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G L Flickinger

Publications and source records attributed to G L Flickinger.

At least 37 records · Page 2Linked to original sources
PubMed1986

Effects of prolactin on steroidogenesis by human luteinized granulosa cells.

The role of prolactin (PRL) in the regulation of human ovarian function is poorly understood, and reported findings are often contradictory. We have evaluated the effects of several doses of PRL on the secretion of progesterone (P) and estradiol (E2) by human granulosa cells from preovulatory follicles of gonadotropin-stimulated women. The effects of PRL were also evaluated when androstenedione (delta 4 A) was added to the cultured cells. Our findings show that the human granulosa lutein cells retain their ability to secrete large amounts of P and lesser quantities of E2 for a prolonged period in culture. E2, but not P, secretion was stimulated by the presence of delta 4 A. PRL in low doses (25 and 50 ng/ml) did not alter the secretion of either E2 or P. In contrast, high doses of PRL (100 and 1000 ng/ml) resulted in a significant suppression of E2 secretion. P secretion was inhibited only by the highest dose (1000 ng/ml) of PRL. We conclude that steroidogenesis by the granulosa lutein cells of preovulatory human follicles is probably not influenced by the quantities of PRL that are normally present in the blood or follicular fluid. Higher doses, however, may suppress production of E2 and P.

Androstenedione↗
PubMed1986

Differences in ovarian stimulation in human menopausal gonadotropin treated woman may be related to follicle-stimulating hormone accumulation.

Two groups of normal ovulatory women who displayed either a marked (high responders; HR) or a more subtle (low responders; LR) ovarian response to a fixed dose of human menopausal gonadotropins (hMG) were evaluated for differences in blood levels of hormones. Serum follicle-stimulating hormone (FSH) levels doubled during the first 3 days of treatment (to approximately 20 mIU/ml) in all patients; thereafter, the levels plateaued in LR but continued to rise steadily (to 35 mIU/ml) in HR. In the latter group, rise in estradiol (E2) and FSH was accompanied by an increase of luteinizing hormone (LH; two to five times) progesterone (P; four to eight times) testosterone (T; three to four times) and prolactin (PRL; 2 times) toward the end of the follicular phase. Positive correlation was found between FSH and E2 in HR and LR. Positive correlation was found, however, between LH, T, and P and between E2, P, and PRL only in HR. The extent of FSH accumulation in the circulation may be a principal factor in determining an individual's response to hMG therapy. Temporal changes of blood hormones indicated that the continuous rise in FSH levels in HR was associated with early luteinization of the follicles. Increased secretion of P in the follicular phase of these women (HR) probably synergized with the elevated E2 levels to elicit LH release. Similar changes in blood hormones were not found in LR.

Estradiol↗
PubMed1986

Changes in serum sex hormone-binding globulin, free estradiol, and testosterone during gonadotropin treatment.

Sex hormone-binding globulin (SHBG), estradiol (E2), percent free E2, percent of E2 bound to SHBG, and testosterone (T) were evaluated in 28 ovulatory women during human menopausal gonadotropin-stimulated cycles for in vitro fertilization. Patients were divided into two categories: low responders, in whom serum E2 concentration reached levels less than 1000 pg/ml (mean, 638 +/- 93), and high responders, with serum E2 levels greater than 1000 pg/ml (mean, 2219 +/- 330). A significant increase in SHBG can occur within a short time in high responders (from 62.8 to 103.9 nmol/l) but not in low responders. This increase is accompanied by a significant decrease in the percent free (bioavailable) E2, but the distribution of E2 between the fraction bound to SHBG or albumin did not vary. Despite the increase in the levels of SHBG, the concentration of bioavailable (free) E2 in hyperstimulated women is higher than in normal cycles. The significant increase in T in high responders, by virtue of its higher affinity for SHBG, probably contributes to the increased levels of bioavailable E2.

Estradiol↗
PubMed1986

Total estradiol, free estradiol, sex hormone-binding globulin, and the fraction of estradiol bound to sex hormone-binding globulin in human follicular fluid.

