Gonadectomy and Blood Sampling Procedures in the Small Size Teleost Model Japanese Medaka (&lt;em&gt;Oryzias latipes&lt;/em&gt;)

Royan, Muhammad Rahmad; Kanda, Shinji; Kayo, Daichi; Song, Weiyi; Ge, Wei; Weltzien, Finn‐Arne; Fontaine, Romain

doi:10.3791/62006

Cited by 10 publications

(6 citation statements)

References 29 publications

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“…We also found significantly lower tshba levels in adult compared to juvenile males where the androgen levels are generally lower [for review, see ( 61 , 62 )], supporting the inhibitory role of androgens on tshba levels. It will be interesting to test this hypothesis in future research using orchidectomy which drastically reduce androgen levels ( 63 ). However, although higher tshb levels are also observed in female half-barred wrasse ( 64 ), and tshb levels are higher in juvenile than in adult male Atlantic salmon ( 65 ), zebrafish show no sexual dimorphism of tshb and pomc ( 66 ), suggesting species differences.…”

Section: Discussionmentioning

confidence: 99%

3D Atlas of the Pituitary Gland of the Model Fish Medaka (Oryzias latipes)

et al. 2021

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In vertebrates, the anterior pituitary plays a crucial role in regulating several essential physiological processes via the secretion of at least seven peptide hormones by different endocrine cell types. Comparative and comprehensive knowledge of the spatial distribution of those endocrine cell types is required to better understand their physiological functions. Using medaka as a model and several combinations of multi-color fluorescence in situ hybridization, we present the first 3D atlas revealing the gland-wide distribution of seven endocrine cell populations: lactotropes, thyrotropes, Lh and Fsh gonadotropes, somatotropes, and pomca-expressing cells (corticotropes and melanotropes) in the anterior pituitary of a teleost fish. By combining in situ hybridization and immunofluorescence techniques, we deciphered the location of corticotropes and melanotropes within the pomca-expressing cell population. The 3D localization approach reveals sexual dimorphism of tshba-, pomca-, and lhb-expressing cells in the adult medaka pituitary. Finally, we show the existence of bi-hormonal cells co-expressing lhb-fshb, fshb-tshba and lhb-sl using single-cell transcriptomics analysis and in situ hybridization. This study offers a solid basis for future comparative studies of the teleost pituitary and its functional plasticity.

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Section: Discussionmentioning

confidence: 99%

3D Atlas of the Pituitary Gland of the Model Fish Medaka (Oryzias latipes)

et al. 2021

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“…The protocols for the sham and OVX operations and E 2 administration are indicated in Figure 1A. OVX and sham operations were performed as described previously 28,29 . Briefly, sexually mature female gnrh1 :EGFP medaka that spawned on the day of operation were anesthetized by immersion in 0.02% tricaine methanesulfonate solution (MS‐222; Sigma‐Aldrich) and their ovaries were excised via i.p.…”

Section: Methodsmentioning

confidence: 99%

Estrogen upregulates the firing activity of hypothalamic gonadotropin‐releasing hormone (GnRH1) neurons in the evening in female medaka

Ikegami

Kajihara

Umatani

et al. 2022

J Neuroendocrinology

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The reproductive function of vertebrates is regulated by the hypothalamic-pituitarygonadal axis. In sexually mature females, gonadotropin-releasing hormone (GnRH) neurons in the preoptic area (POA) are assumed to be responsible for a cyclic large increase in GnRH release, the GnRH surge, triggering a luteinizing hormone (LH) surge, which leads to ovulation. Precise temporal regulation of the preovulatory GnRH/ LH surge is important for successful reproduction because ovulation should occur after follicular development. The time course of the circulating level of estrogen is How to cite this article: Ikegami K, Kajihara S, Umatani C, Nakajo M, Kanda S, Oka Y. Estrogen upregulates the firing activity of hypothalamic gonadotropin-releasing hormone (GnRH1) neurons in the evening in female medaka.

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“…Gonadectomy (GDX), which was shown to drastically reduce circulating sex steroids for at least 4 months (Royan et al, 2020), was performed in male and female medaka as previously described (Kanda et al, 2008). Briefly, after anesthesia using 0.02% Tricaine methanesulfonate (MS222; Sigma), fertile males and females (indicated by spawning and/or the existence of oviposited eggs in the females) were incised to access the intraperitoneal cavity.…”

Section: Methodsmentioning

confidence: 99%

“…Blood sampling was performed as previously described (Royan et al, 2020). After euthanasia with 0.02% MS222, blood was collected from the caudal vein using a glass needle (OD 1 mm, ID 0.5 mm; GD-1; Narishige) coated with 0.05 U/µl heparin sodium (Sigma) in phosphate buffered saline (PBS).…”

Section: Blood and Tissue Samplingmentioning

confidence: 99%

Sexually dimorphic regulation of gonadotrope cell hyperplasia in medaka pituitary via mitosis and transdifferentiation

Royan

Kayo

Weltzien

et al. 2022

Preprint

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The two pituitary gonadotropins, Fsh and Lh, regulate the reproductive function in vertebrates. While many studies have investigated the regulation of gonadotropin production and release by the sex steroid feedback, its role on the regulation of gonadotrope cell number remains unclear. Using medaka as a model and an optimized protocol to restore physiological sex steroids levels following gonadectomy, we show that gonadal sex steroids not only decrease fshb transcript levels, but also Fsh cell number in both sexes. We then investigated the origin of the Fsh cell hyperplasia induced by gonadectomy. In both sexes, BrdU incubation shows that this is achieved via Fsh cell mitosis. In situ hybridization reveals that new Fsh cells also originate from transdifferentiating Tsh cells in females, but not in males. Both phenomena are inhibited by sex steroid supplementation via feeding. In males (but not females), gonadectomy (without recovery with sex steroid supplementation) also reduces sox2 transcript levels and Sox2-immunopositive population volume, suggesting that sox2-progenitors may be recruited to produce new Fsh cells. Opposite to Fsh cells, gonadectomy decreases lhb levels in both sexes, and levels are not restored by sex steroid supplementation. In addition, the regulation of Lh cell number also seems to be sex dependent. Removal of gonadal sex steroids stimulates Lh cell mitosis in male (like Fsh cells), but not in females. To conclude, our study provides the first evidence on sexually dimorphic mechanisms used in the fish pituitary to remodel gonadotrope populations in response to sex steroids.

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Gonadectomy and Blood Sampling Procedures in the Small Size Teleost Model Japanese Medaka (<em>Oryzias latipes</em>)

Abstract: The article describes a quick protocol to gonadectomize and sample blood from small teleost fish, using medaka (Oryzias latipes) as a model, to investigate the role of sex steroids in animal physiology.

Cited by 10 publications

References 29 publications

3D Atlas of the Pituitary Gland of the Model Fish Medaka (Oryzias latipes)

3D Atlas of the Pituitary Gland of the Model Fish Medaka (Oryzias latipes)

Estrogen upregulates the firing activity of hypothalamic gonadotropin‐releasing hormone (GnRH1) neurons in the evening in female medaka

Sexually dimorphic regulation of gonadotrope cell hyperplasia in medaka pituitary via mitosis and transdifferentiation

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