The Melanin‐Concentrating Hormone System in Fish<sup>a</sup>

Balm, P.H.M.; Gröneveld, D.

doi:10.1111/j.1749-6632.1998.tb10760.x

Cited by 31 publications

(18 citation statements)

References 22 publications

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“…In teleost fish, exceptionally, the portal system has been lost but MCH together with other hypophysiotrophic neurones penetrate between the pituitary secretory cells or terminate on the basement membrane that separates them from the neurohypophysis (Ball and Baker, 1969; Batten and Baker, 1988;Powell and Baker, 1987;Batten et al, 1999). Information about the influence of MCH on endocrine secretory activity is still sparse, but there is evidence from teleosts that it can depress the release of corticotropin and one of the corticotropinreleasing factors (Baker et al, 1985b(Baker et al, , 1986, modulate melanotropin release (Baker et al, 1986;Barber et al, 1987, Gröneveld et al, 1995b, and stimulate somatolactin release (Balm and Gröneveld, 1998). The overall picture suggests that MCH acquired a hypophysial regulatory role at a very early stage in vertebrate phylogeny.…”

Section: Discussionmentioning

confidence: 96%

“…A further feature of teleosts is that MCH neurones project into the adenohypophysis and have been shown to affect the secretory activity of the ACTH, MSH and somatolactin producing cells (Baker et al, 1985b;Barber et al, 1987;Gröneveld et al, 1995b;Balm and Gröneveld, 1998). Whether such a hypophysiotrophic function operates in other vertebrates is still unknown, although such a function is possible because immunoreactive MCH fibers are found in the median eminence (Andersen et al, 1986;Bittencourt et al, 1992;Knigge et al, 1996).…”

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confidence: 90%

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Neuronal organization of the melanin‐concentrating hormone system in primitive actinopterygians: Evolutionary changes leading to teleosts

Baker

Bird

2001

J of Comparative Neurology

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Hypothalamic melanin-concentrating hormone (MCH) neurones occur in all vertebrates and have an apparent neuromodulatory role. In teleost fish, however, MCH is used also as a neurohypophysial hormone, controlling skin color, and as a hypophysiotrophic peptide. This work describes the central location of immunoreactive MCH perikarya and their projections to the pituitary in a range of ancestral fish to determine the phylogenetic stage when the peptide adopted these roles. In all actinopterygians examined, including polypteriformes, chondrosteans, holosteans, and teleosts, immunoreactive fibers were abundant in the median eminence or, in the case of teleosts, within the pars distalis itself, suggesting MCH acquired a hypophysial regulatory role early in vertebrate evolution. MCH fibers appeared to be absent from the posterior neurohypophysis of the polypteriform Calamoichthys but were evident in this region in the chondrostean Acipensor, the holosteans Lepisosteus and Amia, and all teleosts, suggesting its use as a neurohypophysial hormone. The ability of MCH to induce skin pallor seems to have arisen at a later stage, probably in the preholosteans. This hormonal role coincides with the migration of MCH perikarya away from the ventricular surface and their enlargement into magnocellular neurones. In the higher teleosts, magnocellular hypothalamo-neurohypophysial neurones predominate in size and number, whereas smaller periventricular MCH neurones associated with the paraventricular organ, that are prominent in lampreys, early actinopterygians and tetrapods, are reduced in teleosts. The data suggest that, in teleost fish, earlier functions of the peptide may have become subordinate to its novel pigmentary role.

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Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 90%

Neuronal organization of the melanin‐concentrating hormone system in primitive actinopterygians: Evolutionary changes leading to teleosts

Baker

Bird

2001

J of Comparative Neurology

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“…VBA is a neuroendocrine response used for camouflage where dark-adapted fish disperse their melanin granules ( Figure 7a) and thus appear darker, whereas light-adapted fish aggregate their melanin into small granules ( Figure 7b) and therefore appear more transparent. 30 As this response is driven through the retino-thalamic tract, blind fish are unable to exhibit this response (Figures 7e and f). After 30 min of dark adaptation followed by 15 min of bright light exposure, 7 d.p.f.…”

