Ein bisher kaum bekanntes gliogenes Melanin des Gehirns („Cerebellares Gliamelanin“)

Summary Melanosis of the dentate nucleus is an extremely rare condition in which pigment is formed within the cytoplasm and cytoplasmic processes of astrocytes in the dentate nucleus and the cerebellar granular cell layer. The pigment occurs as irregular polygonal structures of rather homogeneous appearance unlike granular neuromelanin located within neurons of the substantia nigra. The diameter of these pigment masses may reach 30 m or more. Their absorption of visible light increases steadily towards the shorter wavelengths, and the material is virtually opaque in the violet and ultraviolet region, resembling melanin in this respect. Since the absorption spectrum described by Rabl exhibited a small peak at 525 nm, he regarded the pigment as the hemoglobin derivative pentdyopent. We were unable, however, to confirm this observation. On X-ray diffraction the pigment produced a sharp reflex at 4.93 å as did synthetic melanin prepared from dopamine (but not melanin prepared from serotonin). These observations supported the assumption made by others based on histochemical evidence, that the pigment in the dentate nucleus may belong to the group of melanins. Presumably the glial melanin somehow arises from the metabolic pathway leading to DOPA. An astrocytic site of melanin formation other than in the cerebellum has not been previously described, and this melanin differs in appearance from the granular neuromelanin found in neurons in the substantia nigra. Thus cerebellar glial melanin contrasts with neuromelanin of the substantia nigra both in its site of formation and in its morphology.The underlying cause of the glial melanin formation in the cerebellum is not known. There are six cases in the world literature, 5 females and 1 male, ranging in age from 58 to 103 years.Involutional alterations in metabolism related to endocrine factors may possibly play an important part. To the best of our knowledge cerebellar melanosis is of no clinical relevance.

     

Ultrastructural characterization of the distribution of melanin and epidermal macrophages in photodamaged skin

We examined the characteristics of melanin distribution, the possible mechanisms underlying the histological incontinence of pigment, and the significance of epidermal macrophages in photodamaged skin. We used electron microscopy to compare and quantitate melanin distribution in various types of cells and structures, to qualitatively observe associations of melanin granules with melanophages, and to examine morphological differences of epidermal macrophages in sun-exposed versus sun-protected facial skin. Melanin-containing cells (such as Langerhans cells) and melanin-containing structures (such as colloid bodies) in photodamaged skin were more numerous than in sun-protected skin, in proportion to differences in melanocyte density and in epidermal melanin content. Although the precise mechanism(s) of histological incontinence of pigment in photoaging skin appear to be very complicated, it is certainly one of the morphological hallmarks of photodamaged facial skin, and the degeneration of keratinocytes (noted by their electron-lucent properties), a feature characteristic of photoaging, contributes to that process. Furthermore, the increased numbers of epidermal macrophages in sun-exposed skin may be associated with photoaging processes (probably through their phagocytic function) as well as alterations of the cutaneous immune system.     

Melanocytic Schwa n no ma in the Spinal Canal

A case of melanocytic schwannoma, a rare form of schwannian neoplasm, in the thoracolumbar spinal canal of a 52-year-old man is presented. Histopathologically, the tumor was composed of irregularly interlacing spindle-shaped cells showing cystic degeneration, with occasional pigmented tumor cells. The tumor cells showed a low degree of nuclear pleomorphism without any mitotic figures. These histological features were considered to be consistent with a benign schwannian tumor showing pigmentation. Most of the pigments were considered to be melanin histochemically and immunohistochemically. According to the pathological features of the present tumor and those described previously in the literature, the neoplastic Schwann cells were assumed to have melanogenetic capacity, and the concept of the common neural crest origin of Schwann cells and melanocytes appeared to be demonstrated in the present tumor. Acta Pathol Jpn 41: 685–688, 1991.     

杂色和白色豚鼠听反应阈及耳蜗血管纹细胞增殖活性的差异

目的研究杂色和白色成年豚鼠正常听反应阈及耳蜗血管纹细胞增殖活性的差异。方法用听觉诱发电位仪分别测定杂色和白色豚鼠40Hz听觉相关电位(40HzAERP)及听性脑干反应(ABR)阈值;用免疫组化法检测两种豚鼠耳蜗血管纹增殖细胞核抗原(PCNA)表达的差异。结果杂色和白色豚鼠耳蜗血管纹中间细胞PCNA染色均呈阳性,但前者PCNA的表达显著强于后者;两种豚鼠的听反应阈值无显著性差异。结论正常杂色和白色成年豚鼠血管纹中间细胞均具有增殖能力,但前者的增殖能力显著高于后者,不过这种差异并不造成两种豚鼠的正常听反应阈有明显差异。     

