The Experts below are selected from a list of 84 Experts worldwide ranked by ideXlab platform

Motoyoshi Ohta - One of the best experts on this subject based on the ideXlab platform.

  • Expression of P450 17 alpha-hydroxylase and P450aromatase genes in isolated granulosa, Theca interna, and Theca Externa layers of chicken ovarian follicles during follicular growth.
    Biology of reproduction, 1995
    Co-Authors: Masumi Kato, Kiyoshi Shimada, Noboru Saito, Kenji Noda, Motoyoshi Ohta
    Abstract:

    Concentrations of estradiol (E), testosterone (T), and progesterone (P) and levels of the 1.9-kb and 4.0-kb mRNA encoding P450 17 alpha-hydroxylase (P450 17 alpha) and P450aromatase (P450arom), respectively, were measured in the isolated granulosa, Theca interna, and Theca Externa of the largest preovulatory (F1-F4) follicles of the chicken 20 h and 3 h before expected ovulation of F1. In the granulosa layer, E and T concentrations remained low throughout this period of follicular growth, whereas P concentrations were high 3 h before ovulation in F2 and F1 follicles. E levels were highest in the Theca interna and Externa of the smallest (F4) follicle, decreasing progressively with follicular growth. T content of Theca interna and granulosa was greater in less mature F4-F2 follicles than in the most mature (F1) follicle, whereas Theca Externa contained little T. P was quantifiable in significant amounts only in granulosa tissue, peaking in F2 and F1 follicles at 3 h before ovulation, at which time plasma levels of steroids also rose significantly. P450 17 alpha was expressed mainly in Theca interna, whereas the P450arom mRNA levels found in Theca Externa reflected the pattern of E in this compartment. Expression of these two genes was very low in granulosa tissue, remaining unchanged during follicular growth. These results indicate that E and T synthesis in the chicken ovary is regulated, at least in part, at mRNA levels of P450 17 alpha and P450arom in the Theca interna and Theca Externa layers during follicular growth.

Caiqiao Zhang - One of the best experts on this subject based on the ideXlab platform.

  • prostaglandin e 2 and insulin like growth factor i interact to enhance proliferation of Theca Externa cells from chicken prehierarchical follicles
    Prostaglandins & Other Lipid Mediators, 2013
    Co-Authors: Yudong Jia, Jinxing Lin, Caiqiao Zhang
    Abstract:

    The interactive effect of insulin-like growth factor I (IGF-I) and prostaglandin E2 (PGE2) on the proliferation of Theca Externa cells (TECs) was investigated in the prehierarchical small yellow follicles of laying hens. IGF-I manifested a proliferating effect like PGE2 on TECs, but this stimulating effect was restrained by AG1024 (IGF-IR inhibitor), KP372-1 (PKB/AKT inhibitor) or NS398 (COX-2 inhibitor). AG1024, KP372-1 or NS398 abolished IGF-I-stimulated COX-2 expression and PGE2 production. Meanwhile, KP372-1, NS398 or AG1024 depressed the PGE2-stimulated expression of COX-2 and IGF-IR mRNA. Therefore, the IGF-I receptor pathway up-regulates COX-2 expression and PGE2 synthesis via PKB signaling cascade, and then PGE2 stimulates IGF-IR mRNA expression to promote TEC proliferation in an autocrine pattern. Overall, the reciprocal stimulation of intracellular PGE2 and IGF-I may enhance TEC proliferation and facilitate the development of chicken prehierarchical follicles.

  • Effect of prostaglandin on luteinizing hormone-stimulated proliferation of Theca Externa cells from chicken prehierarchical follicles.
    Prostaglandins & other lipid mediators, 2010
    Co-Authors: Yudong Jia, Jinxing Lin, Weidong Zeng, Caiqiao Zhang
    Abstract:

