea and hirsutism in women as previously shown, but may have little relevance in men.

Localization of lipid peroxidation-derived protein epitopes in the porcine corpus luteum

Reactive oxygen species (ROS) generated within the corpus luteum (CL) are believed to play an integral role in luteolysis. Unsaturated lipids are susceptible to peroxidation by ROS, leading to the formation of toxic aldehydes such as malondialdehyde (MDA) and 4-hydroxy-nonenal (4-HNE) that can attack cellular and extracellular proteins. Aldehyde conjugation of proteins can have diverse effects on cell function, including cross-linking of cell surface receptors, alteration of enzyme activities, and modification of lipoproteins. The objectives of the present study were to 1) determine by immunological techniques whether lipid peroxidation-derived protein epitopes (i.e., MDA- and 4-HNE-lysine) could be detected in situ during the natural life span of the CL, and 2) determine the temporal and spatial localization of these epitopes. Fresh luteal tissue was collected from young gilts at distinct phases of the estrous cycle: early (Days 4-7), mid (Days 8-12), and late (Days 14-18). Immunocytochemistry was performed on tissue sections using monoclonal antibodies against MDA-lysine and 4-HNE-lysine. Positive immunostaining was evident in porcine CL at all stages of the estrous cycle. Immunoactivity was associated primarily with the steroidogenic cells, most consistently with the large luteal cells, and was most intense in regressing tissue (i.e., late). No staining was observed in sections incubated with nonimmune mouse serum or when anti-4-HNE-lysine was preadsorbed with 4-HNE-protein preparations. Immunoblotting of protein extracts from luteal tissue revealed three major reactive bands. At least two of these bands were closely associated with extracted oxidized human low-density lipoprotein (LDL) and with 4-HNE-conjugated human apoprotein B. These results demonstrate the presence of lipid peroxidation-derived protein epitopes within the porcine CL and show that one or more of these may be an oxidized-LDL moiety. This represents the first direct in situ evidence that protein modification by lipid peroxidation products occurs during the natural luteal life span. The physiological consequences remain to be determined.

Expression and function of a scavenger lipoprotein pathway in porcine luteal cells

A pathway(s) for uptake of modified (e.g., acetylated, oxidized) low-density lipoprotein (LDL) moieties has been recently discovered on luteal cells of certain species. The expression and function of this pathway during the life span of the corpus luteum (CL) have not been investigated. Aims of the present study were the following: 1) to determine whether porcine small and large luteal cells take up modified LDL; if so, 2) to compare uptake of native and modified LDL by luteal cell subpopulations during the luteal life span and 3) to compare effects of native and modified LDL on luteal steroidogenesis during the estrous cycle. Collagenase-dispersed luteal cells were prepared from porcine ovaries at various stages of the estrous cycle: early (E, Days 4-6), mid (M, Days 8-10), mid-late (ML, Day 13-14), or late (L, Day 16-17) (estrus = Day 0). Cells were incubated with fluorescent-tagged LDL (Dil-LDL; 0-10 microg/ml) or acetylated LDL (Dil-AC-LDL; 0-10 microg/ml). Fluorescence was analyzed by multiparameter flow cytometry in each of three subpopulations of cells: small (SLC) and large (LLC) luteal cells and nonsteroidogenic cells. The percentage of LLC taking up Dil-LDL remained relatively constant (65-75%) from E to ML cycle and then declined (13.3 +/- 4.1%; p < 0.05); these findings were consistent with previous data. In contrast, the percentage of LLC taking up Dil-AC-LDL gradually increased from E (29.8 +/- 8.5%) to ML (68.3 +/- 5.9%) stage and then declined (17.1 +/- 2.3%; p < 0.05). Similarly, Dil-LDL uptake by SLC was relatively constant (15-20%) from E to M cycle, declining to 2.9 +/- 0.5% at L cycle. Dil-AC-LDL uptake by SLC progressively increased from E (5.4 +/- 2.6%) to ML (24.3 +/- 6.9%) and then fell somewhat (12.9 +/- 6.7%) in L cycle. Few (< 2%) nonsteroidogenic cells labeled for Dil-LDL at all stages, whereas Dil-AC-LDL uptake by nonsteroidogenic cells was similar to that by SLC. Dual-uptake experiments revealed subtypes of LLC that took up either native LDL only or both native and modified LDL. Progesterone (P4) production by E and M luteal cell cultures was dose-dependently increased (p < 0.05) by both native and modified LDL. In contrast, modified LDL suppressed (up to 40-50%, p < 0.05) steroidogenesis by ML and L cultures, whereas LDL had no significant effect. Only native LDL stimulated P4 production by isolated SLC, although both native and modified LDL similarly increased P4 production by LLC. In conclusion, expression of one or more scavenger LDL pathways on porcine luteal cell subtypes is dynamic. Moreover, modified LDL can exert both stimulatory and inhibitory effects on luteal steroidogenesis in vitro. Differential expression and function of a scavenger LDL pathway by subpopulations of cells within the CL may play a novel role in luteal development, function, and/or regression.

