Plasticity of melanotrope cell regulations in <i>Xenopus laevis</i>

Roubos, Eric W.; Wijk, Diane C.W.A. van; Kozicz, Tamás; Scheenen, Wim J.J.M.; Jenks, Bruce G.

doi:10.1111/j.1460-9568.2010.07526.x

Cited by 25 publications

(38 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In amphibians, α ‐MSH secretion is mediated by a simple neuronal circuit in which RGCs project to dopaminergic suprachiasmatic melanotrope inhibitory neurons (SMINs) that innervate cholinergic α ‐MSH‐releasing cells (melanotropes) (Roubos et al., ). As the SMIN‐mediated step in the circuit is inhibitory, we hypothesized that eye removal or melanopsin inhibition by AA92593 would de‐repress the signal and induce α ‐MSH release, darkening the embryo.…”

Section: Resultsmentioning

confidence: 99%

“…Several external stimuli inhibit or stimulate hypothalamic a-MSH secretion from melanotropes, including temperature (Tonosaki et al, 2004), fasting (Calle et al, 2006) and light, as occurs during background adaptation (Kramer et al, 2003). Each stimulus triggers specific neuronal circuits, with the circuit that mediates background adaptation in Xenopus consisting of synapse-mediated inhibition of melanotropes by neurons of the SCN, the SMINs (for review see Roubos et al, 2010). SMINs in animals adapted to a white background secrete inhibitory neurotransmitters, while those in black background-adapted animals do not (Tuinhof et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

“…A possible systemic mediator of the effects of melanopsin inhibition on skin pigmentation is a-MSH: (i) a-MSH is a powerful inducer of pigmentation in amphibians (Roubos et al, 2010), and in humans (Abdel-Malek et al, 1995); (ii) blinded Xenopus increase the release of hypothalamic a-MSH, and dark induction of pigmentation is blocked completely in hypophysectomized animals (Imai and Takahashi, 1971); (iii) a-MSH levels are regulated by dark/white adaptation, and the onset of a-MSH biosynthesis in the pars intermedia pituitary correlates with when retinal circuits become light sensitive (Ayoubi et al, 1991;Bertolesi et al, 2014;Corstens et al, 2005;Kramer et al, 2003).…”

Section: Skin Pigment Aggregation Induced By Melanopsin Inhibition Ismentioning

confidence: 99%

“…Light energy is transduced into an intracellular signal that triggers pigment movement within the melanophore (dispersion /aggregation), to induce colour changes in the integument (Oshima, 2001). The 'secondary colour response' initiates in the eyes and is controlled by the neural and/or endocrine system (Roubos et al, 2010). The photosensitive molecule melanopsin, Opn4, discovered initially in dermal melanophores of Xenopus laevis (Provencio et al, 1998), participates in the movement of pigment granules in vitro (Isoldi et al, 2005;Rollag et al, 2000), suggesting that Opn4 functions in the Significance In vertebrates, melanopsin-based photosensitivity activates retinal circuits that mediate physiological responses, such as circadian rhythm entrainment, sleep responses and the pupillary light reflex.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Bertolesi

Hehr

McFarlane

2015

Pigment Cell Melanoma Res

View full text Add to dashboard Cite

How skin colour adjusts to circadian light/dark cycles is poorly understood. Melanopsin (Opn4) is expressed in melanophores, where in vitro studies suggest it regulates skin pigmentation through a 'primary colour response' in which light photosensitivity is translated directly into pigment movement. However, the entrainment of the circadian rhythm is regulated by a population of melanopsin-expressing retinal ganglion cells (mRGCs) in the eye. Therefore, in vivo, melanopsin may trigger a 'secondary colour response' initiated in the eye and controlled by the neuro-endocrine system. We analysed the expression of opn4m and opn4x and melanin aggregation induced by light (background adaptation) in Xenopus laevis embryos. While opn4m and opn4x are expressed at early developmental times, light-induced pigment aggregation requires the eye to become functional. Pharmacological inhibition of melanopsin suggests a model whereby mRGC activation lightens skin pigmentation via a secondary response involving negative regulation of alpha-melanocyte-stimulating hormone (α-MSH) secretion by the pituitary.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Skin Pigment Aggregation Induced By Melanopsin Inhibition Ismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Bertolesi

