Dopa-positive Cells Research Articles

Immunological changes in the intestines and skin after senna administration

Context: It has been reported that chronic sennoside use is associated with the development of melanosis coli, colonic adenoma, and/or carcinomas.Objectives: In this study, we investigated the immunological changes in the colon and skin after the administration of senna.Materials and methods: In this study, we investigated the colon and epidermis of C57/BL6j mice after a single administration of 10 mg/kg of senna [Cassia angustifolia (Caesalpiniaceae); 3, 6, 12, and 24 h after administration] and after repeated once per week administrations (on days 3, 5, 7, 14, and 21 of administration). The LD50 and ED50 of senna used in this experiment were 165 mg/kg and 13 g/kg, respectively.Results: We demonstrated that the DOPA-positive cells in the colon increased at 12 h after single administration and were further increased from at 5–28 d after repeated administration. We also studied the physiological changes of the small intestine using the charcoal meal test. We found that there was a tendency for peristalsis to be inhibited after repeated senna administration. In the epidermis, we investigated the number of Langerhans cells, because they are important immune cells of the skin. The number of these cells decreased, especially after repeated administration.Discussion and conclusion: The present findings suggested that it is necessary to pay attention to not only the intestine but also the skin, during long-term senna treatment.

Detection of dopa-positive cells in mouse ovaries in response to ocular exposure to ultraviolet B rays.

It is known that the levels of hormones secreted from the pituitary gland are increased by ultraviolet B (UVB) eye irradiation. The ovaries are affected by the hormones secreted from the pituitary gland. Therefore, we observed the influence of UVB eye irradiation on the ovaries. In this study, a 2.5 kJ/m(2) dose of UVB irradiation was delivered by a sunlamp to the eye or the ear of C57BL/6j female mice. Five days after UVB irradiation, we removed the ovaries. The plasma levels of α-melanocyte-stimulating hormone (α-MSH), adrenocorticotropic hormone (ACTH), and β-endorphin were increased 24 h after UVB irradiation of either the eye or the ear. The amounts of ACTH and α-MSH were decreased 5 days after UVB irradiation. However, the β-endorphin level 5 days after UVB eye irradiation did not decrease. In addition, UVB eye irradiation increased the expression of dopa-positive cells, tyrosinase, and dopa decarboxylase, and also increased the immunoreactivity of melanocortin-1 receptor in the ovaries. The dopamine content in the plasma was also increased. These results suggest that the melanin and dopamine systems of the ovary are affected by UVB eye irradiation, and the synthesized dopamine is maintained at high levels as β-endorphin.

Enhancing pigmentation via activation of A3 adenosine receptors in B16 melanoma cells and in human skin explants

A3 adenosine receptor, A3AR, belongs to the Gi proteins coupled receptors. Activation of A3AR by its agonist, IB-MECA, decreases cAMP and was expected to reduce melanin level. Unexpectedly, B16 melanoma cells exposed to IB-MECA increased melanin levels in a dose-dependent manner. Human skin explants exposed to IB-MECA showed an increase in DOPA positive cells and in melanin deposition in keratinocytes. The agonist induced AKT phosphorylation, leading to a rapid translocation of the transcription factor MiTF towards the nucleus. DOPA oxidase activity and melanin levels induced by IB-MECA were further enhanced by PD98509, an inhibitor ERK signalling pathway. Our study shows that IB-MECA decreases cAMP while inducing melanogenesis. The proposed mechanism involves activation of PI3K/AKT signalling pathway by β/γ subunits of the G protein coupled to A3AR. The increase in melanin level in human skin explants suggests that IB-MECA may be a potential candidate to the treatment of hypopigmentation of skin.

Ultraviolet‐A Irradiation to the Eye Modulates Intestinal Mucosal Functions and Properties of Mast Cells in the Mouse

We previously reported that topical irradiation of the eye by ultraviolet-B (UVB) activated hypothalamo-pituitary-adrenal axis (HPA-A) of the mouse to increase 3, 4-dihydroxyphenylalanine (DOPA)-positive melanocytes in the skin by an inducible nitric oxide synthase (iNOS)-dependent mechanism. This work demonstrates that irradiation of the eye by ultraviolet-A (UVA) specifically increased DOPA-positive cells in the mucosa of the jejunum and colon of C57BL/6J mice by some HPA- and iNOS-independent mechanism. UVA-induced increase in DOPA-positive cells in the intestine was inhibited by the administration of hexamethonium or prazosin plus propranolol, blockers for the sympathetic nervous system. UVA irradiation of the eye increased DOPA- and histidine decarboxylase (HDC)-positive cells in the intestinal mucosa of both C57BL/6J and WBB6F1/J mice but not in the mutant strain W/Wv of the latter that lack mast cells. UVA irradiation of the eye suppressed the intestinal peristalsis of control, hypophysectomized or iNOS(-/-) C57BL/6J mice by the mechanism that was inhibited by hexamethonium or prazosin plus propranolol. These observations suggest that UVA irradiation of the eye stimulated the sympathetic nervous system to increase the mucosal DOPA- and HDC-positive mast cells and suppressed the peristalsis of the small intestine of the mouse.

