Similar luteinizing hormone-releasing hormone binding sites in rat anterior pituitary and ovary.

Reeves, Jerry J.; Séguin, Carl; Lefebvre, Fleur-Ange; Kelly, Paul A.; Labrie, Fernand

doi:10.1073/pnas.77.9.5567

Cited by 104 publications

(36 citation statements)

References 37 publications

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“…GnRH receptors in rat anterior pituitary and rat ovarian granulosa cells exhibit similar binding affinities for GnRH and its analogs (10)(11)(12)(13)(14)(15). These data suggest the presence of similar binding sites for GnRH in these two locations.…”

Section: Discussionsupporting

confidence: 58%

“…These data suggest that the hormone has a direct ovarian site that could play a role in its antifertility effect. Indeed, the presence of stereospecific high-affinity binding sites for GnRH has recently been shown in luteal and granulosa cells as well as in ovarian membrane preparations (10)(11)(12)(13)(14)(15). These receptors exhibited binding characteristics similar to those of GnRH receptors in the anterior pituitary.…”

mentioning

confidence: 86%

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Photoaffinity-labeling and fluorescence-distribution studies of gonadotropin-releasing hormone receptors in ovarian granulosa cells.

Hazum¹,

Nimrod²

1982

Proc. Natl. Acad. Sci. U.S.A.

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Photoaffinity labeling of rat ovarian granulosa cells and membrane preparations with a bioactive photoaffinity derivative of gonadotropin-releasing hormone resulted in identification of two specific components with apparent molecular weights of 60,000 and 54,000. Fluorescent visualization of gonadotropin-releasing hormone receptors in these cells, by using a bioactive rhodamine derivative ofthe hormone, indicated that the fluorescently labeled receptors were initially distributed uniformly on the cell surface and then formed patches that subsequently internalized (at 37C) into endocytic vesicles. These processes were dependent on specific binding sites for the rhodaminelabeled peptide on the granulosa cells. These studies may provide an experimental basis for understanding the molecular events involved in the action of the hormone in the ovary.Gonadotropin-releasing hormone (GnRH) is believed to mediate the hypothalamic control of pituitary gonadotropin secretion. However, recent studies have indicated an extrapituitary action of GnRH and its agonists (1-9). It has been shown that the hormone and its agonists inhibit a variety of female reproductive functions, including ovarian steroidogenesis, ovulation, ovum transport, and implantation (1-9). These data suggest that the hormone has a direct ovarian site that could play a role in its antifertility effect. Indeed, the presence of stereospecific high-affinity binding sites for GnRH has recently been shown in luteal and granulosa cells as well as in ovarian membrane preparations (10-15). These receptors exhibited binding characteristics similar to those of GnRH receptors in the anterior pituitary. In view of these observations, GnRH receptors of rat granulosa membranes have been identified directly by using a photoaffinity-labeling technique. In addition, GnRH receptors in rat granulosa cells have been visualized by using image-intensified fluorescence microscopy. MATERIALS AND METHODSGranulosa Cells and Membrane Preparation. Granulosa cells were collected from immature (26-day-old) rats 48 hr after subcutaneous administration of15 units ofpregnant mare serum gonadotropin (Gestyl, Organon). Cells were expressed from the ovarian follicles into phosphate-buffered saline/0. 1% bovine serum albumin (for binding studies) or into McCoy's 5a tissue culture medium (for culture and fluorescence microscopy). Granulosa cell cultures were carried out as described (16), except that serum-coated glass coverslips were introduced into the culture dishes to serve as substrate for cell adhesion. After 24 hr ofculture, the coverslips were washed and incubated (37°C, 1 hr) in three changes of phosphate-buffered saline/0.2% bovine serum albumin/I mM CaCl2.Membranes were prepared by homogenizing freshly collected granulosa cells with a Dounce homogenizer at 40C in assay buffer (10 mM Tris HCl, pH 7.4/0.1% bovine serum albumin/i mM dithiothreitol) and centrifuged for 10 min at 1000 x g. The supernatant was then centrifuged for 20 min at 20,000 x g. The pellet was suspended in a...

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Section: Discussionsupporting

confidence: 58%

mentioning

confidence: 86%

Photoaffinity-labeling and fluorescence-distribution studies of gonadotropin-releasing hormone receptors in ovarian granulosa cells.

Hazum¹,

Nimrod²

1982

Proc. Natl. Acad. Sci. U.S.A.

