Control de la ingesta alimentaria: rol del receptor 4 de melanocortina en el desarrollo de obesidad / Role of melanocortin receptor 4 in the control of food intake and the development of obesity

Arquate nucleus, a convergence site of peripheral and central signals, plays a fundamental role in the control of food intake. Orexigenic neurons that secrete neuropeptide Y (NPY) and Agouti-related peptide (AgRP) and anorexigenic neurons secreting Pro-opiomelanocortin (POMC) are involved in this action. Both groups of neurons respond to peripheral signals such as insulin and leptin and are reciprocally inhibited. alpha Type melanocyte stimulating hormone (alphaMSH), liberated by POMC neurons, reduces food intake activating melanocortin receptor 4 (MC4R), located in second order neurons of the paraventricular nucleus. NPY/AgRP antagonize the effects of this peptide on MC4R receptors,maintaining an inhibitory tone on áMHS liberation, mediated by the activation of gabaergic receptors of POMC neurons. The study of these mechanisms will allow the development of new medications, especially MC4R agonists, to reduce nutrient intake...

Mechanisms regulating melanogenesis* / Mecanismos reguladores da melanogênese

Skin pigmentation is an important human phenotypic trait whose regulation, in spite of recent advances, has not yet been fully understood. The pigment melanin is produced in melanosomes by melanocytes in a complex process called melanogenesis. The melanocyte interacts with endocrine, immune, inflammatory and central nervous systems, and its activity is also regulated by extrinsic factors such as ultraviolet radiation and drugs. We have carried out a review of the current understanding of intrinsic and extrinsic factors regulating skin pigmentation, the melanogenesis stages and related gene defects. We focused on melanocyte-keratinocyte interaction, activation of melanocortin type 1 receptor (MC1-R) by peptides (melanocyte-stimulating hormone and adrenocorticotropic hormone) resulting from proopiomelanocortin (POMC) cleavage, and mechanisms of ultraviolet-induced skin pigmentation. The identification and comprehension of the melanogenesis mechanism facilitate the understanding of the pathogenesis of pigmentation disorders and the development of potential therapeutic options.

A pigmentação da pele é um importante traço fenotípico do ser humano mas apesar dos recentes avanços a sua regulação não está ainda totalmente esclarecida. O pigmento melanina é produzido nos melanossomas pelos melanócitos, num processo complexo designado por melanogénese. O melanócito interatua com os sistemas endócrino, imunitário, inflamatório e nervoso central e a sua atividade é também regulada por fatores extrínsecos como a radiação ultravioleta e fármacos. Fizemos uma revisão do conhecimento atual sobre os fatores intrínsecos e extrínsecos reguladores da pigmentação cutânea, etapas da melanogénese e defeitos genéticos relacionados. Fizemos enfoque na interação melanócito-keratinócito, na ativação do receptor da melanocortina tipo 1 (MC1-R) pelos péptidos (hormona estimuladora do melanócito e hormona adrenocorticotrófica) resultantes da clivagem da proopiomelanocortina (POMC) e mecanismos da pigmentação induzida pela radiação ultravioleta. A identificação e compreensão dos mecanismos reguladores da pigmentação cutânea facilitam o conhecimento dos mecanismos patogénicos dos distúrbios da pigmentação e o desenvolvimento de potenciais opções terapêuticas.

The effect of melanocortin (Mc3 and Mc4) antagonists on serotonin-induced food and water intake of broiler cockerels

The current study was designed to examine the effects of intracerebroventricular injections of SHU9119 [a nonselective melanocortin receptor (McR) antagonist] and MCL0020 (a selective McR antagonist) on the serotonin-induced eating and drinking responses of broiler cockerels deprived of food for 24 h (FD24). For Experiment 1, the chickens were intracerebroventricularly injected with 2.5, 5, and 10 microg serotonin. In Experiment 2, the chickens received 2 nmol SHU9119 before being injected with 10 microg serotonin. For Experiment 3, the chickens were given 10 microg serotonin after receiving 2 nmol MCL0020, and the level of food and water intake was determined 3 h post-injection. Results of this study showed that serotonin decreased food intake but increased water intake among the FD24 broiler cockerels and that these effects occurred in a dose-dependent manner. The inhibitory effect of serotonin on food intake was significantly attenuated by pretreatment with SHU9119 and MCL0020. However, the stimulatory effect of serotonin on water intake was not altered by this pretreatment. These results suggest that serotonin hypophagia and hyperdipsia were mediated by different mechanisms in the central nervous system, and that serotonin required downstream activation of McRs to promote hypophagia but not hyperdipsia in the FD24 chickens.

Diagnosis and Treatment of Unilateral Maxillary Sinus Hypoplasia

Research of cellular toxic effect to Hep-2 of recombinant toxin MSH-Ang / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To study the cytotoxicity of recombinate toxin MSH-Ang to Hep-2.@*METHOD@#The depurated MSH-Ang were applied in cytotoxicity experiment, and the growth inhibiting action to laryngeal carcinoma cell Hep-2 were observed.@*RESULT@#Recombination protein inhibited the growth of laryngeal carcinoma cell Hep-2, and its inhibiting action enhanced and corpuscular mortality rate increased along with the concentration increasing.@*CONCLUSION@#Recombinant toxin MSH-Ang can not only take special effect in tumors with high MSHR, but also target to many other popular tumors.