Sex hormone-binding globulin (SHBG), percent free estradiol (E2), the fraction of E2 bound to SHBG, and total E2 were measured in the serum and follicular fluid of 12 women (25 follicles) who had received gonadotropin stimulation in an in vitro fertilization program. The women were classified as high or low responders based on peak serum E2 levels (high responders: peak E2, greater than 1500 pg/ml; low responders: peak E2, less than 1000 pg/ml). During treatment, serum levels of SHBG increased in high responders from 55 +/- 8.8 (+/- SEM) to 96 +/- 16 nM (P less than 0.01), but did not change in low responders. SHBG was more concentrated in follicular fluids from high responders (142 +/- 12.5 nM) than in those from low responders (44.4 +/- 5.8 nM). A positive correlation was found between serum and follicular fluid levels of SHBG (r = 0.873; P less than 0.01). In follicular fluid, total E2 levels, which varied from 100-2650 ng/ml, correlated (r = 0.790; P less than 0.01) closely with SHBG levels. The percent free E2 averaged 5.9% (range, 4-10.6%) in follicular fluid compared to 1.8% (range, 1.5-2.1%) in serum. An inverse correlation (r = -0.661; P less than 0.01) was found between total E2 concentrations and percent free E2 in follicular fluid. The relationship between serum and follicular fluid levels of SHBG suggests that SHBG in follicles arises from the circulation. Although SHBG is present in follicular fluid in amounts similar to those in serum, the large quantities of E2 in preovulatory follicules exceed the binding capacity for SHBG, and the majority of E2 appears to be bound to albumin. Hence, it seems unlikely that SHBG in follicular fluid regulates estrogen action in ovarian target cells.

Adult↗
PubMed1984

Levels of urinary cathepsin B-like substance in patients with gynecologic malignancy.

Because certain proteolytic enzymes are thought to be released by malignant cells, we have measured the activity of cathepsin B in the urine samples of 57 patients with gynecologic malignancies and 60 disease-free controls. A unit (U) of enzyme activity is the release of one n-mol of 7-amino-4-fluoromethylcoumarin (AFC) from BZ-val-lys-lys-arg-MNA min-1 ml-1. Units of activity in the malignant group (10.6 +/- 9.8) differed significantly (p less than 0.0001) from controls (2.8 +/- 3.3). Although enzyme activity in both groups correlated with increasing age, the difference between those subjects with malignancies and those with none remained significant (p = 0.049) by analysis of covariance after adjusting for age. There was no correlation between titers and the race or weight of the subjects in either group. Enzyme activity of subjects with malignant disease correlated (p = 0.003) with the clinical stage of disease. Optimum sensitivity and specificity as determined by Receiver Operator Characteristic Analysis with an upper normal level of 5 U were 84.2% and 86.7%, respectively. Our findings suggest that measurement of urinary cathepsin B might be useful in detecting and managing patients with gynecologic tumors.

Adult↗
PubMed1983

Hormonal regulation of progesterone secretion by cultured mouse granulosa cells.

Secretion of progesterone by granulosa cells from preovulatory follicles of mice was determined during 2 weeks of cell culture in the presence of androgens, estrogen and pituitary gonadotropins. Androstenedione (10(-7) M) and dihydrotestosterone (10(-7) M) stimulated (P less than 0.05) progesterone secretion during the first 11 days of culture. In contrast, 17 beta-estradiol (10(-11)-10(-7) M) did not alter (P greater than 0.10) progesterone secretion throughout the culture period. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) stimulated (P less than 0.01) the granulosa cells in a dose-dependent manner during the first few days of culture. This luteotropic effect was rapidly lost and at later times when FSH was not effective, LH suppressed (P less than 0.05) progesterone secretion. In the presence of prolactin (Prl) (1 microgram/ml), granulosa cells progressively secreted more progesterone during the first week of culture. After maximal stimulation on Days 7-9, progesterone secretion by Prl-treated cells began to decline, but the amount of steroid produced on Day 13 was still higher (P less than 0.05) than in control cultures. Androstenedione and Prl gave an additive effect on progesterone secretion during Days 3-5 of culture. Thereafter, the androgen, although stimulatory by itself, did not influence the luteotropic action of Prl. Unlike the early effect of androgens, 17 beta-estradiol acted synergistically with Prl to maintain maximal secretion of progesterone during the last 4 days of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Androstenedione↗
PubMed1983

Macrophages: a source of luteotropic cybernins.

