Dynamics of background adaptation in Xenopus laevis: Role of catecholamines and melanophore-stimulating hormone

Zoest, I.D. van; Heijmen, P.S.; Cruijsen, Peter M. J. M.; Jenks, Bruce G.

doi:10.1016/0016-6480(89)90028-2

Cited by 58 publications

(28 citation statements)

References 15 publications

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“…The antiserum used for the aM SH radio immunoassay cross-reacts for 100% with des-, mono-and di-acetyl aM SH (Vaudry et al, 1978), and was used in a final dilution of 1:60,000. Immunocomplexes were precipitated by 7.5 % (w/v) polyethylene glycol and 2.5 % (w/v) bovine serum albumin (Zoest et al, 1989). The detection limit was 25.2 pg/ml sample.…”

Section: Physiological Parametersmentioning

confidence: 99%

Background adaptation and water acidification affect pigmentation and stress physiology of tilapia, Oreochromis mossambicus

Salm

Spanings

Gresnigt

et al. 2005

General and Comparative Endocrinology

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The ability to adjust skin darkness to the background is a common phenomenon in fish. The hormone a-melanophore stimulating hormone (aMSH) enhances skin darkening. In Mozambique tilapia, Oreochromis mossambicus L., aMSH acts as a corticotropic hormone during adaptation to water with a low pH, in addition to its role in skin colouration. In the current study, we investigated the responses of this fish to these two environmental challenges when it is exposed to both simultaneously. The skin darkening of tilapia on a black background and the lightening on grey and white backgrounds is compromised in water with a low pH, indicating that the two vastly different processes both rely on aMSH -regulatory mechanisms.If the water is acidified after 25 days of undisturbed background adaptation, fish showed a transient pigmentation change but recovered after two days and continued the adaptation of their skin darkness to match the background. Black backgrounds are experienced by tilapia as more stressful than grey or white backgrounds both in neutral and in low pH water. A decrease of water pH from 7.8 to 4.5 applied over a twoday period was not experienced as stressful when combined with background adaptation, based on unchanged plasma pH and plasma aMSH and Na levels. However, when water pH was lowered after 25 days of undisturbed background adaptation, particularly aMSH levels increased chronically. In these fish, plasma pH and Na levels had decreased, indicating a reduced capacity to maintain ion-homeostasis, implicating that the fish indeed experience stress. We conclude that simultaneous exposure to these two types of stressor has a lower impact on the physiology of tilapia than subsequent exposure to the stressors. * Cover Letter

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Section: Physiological Parametersmentioning

confidence: 99%

Background adaptation and water acidification affect pigmentation and stress physiology of tilapia, Oreochromis mossambicus

Salm

Spanings

Gresnigt

et al. 2005

General and Comparative Endocrinology

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“…Dilutions of rainbow trout (Oncorhynchus mykiss) plasma were compared with the N-ac-/0-END( 1-8) standard curve. The a-MSH antibody used has been described previously (33). It was raised against a-MSH, but fully recognizes des-acetylated-and diacetylated a-MSH.…”

Section: Assaysmentioning

confidence: 99%

Endorphin and MSH in concert form the corticotropic principle released by tilapia (Oreochromis mossambicus; Teleostei) melanotropes

1995

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diacetyl-tt-MSH. Evidence is presented that the noteworthy corticotropic potency of this HPLC fraction, previously attributed to diacetyl-tt-MSH, results from END and MSH acting in a coordinated fashion. Confinement stress had no effect on plasma N-ac-/?-END immunoreactivity, but led to a decrease in plasma or-MSH levels. Therefore, it seems unlikely that the corticotropic action of the peptides regulates the elevation of cortisol production that takes place during confinement, but it may play a role during other forms of stress that are known to activate the melanotropes.

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“…The details of the assay have been reported earlier [13]. Bound and free label were separated using the polyethylene glycol precipitation method.…”

Section: Methodsmentioning

confidence: 99%

Dual Action of GABA<sub>A</sub> Receptors on the Secretory Process of Melanotrophs of <i>Xenopus laevis</i>

Jenks

Koning²,

Valentijn³

et al. 1993

Neuroendocrinology

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The effects of GABA_a receptor activation on the secretion of α-melanocyte-stimulating hormone (α-MSH) from the superfused pars intermedia of the amphibian Xenopus laevis wereexamined. The GABA_a receptor agonist isoguvacine inhibited secretion of α-MSH from the pars intermedia, an action completely antagonized by the chloride channel blocker picrotoxin. Isoguvacine stimulated secretion from picrotoxin-treated tissue. Both effects were blocked by the GABA_A receptor antagonist bicuculline, indicating that it is a specific action via the GABA_A receptor. We conclude that, besides the inhibitory chloride channel, there is a stimulatory signaling property associated with the GABA_A receptor. Isoguvacine stimulated the production of c-AMP, an action that was not blocked by picrotoxin. This suggests that the stimulatory mechanism of the GABA_A receptor involves, directly or indirectly, the generation of c-AMP.

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Dynamics of background adaptation in Xenopus laevis: Role of catecholamines and melanophore-stimulating hormone

Cited by 58 publications

References 15 publications

Background adaptation and water acidification affect pigmentation and stress physiology of tilapia, Oreochromis mossambicus

Background adaptation and water acidification affect pigmentation and stress physiology of tilapia, Oreochromis mossambicus

Endorphin and MSH in concert form the corticotropic principle released by tilapia (Oreochromis mossambicus; Teleostei) melanotropes

Dual Action of GABA<sub>A</sub> Receptors on the Secretory Process of Melanotrophs of <i>Xenopus laevis</i>

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