Does MCH play a role on establishment or maintenance of social hierarchy in Nile tilapia?

Ramanzini, Guilherme Corrêa; Volpato, Gilson Luiz; Visconti, Maria Aparecida

doi:10.1016/j.physbeh.2017.10.016

Cited by 4 publications

(5 citation statements)

References 28 publications

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“…Eye and body darkening are associated with subordinance (Ramanzini, Volpato, & Visconti, 2018;Volpato et al, 2003) and a reactive coping style in Nile tilapia (Vera Cruz & Tauli, 2015), as found in our study. Thus, our results are consistent with the idea that crowding during aquaculture intensification makes Nile tilapia chronically stressed, and as seen in other species, this results in body and eye darkening, neophobia, and -more generally, in a shift from a proactive to a reactive stress coping style.…”

Section: Discussionsupporting

confidence: 86%

Density-dependent changes in neophobia and stress-coping styles in the world’s oldest farmed fish

Champneys

Castaldo

Consuegra

et al. 2018

Preprint

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Farmed fish are typically reared at densities much higher than those observed in the wild, but 1 to what extent crowding results in abnormal behaviours that can impact welfare and stress 2 coping styles is subject to debate. Neophobia (i.e. fear of the 'new') is thought to be adaptive 3 under natural conditions by limiting risks, but it is potentially maladapted in captivity, where 4 there are no predators or novel foods. We reared juvenile Nile tilapia (Oreochromis niloticus) 5 for six weeks at either high (50g/L) or low density (14g/L), assessed the extent of skin and 6 eye darkening (two proxies of chronic stress), and exposed them to a novel object in an open-7 test arena, with and without cover, to assess the effects of density on neophobia and stress 8 coping styles. Fish reared at high density were darker, more neophobic, less aggressive, less 9 mobile and less likely to take risks than those reared at low density, and these effects were 10 exacerbated when no cover was available. Thus, the reactive coping style shown by fish at 11 high density was very different from the proactive coping style shown by fish at low density. 12Our findings provide novel insights into the plasticity of fish behaviour and the effects of 13 aquaculture intensification on one of the world's oldest farmed and most invasive fish, and 14 highlight the importance of considering context. Crowding could have a positive effect on the 15 welfare of tilapia by reducing aggressive behaviour, but it can also make fish chronically 16 stressed and more fearful, which could make them less invasive.

show abstract

Section: Discussionsupporting

confidence: 86%

Density-dependent changes in neophobia and stress-coping styles in the world’s oldest farmed fish

Champneys

Castaldo

Consuegra

et al. 2018

Preprint

View full text Add to dashboard Cite

show abstract

“…Melanocyte-stimulating hormone (α-MSH) and melanin-concentrating hormone (MCH) are the two main hormones involved in the modulation of chromatophore dispersal [68–71], and it has been shown that social stress can increase α-MSH in plasma and result in body darkening in salmonids [72,73]. Eye and body darkening are associated with subordinance [41,74] and a reactive coping style in Nile tilapia [42], as found in our study. Thus, our results are consistent with the idea that crowding during aquaculture intensification makes Nile tilapia chronically stressed, and as seen in other species, this results in body and eye darkening, neophobia and, more generally, in a shift from a proactive to a reactive stress coping style.…”

Section: Discussionmentioning

confidence: 99%

Density-dependent changes in neophobia and stress-coping styles in the world's oldest farmed fish

et al. 2018

View full text Add to dashboard Cite

Farmed fish are typically reared at densities much higher than those observed in the wild, but to what extent crowding results in abnormal behaviours that can impact welfare and stress coping styles is subject to debate. Neophobia (i.e. fear of the ‘new’) is thought to be adaptive under natural conditions by limiting risks, but it is potentially maladapted in captivity, where there are no predators or novel foods. We reared juvenile Nile tilapia (Oreochromis niloticus) for six weeks at either high (50 g l−1) or low density (14 g l−1), assessed the extent of skin and eye darkening (two proxies of chronic stress), and exposed them to a novel object in an open test arena, with and without cover, to assess the effects of density on neophobia and stress coping styles. Fish reared at high density were darker, more neophobic, less aggressive, less mobile and less likely to take risks than those reared at low density, and these effects were exacerbated when no cover was available. Thus, the reactive coping style shown by fish at high density was very different from the proactive coping style shown by fish at low density. Our findings provide novel insights into the plasticity of fish behaviour and the effects of aquaculture intensification on one of the world's oldest farmed and most invasive fish, and highlight the importance of considering context. Crowding could have a positive effect on the welfare of tilapia by reducing aggressive behaviour, but it can also make fish chronically stressed and more fearful, which could make them less invasive.

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“…MCH, an important neuropeptide that regulates pigment changes in fish [121], and is directly linked to fshb in our network, has previously been demonstrated to be upregulated in dominant Nile tilapia [122], where the melanophores of established dominant fish exhibit lower sensitivity to MCH application, suggesting a chronic effect of MCH activity that produces a brighter dominant fish. As with oxytocin, MCH is known for its regulatory role in LH secretion in mammals [123].…”

Section: Discussionmentioning

confidence: 99%

Identifying the Interaction of the Brain and the Pituitary in Social – and Reproductive – State of Tilapia by Transcriptome Analyses

Hollander-Cohen¹,

Meir²,

Shulman³

et al. 2022

Neuroendocrinology

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Introduction: As in all vertebrates, reproduction in fish is regulated by GnRH control on gonadotrophic hormones (GtH) activity. However, the neuroendocrine factors that promote GnRH and GtH activity are unknown. In Nile tilapia (Oreochromis niloticus), sexual activity and reproduction ability depend on social rank; only dominant males and females reproduce. Here, this characteristic of dominant fish allows us to compare brain and pituitary gene expression in animals that do and do not reproduce, aiming to reveal mechanisms that regulate reproduction. Methods: an extensive transcriptome analysis was performed, combining two sets of transcriptomes: a novel whole-brain and pituitary transcriptome of established dominant and subordinate males, together with a cell-specific transcriptome of LH and FSH cells. Pituitary incubation assay validated the direct effect of steroid application on chosen genes and GtH secretion. Results: in most dominant fish, as determined behaviorally, the gonadosomatic index was higher than in subordinate fish, and the leading upregulated pituitary genes were those coding for GtHs. In the brain, various neuropeptide genes, including isotocin, cholecystokinin, and MCH, were upregulated; these may be related to reproductive status through effects on behavior and feeding. In a STRING network analysis combining the two transcriptome sets, brain aromatase, highly expressed in LH cells, is the most central gene with the highest number of connections. In the pituitary incubation assay, testosterone and estradiol increased the secretion of LH and specific gene transcription. Conclusions: the close correlation between behavioral dominance and reproductive capacity in tilapia allows unraveling novel genes that may regulate the HPG axis, highlighting aromatase as the main factor affecting the brain and pituitary in maintaining a sexually active organism.

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Does MCH play a role on establishment or maintenance of social hierarchy in Nile tilapia?

Cited by 4 publications

References 28 publications

Density-dependent changes in neophobia and stress-coping styles in the world’s oldest farmed fish

Density-dependent changes in neophobia and stress-coping styles in the world’s oldest farmed fish

Density-dependent changes in neophobia and stress-coping styles in the world's oldest farmed fish

Identifying the Interaction of the Brain and the Pituitary in Social – and Reproductive – State of Tilapia by Transcriptome Analyses

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