A macrophage homogenate contained substances which stimulated primary cultures of mouse granulosa cells to secrete more progesterone. The response to the luteotropic substances was similar to that observed when intact macrophages were co-cultured with granulosa cells. The bioactive polypeptides present in cytosolic and particulate fractions of cell homogenates were non-dialyzable, heat labile and trypsin sensitive. When the surface of intact macrophages was treated with trypsin there was a loss of activity from the particulate fraction suggesting that some luteotropic proteins reside on the plasma membrane of mononuclear phagocytes. Treatment of macrophages with Con A but not the succinyl derivative of the lectin caused a release of luteotropic proteins with apparent molecular weights of 26,000 and 41,000. These findings in conjunction with our prior observation that macrophages must contact granulosa cells to stimulate progesterone secretion suggest that aggregation of mononuclear cell surface proteins may occur when the two cells interact thus resulting in the expression of luteotropic activity. Hence, it appears that macrophages which are found within corpus luteum may be a source of ovarian cybernins. This is the first description that a cell of the immune system can communicate at the molecular level with a steroid secreting cell of the ovary.

Animals↗
PubMed1981

Effects of gossypol on pituitary-ovarian endocrine function, ovulation and fertility in female hamsters.

Oral administration of gossypol acetic acid altered pituitary and ovarian hormones during proestrus and estrus in hamsters. These changes in endocrine function were not however, accompanied by alterations of estrous cycle length, number of ovulations or pregnancy rates. Changes in body weight and appearance of the liver suggested that female hamsters may be more susceptible than males to the the toxic effects of gossypol.

Animals↗
PubMed1978

Effect of luteinizing hormone of the lipid composition of rat ovaries.

The lipid composition of immature rat ovaries was examined after induction of ovulation with pregnant mare serum gonadotrophin and human chorionic gonadotrophin and subsequent (7--8 days later) stimulation with 10 micgogram LH. Two hours after the administration of LH, there was a decrease of approximately 50% in the concentration of cholesteryl esters in the ovary. The percentages (by weight) of sterol esters containing stearate, linoleate, eicosatrienoate and arachidonate were reduced by LH treatment, whereas the percentage of the C24:4 acid increased. No changes were observed in either the concentrations or fatty acid composition of phospholipids and triglycerides. These observations suggest that the metabolism of cholesteryl esters is acutely affected by LH and that sterol esters bearing long-chain polyunsaturated fatty acids are preferentially mobilized. Liberation of these unsaturated fatty acyl moieties may have significant effects on metabolism in the ovarian cell.

Animals↗
PubMed1977

Lysosomal phospholipase A activities of rat ovarian tissue.

1.1. Lysosome-enriched fractions were prepared by differential centrifugation of homogenates of luteinized rats ovaries. Acid phospholipase A activities were characterized with [U-14C]diacyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-[9,10-3H]- or [1-14C]oleoyl-sn-glycero-3-phosphocholine as substrates. Acid phospholipase A1 activity had properties similar to other hydrolases of lysosomal origin; subcellular distribution, latency and acidic pH optimum. Acid phospholipase A2 activity with similar characteristics was also tentatively identified. We were unable to exclude the possibility that the combined action of phospholipase A1 and lysophospholipase contributed to the release of acyl moieties from the 2-position of the synthetic substrates. 2. Lysophospholipase activity was present in the lysosome-enriched fractions. This activity had an alkaline pH optimum. 3. Phospholipase A1 and A2 activities solubilized from lysosome fractions by freeze-thawing were inhibited by Ca2+ and slightly activated by EDTA. A Ca2+- stimulated phospholipase A2 activity, with an alkaline pH optimum, remained in the particulate residue of freeze-thawed lysosome preparations. This activity is believed to represent mitochondrial contamination. 4. Activities of acid phospholipase A, as well as other acid hydrolases, increased approx. 1.5-fold between 1 and 4 days following induction of luteinizatin, suggesting a hormonal influence on lysosomal enzyme activities.

Animals↗