    The effect of prostaglandin (PG) on proliferation of chicken Theca Externa cells from prehierarchical small yellow follicles (SYF) was evaluated and involved signaling pathways as well as mRNA expression of cAMP response element binding protein (CREB1), cyclins (CCND1 and CCNE1) and cyclin-dependent kinases (CDKs) were investigated. Results showed that PGE(1) (1-100 ng/ml) manifested a similar proliferating effect as LH on Theca Externa cells, and this stimulating effect was restrained by the prostaglandin receptor antagonist SC19220 at 10(-7) to 10(-5)M. Moreover, prostaglandin synthase inhibitor indomethacin (10(-7) to 10(-5)M) suppressed LH-induced increase in the cell number. In addition, PGE(1)-stimulated cell proliferation was also predominantly hindered by H(89) (PKA inhibitor) instead of H(7) (PKC inhibitor). Meanwhile, BrdU incorporation experiment displayed similar changes with the cell number. Furthermore, H(89), SC19220 and indomethacin abolished the PGE(1)-stimulated increase in the expression of CREB1, CCND1/CDK6 and CCNE1/CDK2 mRNAs, indicating that cAMP/PKA/CREB1 signaling cascade was involved in PGE(1)-stimulated DNA synthesis. In conclusion, PG could promote proliferation of Theca Externa cells from prehierarchical follicles through changes in cyclin D1/CDK6, cyclin E1/CDK2 and CREB1 mRNA expression via cAMP/PKA and CREB1 signaling cascade. These results suggest that PG may promote development of chicken prehierarchical follicles and is related to dominant follicle selection in laying hens.

M. E. El Halawani - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of dissimilar steroid productions by granulosa, Theca interna and Theca Externa cells during follicular maturation in the turkey (Meleagris gallopavo).
    General and comparative endocrinology, 1991
    Co-Authors: Tom E. Porter, Billy M. Hargis, J.l. Silsby, M. E. El Halawani
    Abstract:

    Unlike the established models for steroidogenesis in the rat and human, we have previously demonstrated that in the turkey progesterone (P), androgen (A), and estrodiol (E) are primarily produced by the granulosa, Theca interna, and Theca Externa cells, respectively. In the present study, experiments were conducted to further characterize steroid productions by these cell types during follicular maturation. In Experiments 1 and 2, granulosa cells and Theca internal cells, respectively, from the larger (F1) and fifth largest (F5) preovulatory follicles were incubated (1 x 10(5) cells/ml) with ovine luteinizing hormone (oLH) or porcine follicle stimulating hormone (pFSH) for 5 hr. Granulosa production of P from both follicles was stimulated in response to oLH, with both basal and LH-stimulated P production greater in the larger F1 than in the smaller F5 follicle. No A or E production was detected in granulosa cells from either follicle size tested. Theca interna cell productions of P and A were stimulated by oLH in the smaller F5, but not in the larger F1, with both basal and stimulated levels of A greater in F5 than in F1. Medium content of E was non-detectable in cultures of Theca interna cells from all follicles tested. In Experiment 3, Theca Externa cells were incubated (1 x 10(6) cells/ml) from F1 and F5 follicles. The Theca interna cells from F5 and the seventh largest follicle (F7) were pooled (1 x 10(5) cells/ml) to provide substrate(s) for Theca Externa steroidogenesis. Theca Externa cells were incubated alone and in combination with the pooled Theca interna cells and with or without oLH or pFSH.(ABSTRACT TRUNCATED AT 250 WORDS)

Kiyoshi Shimada - One of the best experts on this subject based on the ideXlab platform.

  • expression of messenger ribonucleic acids of luteinizing hormone receptor p450 17 α hydroxylase and p450 aromatase in isolated granulosa Theca interna and Theca Externa layers of chicken ovarian follicles during follicular growth
    Nihon Chikusan Gakkaiho, 1999
    Co-Authors: Norio Kansaku, Noboru Saito, Yukimi Tsuji, Kiyoshi Shimada
    Abstract:

    The present study was conducted to investigate the association of luteinizing hormone receptor (LHR) mRNA expression with follicular growth and steroidgenesis in the ovarian follicles of laying chickens. Levels of LHR mRNA of granulosa, Theca interna and Theca Externa layers of the preovulatory follicles were determined by Northern hybridization in relation to mRNA expression of P450 17α-hydroxylase/17, 20-lyase (P450c17)and P450 aromatase (P450 arom). LHR mRNA was clearly detected in the granulosa layers of larger follicles, whereas little mRNA of P450c17 and P450 arom was observed. On the other hand, little LHR mRNA was detected in the Theca interna and External layers of any follicles, whereas P450c17 mRNA and P450 arom mRNA expression was localized to the Theca interna and Externa layers of the follicles, respectively. These changes during follicular development suggest that progesterone production in the granulosa layer is induced by LH via the LHR and production of subsequent metabolites (androgen and estrogen) in the Theca interna and Externa layers is independent upon regulation by LH.