Androgen production by monkey luteal cell subpopulations at different stages of the menstrual cycle

Androgens produced by the primate corpus luteum (CL) serve as precursors for estrogen synthesis; moreover, detection of androgen receptors in luteal tissue suggests a regulatory role within the CL. To determine the cellular source(s) and agonist regulation of androgen production during the lifespan of the primate CL, luteal tissues were collected from rhesus monkeys in the early (days 3-5 post-LH surge), mid (days 7-8), mid-late (days 11-12), and late (days 14-15) luteal phase of the menstrual cycle. Collagenase-dispersed cells (i.e., mixed cells) were analyzed by flow cytometry based on light scatter properties and sorted into populations of small (< or = 15 microns) and large (> 20 microns) luteal cells. Cells (n = 4 animals/stage) were incubated in Ham's F-10 and 0.1% BSA for 3 h at 37 C with or without hCG (100 ng/mL), PGE2 (14 mumol/L), or dibutyryl cAMP (dbcAMP; 5 mmol/L), and androstenedione (A4) and testosterone were measured. Basal A4 production by large cells was markedly higher (P < 0.05) than that by small cells (e.g. mid-late luteal phase, 821 +/- 188 vs. 69 +/- 25 pg/mL.5 x 10(4) cells/3 h; mean +/- SEM), whereas that by mixed cells was intermediate (317 +/- 205 pg/mL). In the early luteal phase, hCG stimulated A4 synthesis by mixed (1.6-fold; P < 0.05) and large (3.1-fold; P < 0.05) luteal cells, but not by small cells (1.3-fold). By the mid-late luteal phase, hCG did not increase A4 production by any cell type, although hCG responsiveness returned to large cells (2.0-fold increase; P < 0.05) by the late luteal phase. PGE2 responsiveness by cell types was similar to that of hCG, except large cell responsiveness did not return in the late luteal phase. In all cell types, dbcAMP stimulated the largest increase in A4 levels; in the mid-late luteal phase, small and large cells responded to dbcAMP with 8.2- and 3.0-fold increases (P < 0.05) in A4 production, respectively. When luteal cells were incubated with the steroidogenic substrates, 17 alpha-hydroxyprogesterone or 17 alpha-hydroxypregnenolone (1 mumol/L), large cells produced much more (P < 0.05) A4, testosterone, estrone, and estradiol than small cells. Both substrates elicited similar patterns of androgen production, with A4 synthesis predominant in all luteal cell types. Thus, cell subpopulations in the primate CL can be distinguished by their ability to produce androgen and estrogen. Changes in agonist-responsive androgen production may influence the local steroid milieu and function of the CL during the menstrual cycle.

Gonadotropin control of follicle and oocyte maturation: implications for ovulation induction

Development and maturation of follicles and oocytes during the menstrual cycle are complex processes that are poorly understood. Current gonadotropin therapy for ovulation induction/IVF may result in the production of suboptimal oocytes. As we learn more about the interdependency of follicle and oocyte in natural cycles, we should enhance our ability to produce better quality oocytes in artificial cycles. This will lead to improved success in the treatment of infertility.