Immunohistochemical localization of a melanin concentrating hormone-like peptide in the rat brain

Using antisera generated in rabbits against salmon melanin concentrating hormone (MCH) coupled to human thyroglobulin, the distribution of MCH-like immunoreactivity was mapped throughout the rat central nervous system. The distribution of MCH-like immunoreactivity in rat brain is unique and different from the distribution of other neuropeptides. MCH-like immunoreactive perikarya and fibers are predominant in the posterior hypothalamic area, mostly in the medial forebrain bundle-lateral hypothalamic area subzona incerta and the perifornical area. Cell bodies are located mainly in the medial forebrain bundle and in proximity to well defined hypothalamic nuclei. Fibers are seen throughout the rat brain in all neocortical areas, the neostriatum and the amygdala, in the diencephalon in most hypothalamic nuclei, the habenula, the mamillary body and very dense in the medial forebrain bundle and just ventral to the zona incerta ("subzona incerta"). In the mesencephalon there are fibers in the central gray; in the pons-medulla fibers are contained in the dorsal and ventral parabrachial nuclei; in the tegmental area ventral to the fourth ventricle; in the spinal trigeminal area, the substantia gelatinosa and the reticular nuclei. In the spinal cord there are more fibers in the dorsal than in the ventral horn. The posterior pituitary also contained few MCH-like fibers. It is suggested that a peptide similar, but not identical, to salmon MCH is present in the rat central nervous system.     

Kojic Acid Peptide: A New Compound with Anti-Tyrosinase Potential

BackgroundKojic acid was used for decades in the cosmetic industry as an antimelanogenic agent. However, there are two major drawbacks of Kojic acid, one is cytotoxicity and second are instability on storage. These limitations led the scientist to synthesize the active Kojic acid peptides.ObjectiveIn the present study, we synthesize and investigate the effect of five Kojic acid peptides to overcome the limitation of Kojic acid.MethodsThe peptide was analyzed and purified by high-performance liquid chromatography and matrix-assisted laser desorption ionization time of flight mass spectroscopy. Further, the tyrosinase activities of the Kojic acid and Kojic acid peptides were compared. The toxicity was measured and the melanin content is recorded in B16F10 mouse melanoma cells.ResultsMaximum tyrosinase activity was measured by Kojic acid peptides. Therefore, Kojic acid peptides were subjected to melanin assay and cytotoxicity assay and finally the stability of the Kojic acid peptide was measured.ConclusionIt was observed that this newly synthesized Kojic acid peptide is stable and potent to inhibit the tyrosinase activity and melanin content of B16F10 mouse melanoma cells without exhibiting cell toxicity. Together, these preliminary results suggest that a further exploration is being needed to establish Kojic acid peptide as antimelanogenic agent.     

甘草黄酮对黑素细胞生物学作用的比较

目的 研究甘草黄酮对体外培养的鼠黑素瘤B16细胞及人表皮黑素细胞的生物学作用。方法 建立正常人表皮黑素细胞培养体系和培养黑素瘤B16细胞,添加甘草黄酮后,测定黑素细胞活力、酪氨酸酶活性以及黑素含量的变化,并与氢醌的作用结果进行比较。结果 两种黑素细胞对药物的反应有所不同。与氢醌比较,甘草黄酮具有较强的浓度依赖性黑素合成抑制作用,且对黑素细胞的细胞毒性较小。结论 用体外培养的人黑素细胞作为研究对象与鼠黑素瘤B16细胞比较具有一定的差异;甘草黄酮可作为一种安全有效的皮肤美白物质。     

黑素生成过程中黄芩的调节作用

目的 :观察中药黄芩对B16F小鼠黑素瘤细胞增殖、黑素含量、酪氨酸酶活性的影响。方法 :采用体外培养的小鼠B16F黑素瘤细胞株 ,用MTT法测定细胞增殖情况 ;NaOH裂解法测定黑素合成 ;多巴氧化法测定酪氨酸酶活性。结果 :在浓度为 0 .0 1～ 1.0 g·L-1时 ,黄芩可浓度依赖性促进B16F细胞增殖 ,酪氨酸酶活性和黑素含量 ,以 1.0 g·L-1为最佳。结论 :黄芩可促进细胞增殖 ,激活酪氨酸酶活性 ,提高黑素含量 ,从而为黄芩治疗白癜风的临床应用提供了实验依据。