Section: Resultsmentioning

confidence: 99%

Rip3 knockdown rescues photoreceptor cell death in blind pde6c zebrafish

et al. 2014

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Achromatopsia is a progressive autosomal recessive retinal disease characterized by early loss of cone photoreceptors and later rod photoreceptor loss. In most cases, mutations have been identified in CNGA3, CNGB3, GNAT2, PDE6C or PDE6H genes. Owing to this genetic heterogeneity, mutation-independent therapeutic schemes aimed at preventing cone cell death are very attractive treatment strategies. In pde6c w59 mutant zebrafish, cone photoreceptors expressed high levels of receptor-interacting protein kinase 1 (RIP1) and receptor-interacting protein kinase 3 (RIP3) kinases, key regulators of necroptotic cell death. In contrast, rod photoreceptor cells were alternatively immunopositive for caspase-3 indicating activation of caspase-dependent apoptosis in these cells. Morpholino gene knockdown of rip3 in pde6c w59 embryos rescued the dying cone photoreceptors by inhibiting the formation of reactive oxygen species and by inhibiting second-order neuron remodelling in the inner retina. In rip3 morphant larvae, visual function was restored in the cones by upregulation of the rod phosphodiesterase genes (pde6a and pde6b), compensating for the lack of cone pde6c suggesting that cones are able to adapt to their local environment. Furthermore, we demonstrated through pharmacological inhibition of RIP1 and RIP3 activity that cone cell death was also delayed.Collectively, these results demonstrate that the underlying mechanism of cone cell death in the pde6c w59 mutant retina is through necroptosis, whereas rod photoreceptor bystander death occurs through a caspase-dependent mechanism. This suggests that targeting the RIP kinase signalling pathway could be an effective therapeutic intervention in retinal degeneration patients. As bystander cell death is an important feature of many retinal diseases, combinatorial approaches targeting different cell death pathways may evolve as an important general principle in treatment.

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“…On a dark background, melanosomes are widely distributed throughout the melanophore's processes, giving the larva a dark appearance. In most teleosts, this cellular behavior is mediated by a direct projection of the retina to the hypothalamus, which in turn, activates the secretion of two hormones from the pituitary, which acts on the melanophores (Balm and Groneveld, 1998). Many mutants lack this background adaptation ("expanded melanophore phenotype" Kelsh et al, 1996).…”

Section: Maturation Of the Visual System And Emergence Of Form Visionmentioning

confidence: 99%

Behavioral genetic approaches to visual system development and function in zebrafish

2002

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ABSTRACT:The zebrafish is a recent vertebrate model system that shows great potential for a genetic analysis of behavior. Early development is extraordinarily rapid, so that larvae already display a range of behaviors 5 days after fertilization. In particular the visual system develops precociously, supporting a number of visually mediated behaviors in the larva. This provides the opportunity to use these visually mediated behaviors to screen chemically mutagenized strains for defects in vision. Larval optokinetic and optomotor responses have already been successfully employed to screen for mutant strains with defects in the visual system. In the adult zebrafish a visually mediated escape response has proved useful for screening for dominant mutations of the visual system. Here, I summarize visually mediated behaviors of both larval and adult zebrafish and their applicability for genetic screens, and present, the approaches and results of visual behavior carried out to date.

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The Melanin‐Concentrating Hormone System in Fish^a

Cited by 31 publications

References 22 publications

Neuronal organization of the melanin‐concentrating hormone system in primitive actinopterygians: Evolutionary changes leading to teleosts

Neuronal organization of the melanin‐concentrating hormone system in primitive actinopterygians: Evolutionary changes leading to teleosts

Rip3 knockdown rescues photoreceptor cell death in blind pde6c zebrafish

Behavioral genetic approaches to visual system development and function in zebrafish

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The Melanin‐Concentrating Hormone System in Fisha

Cited by 31 publications

References 22 publications

Neuronal organization of the melanin‐concentrating hormone system in primitive actinopterygians: Evolutionary changes leading to teleosts

Neuronal organization of the melanin‐concentrating hormone system in primitive actinopterygians: Evolutionary changes leading to teleosts

Rip3 knockdown rescues photoreceptor cell death in blind pde6c zebrafish

Behavioral genetic approaches to visual system development and function in zebrafish

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The Melanin‐Concentrating Hormone System in Fish^a