Hydrogen peroxide suppresses low-density lipoprotein (LDL) uptake and LDL-supported steroidogenesis by porcine luteal cells

The present study tested the hypothesis that hydrogen peroxide (H2O2) inhibits low-density lipoprotein (LDL) uptake and LDL-supported steroidogenesis by luteal cells. LDL uptake: dispersed porcine luteal cells from mid-cycle (days 6-11, estrus = day 0) were incubated for 0-120 min at 37 degrees C in F-10 medium + 0.1% BSA containing various concentrations of H2O2 (0-1000 microM). Cells were washed with catalase (2800 U/ml), and then with fresh medium. Cell viability based on trypan blue exclusion was unaltered by H2O2 exposure through 60 min. H2O2-exposed cells were incubated with fluorescent-tagged-LDL (Dil-LDL; 1 microgram/ml) for 10 min at 37 degrees C. Fluorescence of small (SLC) and large (LLC) luteal cells was analyzed by flow cytometry (n = 6 experiments). H2O2 (> or = 10 microM) caused a progressive reduction (P < 0.01) in mean fluorescence intensity (MFI) of SLC and LLC indicative of up to a 30-35% decline in LDL uptake. Progesterone (P) production: dispersed luteal cells (4 x 10(4)/0.2 ml) were pre-cultured in DMEM/F-12 medium overnight (approximately 18 h) in 96-well culture plates. Wells were rinsed and fresh media (0.2 ml) containing H2O2 (0-500 microM) was added. After 30 min, the following treatments were added: human(h)LDL (0 or 50 micrograms/ml), human chorionic gonadotropin (hCG; 0 or 100 ng/ml), hCG + LDL, or 22R-hydroxycholesterol (22[OH]-C; 0 or 25 micrograms/ml). Cells were incubated for an additional 4 h, and P concentrations in final media samples were measured by RIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of low-density lipoprotein utilization by regressing porcine luteal cells: effects of protein kinase C activation

We recently reported a decline in low-density lipoprotein (LDL) uptake by regressing porcine luteal cells that correlated with diminished LDL stimulation of progesterone (P) production. The objectives of the present study were to determine 1) whether loss of LDL utilization is a specific lesion in the steroidogenic pathway in regressing luteal cells and 2) whether in vitro activation of protein kinase C (PKC) in mid-cycle luteal cells acutely suppresses LDL utilization. Dispersed cells (4 x 10(4)/0.2 ml) from mid-(Days 6-10, estrus = Day 0; n = 5) or late-(Days 15-18; n = 7) cycle porcine CL were cultured in Dulbecco's Modified Eagle/F-12 medium supplemented with insulin, transferrin, sodium selenite, and aprotinin for 24 h with human (h) LDL (0-100 micrograms/ml), 22(R)-hydroxycholesterol (22[OH]-C;-0-25 micrograms/ml), or pregnenolone (0-1000 nM). P production by mid-cycle luteal cells was dose-dependently increased (p < 0.05) by LDL (up to 2.8-fold), 22(OH)-C (up to 3.2-fold), and pregnenolone (> 3-fold). In contrast, LDL (10-100 micrograms/ml) failed to stimulate P production by late-cycle luteal cells. But 22(OH)-C (up to 4-fold) and pregnenolone (> 10-fold) were as effective in promoting (p < 0.05) steroidogenesis relative to basal levels in late luteal cells as in mid-cycle cultures. The PKC activator, TPA (12-O-tetradecanoyl-phorbol-13-acetate; 10 ng/ml), inhibited (approximately 20%; p < 0.01) basal and LDL-supported steroidogenesis, but did not suppress 22(OH)-C-stimulated P secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Decline in fluorescent low density lipoprotein (LDL) uptake by small and large porcine luteal cells with advancing age of the corpus luteum