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“…The presence of GNRHR in the ovary, through ligandspecific binding sites, was initially seen in rat granulosa and luteal cells [15][16][17]. Afterward, the presence of GNRHR mRNA was also evidenced in human granulosa luteal cells [18] and in cattle follicles and CL [19].…”

Section: Discussionmentioning

confidence: 85%

Gonadotropin-Releasing Hormone 1 Directly Affects Corpora Lutea Lifespan in Mediterranean Buffalo (Bubalus bubalis) During Diestrus: Presence and In Vitro Effects on Enzymatic and Hormonal Activities1

Zerani

Colella

Maranesi

et al. 2012

Biology of Reproduction

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The expression of gonadotropin-releasing hormone (GNRH) receptor (GNRHR) and the direct role of GNRH1 on corpora lutea function were studied in Mediterranean buffalo during diestrus. Immunohistochemistry evidenced at early, mid, and late luteal stages the presence of GNRHR only in large luteal cells and GNRH1 in both small and large luteal cells. Real-time PCR revealed GNRHR and GNRH1 mRNA at the three luteal stages, with lowest values in late corpora lutea. In vitro corpora lutea progesterone production was greater in mid stages and lesser in late luteal phases, whereas prostaglandin F2 alpha (PGF2alpha) increased from early to late stages, and PGE2 was greater in the earlier-luteal phase. Cyclooxygenase 1 (prostaglandin-endoperoxide synthase 1; PTGS1) activity did not change during diestrus, whereas PTGS2 increased from early to late stages, and PGE2-9-ketoreductase (PGE2-9-K) was greater in late corpora lutea. PTGS1 activity was greater than PTGS2 in early corpora lutea and lesser in late luteal phase. In corpora lutea cultured in vitro, the GNRH1 analog (buserelin) reduced progesterone secretion and increased PGF2alpha secretion as well as PTGS2 and PGE2-9-K activities at mid and late stages. PGE2 release and PTGS1 activity were increased by buserelin only in late corpora lutea. These results suggest that GNRH is expressed in all luteal cells of buffalo, whereas GNRHR is only expressed in large luteal phase. Additionally, GNRH directly down-regulates corpora lutea progesterone release, with the concomitant increases of PGF2al-pha production and PTGS2 and PGE2-9-K enzymatic activities.buffalo, corpus luteum, gonadotropin-releasing hormone 1 (GNRH1), progesterone, prostaglandin F2alpha

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“…The first evidence for the presence of ovarian GNRHR, through ligand-specific binding sites, was observed in rat granulosa and luteal cells (Reeves et al 1980, Pieper et al 1981, Olofsson et al 1995. Subsequently, the presence of GNRHR mRNA was also identified in human granulosa luteal cells (Kang et al 2000) and in both follicles and CL of bovine ovary (Ramakrishnappa et al 2001).…”

Section: Discussionmentioning

confidence: 87%

Expression of type I GNRH receptor and in vivo and in vitro GNRH-I effects in corpora lutea of pseudopregnant rabbits

Zerani¹,

Parillo²,

Brecchia³

et al. 2010

Journal of Endocrinology

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The expression of type I GNRH receptor (GNRHR-I) and the direct role of GNRH-I on corpora lutea (CL) function were studied in the pseudopregnant rabbit model. Immunohistochemistry evidenced GNRHR-I and GNRH-I in luteal cells at early (day 4 pseudopregnancy)-, mid (day 9)-, and late (day 13)-luteal stages. Real-time RT-PCR and western blotting revealed GNRHR-I mRNA and protein at the three luteal stages. Buserelin in vivo treatment at days 9 and 13 decreased plasma progesterone levels for 48 and 24 h respectively. In in vitro cultured CL, buserelin reduced progesterone secretion, increased prostaglandin F 2a (PGF 2a ) secretion and cyclooxygenase-2 (COX-2) and nitric oxide synthase (NOS) activities at days 9 and 13, and decreased PGE 2 at day 13. Co-incubation with antagonists for GNRH-I (antide), inositol 1,4,5-trisphosphate (IP 3 , 2-amino-ethoxydiphenylborate), and diacylglycerol (DAG, 1-hexadecyl-2-acetyl glycerol) or inhibitors for phospholipase C (PLC, compound 48/80), and protein kinase C (PKC, staurosporine) counteracted the buserelin effects. Buserelin co-incubated with COX inhibitor (acetylsalicylic acid) increased progesterone and decreased PGF 2a and NOS activity at days 9 and 13, whereas co-incubation with NOS inhibitor (N-nitro-L-arginine methyl ester) increased progesterone at the same luteal stages. These results suggest that GNRHR-I is constitutively expressed in rabbit CL independently of luteal stage, whereas GNRH-I down-regulates directly CL progesterone production via PGF 2a at mid-and late-luteal stages of pseudopregnancy, utilizing its cognate type I receptor with a post-receptorial mechanism that involves PLC, IP 3 , DAG, PKC, COX-2, and NOS.

show abstract

Similar luteinizing hormone-releasing hormone binding sites in rat anterior pituitary and ovary.

Cited by 104 publications

References 37 publications

Photoaffinity-labeling and fluorescence-distribution studies of gonadotropin-releasing hormone receptors in ovarian granulosa cells.

Photoaffinity-labeling and fluorescence-distribution studies of gonadotropin-releasing hormone receptors in ovarian granulosa cells.

Gonadotropin-Releasing Hormone 1 Directly Affects Corpora Lutea Lifespan in Mediterranean Buffalo (Bubalus bubalis) During Diestrus: Presence and In Vitro Effects on Enzymatic and Hormonal Activities1

Expression of type I GNRH receptor and in vivo and in vitro GNRH-I effects in corpora lutea of pseudopregnant rabbits

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