Morphologic Changes of Zebrafish Melanophore after Intense Pulsed Light and Q-Switched Nd:YAG Laser Irradiation

BACKGROUND: Recently, the pulse-in-pulse mode of intense pulsed light (IPL) has been used increasingly for the treatment of melasma. OBJECTIVE: To observe the morphologic changes in the melanophore in adult zebrafish after irradiation with conventional and pulse-in-pulse IPL and Q-switched Nd:YAG (QSNY) laser. METHODS: Adult zebrafish were irradiated with conventional and pulse-in-pulse mode of IPL. The conditions for conventional IPL were 3 mJ/cm², 560 nm filter, and pulse widths of 7, 20, and 35 msec. The pulse-in-pulse conditions were 3 mJ/cm² and on-time 1/off-time 2. The QSNY laser was used with the settings of 1,064 nm, 0.4 J/cm², a 7 mm spot size, and one shot. Specimens were observed using a light microscope, a transmission electron microscope (TEM), a scanning electron microscope (SEM) and a confocal microscope. RESULTS: After conventional IPL irradiation with a 7 msec pulse width, melanophore breakage was observed using light microscopy. Under TEM, irradiation with conventional IPL for 7 msec and pulse-in-pulse IPL induced melanophore thermolysis with vacuolization. However, changes in the melanophore were not observed with 35 msec IPL. Under SEM, unlike the control and QSNY groups, IPL-irradiated zebrafish showed finger-like fusion in the protein structure of scales. Specimens examined by a confocal microscope after conventional IPL irradiation showed a larger green-stained area on TUNEL staining than that after pulse-in-pulse mode IPL irradiation. CONCLUSION: Zebrafish irradiated with long pulse-IPL showed no morphologic changes using light microscopy, while morphological changes in melanophores were evident with use of TEM. Pulse-in-pulse mode IPL caused less damage than conventional IPL.

The expression of melanopsin and clock genes in Xenopus laevis melanophores and their modulation by melatonin

Vertebrates have a central clock and also several peripheral clocks. Light responses might result from the integration of light signals by these clocks. The dermal melanophores of Xenopus laevis have a photoreceptor molecule denominated melanopsin (OPN4x). The mechanisms of the circadian clock involve positive and negative feedback. We hypothesize that these dermal melanophores also present peripheral clock characteristics. Using quantitative PCR, we analyzed the pattern of temporal expression of Opn4x and the clock genes Per1, Per2, Bmal1, and Clock in these cells, subjected to a 14-h light:10-h dark (14L:10D) regime or constant darkness (DD). Also, in view of the physiological role of melatonin in the dermal melanophores of X. laevis, we determined whether melatonin modulates the expression of these clock genes. These genes show a time-dependent expression pattern when these cells are exposed to 14L:10D, which differs from the pattern observed under DD. Cells kept in DD for 5 days exhibited overall increased mRNA expression for Opn4x and Clock, and a lower expression for Per1, Per2, and Bmal1. When the cells were kept in DD for 5 days and treated with melatonin for 1 h, 24 h before extraction, the mRNA levels tended to decrease for Opn4x and Clock, did not change for Bmal1, and increased for Per1 and Per2 at different Zeitgeber times (ZT). Although these data are limited to one-day data collection, and therefore preliminary, we suggest that the dermal melanophores of X. laevis might have some characteristics of a peripheral clock, and that melatonin modulates, to a certain extent, melanopsin and clock gene expression.

Alpha1 and alpha2 adrenoceptor mediated melanosome aggregatory responses in vitro in Oreochromis mossambica (Peters) melanophores.