The present study was designed to test the hypothesis that the ability of small luteal cells (SLC) and/or large luteal cells (LLC) to take up low density lipoprotein (LDL) declines with advancing age of the CL. Ovaries from 100-110-kg gilts were classified as early (Days 4-6; n = 5), mid (Days 8-12; n = 6)-, or late (Days 15-18; n = 5) cycle on the basis of gross morphology. Multiple CL from each ovary were pooled and enzymatically dissociated. An aliquot of dispersed luteal cells was reserved for cell culture. Remaining cells were incubated (approximately 4 x 10(5) cells/0.25 ml Dulbecco's Modified Eagle's Medium [DMEM] + 0.1% BSA) for 20 min at 37 degrees C with human LDL (10 micrograms/ml) tagged with the fluorescent probe, Dil (Dil-LDL). Washed and fixed cells were then isolated by flow cytometry into SLC and LLC subpopulations on the basis of forward and 90 degrees light scatter. Cellular fluorescence was analyzed within each subpopulation. The percentage of fluorescent, i.e., Dil-LDL-positive (+), SLC did not differ between early (29.8 +/- 5.9%) and mid (40.5 +/- 6.8%)-cycle, but declined (p < 0.01) in late CL (7.0 +/- 1.6%). Similarly, the percentage of Dil-LDL-(+) LLC was unchanged between early (80.5 +/- 2.0%) and mid (78.6 +/- 4.2%)-cycle, but diminished (p < 0.01) in late (40.2 +/- 1.9%) CL. Moreover, the percentage of total cells isolated in the LLC subpopulation declined dramatically (p < 0.01) between mid (8.0 +/- 0.9%)- and late (1.6 +/- 0.2%) cycle, but the percentage of SLC did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of ovine luteal cell subpopulations by flow cytometry

Differences in the characteristics of small and large luteal cells, as reported by various laboratories, may be due to species diversity and/or methodological differences in cell preparation. To evaluate whether the method of cell separation affects the properties of luteal cell subpopulations, we sorted and characterized sheep luteal cells by flow cytometry via methods previously used to investigate luteal cell subtypes from the macaque corpus luteum. Corpora lutea were obtained from superovulated ewes on Day 10 after hCG injection and enzymatically dissociated. Dispersed cells were shipped overnight on ice from the University of Arizona to the Oregon Regional Primate Research Center. Viability of cells upon arrival was > or = 80%. When dispersed cells were analyzed by flow cytometry based on forward and 90 degrees light scatter, three distinct subpopulations (P1, P2, P3) were identified. In P1, 35.5 +/- 2.1% of cells, most (97.0 +/- 0.6%; n = 3) of which were 15-22 microns in diameter, stained positive (+) for 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity. The remainder of P1 cells were 3 beta-HSD negative and < or = 22 microns. The size distribution of P2 was similar to that of P1, but P2 contained more (53.3 +/- 4.2%; n = 4) 3 beta-HSD (+) cells. P3 consisted mostly (88.5 +/- 4.6%; n = 3) of 3 beta-HSD (+) cells > 25 microns in diameter. Cell subpopulations were incubated (n = 6) at 37 degrees C for 3 h with or without hCG (0.1-100 ng/ml), prostaglandin E2 (PGE2; 500 ng/ml), or dibutyryl (db)-cAMP (5 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Native and modified (acetylated) low density lipoprotein-supported steroidogenesis by macaque granulosa cells collected before and after the ovulatory stimulus: correlation with fluorescent lipoprotein uptake

