Regulation of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) gene expression by gonadotropin-releasing hormone (GnRH) and sexual steroids in the Mediterranean Sea bass

Mateos, Jorge; Mañanós, Evaristo L.; Carrillo, Manuel; Zanuy, Silvia

doi:10.1016/s1096-4959(01)00535-8

Cited by 133 publications

(65 citation statements)

References 51 publications

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“…The contrary regulation of LHb and FSHb mRNA expression in response to sexual steroids was confirmed in further experiments from our workgroup, even if the mechanism remains unclear (Urbatzka et al 2008). From studies in fish, it is known that sexual steroids can regulate gonadotrophins differently, inhibiting one gene and stimulating the other (Sohn et al 2001, Mateos et al 2002.…”

Section: Discussionmentioning

confidence: 99%

Exposure of Xenopus laevis tadpoles to finasteride, an inhibitor of 5-α reductase activity, impairs spermatogenesis and alters hypophyseal feedback mechanisms

Urbatzka¹,

Watermann²,

Lutz³

et al. 2009

Journal of Molecular Endocrinology

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Sexual steroids have major regulatory functions in gonadal development, maturation of gametes and sexual differentiation in vertebrates. Previous studies in amphibians provided evidence that dihydrotestosterone and activity of 5-a reductases might play a significant role in androgen-mediated reproductive biology. To test the involvement of 5-a reductases in maturation of gametes in amphibians, Xenopus laevis was exposed to finasteride (FIN), a known inhibitor of 5-a reductase enzyme activity. In a long-term exposure from stage 46 to 66, severe disruption of spermatogenesis was observed in histological analysis of testes as detected by occurrence of empty spermatocysts, while ovaries remained unaffected. Real-time PCR analyses of male and female brain revealed an increase of LHb mRNA and a decrease of FSHb mRNA in males, suggesting a signalling on testes that could result in increased steroidogenesis and reduced Sertoli cell proliferation. Accordingly, the mRNA expression of P450 side chain cleavage enzyme and 5-a reductase type 2 was increased in testes, while no effects could be observed on steroidogenic genes in ovaries. A short-term exposure to testosterone, FIN and testosteroneCFIN showed that transient effects of FIN targeted males selectively and, in particular, interfered with the hypothalamus-pituitary-gonad axis. Furthermore, a negative feedback of testosterone on LHb was observed on males and females. This study provides evidence that exposure of X. laevis to FIN, an inhibitor of 5-a reductases, impaired spermatogenesis and involved sex-specific hypophyseal feedback mechanisms.

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Section: Discussionmentioning

confidence: 99%

Exposure of Xenopus laevis tadpoles to finasteride, an inhibitor of 5-α reductase activity, impairs spermatogenesis and alters hypophyseal feedback mechanisms

Urbatzka¹,

Watermann²,

Lutz³

et al. 2009

Journal of Molecular Endocrinology

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“…The present study shows that an inhibitory action of T and E 2 occurs on fshβ mRNA levels in sea bass, as Table 1. Summary of the gene expression changes in the brain by RT-PCR after castration and testosterone and estradiol replacement in males and females, respectively, in the European sea bass previously reported in this species (Mateos et al, 2002). Thus a combination of several mechanisms of action of sex steroids on the gonadotropic function might be considered to include the effect of steroids at the level of the pituitary, the hypothalamus or both.…”

Section: Discussionmentioning

confidence: 99%

Actions of sex steroids on kisspeptin expression and other reproduction-related genes in the brain of the teleost fish european sea bass