Effects of specific and non-specific adrenoceptor agonists and antagonists were examined on the isolated scale melanophores of O. mossambica in physiological Ringer solution. The responses were recorded as melanophore size index. It was observed that adrenaline, nor-adrenaline, phenylpropanolamine, clonidine and phenylepherine induced melanosome aggregation in a dose-dependent manner. Denervation of the fish melanophores increased the sensitivity of the melanophores to adrenaline but not to nor-adrenaline. Phentolamine (3.55 x 10(-5) M), prazosin (2.38 x 10(-5) M) and yohimbine (2.821 x 10(-5) M) significantly inhibited the aggregatory responses of the fish melanophores to adrenaline, nor-adrenaline, clonidine and phenylepherine. The blocking effect of yohimbine was significantly higher than that of prazosin. It is concluded that the effect of adrenaline is directly mediated through the receptors and alpha2 adrenoceptors are predominantly involved in the aggregatory responses of this fish melanophores, while alpha1 adrenoceptors presence has been indicated.

Evidence for presence of GABA-ergic receptor mediated dispersion in isolated scale melanophores of a carp, Cirrhinus mrigala Ham.

Effects of GABA-ergic agonists and antagonists were examined on the melanophores of a carp C. mrigala in vitro. GABA and baclofen both induced concentration - related dispersion in fish melanophores. Denervation of the melanophores by reserpine treatment potentiated the sensitivity of the melanophores to GABA. While denervation by cooling treatment inhibited the sensitivity of the melanophores to GABA, atropine, bicuculline and pentylenetetrazole all inhibited the dispersal responses of the melanophores induced by higher concentrations of GABA. 5-aminovaleric acid also significantly inhibited the dispersion of the melanophores induced either by GABA or baclofen. It is concluded that GABA-ergic agonist induced dispersal responses in C mrigala melanophores are mediated through specific GABA receptors. The presence of both GABAA and GABAB receptors in this fish melanophores has been indicated.

Responses of isolated scale melanophores of a fresh water carp, Cirrhinus mrigala (Ham.) to zidovudine.

Zidovudine (AZT) induced concentration related aggregation in C. mrigala melanophores. Denervated melanophores failed to respond to AZT. Specific and nonspecific alpha adrenoceptor antagonists completely blocked the responses of fish melanophores to AZT. Histamine and prostaglandin antagonists also inhibited aggregation of the melanophores induced by AZT. The results suggest that AZT may release a mixture of neurotransmitter like substances, which cause the aggregation of this fish melanophores.

Effect of histaminergic drugs on integumental melanophores of adult Bufo melanostictus.

Histamine and 2-methyl histamine caused dose-dependent aggregation of melanophores in toad B. melanostictus. The effects were effectively antagonised by mepyramine, a specific H1 histamine receptor antagonist, and metiamide a specific H2 receptor antagonist. On the other, hand 4-methyl histamine, a specific H2 receptor agonist dispersed the melanophores. The results suggest that adult Bufo melanophores have H1 histamine receptors which mediate melanophore aggregation, however, dispersion of melanophores may be controlled by undifferentiated histamine receptors of H2 type.

Mechanism of histamine induced dispersal response in the isolated web melanophores of a frog, Rana tigerina (Daud.).

Effects of histamine and specific H1, H2 receptor agonists have been investigated on the isolated web skin melanophores of the frog, R. tigerina. Histamine, 2-methyl-histamine and 4-methyl-histamine all induced dose dependent dispersion in the frog melanophores. Reserpine treatment of the frog skin, either in vivo, or in vitro potentiated the dispersal response of the frog skin melanophores elicited by histamine. Histamine induced dispersal responses in the frog integumentary melanophores were partially blocked by mepyramine and ranitidine. Atropine failed to inhibit the dispersal response in any degree. Propranolol partially inhibited the dispersion of frog melanophores induced by histamine and 2-methyl-histamine. However, propranolol completely blocked the dispersal response of the mealnophores to 4-methyl-histamine. It is suggested that histamine induced dispersion in the frog skin melanophores in vitro is mediated partially through specific H1, H2 and beta adrenergic receptors.

Control of melanosome movements in isolated skin melanophores of a catfish Clarias batrachus (Linn.).