We recently reported that uptake of fluorescent-tagged low density lipoprotein (DiI-LDL) by macaque granulosa cells (GC) was greatly enhanced within 27 h of an ovulatory stimulus (hCG injection). The present study was designed to determine whether increased DiI-LDL uptake correlated with an increased capacity for LDL-supported steroidogenesis. We also tested whether modified [acetylated (ac)] LDL or high density lipoprotein (HDL), which are not ligands for the LDL receptor, supported progesterone (P) production. Beginning at menses, adult female rhesus macaques were treated with human (h) FSH and hLH for 9 days to promote development of multiple follicles. On day 10, monkeys were injected with hCG (1000 IU) or received no ovulatory stimulus. Large follicles were aspirated on day 10 (nonluteinized GC) or 27-34 h after hCG administration (luteinizing GC). GC (2 x 10(4)/0.2 ml) were cultured in Dulbecco's Modified Eagle's Medium-Ham's F-12 plus insulin, transferrin, H2SeO3, and aprotinin, with 0-100 micrograms hLDL, ac-hLDL, or hHDL. P concentrations in medium were determined by RIA. LDL (1-25 micrograms/ml) dose-dependently increased (up to 15-fold; P < 0.05) basal and hCG-stimulated P production by luteinized GC on days 1-8 of culture. However, LDL (25 micrograms/ml) did not alter basal P production by nonluteinized GC and increased (2-fold; P < 0.05) hCG-stimulated P secretion only on days 4-8. Basal and hCG-stimulated P production by luteinized GC were initially (days 1-2) increased (up to 2-fold; P < 0.05), but later (days 6-8) suppressed (P < 0.05) in a dose-dependent manner by 1-100 micrograms ac-LDL/ml. Ac-LDL did not alter basal or hCG-stimulated P production by nonluteinized GC. HDL (1-100 micrograms/ml) did not alter P production by either luteinized or nonluteinized GC. The number of viable luteinized GC on day 8 was reduced (30-50%; P < 0.05) after exposure to 10 micrograms ac-LDL/ml or more, whereas only the highest dose (100 micrograms/ml) of LDL or HDL reduced cell survival. Ac-LDL did not alter the survival of nonluteinized GC in culture. Flow cytometric analyses using fluorescent-tagged lipoproteins (DiI-LDL/DiI-ac-LDL) demonstrated the uptake of both native and ac-LDL by luteinized GC. Uptake of DiI-LDL was competitively suppressed in a dose-dependent manner by unlabeled LDL, but not by ac-LDL. In contrast, DiI-ac-LDL uptake was competitively inhibited by both ac-LDL and LDL.(ABSTRACT TRUNCATED AT 400 WORDS)

Gonadotropin surge increases fluorescent-tagged low-density lipoprotein uptake by macaque granulosa cells from preovulatory follicles

In the primate ovary, luteal steroidogenesis is largely dependent upon cholesterol derived from receptor-mediated uptake of circulating low-density lipoprotein (LDL). However, granulosa cells (GC) of preovulatory follicles possess few LDL binding sites compared to those present in developing and mature corpora lutea. We recently reported (Endocrinology 1991; 129:3247-3253) that uptake of LDL tagged with the fluorescent probe 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) can be monitored in macaque luteal cells by fluorescence-activated flow cytometry. This study was designed to determine whether an ovulatory stimulus induced uptake of DiI-LDL in GC aspirated from preovulatory follicles of macaques undergoing ovarian stimulation. Development of multiple large follicles was stimulated in adult rhesus macaques with human gonadotropin treatment for 9 days. On Day 10, monkeys received either no ovulatory stimulus or 1000 IU hCG to initiate ovulatory events. GC were aspirated on Day 10 in monkeys receiving no ovulatory stimulus (nonluteinized GC) or 27 h or 34 h after hCG injection (luteinizing GC). GC were resuspended in Ham's F-10 medium + 0.1% BSA and incubated with several concentrations (0-25 micrograms/ml) of DiI-LDL (Biomedical Technologies, Stoughton, MA) for various time intervals (2-60 min). DiI-LDL uptake by GC was time- and concentration-dependent. Coincubation of cells with DiI-LDL and unlabeled LDL dose-dependently suppressed the percentage of fluorescent cells. In contrast, coincubation with up to a 250-fold excess of acetylated LDL or high-density lipoprotein did not alter the percentage of fluorescent GC.(ABSTRACT TRUNCATED AT 250 WORDS)