Clinical pathology observe of primary malignant melanoma of parotid gland

Objective To observe the clinical pathology form of primary malignant melanoma. Methods Specimens were observed by histopathology and immunohistopathologic (S-100, HMB-45, Male-A). Results Tumor islocated on the side, and infiltration of radiofrequent pushed its way to the edge of the Parotid gland tissue. the distribution of dispersoids tumor cells, there were sinusal-like vessel and a little fiber interstitialoma separated, tumor cells have multiformity, nuclear heterotype obvious, fringe cytoplasmic individual tumor cells and the tumor interstitialoma capsulelike brown yellow-brown pigment particles. Innunohistochemistry: The tumor cells were positive for S-100, HMB-45 and Amale-A, weak positive for NSE, Vimentin, but negative for LCA,CD15, CD30, Cytokeratin, EMA, Desmin, SMA, PLAP, Synapsin and Chromogranin A. Conclusion Primary malignant melanoma of the Parotid gland is extremely rare, its histogenesis was disputed, may be the origin of the parotid duct or even DOPA-positive cells in aciner. Key words: Parotid gland; Malignant melanoma; Clinical pathology

Increased alpha‐melanocyte‐stimulating hormone (α‐MSH) levels and melanocortin receptors expression associated with pigmentation in an NC/Nga mouse model of atopic dermatitis

Patients with a specific subtype of atopic dermatitis (AD) display particular patterns of pigmentation, such as ripple pattern pigmentation on the neck, pigmented macules on the lip and diffuse pigmentation. However, the mechanism underlying these patterns has not been determined. The purpose of our research is to investigate the factors influencing this type of pigmentation in AD. We observed that AD model mice (NC/Nga mice) displayed an increase in the number of 3, 4-dihydroxyphenylalanine (Dopa)-positive melanocytes in the epidermis and intestine (jejunum and colon) while in the inflammatory state. The plasma levels of alpha-melanocyte-stimulating hormone (alpha-MSH) and adrenocoticotropin (ACTH) also increased in NC/Nga mice with dermatitis. Furthermore, the expression of melanocortin receptor 5 and melanocortin receptor 1 (MC1R) increased in the skin, and melanocortin receptor 3 (MC3R) expression increased in the intestine. However, the changes in the Dopa-positive cells of conventional NC/Nga mice were not induced by treatment with either agouti (an MC1R antagonist) or agouti-related protein (an MC3R antagonist). These results indicate that the pigmentation of AD is related to increased levels of alpha-MSH, MC1R (in the skin) and MC3R (in the intestines).

Effects of Ultraviolet Light on Melanocyte Differentiation: Studies with Mouse Neural Crest Cells and Neural Crest‐derived Cell Lines

To evaluate the etiologic role of ultraviolet (UV) radiation in acquired dermal melanocytosis (ADM), we investigated the effects of UVA and UVB irradiation on the development and differentiation of melanocytes in primary cultures of mouse neural crest cells (NCC) by counting the numbers of cells positive for KIT (the receptor for stem cell factor) and for the L-3,4-dihydroxyphenylalanine (DOPA) oxidase reaction. No significant differences were found in the number of KIT- or DOPA-positive cells between the UV-irradiated cultures and the non-irradiated cultures. We then examined the effects of UV light on KIT-positive cell lines derived from mouse NCC cultures. Irradiation with UVA but not with UVB inhibited the tyrosinase activity in a tyrosinase-positive cell line (NCCmelan5). Tyrosinase activity in the cells was markedly enhanced by treatment with alpha-melanocyte-stimulating hormone (alpha-MSH), but that stimulation was inhibited by UVA or by UVB irradiation. Irradiation with UVA or UVB did not induce tyrosinase activity in a tyrosinase-negative cell line (NCCmelb4). Levels of KIT expression in NCCmelan5 cells and in NCCmelb4 cells were significantly decreased after UV irradiation. Phosphorylation levels of extracellular signal-regulated kinase 1/2 in cells stimulated with stem cell factor were also diminished after UV irradiation. These results suggest that UV irradiation does not stimulate but rather suppresses mouse NCC. Thus if UV irradiation is a causative factor for ADM lesions, it would not act directly on dermal melanocytes but may act in indirect manners, for instance, via the overproduction of melanogenic cytokines such as alpha-MSH and/or endothelin-1.