  • Expression of P450 17 alpha-hydroxylase and P450aromatase genes in isolated granulosa, Theca interna, and Theca Externa layers of chicken ovarian follicles during follicular growth.
    Biology of reproduction, 1995
    Co-Authors: Masumi Kato, Kiyoshi Shimada, Noboru Saito, Kenji Noda, Motoyoshi Ohta
    Abstract:

    Concentrations of estradiol (E), testosterone (T), and progesterone (P) and levels of the 1.9-kb and 4.0-kb mRNA encoding P450 17 alpha-hydroxylase (P450 17 alpha) and P450aromatase (P450arom), respectively, were measured in the isolated granulosa, Theca interna, and Theca Externa of the largest preovulatory (F1-F4) follicles of the chicken 20 h and 3 h before expected ovulation of F1. In the granulosa layer, E and T concentrations remained low throughout this period of follicular growth, whereas P concentrations were high 3 h before ovulation in F2 and F1 follicles. E levels were highest in the Theca interna and Externa of the smallest (F4) follicle, decreasing progressively with follicular growth. T content of Theca interna and granulosa was greater in less mature F4-F2 follicles than in the most mature (F1) follicle, whereas Theca Externa contained little T. P was quantifiable in significant amounts only in granulosa tissue, peaking in F2 and F1 follicles at 3 h before ovulation, at which time plasma levels of steroids also rose significantly. P450 17 alpha was expressed mainly in Theca interna, whereas the P450arom mRNA levels found in Theca Externa reflected the pattern of E in this compartment. Expression of these two genes was very low in granulosa tissue, remaining unchanged during follicular growth. These results indicate that E and T synthesis in the chicken ovary is regulated, at least in part, at mRNA levels of P450 17 alpha and P450arom in the Theca interna and Theca Externa layers during follicular growth.

Masumi Kato - One of the best experts on this subject based on the ideXlab platform.

  • Expression of P450 17 alpha-hydroxylase and P450aromatase genes in isolated granulosa, Theca interna, and Theca Externa layers of chicken ovarian follicles during follicular growth.
    Biology of reproduction, 1995
    Co-Authors: Masumi Kato, Kiyoshi Shimada, Noboru Saito, Kenji Noda, Motoyoshi Ohta
    Abstract:

    Concentrations of estradiol (E), testosterone (T), and progesterone (P) and levels of the 1.9-kb and 4.0-kb mRNA encoding P450 17 alpha-hydroxylase (P450 17 alpha) and P450aromatase (P450arom), respectively, were measured in the isolated granulosa, Theca interna, and Theca Externa of the largest preovulatory (F1-F4) follicles of the chicken 20 h and 3 h before expected ovulation of F1. In the granulosa layer, E and T concentrations remained low throughout this period of follicular growth, whereas P concentrations were high 3 h before ovulation in F2 and F1 follicles. E levels were highest in the Theca interna and Externa of the smallest (F4) follicle, decreasing progressively with follicular growth. T content of Theca interna and granulosa was greater in less mature F4-F2 follicles than in the most mature (F1) follicle, whereas Theca Externa contained little T. P was quantifiable in significant amounts only in granulosa tissue, peaking in F2 and F1 follicles at 3 h before ovulation, at which time plasma levels of steroids also rose significantly. P450 17 alpha was expressed mainly in Theca interna, whereas the P450arom mRNA levels found in Theca Externa reflected the pattern of E in this compartment. Expression of these two genes was very low in granulosa tissue, remaining unchanged during follicular growth. These results indicate that E and T synthesis in the chicken ovary is regulated, at least in part, at mRNA levels of P450 17 alpha and P450arom in the Theca interna and Theca Externa layers during follicular growth.