Activin-A inhibits progesterone production by macaque luteal cells in culture

Since inhibin is produced during the luteal phase of the menstrual cycle in women and nonhuman primates, the primate corpus luteum (CL) may be a local site of inhibin/activin action. This study was designed to determine whether inhibin or activin altered steroidogenesis by macaque luteal cells in vitro. Luteal cells were obtained by enzymatic dispersion of CL from rhesus monkeys at midluteal phase of the menstrual cycle. Cells (2 x 10(4)/0.2 mL) were cultured in wells coated with extracellular matrix from bovine corneal endothelial cells in Dulbecco's modified Eagle's medium/F-12 medium (1:1 vol/vol) + insulin (2 ng/mL), transferrin (5 ng/mL), H2SeO3 (0.25 nmol), and aprotinin (10 micrograms/mL). Various concentrations (0-400 ng/mL) of recombinant human-inhibin-A, recombinant human-activin-A or human CG (hCG) (100 ng/mL; CR123) alone or in combination with inhibin or activin were added to the culture media (n = 5 Exp). Media were changed daily for 4 days and progesterone (P) concentrations were determined by RIA. Inhibin exposure did not alter P levels compared to that of control (untreated) cultures. In contrast, activin (10-400 ng/mL) suppressed P production (P less than 0.05) below controls and inhibin-treated cultures by days 3 and 4. Exposure to hCG increased P levels throughout culture (9 x control levels by day 4; P less than 0.05). hCG-stimulated P production was unaltered by inhibin, whereas activin (50-400 ng/mL) reduced (maximal inhibition of 40%; P less than 0.05) hCG-stimulated P production by day 4 of culture. Cell number on day 4 was not altered by any dose of inhibin or activin, but the number of cells staining for 3 beta-hydroxysteroid dehydrogenase was reduced (P less than 0.05) by 32.9 +/- 2.6% in activin-treated cultures. Since P levels declined during culture in all treatment groups, in a second series of experiments (n = 4), luteal cells were cultured for 4 days with or without hCG (100 ng/mL) and low density lipoprotein (LDL; 100 micrograms/mL) +/- 0-400 ng activin/mL. P production in the presence of hCG+LDL was greatly enhanced compared to other treatment groups and was sustained during days 2-4 of culture. Activin at doses of 50-400 ng/mL suppressed (maximal inhibition of approximately 35%; P less than 0.05) hCG+LDL-stimulated P production on days 3 and 4. These results suggest that the primate CL is a target for activin action to suppress luteal cell activities, including gonadotropin-regulated, lipoprotein-mediated steroidogenesis.

Inhibin production by macaque granulosa cells from pre- and periovulatory follicles: regulation by gonadotropins and prostaglandin E2

Although inhibin (IN) is secreted by granulosa cells (GC) of preovulatory follicles, the major source of immunoreactive IN circulating during the primate ovarian cycle is the corpus luteum. The aims of this study were (1) to investigate culture conditions for optimal IN production by luteinized GC (LGC) from rhesus monkeys and (2) to compare IN and progesterone (P) production by nonluteinized GC (NGC) and LGC in response to putative agonists. Animals were treated for up to 9 days with human menopausal gonadotropins to promote the development of multiple preovulatory follicles. GC were obtained from large follicles before (NGC) or 27 h after (LGC) an ovulatory injection of hCG. For Aim 1, cells were cultured in Hams F-10 medium +/- hCG (100 ng/ml) with or without the addition of insulin/transferrin/selenium, 10% fetal bovine serum, or 10% Serum-Plus (JRH Biosciences, Lenexa, KS). Medium was changed on Days 1, 2, 4, 6, and 8, and IN and P concentrations were determined by RIA. Basal (unstimulated) IN production by LGC was enhanced and maintained for 6-8 days in the presence of serum, but rapidly declined in the absence of serum. In contrast, basal P secretion declined regardless of exposure to serum. Human CG consistently increased (p less than 0.05) IN production only in the presence of serum but stimulated (p less than 0.05) P production under all conditions. For Aim 2, cells were cultured for 4 days in Ham's F-10 medium + 10% macaque serum +/- hCG (100 ng/ml), hFSH (100 ng/ml), prostaglandin E2(PGE2; 14 microns), or dibutyryl(db)-cAMP (5 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Differential uptake of fluorescent-tagged low density lipoprotein by cells from the primate corpus luteum: isolation and characterization of subtypes of small and large luteal cells