Fibronectin Combined with Stem Cell Factor Plays an Important Role in Melanocyte Proliferation, Differentiation and Migration in Cultured Mouse Neural Crest Cells

Stem cell factor (SCF) is essential to the migration and differentiation of melanocytes during embryogenesis because mutations in either the SCF gene, or its ligand, KIT, result in defects in coat pigmentation in mice. Using a neural crest cell (NCC) primary culture system from wild-type mice, we previously demonstrated that KIT-positive and/or L-3, 4-dihydroxyphenylalanine (DOPA)-positive melanocyte precursors proliferate following the addition of SCF to the culture medium. Extracellular matrix (ECM) proteins are considered to play a role in the migration and differentiation of various cells including melanocytes. We cultured mouse NCCs in the presence of SCF in individual wells coated with ECM; fibronectin (FN), collagen I (CLI), chondroitin sulphate, or dermatan sulphate. More KIT-positive cells and DOPA-positive cells were detected in the presence of SCF on ECM-coated wells than on non-coated wells. A statistically significant increase in DOPA-positive cells was evident in FN and CLI wells. In contrast, in the absence of SCF, few DOPA-positive cells and KIT-positive cells were detected on either the ECM-coated or non-coated wells. We concluded that ECM affect melanocyte proliferation and development in the presence of SCF. To determine the key site of FN function, RGDS peptides in the FN sequence, which supports spreading of NCCs, were added to the NCC culture. The number of DOPA-positive cells decreased with RGDS concentration in a dose-dependent fashion. Immunohistochemical staining revealed the presence of integrin alpha5, a receptor of RGDS, in NCCs. These results suggest the RGDS domain of FN plays a contributory role as an active site in the induction of FN function in NCCs. In addition, we examined the effect of FN with SCF on the NCC migration by measuring cluster size, and found an increase in size following treatment with FN.

Melanocyte reservoir in vitiligo.

Dopa-negative, inactive melanocytes, present in the middle portion of the hair follicle, but also in hair bulbs, have been reported as a source of pigment cells, when repopulation of epidermal melanocytes occurs. A melanocyte reservoir in these anatomical sites has been suggested. Our objective was to investigate the ability of the lower third of the hair follicle (hair bulb) to repigment achromic skin in vitiligo. Scalp hair bulbs were transplanted within leukodermic areas in 10 patients with vitiligo. Repigmentation around the grafts was suitable for evaluation in four cases. Dopa-positive (+) cells were seen in the epidermal basal cell layer of the repigmented areas. Although these findings were observed only in a few patients, they suggest that melanocytes from the implanted lower third portion of the hair follicle (hair bulb) act as a reservoir in this anatomic location and are able to migrate and repigment achromic areas in vitiligo.

Pigment cell pattern formation in amphibian embryos: A reexamination of the dopa technique

Neural crest-derived melanophores form species-specific patterns in the dermis of amphibian embryos. Melanophore patterns may be generated by one of two general mechanisms: pigment cell precursors disperse throughout the embryo, with melanophores differentiating in certain regions due to environmental cues, or melanoblasts may localize in different regions as a result of a hierarchy of tissue affinities. Both of these mechanisms have been proposed to be responsible for the dorso-ventral patterning of melanophores in Xenopus laevis. We have reexamined the distribution of melanoblasts in X. laevis and Taricha torosa using the dopa (3,4-dihydroxyphenyl-alanine)-staining technique. We have found that many of the dopa-positive cells identified as melanoblasts by some researchers are actually not derived from the neural crest: dopa-positive cells in T. torosa were identified in the transmission electron microscope to be either leukocytes or erythrocytes, in X. laevis dopa-positive cells are found between the ectoderm and somites where neural crest cells are not found, and X. laevis embryos surgically depleted of neural crest have dopa-staining patterns identical to control embryos. Melanoblasts are apparently not found in the ventralmost regions of early T. torosa and X. laevis embryos, providing additional evidence for the role of differential tissue affinities in directing the formation of embryonic pigment cell patterns.

