Seasonal changes in expression of genes encoding five types of gonadotropin-releasing hormone receptors and responses to GnRH analog in the pituitary of masu salmon

Jodo, Aya; Kitahashi, Takashi; Taniyama, Shinya; Ueda, Hiroshi; Urano, Akihisa; Ando, Hironori

doi:10.1016/j.ygcen.2005.04.001

Cited by 17 publications

(8 citation statements)

References 52 publications

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“…These results suggest that this receptor plays an important role during sexual maturation, and is thus probably involved in the regulation of gonadotropin gene expression and secretion. In masu salmon, mRNA levels of a pituitary-specific form of Gnrhr increase prior to precocious maturation in males, and in the prespawning period in females [9], further supporting our hypothesis that this subtype of receptors is involved in sexual maturation and reproduction. Conversely to mammals, LH and FSH reside in two different cell populations in the chicken pituitary [29,30], suggesting that the two gonadotropins are controlled by different mechanisms.…”

supporting

confidence: 80%

“…vertebrates, more than one type of GNRHR has been identified [8][9][10][11][12], and as reported in the bullfrog [11] and the masu salmon [9], one form appears to be pituitary-specific. To date, one GNRHR has been identified in chickens, and it was shown to be expressed in many brain regions as well as other tissues such as the testes, spleen, and heart [20].…”

Section: Discussionmentioning

confidence: 83%

“…In addition, a third form (GnRH III) has also been identified in fish [7]. The existence of more than one GNRHR has been reported in several species [5,[8][9][10][11][12], and in addition to full-length GNRHRs, splice variants have also been cloned [13][14][15][16]. Whether these splice variants possess any physiological significance remains to be elucidated.…”

Section: Introductionmentioning

confidence: 99%

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Identification of a Novel Pituitary-Specific Chicken Gonadotropin-Releasing Hormone Receptor and Its Splice Variants1

Shimizu

Bédécarrats

2006

Biology of Reproduction

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In all vertebrates, GnRH regulates gonadotropin secretion through binding to a specific receptor on the surface of pituitary gonadotropes. At least two forms of GnRH exist within a single species, and several corresponding GnRH receptors (GNRHRs) have been isolated with one form being pituitary specific. In chickens, only one type of widely expressed GNRHR has previously been identified. The objectives of this study were to isolate a chicken pituitary-specific GNRHR and to determine its expression pattern during a reproductive cycle. Using a combined strategy of PCR and rapid amplification of cDNA ends (RACE), a new GNRHR (chicken GNRHR2) and two splice variants were isolated in domestic fowl (Gallus gallus domesticus). Full-length GNRHR2 and one of its splice variant mRNAs were expressed exclusively in the pituitary, whereas mRNA of the other splice variant was expressed in most brain tissues examined. The deduced amino acid sequence of full-length chicken GNRHR2 reveals a seven transmembrane domain protein with 57%-65% homology to nonmammalian GNRHRs. Semiquantitative real-time PCR revealed that mRNA levels of full-length chicken GNRHR2 in the pituitary correlate with the reproductive status of birds, with maximum levels observed during the peak of lay and 4 wk postphotostimulation in females and males, respectively. Furthermore, GnRH stimulation of GH3 cells that were transiently transfected with cDNA that encodes chicken GNRHR2 resulted in a significant increase in inositol phosphate accumulation. In conclusion, we isolated a novel GNRHR and its splice variants in chickens, and spatial and temporal gene expression patterns suggest that this receptor plays an important role in the regulation of reproduction.

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supporting

confidence: 80%

Section: Discussionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Identification of a Novel Pituitary-Specific Chicken Gonadotropin-Releasing Hormone Receptor and Its Splice Variants1

Shimizu

Bédécarrats

2006

Biology of Reproduction

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“…The levels of all five gnrhr types cloned from the masu salmon are low during the spawning period, when DHP levels are high relative to vitellogenesis [77]. Using real-time PCR, significantly higher mRNA levels of gnrhr (similar to gnrhr3) have been shown in the pituitaries of striped bass at advanced stages of ovarian development, compared with the pituitaries of fish with less developed ovaries [78].…”