Three enriched populations of cells [C alpha, non-steroidogenic cells less than or equal to 15 microns in diameter; R1, small (less than or equal to 15 microns) steroidogenic cells; and R3, large (greater than 20 microns) steroidogenic cells] have been isolated from the macque corpus luteum using flow cytometry based on light scatter properties. To determine whether the cell populations differ in their ability to bind and internalize low-density lipoprotein (LDL), collagenase-dispersed cells were prepared from the corpus luteum of rhesus monkeys at midluteal phase of the menstrual cycle. Cells were incubated in Hams F-10 medium containing fluorescent-tagged LDL (DiI-LDL). Optimal labeling occurred at 10 micrograms DiI-LDL/10(6) cells.ml incubated for 20 min at 37 degrees C. Labeled cells were analyzed and sorted by flow cytometry based on light scatter and fluorescence. Only 8.2 +/- 1.0% (n = 10) of C alpha cells exhibited fluorescence intensity greater than the autofluorescence of unlabeled cells. In contrast, 52.3 +/- 3.4% of R1 cells and 83.9 +/- 2.3% of R3 cells were fluorescent. Uptake of DiI-LDL was competitively inhibited when cells were conincubated with either unlabeled monkey or human LDL, but human high-density lipoprotein and very low-density lipoprotein were less effective. Progesterone (P) production by fluorescent [DiI-LDL(+)] R1 luteal cells was increased (P less than 0.001) in the presence of pregnenolone, but not human (h) CG, consistent with earlier results for the R1 population. Surprisingly, basal P production by the nonfluorescent [DiI-LDL(-)] R1 cells was similar to that by fluorescent cells and was stimulated by both hCG (P less than 0.01) and pregnenolone (P less than 0.001). Basal P production by DiI-LDL(+) R3 cells was nearly 10-fold greater than that by DiI-LDL(-) R3 cells. P secretion by both DiI-LDL(+) and (-) R3 cells was stimulated by hCG (P less than 0.01) and pregnenolone (P less than 0.001). DiI-LDL(-) C alpha cells produced barely detectable levels of P, but DiI-LDL(+) C alpha cells secreted P at levels similar to R1 cells. We conclude that: 1) multiparameter (light scatter and fluorescence) cell sorting is a useful method for separating enriched populations of cells from the corpus luteum; and 2) small and large luteal cell populations from the macaque corpus luteum consist of subtypes of steroidogenic cells that differ in lipoprotein uptake and/or gonadotropin sensitivity.

Involvement of prostaglandins in LH-induced superovulation in the cyclic hamster

Osmotic minipumps containing 400 micrograms ovine LH were inserted subcutaneously (sc) on day 1 (estrus) at 09:00-10:00h of the cycle in the hamster. This treatment induced increased ovarian blood flow by day 3 and superovulation of 30.0 +/- 1.4 ova at the next estrus compared to controls (16.5 +/- 0.8 ova). The continuous infusion of LH throughout the cycle increased prostaglandin F (PGF) and decreased prostaglandin E (PGE) in the growing follicles destined to ovulate and suppressed a day 3 increase in PGF concentrations in the nonluteal ovarian remnant devoid of the larger follicles. Indomethacin, a cyclooxygenase inhibitor, given sc (2 or 4 mg regimens) at 12:00-14:00h on days 1 and 2, at 09:00h and 17:00h on day 3 and at 09:00h on day 4 of the cycle to LH-infused and saline treated animals suppressed ovarian prostaglandin levels, prevented the superovulation and prevented the increased ovarian blood flow. Exogenous PGF2 alpha or PGE2 restored the superovulatory effect of LH infusion in the presence of indomethacin. The results suggest that the superovulation in response to continuous LH infusion may be mediated in part by prostaglandins via altered ovarian blood flow.