Melanocyte autologous grafting for treatment of leukoderma

Patients with three types of leukoderma--vitiligo, idiopathic guttate hypomelanosis, and postinflammatory leukoderma--had successful repigmentation after transplantation of autologous melanocytes. The procedure was performed easily by producing blisters on normal skin and on depigmented lesions. Blisters were produced by suction or by freezing with liquid nitrogen. The roof of the blister from donor skin was grafted to the raw surface of the recipient site. Repigmentation was visible within 7 to 14 days. Direct immunofluorescence staining with bullous pemphigoid antibodies suggested that the separation of the epidermis from the dermis occurs within the lamina lucida. Histochemical studies confirmed the absence of dopa-positive cells in the areas of leukoderma prior to grafting. Melanocytes were present in the successful grafts.

Density of Dopa-Positive Melanocytes in Dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria, one of the hereditary diseases characterized by the presence of pigmented and hypopigmented spots on the extremities, was studied by the splitting dopa stain on the hypopigmented area. There were 190 +/- 58/mm2 dopa-positive cells, i.e. less than the normal value of the Japanese population. This suggests that the pigment anomaly in this disease may be due to the small number of melanocytes.

Melanophore differentiation inXenopus laevis, with special reference to dorsoventral pigment pattern formation

During the development of Xenopus laevis, after stage 26, a large number of dopa-positive cells were observed in the ventral region. Electron microscopic observations revealed that these cells became localized in the epidermal layer and contained premelanosomes. In cultured ventral skin, fully matured melanophores appeared. These results strongly suggest that a large number of melanoblasts are present in the ventral epidermis and remain there without final differentiation into melanized melanophores. Thus the positional difference of melanoblasts differentiation mainly contributes to dorsoventral pigment pattern formation of Xenopus laevis.

Genetic Basis of Three Mutant Color Varieties of Xiphophorus maculatus: The Gray, Gold and Ghost Platyfish

The olivaceous background coloration of the platyfish, Xiphophorus maculatus, results from the presence of micromelanophores interspersed among small xanthophores in the epidermis of the scales and from the arrangement of the micromelanophores in a reticular pattern in the dermis of the flank. Two autosomal loci, St and R, with two alleles each have been identified which control the presence or absence of these pigment cells. St - R - fish have the wild-type coloration. The St - r r genotype, gray lack the xanthophores, but the micromelanophore pattern is indistinguishable from that of St fish. Fish of genotype st st R are yellow all over. They are virtually free of micromelanophores in the scales and dermis, but the number of xanthophores is increased manyfold in the scales. The dermis and the perineural lining of the brain are densely and uniformly populated by xanthophores. By contrast, xanthophores are absent from these two tissues in the St fish. The double recessive fish, st st r r, have a whitish appearance, ghost, and lack micromelanophores and the background xanthophores throughout the integument. In st st R - and st st r r fish, melanophores are also absent from the perivascular lining of the blood vessels, the gill arches and the wall of the swim bladder. Neither the St nor the R locus have any detectable effect on the retinal pigment layer or on the melanophore pigmentation of the connective tissue sheath of the spinal cord. Dopa positive cells could be demonstrated in the scales and in the dermis of st st R - and in the scales of st st r r fish. The dermis of the double recessive was Dopa negative. The St locus has at best a minor effect on the expression of the macromelanophore patterns which are controlled by sex-linked genes. Similarly, the R locus has no effect on the expression of the sex-linked xanthophore and xantho-erythrophore patterns. The existence of several main lineages of pigment cells can be discerned in X. maculatus and the action of St and R loci are restricted to only one of these lines. The St locus of X. maculatus may be homologous to the B locus of Poecilia reticulata and the R locus of X. maculatus may be homologous to the R locus of P. reticulata and the Gr locus of Poeciliopsis viriosa. No gene homologous to the G locus of P. reticulata, which also effects the background melanophores and xanthophores, has been identified in X. maculatus.

Induction of active melanocytes in mouse skin by carcinogens: a new method for detection of skin carcinogens.

Application of potent skin carcinogens, such as 7,12-dimethylbenz[a]anthracene, 3-methylcholanthrene, benzo[a]pyrene and 4-nitroquinoline-1-oxide, induced numerous dihydroxyphenylalanine (dopa)-positive cells in the interfollicular epidermis of C57BL/6 mice in a dose- and time-dependent fashion. Chrysene, a weak skin carcinogen, and croton oil, a tumor promoter, also induced 3--4 times more dopa-positive cells than acetone. Liver carcinogens, such as 3'-methyl-4-dimethylaminoazobenzene and N-2-acetylaminofluorene, and non-carcinogenic aromatic hydrocarbons, such as anthracene, fluoranthene, fluorene and pyrene, did not induce increase in these cells. These results indicate that increase in the number of dopa-positive cells after application of chemicals is well correlated with the abilities of these compounds to induce skin carcinogenesis and suppress sebaceous glands.