Effect of Tribulus terrestris extract on melanocyte-stimulating hormone expression in mouse hair follicles / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of Tribulus terrestris extract on melanocyte stimulating hormone (MSH) expression in C57BL/6J mouse hair follicles, and investigate the role of Tribulus terrestris extract in activation, proliferation, epidermal migration of dormant hair follicle melanocytes.</p><p><b>METHODS</b>The aqueous extract of Tribulus terrestris was administered orally in specific pathogen-free C57BL/6J mouse at the daily dose equivalent to 1 g/1 kg in adult human, and the expression and distribution of MSH in the mouse hair follicles was observed with immunohistochemistry.</p><p><b>RESULTS</b>The positivity rate of MSH expression in the hair follicle melanocytes was 75% in mice treated with the extract, significantly higher than the rate of only 18.75% in the control group (P<0.01).</p><p><b>CONCLUSION</b>The aqueous extract of Tribulus terrestris can significantly increase MSH expression in the hair follicle melanocytes by activating tyrosinase activity and promoting melanocyte proliferation, melanine synthesis, and epidermal migration of dormant melanocytes.</p>

Electron microscopical studies of pituitary gland of male hamsters under the effect of estrogen treatment

The ultrastructure of the normal pars intermedia of male hamsters showed two types of cells. The light cells were numerous, regular in shape with rounded or elongated nuclei have different size of secretory granules and were considered as a source of melanocyte stimulating hormone [MSH]. The dark cells were less in number, showed less display of secretory granules and were concerned with colloid production. Some of the dark cells showed foot like processes and irregular nuclear membranes. Progressive changes in the cell organelles were observed in the pars intermedia cells after long term of estrogen treated hamsters over the studied period

Changes in Incidence of Infantile Transient Methemoglobinemia Associated with Infectious Diarrhea during 1989-1999 in Kyungnam Province

PURPOSE: Infantile transient methemoglobinemia(ITM) may develop in association with infectious diarrhea without exposure to any toxic oxidizing agents. We observed that the number of ITM associated with infectious diarrhea have increased at the Gyeongsang National University Hospital (GNUH), located in the western area of Kyungnam province during the last 4 years. To determine whether this phenomenon was similarily observed in the rest of Kyungnam province, we studied the incidence of ITM associated with infectious diarrhea over the last 10 years in Kyungnam Provine. METHODS: All cases with ITM associated with infectious diarrhea were enrolled for this study from Ulsan Donggang Hospital(UDH), Masan Samsung Hospital(MSH), and GNUH over the last 10 years. Their medical records were reviewed retrospectively. RESULTS: Six and twelve cases were identified at UDH and GNUH, respectively, while none were identified at MSH. All the infants were less than 2 months of age and prosented with severe mucoid diarrhea with metabolic acidosis, high C-reactive protein(CRP) concentrations and/or leukocytosis with shift to left. Twelve cases were identified to reveal stool leukocytosis at UGH and GNUH. Eight cases had histories of ingestion of well water. Nine cases occurred in the spring season (May, April, March). Before 1996, a total of six cases occurred at UDH. But one case in 1990 and eleven cases occurred during 1996-99 at GNUH. The increase in the incidence of ITM associated with infectious diarrhea paralleled the increase in the infectious diarrhea in infants during 1996-99 at GNUH. CONCLUSION: The increased in the incidence of ITM associated with infectious diarrhea during the last4 years at GNUH was not observed in other parts of Kyungnam province. Infectious diarrhea, severe acidosis, severe dehydration, cow milk feeding, the spring season and ingestion of well water were considered to be important associateion factors of ITM.

The Effect of alpha-MSH on the Morphologic Changes, Survival, and Melanization of Cultured Human Melanocytes / 대한피부과학회지

BACKGROUND: The effects of melanocyte stimulating hormone(MSH) on the integument of many species, including mammals, are well known. The significance of MSH as a physiological regulator of cutaneous pigmentation in humans is still controversial. Although the administration of MSH results in skin darkening, previous reports suggest that cultured human melanocytes are relatively unresponsive to this peptide. This may be related to the conditions under which the melanocytes were cultured. OBJECTIVE: The purpose of this study was to investigate the effect of alpha-MSH on the morphological changes, survival, and melanization of cultured human melanocytes in a basal medium without any mitogen. METHOD: We examined the morphological changes, number and melanin contents of cultured human melanocytes in control(absence of alpha-MSH) and experimental groups(presence of 10(-8) M, 10(-7) M, and 10(-6) M alpha-MSH). RESULTS: 1. There were no significant morphological changes of cells between the control and experimental groups after 24, 48, and 72 hours' culture. The number and length of melanocyte dendrites showed no significant difference between the groups after 24, 48, and 72 hours' culture. 2. The number of melanocytes in the experimental groups(presence of 10(-7) M, and 10(-6) M alpha-MSH) were significantly higher than the number of melanocytes in control group after 72 hours culture(p<0.05). This effect of alpha-MSH was dose-related. 3. The melanin contents slightly increased in the experimental groups. The significant difference between the groups was showed in the presence of 10(-8) M alpha-MSH. CONCLUSIONS: alpha-MSH has no effect on the morphology, but increases the survival of cultured human melanocytes and has a melanogenic effect.