Progesterone production by monkey luteal cell subpopulations at different stages of the menstrual cycle: changes in agonist responsiveness

Small (less than or equal to 15 microns diameter) and large (greater than 20 microns diam.) luteal cells of the rhesus monkey have been separated by flow cytometry based on light scatter properties. To determine whether the steroidogenic ability and agonist responsiveness of luteal cell subpopulations vary during the life span of the corpus luteum, small and large cells were obtained at early (Days 3-5), mid (Days 7-8), mid-late (Days 11-12), and late (Days 14-15) luteal phase of the cycle. Cells (n = 4 exp./group) were incubated in Ham's F-10 medium + 0.1% BSA for 3 h at 37 degrees C with or without hCG (100 ng/ml), prostaglandin E2 (PGE2; 14 microM), dibutyryl-cAMP (db-cAMP; 5 mM), or pregnenolone (1 microM). Basal progesterone (P) production by large cells was up to 30-fold that by small cells depending on the stage of the cycle. HCG stimulated (p less than 0.05) P secretion by both small (1.8 +/- 0.2-fold) and large (3.7 +/- 0.7-fold) cells in the early luteal phase. HCG responsiveness declined during the luteal lifespan; P production by small cells was not significantly enhanced by hCG by mid luteal phase, whereas that by large cells was stimulated 1.7 +/- 0.2-fold (p less than 0.05) even at late luteal phase. Cell responses to db-cAMP were similar to those for hCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Exogenous progesterone reduces follicular prostaglandin E and 6-keto prostaglandin F-1 alpha in the cyclic hamster

In cyclic hamsters, exogenous progesterone (100 micrograms) administered s.c. at 09:00 h on the day of dioestrus II reduced prostaglandin (PG) E and 6-keto PGF-1 alpha but not PGF concentrations in preovulatory follicles measured at 09:00 h of pro-oestrus. The injection of 10 micrograms ovine LH (NIADDK-oLH-25) concurrently with 100 micrograms progesterone on dioestrus II prevented the decline in follicular PGE and 6-keto PGF-1 alpha values. Administration of LH alone did not significantly alter follicular PG concentrations. Inhibition of follicular PGE accumulation by progesterone was due to a decline in granulosa PGE concentration and not thecal PGE. Progesterone administration also reduced follicular oestradiol concentrations. Administration of oestradiol-17-cyclopentanepropionate (ECP) (10 micrograms) with progesterone did not prevent the decline in follicular PGE and 6-keto PGF-1 alpha but did increase follicular PGF concentrations. However, ECP given alone on dioestrus II reduced follicular PGE and increased PGF concentrations in preovulatory follicles on pro-oestrus. It is concluded that exogenous progesterone administered on dioestrus II inhibits granulosa PGE and 6-keto PGF-1 alpha accumulation in preovulatory follicles, probably by reducing serum LH concentrations, and that the granulosa cells, which are LH-dependent, are a major source of follicular PGE.

Short and long phases of progesterone secretion during the oestrous cycle of the African elephant (Loxodonta africana)

Serum samples were collected from 3 mature female African elephants once each week for 15-18 months. Circulating concentrations of progesterone, oestradiol and LH were determined by radioimmunoassay (RIA). The LH RIA was validated by demonstrating parallel cross-reaction with partly purified elephant LH pituitary fractions. Changing serum progesterone concentrations indicated an oestrous cycle length of 13.3 +/- 1.3 weeks (n = 11). The presumed luteal phase, characterized by elevated serum progesterone values, was 9.1 +/- 1.1 weeks (n = 11). Two abbreviated phases of progesterone in serum lasting 2-3 weeks were observed in 2 elephants, indicating short luteal phases. Oestradiol concentrations in serum were variable, with no clear pattern of secretion. More frequent blood samples were collected during periovulatory periods and 9 distinct LH peaks were detected; all were followed by rises in serum progesterone concentrations. Periovulatory changes in progesterone and LH in sera correlated with external signs of oestrus and mating behaviour.