Melanin and dopa-positive cells in the skin of tropical cattle.

Various histochemical and histological techniques were used to study the melanin and dopa-positive cell distribution in the skin of some tropical and temperate breeds of cattle in Nigeria. Melanin pigments were concentrated in the basal and lower spinous layers of the epidermis and in the hair cortex, follicle sheaths and papillae of the various breeds. In the White Fulani and N'Dama breeds, melanin pigments were however found in all layers of the epidermis. Dopa-positive cells (melanocytes) were observed in the epidermis, dermis and hair follicles; the distribution pattern varied among breeds, being copiously disposed in the basal epidermis and papillary dermis in the White Fulani and Muturu and, except in areas of thick epidermal ridges, scanty in the epidermis and dermis of the Friesian and N'Dama. Mast cell distribution pattern in the various breeds was similar to that of the dopa-positive cells. Peroxidase-positive cells were present in the basal epidermis and upper dermis of the Muturu, widespread in the subepidermal layer of the N'Dama and very scanty in the dermis of the White Fulani and Friesian. Acid phosphatase activity was intense in the granular layer of the Muturu and N'Dama breeds and also in the papillary dermis and hair follicles, whereas alkaline phosphatase-positive dendritic cells, and 'clear' cells were also observed in the basal and upper epidermis.

Dopa-positive cells and melanin in basal cell epithelioma (BCE).

In 47 out of 61 bce's, melanocytes were detectable with the aid of Dopa-reaction. In 24 of these cases, the percentage of tumour cells was less 5%, and in 23 it was more. The melanocytes preferred the periphery of the epithelial tumour formations. Only when the proportion of melanocytes exceeded 5% were they also to be found in the central parts of the tumours. Generally the melanocytes were more numerous in the upper parts of tumours, next to the epidermis. Our findings strengthen the opinion, that bce is a tumour of the primary hair germ.

Increase of melanocytes around malignant melanoma.

In split epidermal sheets with clinically normal appearance a quantitative study was carried out on dopa-positive cells in the vicinity of malignant melanomas. These data were then compared with the number of melanocytes found in the skin of the contralateral body side of the same patient. In the epidermis around superficial spreading melanoma and lentigo maligna melanoma, the number of dopa-positive cells was usually significantly higher than in the contralateral body side. On the other hand, no difference was generally found around nodular melanoma.

The Induction Of Melanogenesis By Ultraviolet Light In The Pigmentary System Of Rhesus Monkeys

Except for the face, eyelids, friction surfaces, and lips, the epidermis of the rhesus monkey contains no discernible melanocytes. After ultraviolet irradiation, however, dopa-positive dendritic cells appeared. With daily sequential irradiation, the number of histochemically demonstrable dopa-positive dendritic cells peaked after 30 exposures, then declined to a basal level which was maintained for the duration of the experiment (216 exposures or 43 weeks). Pigment cells can be restimulated by shading part of the irradiated area and then reirradiating after 3 months. While shaded, dopa-positive cells disappeared; but when reirradiated, they reappeared, increased, then declined again to a basal level. These melanocytes, unlike those in other primates, require high threshold levels of irradiation to produce a response, have a definite period during which they are active, and transfer very little melanin to the surrounding keratinocytes. Long-term ultraviolet irradiation has no discernible effect on dermal pigment-containing cells.

Hypopigmented Macules of Sun Exposed Skin in Xeroderma Pigmentosum. An Electron Microscopic Study

Patients with Xeroderma Pigmentosum (XP) frequently exhibit small, white hypopigmented spots on the parts of the body not exposed to the sun. These hypopigmented spots, 1–5 mm in diameter, appear early in the life. Punch biopsies were performed for electron microscopic studies and DOPA reaction. Melanocytes were either absent or occasionally found along the basal layer of the hypopigmented area; Langerhans cells were numerous; DOPA positive cells were rare or absent. Thus a vitiligo‐like syndrome is realized. In clinically normal skin, Langerhans cells were observed within the basal layer. These findings may help explain the clinical appearance of the white macules and the fact that the absence of pigment protection on sun exposed areas exposes the skin widely to UV radiation. It seems logical to propose that apart from the genetic enzymatic defect of XP, there is a genetic melanocytic abnormality leading to conditions which increase the general sensitivity to UV radiation.