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- Einarsdottir, Ingibjörg, 1951, et al.
(författare)
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Occurrence of ghrelin-producing cells, the ghrelin receptor and Na+,K+-ATPase in tissues of Atlantic halibut
- 2011
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Ingår i: Cell and Tissue Resarch. - 0302-766X. ; 344:3, s. 481-498
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin is a pituitary growth hormone (GH)-secretagogue that also has metabolic, reproductive, proliferative, immunological and brain functions in mammals. Far less is known about its role in fish. We have therefore performed an immunohistochemical determination of its tissue distribution in the developing Atlantic halibut (Hippoglossus hippoglossus) to gain insights into its potential function. Ghrelin immunoreactivity was detected in first-feeding halibut larvae in the skin, urinary bladder, gastrointestinal (GI) tract and olfactory lobe of the brain. In subsequent stages up to metamorphosis, ghrelin immunoreactivity declined in the skin and became evident in the gills. When the stomach developed, ghrelin immunoreactivity declined throughout the GI tract with the exception of the stomach, which exhibited an intense signal. Immunoreactive ghrelin cells were also present in the olfactory lobe, nerve and epithelium and in occasional cells of the buccal cavity and oesophagus. Ghrelin immunoreactivity had an overlapping distribution with that for Na(+),K(+)-ATPase, colocalisation also being observed in some ionocytes of the gill. The co-expression of ghrelin and the GH-secretagogue receptor in the same tissue indicates that ghrelin can exert both endocrine and paracrine actions in the developing halibut. The presence of immunoreactive ghrelin in several osmoregulatory tissues, the GI tract and sensory tissue provides strong evidence that ghrelin has multiple functions during development and also suggests targets for future investigations.
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| 2. |
- Hildahl, Jon, 1976, et al.
(författare)
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Involvement of growth hormone-insulin-like growth factor I system in cranial remodeling during halibut metamorphosis as indicated by tissue- and stage-specific receptor gene expression and the presence of growth hormone receptor protein.
- 2008
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Ingår i: Cell and tissue research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 332:2, s. 211-25
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Tidskriftsartikel (refereegranskat)abstract
- The role of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in the tissue remodeling associated with the transition of a symmetrical larva to an asymmetrical juvenile during flatfish metamorphosis is unknown. In order to investigate the potential role of these hormones in the remodeling of cranial bone and soft tissue that accompanies eye migration during metamorphosis of Atlantic halibut (Hippoglossus hippoglossus) larvae, tissue-specific gene expression was monitored by in situ hybridization for Atlantic halibut type I growth hormone receptor (hhGHR), type II hhGHR, and insulin-like growth factor-I receptor (hhIGF-IR). Polyclonal antibody generated against the extracellular domain of type I hhGHR was used for the immunohistochemical localization of type I GHR protein. Type I hhGHR, type II hhGHR, and hhIGF-IR mRNA were expressed in fibroblasts, frontal bone osteocytes, and dorsal chondrocytes at the onset of metamorphosis (stage 8), during metamorphic climax (stage 9), and in fully metamorphosed juveniles (stage 10). Type I GHR protein showed similar expression patterns to those of type I hhGHR mRNA, except in chondrocytes in which little GHR protein was detected. The localization of GHR and IGF-IR transcripts and GHR protein in cranial structures that undergo remodeling is intriguing and suggests that, in addition to thyroid hormones, the GH-IGF-I system is involved in morphological transformations during metamorphosis in Atlantic halibut.
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