Adrenergic and cholinergic receptors have been studied in isolated skin melanophores of a catfish Clarias batrachus. Catecholamines induced a strong aggregatory effect on the melanophores. Melanosome aggregation induced by adrenaline and noradrenaline was partially blocked by alpha adrenergic receptor blockers and a beta receptor blocker. Cholinomimetic drugs aroused a significant dispersion of melanophroes. Atropine effectively blocked the dispersal, responses of melanophores to acetylcholine and carbachol, while, hexamethonium blocked the nocotine induced dispersal responses of the melanophores.

Effect of histaminergic drugs on tail melanophores of tadpole, Bufo melanostictus.

The H1 and H2 receptor agonist histamine caused a powerful aggregation of B. melanostictus tail melanophores, which was completely blocked by metiamide, a specific H2 receptor antagonist, while mepyramine an H1 receptor blocker partially blocked the aggregating response. The strong melanin aggregating effect of 4-methyl histamine a specific H2 receptor agonist and its complete blockade by metiamide further supports the conclusion that there exists a dominant population of H2 type of histamine receptors along with sparse population of H1 receptor on the tail melanophores of the toad, which mediate centripetal movement of melanin granules within the pigment cells leading to blanching of the animal.

Evidence for melanin concentrating hormone (MCH) receptors mediating melanosome aggregation in Labeo melanophores.

Melanin concentrating hormone (MCH: 5 x 10(-12)-5 x 10(-8) M) induced a concentration related, rapid and reversible pigment aggregation in innervated melanophores of Labeo rohita. In inducing melanosome aggregation MCH was found to be 10(4) times more potent than norepinephrine. Experiments employing phentolamine and propranolol suggest that MCH acts through its own specific receptors on the melanophores unrelated to adrenoceptors. MCH was able to aggregate the melanosomes even in the absence of extracellular Ca2+.

Dermatosis cenicienta: presentación de cinco observaciones / Ashy dermatosis: a report of five patients

Se presentan 5 observaciones de dermatosis cenicienta en tres hombres y dos mujeres, con edades que oscilan entre 30 y 54 años, evolución entre tres meses y 17 años y crecimiento progresivo. En ninguno hubo antecedentes de consumo de drogas antiparasitarias, vitaminas o antecedentes de infecciones , inflamaciones, inmunizaciones ni exposición al sol por largas horas. La histopatología fue típica en todos ellos, tanto en las porciones centrales como en los bordes activos. El tratamiento con crioterapia parece tener algún efecto beneficioso, pero necesitamos ensayarlo en más casos.

The sympathetic neuro-melanophore transmission in a fresh-water Indian major carp, Labeo rohita (Ham.).

Adrenaline was effective in aggregating the melanosomes both in innervated as well as denervated melanophores. Isotonic KCl could induce pigment aggregation only in innervated melanophores. Adrenaline- and K+-induced pigment aggregation response in these melanophores was blocked by phentolamine: propranolol failed to do so. It is suggested that the chromatic nerves in the fish, Labeo rohita are adrenergic and via post-synaptic alpha-adrenoceptors, control the melanosome aggregation.

The Infuluences of Sympathomimetic Amines on Melanophores of the Frog Skin / 대한피부과학회지

The chromatic activity and potency of various sympathomimetic amines were examined in the normal frogs using the Hogben and Slome Index as a simple method for measuring melanophore responses. All the sympathomimetic amines tested in this experiment exhibited the marked aggregation of melanophores. Among these amines, the order of potency in producing the melanophoreaggregation was catecholethylamine derivatives (epinephrine and isoproterenol) monohydroxyphenylethylamine derivative (tyramine) with exception of phenylephrine>nonhydroxyphenyletyhlamine derivatives (ephedrine and propadrine). Of catecholethylamine derivatives, thc melanophore-aggregating activity of epinephrine was more potent than that of isoproterenol. On the other hand, phenylephrine belong to the monohydroxyphenylethylamine derivatives was the least potent agent than the other amines tested.