Search PubMed⌕ Search

Biomedical subjects

B L Marrone

Publications and source records attributed to B L Marrone.

51 records · Page 3Linked to original sources
PubMed1985

Decreased androstenedione production with increased follicular maturation in theca cells from the domestic hen (Gallus domesticus).

Collagenase-dispersed theca cells from the 3rd and 4th largest ovarian follicles (T3) were responsive to LH stimulation of both oestrogen and androstenedione production, whereas theca cells from the largest follicle (T1) failed to respond to the gonadotrophin stimulation. Similarly, 8-bromo cAMP and forskolin were more effective in stimulating oestrogen and androstenedione production in T3 than in T1 cells, indicating that post-receptor events were involved in the decreased LH responsiveness of T1 cells. The C17-20-lyase activity, as measured by conversion of [3H]17-hydroxyprogesterone to androstenedione, was greatly reduced in T1 cells as compared to T3 cells. The results demonstrate that a decrease in C17-20-lyase activity, in addition to a decrease in aromatase activity, contributes to the loss of LH-stimulated steroidogenesis in mature theca cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1983

Steroid metabolism by avian ovarian cells during follicular maturation.

The profiles of steroid hormones produced by ovarian cells from the domestic hen were examined. Theca cells from the immature, small white follicles (SWFT), the third largest (T3), and largest (T1) preovulatory follicles, and the ruptured, postovulatory follicle (POFT) were incubated for 3 h at 37 degrees with [3H] progesterone (Prog) or [3H] pregnenolone (Preg). Granulosa cells from the largest preovulatory follicle were incubated with [3H] Preg or were coincubated with theca cells and [3H] Preg. The production of specific steroid metabolites was determined on the basis of coelution of radioactivity with known standard compounds, using an isocratic high-pressure liquid chromatography (HPLC) technique. Granulosa cells converted 93% of [3H] Preg substrate to Prog. More Prog was utilized by T3 cells than by T1 and SWFT cells, either when [3H] Prog was the substrate or when coincubated with granulosa cells and [3H] Preg. The major metabolites of Prog were androstenedione, 17-hydroxyprogesterone, and an unidentified compound with an elution time of 53 min. The POFT cells metabolized [3H] Prog to the same extent as T3 cells did, but their profile of steroidogenesis favored production of the unidentified 53 min metabolite. SWFT cells utilized the least amount of [3H] Preg substrate. The results point to marked changes in enzyme activities in theca cells during maturation and following ovulation.

Animals↗
PubMed1983

Steroidogenesis by avian ovarian cells: effects of luteinizing hormone and substrate availability.

The production of progesterone (P) and estrogen (E) by enzymatically dispersed granulosa and theca cells from chicken preovulatory follicles was examined in 3-h incubations. Accumulation of the P produced by granulosa cells was significantly reduced by the addition of theca cells, whereas E production was increased. The decrease in P accumulation was shown to be due to extensive metabolism of P by theca cells. There were no synergistic effects of luteinizing hormone (LH) and any substrate tested on E production by theca cells. Maturation of granulosa cells was characterized by an increased sensitivity to LH stimulation of P production, but there was no change in pregnenolone conversion to P. Conversely, maturation of theca cells was accompanied by decreased in both sensitivity to LH and the ability to convert substrates to E. The results are discussed in terms of the contribution of each cell type in the production of steroids by chicken follicles during maturation.

Animals↗
PubMed1982

Progesterone metabolism by the hypothalamus, pituitary, and uterus of the aged rat.

Progesterone metabolism was examined in tissues of rats in three stages of reproductive senescence (constant estrus, repeated pseudopregnancies, and anestrus) and in young rats. Metabolites were quantitated by reverse isotopic dilution analysis after incubation of the hypothalamus, pituitary, and uterus with [3H]progesterone. The metabolism of progesterone to 5 alpha-dihydroprogesterone and to 20 alpha-hydroxy-5 alpha-pregnan-3-one and the formation of total 5 alpha-reduced products was significantly reduced (by half) in pituitaries of constant estrous rats compared to rats in all other stages. The formation of 3 alpha-hydroxy-5 alpha-pregnan-20-one and total 3 alpha-reduced products was about 2-fold higher in pituitaries and hypothalami of pseudopregnant and anestrous rats than in constant estrous and young rats, but these differences were statistically significant only in the pituitary samples. In the uterus, progesterone metabolism to 20 alpha-dihydroprogesterone was significantly increased in anestrous rats compared to that in constant estrous and pseudopregnant rats. The results indicate that progesterone metabolism by target tissues, particularly the pituitary, is altered during reproductive senescence. They suggest the possibility that changes in the tissue metabolism of progesterone may be one means by which the effectiveness of progesterone is decreased during aging.

