Showing papers by "Christina Wang published in 1980"
TL;DR: The effect of gonadotropin-releasing hormone and its agonists upon FSH induction of LH/hCG receptor and aromatases was studied and the presence of antrumcontaining folli...
Abstract: The effect of gonadotropin-releasing hormone (GnRH) and its agonists upon FSH induction of LH/hCG receptor and aromatases was studied. Immature, hypophysectomized, estrogen-treated female rats were injected with FSH and/or GnRH agonists twice daily for 2 days. FSH (100 μg/injection) increased LH/hCG receptor in granulosa cells by 66-fold, whereas concomitant treatments with GnRH (100 μg/injection) or GnRH agonist (50 μg [d-Leu6(N0Me)Leu7]GnRH or 10 μg des-Gly10-[d-Trp6,Pro9-NHEt]GnRH) inhibited the FSH-induced increase in LH/hCG receptor by 95%. Incubation of granulosa cells obtained from FSH-treated animals with graded doses of aromatase substrate (Δ4-androstenedione) resulted in a dose-dependent increase in estrogen production (maximal production, 1.65 ng/105 cells; ED50 = 3 × 10−8 m). In contrast, concomitant treatment with GnRH agonists depressed estrogen production. Histological examination of the ovaries from animals treated with FSH plus GnRH agonist indicated the presence of antrumcontaining folli...
160 citations
TL;DR: It is demonstrated that PRL acts directly on rat granulosa cells in vitro to suppress basal and gonadotropin-induced increases in estrogen production and causes a dose-related increase in progesterone and 20 alpha-dihydroprogesterone secretion.
102 citations
TL;DR: The findings suggest that although low dosage CPA was able to induce changes in seminal analyses, azoospermia was present in only one out of 15 subjects exposed to the drug and renders CPA unsuitable as a single entity agent for long-term male contraception.
52 citations
TL;DR: Serial studies were conducted in five adult men to determine the testicular steroidogenic responsiveness to different modes of LH/hCG stimulation during 12- to 24-h periods of observation, and circulating steroids exhibited a biphasic pattern of response.
Abstract: Serial studies were conducted in five adult men to determine the testicular steroidogenic responsiveness to different modes of LH/hCG stimulation during 12- to 24-h periods of observation. Sustained 5- to 40-fold increments in circulating LH levels were achieved by the administration of hCG (2000 IU, im), pulses of LH (500 IU at 90-min intervals for four doses, iv), or LH as a constant infusion (2000 IU/6 h). Responses of circulating levels of androgens, estrogens, and their C-21 biosynthetic precursors were analyzed and compared with levels during saline control experiments. Regardless of the mode of delivery of LH/hCG or the incremental rise in serum LH observed, circulating steroids exhibited a biphasic pattern of response: a small initial rise followed by a fall to basal levels within 4 h and a secondary rise plateauing 12–24 h after initiation of LH/hCG administration. The initial rise of all steroids ranged from 130–170% of basal levels. The secondary increases (mean ± SE) of testosterone and Δ4-and...
24 citations
TL;DR: In four male subjects with acute myeloid leukemia treated by intermittent chemotherapy not containing any alkylating agents, FSH, LH, and T levels were normal, and these findings suggest that the testicular damage is not restricted to the germinal tissue.
Abstract: After at least four courses of intermittent chemotherapy, 14 of the 15 men with malignant lymphoma had elevated serum follicle-stimulating hormone (FSH). In three of these subjects, serial studies showed progressive increases in basal FSH and exaggerated FSH responses to luteinizing hormone releasing hormone (LHRH). Although gonadal biopsies were not done, this elevation of FSH is indicative of progressive and severe damage to the germinal epithelium by chemotherapy. Elevated leutinizing hormone (LH) was found in seven and decreased testosterone (T) in two of these subjects. Increased LH responses to LHRH stimulation were also found in the three subjects studied. These findings suggest that the testicular damage is not restricted to the germinal tissue. In four male subjects with acute myeloid leukemia treated by intermittent chemotherapy not containing any alkylating agents, FSH, LH, and T levels were normal. Three of the 4 female patients with malignant lymphoma and two with acute myeloid leukemia had normal basal, serial, and LHRH-stimulated FSH, LH, and estradiol (E2) levels. Elevated gonadotropins and low E2 were found only in subjects who had received abdominal irradiation.