Section: Discussionmentioning

confidence: 98%

Sex Steroids Are Involved in the Regulation of Gonadotropin-Releasing Hormone and Dopamine D2 Receptors in Female Tilapia Pituitary1

Levavi‐Sivan¹,

Biran²,

Fireman³

2006

Biology of Reproduction

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Although molecular mechanisms underlying steroid effects on GnRH and dopamine receptors are well documented in mammals, little is known in fish. Herein, we describe the expression of pituitary GnRH and dopamine receptors relative to gonadotropin expression and release. We exposed female tilapia to graded doses of estradiol or 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP) in vitro, and of estradiol in vivo, and determined mRNA levels of gnrhr1, gnrhr3, drd2, lhb, and fshb by real-time PCR. We also determined gonadotropin levels using specific ELISAs. Exposure to low doses of estradiol caused increased gnrhr3 mRNA levels in vivo and in vitro, probably related to positive feedback on FSH release. Increasing concentrations of estradiol resulted in increased drd2 mRNA levels in vivo and in vitro, inhibition of LH and FSH release, and inhibition of lhb mRNA levels in vivo, possibly related to negative feedback. At high doses of estradiol, FSH release increased in preparation for a new generation of follicles. Exposure to nanomolar doses of DHP resulted in increased drd2 mRNA levels, probably related to negative feedback on LH release. A decrease in drd2 levels at the micromolar range of DHP (concomitant with increased gnrhr3 and fshb mRNA levels) may be related to the recruitment of a new generation of oocytes. Exposure to DHP also resulted in increased lhb mRNA levels toward final oocyte maturation. Salmon GnRH analog (sGnRHa) increased mRNA levels of gnrh1and gnrh3; when combined with DHP, sGnRHa synergistically increased expression of gnrh3 only. These results emphasize the role of sex steroids on positive and negative feedbacks controlling the reproductive cycle.

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“…GnRH stimulates the synthesis and release of pituitary gonadotropins, including follicle stimulating hormone and luteinizing hormone; these hormones then stimulate spawning behavior [7, 8]. Analyses of how GnRH is involved in spawning processes are complicated, because there are multiple forms of GnRH in the brains of some fish species [9–11]. In association with the different forms of GnRH, there are multiple forms of GnRH receptors (GnRH-Rs); these receptors bind to GnRH, initiating the intracellular signaling system [9, 12].…”

Section: Introductionmentioning

confidence: 99%

Changes of gonadotropin-releasing hormone receptor 2 during the anadromous spawning migration in Coilia nasus

et al. 2016

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BackgroundAn increase in the activity of the pituitary-gonad axis (PG-axis) and gonad development are essential for the onset of spawning migration in teleosts. In the fish Coilia nasus, gonad development and spawning migration up the Yangtze River occurs by the end of each summer. We hypothesized that gonadotropin releasing hormones receptor 2 (GnRH-R2), which together produce a signal that interacts with the PG-axis, may help to regulate spawning migration processes.ResultsIn this regard, we (1) characterized the gonadosomatic index (GSI) in the anadromous fish C. nasus; (2) analyzed the GnRH-R2 mRNA expression levels in ovary and brain, and concentrations in the serum; and (3) identified the GnRH-R2 protein distribution in the brain and ovaries. We found strong relationships between all of these indices.ConclusionsThe results indicate that GnRH-R2 could act together to promote spawning during the anadromous migration. There is some evidence that the GnRH-R2 gene expression levels and protein distributions change in association with the migratory behavior.

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Seasonal changes in expression of genes encoding five types of gonadotropin-releasing hormone receptors and responses to GnRH analog in the pituitary of masu salmon

Cited by 17 publications

References 52 publications

Identification of a Novel Pituitary-Specific Chicken Gonadotropin-Releasing Hormone Receptor and Its Splice Variants1

Identification of a Novel Pituitary-Specific Chicken Gonadotropin-Releasing Hormone Receptor and Its Splice Variants1

Sex Steroids Are Involved in the Regulation of Gonadotropin-Releasing Hormone and Dopamine D2 Receptors in Female Tilapia Pituitary1

Changes of gonadotropin-releasing hormone receptor 2 during the anadromous spawning migration in Coilia nasus

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