Alvarado

Servili

Molés

et al. 2016

Journal of Experimental Biology

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Kisspeptins are well known as mediators of the coordinated communication between the brain-pituitary axis and the gonads in many vertebrates. To test the hypothesis that gonadal steroids regulate kiss1 and kiss2 mRNA expression in European sea bass (a teleost fish), we examined the brains of gonad-intact (control) and castrated animals, as well as castrated males (GDX) and ovariectomized females (OVX) that received testosterone (T) and estradiol (E 2 ) replacement, respectively, during recrudescence. In GDX males, low expression of kiss1 mRNA is observed by in situ hybridization in the caudal hypothalamus (CH) and the mediobasal hypothalamus (MBH), although hypothalamic changes in kiss1 mRNA levels were not statistically different among the groups, as revealed by real-time PCR. However, T strongly decreased kiss2 expression levels in the hypothalamus, which was documented in the MBH and the nucleus of the lateral recess (NRLd) in GDX T-treated sea bass males. Conversely, it appears that E 2 evokes low kiss1 mRNA in the CH, while there were cells expressing kiss2 in the MBH and NRLd in these OVX females. These results demonstrate that kisspeptin neurons are presumably sensitive to the feedback actions of sex steroids in the sea bass, suggesting that the MBH represents a major site for sex steroid actions on kisspeptins in this species. Also, recent data provide evidence that both positive and negative actions occur in key factors involved in sea bass reproductive function, including changes in the expression of gnrh-1/gonadotropin, cyp19b, er and ar genes and sex steroid and gonadotropin plasma levels in this teleost fish.

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“…Previous studies have reported overlapping expression of gnrhr2a with both fshb and lhb in pituitary cells of European sea bass (González-Martínez et al 2004), findings supporting a putative influence of Gnrh-derived signaling on gonadotropin subunits transcription and gonadotropin release. However, such an effect has only been verified experimentally in European sea bass for cga and lhb mRNAs and for Lh secretion, while fshb transcription was shown to be unaffected by Gnrh treatment (Forniés et al 2003, Mateos et al 2002 and no information for Fsh release is presently available. These findings agree with data obtained for zebrafish (Lin & Ge 2009), although other studies have reported significant effects of Gnrh treatments on pituitary fshb mRNA levels and Fsh release in female teleost fish (Levavi-Sivan et al 2010).…”

Section: Endocrine Responses To Ulomentioning

confidence: 99%

Mechanisms of oocyte development in European sea bass (Dicentrarchus labrax L.): investigations via application of unilateral ovariectomy

García-López¹,

Sánchez-Amaya²,

Tyler³

et al. 2011

Reproduction

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Unilateral ovariectomy (ULO) was performed in European sea bass (Dicentrarchus labrax L.) during late pre-vitellogenesis/early vitellogenesis. Plasma steroid levels and the expression of a suite of potential oogenesis-relevant genes in the ovary, brain, and pituitary were evaluated with the aim of understanding their involvement in the compensatory oocyte development occurring within the remaining ovarian lobe. After 69 days of surgery the remaining ovarian lobe in ULO fish was gravimetrically equivalent to an intactpaired ovary of sham operated, control fish. This compensatory ovarian growth was based on an increased number of early perinucleolar oocytes and mid-late stage vitellogenic follicles without an apparent recruitment of primary oocytes into the secondary growth phase. Plasma steroid levels were similar in ULO and control females at all time points analyzed, suggesting an increased steroid production of the remaining ovarian lobe in hemi-castrated females. Results of the gene expression survey conducted indicate that the signaling pathways mediated by Fsh and Gnrh1 constitute the central axes orchestrating the observed ovarian compensatory growth. In addition, steroid receptors, Star protein, Igfs, and members of the transforming growth factor beta superfamily including anti-Mullerian hormone and bone morphogenetic protein 4 were identified as potentially relevant players within this process, although their specific actions and interactions remain to be established. Our results demonstrate that ULO provides an excellent in vivo model for elucidating the interconnected endocrine and molecular mechanisms controlling oocyte development in European sea bass.

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Regulation of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) gene expression by gonadotropin-releasing hormone (GnRH) and sexual steroids in the Mediterranean Sea bass

Cited by 133 publications

References 51 publications

Exposure of Xenopus laevis tadpoles to finasteride, an inhibitor of 5-α reductase activity, impairs spermatogenesis and alters hypophyseal feedback mechanisms

Exposure of Xenopus laevis tadpoles to finasteride, an inhibitor of 5-α reductase activity, impairs spermatogenesis and alters hypophyseal feedback mechanisms

Actions of sex steroids on kisspeptin expression and other reproduction-related genes in the brain of the teleost fish european sea bass

Mechanisms of oocyte development in European sea bass (Dicentrarchus labrax L.): investigations via application of unilateral ovariectomy

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