Aging↗
PubMed1981

Progesterone metabolism by the hypothalamus, pituitary, and uterus of the rat during pregnancy.

Metabolites of [3H]progesterone were quantitated from incubations of hypothalamus, pituitary, and uterus of rats during different stages of pregnancy. The hypothalamus, anterior pituitary, and a section of uterus from five rats on Days 1, 8, 15, and 21 of pregnancy were incubated individually with [3H]progesterone and analyzed for metabolite formation by reverse isotopic dilution analysis. The radioactive metabolites present were 5 alpha-pregnane-3,20-dione (5 alpha-DHP), 3 alpha-hydroxy-5 alpha-pregnan-20-one, 20 alpha-hydroxy-4-pregnen-3-one, 20 alpha-hydroxy-5 alpha-pregnan-3-one, and 5 alpha-pregnane-3 alpha, 20 alpha-diol. The major metabolite formed by the hypothalamus and pituitary was 5 alpha-DHP. In the pituitary samples, formation of 5 alpha-DHP was decreased on Days 15 and 21 of pregnancy compared to Day 1, and formation of 20 alpha-hydroxy-5 alpha-pregnan-3-one was decreased on Day 21 compared to Day 1. In the uterine samples, 3 alpha-hydroxy-5 alpha-pregnan-20-one was the major metabolite formed at all stages of pregnancy. The formation of all metabolic products of progesterone by the uterus was increased on Day 21 compared to Days 1, 8, and 15 of pregnancy. No changes in the formation of progesterone metabolites were observed in the hypothalamic samples during pregnancy. It is concluded that there are different profiles in the in vitro metabolism of [3H]progesterone by the hypothalamus, pituitary, and uterus of the rat during the course of pregnancy.

Animals↗
PubMed1979

Intrahypothalamic implants of progesterone inhibit lordosis behavior in ovariectomized, estrogen-treated rats.

Intracranial implants of crystalline progesterone (P) were used to examine in site of action of P's facilitatory and inhibitory effects on lordosis behavior in the ovariectomized, estradiol-benzoate (EB)-primed RAT. P implanted in the medial basal hypothalamus (MBH) 1 h prior to subcutaneous (s.c.) EB injection inhibited lordosis in response to a systemic P injection 44 h after EB (concurrent inhibition). P implanted in the MBH did not facilitate lordosis when implanted 44 h after EB injection, but this same implant of P inhibited lordosis in response to P injection 68 h after EB (sequential inhibition). Cholesterol (Chol) implants in the MBH did not inhibit lordosis behavior in either the concurrent or the sequential inhibition experimental paradigms. The results indicate that the MBH is an important site of P inhibition of sexual receptivity in the rat.

Animals↗
PubMed1977

Role of catechol estrogens in activation of lordosis in female rats and guinea pigs.

In a variety of experiments, we tested the effectiveness of the 2-hydroxylated estrogen in facilitating sexual receptivity. A single injection of 2-hydroxy-estradiol-17beta (2-OHE2) to ovariectomized rats or 2-hydroxy-estrone (2-OHE1) to ovariectomized guinea pigs was ineffective in priming animals for facilitation of sexual receptivity even when a subsequent injection of progesterone was administered. The only facilitatory effect of catechol estrogens on lordosis that was demonstrated in this study occurred when 2-OHE2 was injected in combination with E2 and a subsequent injection of progesterone was given to rats. These results suggest a cooperatively between catechol estrogen and E2, but they also indicate that catechol estrogens, by themselves, do not play a crucial role in mediating sexual receptivity in rodents.

Animals↗