Hehr

McFarlane

2015

Pigment Cell Melanoma Res

View full text Add to dashboard Cite

show abstract

“…Under neuroendocrine control, melanosomes promote physiological color changes according to the state of aggregation or dispersion in the cytoplasm of dermal melanophores (Castrucci et al, 1984;Aspengren et al, 2009;Roubos et al, 2010). Melanomacrophages also respond to the synthetic melanocyte-stimulating hormone analogue (NDP-MSH).…”

Section: Introductionmentioning

confidence: 99%

Sex hormones change visceral pigmentation in Eupemphix nattereri (Anura): effects in testicular melanocytes and hepatic melanomacrophages

et al. 2015

View full text Add to dashboard Cite

Melanomacrophages and melanocytes are able to modify pigment intensity on the body surface as a response to temperature change, hibernation, hypoxia, infection, oxidative stress and exogenous use of hormones. This study evaluated the effect of the sex hormones 17β-estradiol and testosterone cypionate on the hepatic melanomacrophages and testicular melanocytes of Eupemphix nattereri under hyperestrogenic and hyperandrogenic conditions, eight days after daily hormonal administration as well as after a 15-day recovery period. Animals were injected subcutaneously with 17β-estradiol, testosterone cypionate or the carrier medium (as control). Histological analysis was used to examine the effect of the treatments. The results show that sex hormones altered the pigmentation of hepatic melanomacrophages and testicular melanocytes. Both liver melanomacrophages and testicular melanocytes in E. nattereri males displayed increased pigmentation after testosterone treatment, while estradiol decreased liver pigmentation only. This study describes, for the first time, the effects of sex hormones on visceral pigmentation of anura, showing the responsiveness of melanocytes and melanomacrophages to sex hormones.

show abstract

Expression patterns of Pax6 and Pax7 in the adult brain of a urodele amphibian, Pleurodeles waltl

Joven

Morona

González

et al. 2013

J of Comparative Neurology

View full text Add to dashboard Cite

Expression patterns of Pax6, Pax7, and, to a lesser extent, Pax3 genes were analyzed by a combination of immunohistochemical techniques in the central nervous system of adult specimens of the urodele amphibian Pleurodeles waltl. Only Pax6 was found in the telencephalon, specifically the olfactory bulbs, striatum, septum, and lateral and central parts of the amygdala. In the diencephalon, Pax6 and Pax7 were distinct in the alar and basal parts, respectively, of prosomere 3. The distribution of Pax6, Pax7, and Pax3 cells correlated with the three pretectal domains. Pax7 specifically labeled cells in the dorsal mesencephalon, mainly in the optic tectum, and Pax6 cells were the only cells found in the tegmentum. Large populations of Pax7 cells occupied the rostral rhombencephalon, along with lower numbers of Pax6 and Pax3 cells. Pax6 was found in most granule cells of the cerebellum. Pax6 cells also formed a column of scattered neurons in the reticular formation and were found in the octavolateral area. The rhombencephalic ventricular zone of the alar plate expressed Pax7. Dorsal Pax7 cells and ventral Pax6 cells were found along the spinal cord. Our results show that the expression of Pax6 and Pax7 is widely maintained in the brains of adult urodeles, in contrast to the situation in other tetrapods. This discrepancy could be due to the generally pedomorphic features of urodele brains. Although the precise role of these transcription factors in adult brains remains to be determined, our findings support the idea that they may also function in adult urodeles.

show abstract

Plasticity of melanotrope cell regulations in Xenopus laevis

Cited by 25 publications

References 31 publications

Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Melanopsin photoreception in the eye regulates light‐induced skin colour changes through the production of α‐MSH in the pituitary gland

Sex hormones change visceral pigmentation in Eupemphix nattereri (Anura): effects in testicular melanocytes and hepatic melanomacrophages

Expression patterns of Pax6 and Pax7 in the adult brain of a urodele amphibian, Pleurodeles waltl

Contact Info

Product

Resources

About