24 citations
TL;DR: Results of this study indicate enchomiphene citrate, like E2, has a direct inhibitory effect on the testis, whereas high doses of these compounds further decrease testicular LH/hCG receptor content and spermatogenesis.
Abstract: The direct effects of estradiol (E2) and enclomiphene citrate on testicular LH/hCG receptor content, steroidogenesis and morphology were studied in immature, hypophysectomized rats treated with FSH. Treatment with FSH (100 pg bovine FSH for 5 days) caused a marked increase in testis weight. This increase was abolished by concomitant injections of E2 (1 or 10 pg), while concomitant treatment with enclomiphene citrate (1—?�1 00 pg) had no significant effect. The sper matogenesis maintained by FSH was inhibited by concomitant daily treatment with E2 (1 or 10 pg) or enchomiphene citrate (100 pg). FSH treatment increased the LH/hCG receptor content of the testis. Concomitant administration of E2 (1 or 10 pg) or a high dose of enclomiphene citrate (100 pg) abolished the FSH-induced increase in LH/hCG receptors. In vitro incubations of the testis demonstrated that FSH treatment caused a marked rise in basal and hCG-stimulated testos terone production whereas concomitant treatment with E2 or enclomiphene citrate inhibited the FSH stimulated increase in testosterone production. The steroidogenic responsiveness to hCG was markedly depressed by treatment with either 1 or 10 pg E2 (71 and 91% decreases, respectively). Likewise, treatment with 1 or 100 pg enchomiphene citrate decreased testosterone production by 32 and 60%, respectively. Associated with the decrease in testosterone production, marked sup pression of androstenedione and dehydroepiandrosterone (DHEA) production was observed in animals treated with estradiol or enclomiphene citrate while that of the 17a-hydroxylated pre cursors was less severely affected. These steroidogenic changes were accompanied by accumulation of C2, steroid intermediates (progesterone and pregnenolone) suggesting that the inhibitory effect of E2 and enchomiphene citrate was associated with a defect in 17cs-hydroxylase and/or 17—20 desmohaseactivity. The results of this study indicate @that enchomiphene citrate, like E2, has a direct inhibitory effect on the testis. Low doses of these compounds inhibit testosterone production mediated via decreased steroidogenic enzyme activity, whereas high doses of these compounds further decrease testicular LH/hCG receptor content and spermatogenesis.
18 citations
TL;DR: The data demonstrate a different pattern of testicular steroidogenic responsiveness after pharmacological doses of hLH, with increased concentrations of circulating testosterone in subjects with HH compared to a disproportionate increase in estrogen and progestin levels in normal men.
Abstract: The responses of circulating levels of androgens, estrogens, and their C-21 biosynthetic precursors to a 6-h constant infusion of human LH (hLH; 2000IU) were studied in four males with hypogonadotropic hypogonadism (HH) and compared with those in normal male controls. Although similar levels of circulating LH were achieved, the initial and secondary increases in testosterone were significantly greater in the hypogonadotropic subjects than in the normal controls. In contrast, the responses of estradiol, estrone, 17α-hydroxyprogesterone, and 17α-hydroxypregnenolone to exogenous hLH were significantly lower in HH than in normal controls. The data demonstrate a different pattern of testicular steroidogenic responsiveness after pharmacological doses of hLH, with increased concentrations of circulating testosterone in subjects with HH compared to a disproportionate increase in estrogen and progestin levels in normal men.
13 citations