Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is evidence that alpha-melanocyte-stimulating hormone (alpha-MSH) has immunomodulatory and anti-inflammatory actions within the brain. In this study, we tested whether these actions are due to inhibition of the synthesis of nitric oxide (NO) and prostaglandins induced by lipopolysaccharide (LPS). Since melanocortin subtype MC4 receptor has been detected in the hypothalamus, we investigated the effect of central administration of alpha-MSH and HS024 (a selective MC4 receptor antagonist) on the gene expression of inducible, neuronal and endothelial NO synthase (iNOS, nNOS and eNOS) and on cyclooxygenase (COX-1 and COX-2) expression in the mediobasal hypothalamus (MBH) of LPS-treated male Wistar rats. Peripheral administration of LPS (250 microg/rat, 3 h) induced iNOS and COX-2 gene expression in the MBH. This stimulatory effect was reduced by alpha-MSH (3 nmol/rat) injected 30 min before LPS. alpha-MSH and HS024 (1 nmol/rat) alone had no effect on iNOS and COX-2 expression. The action of alpha-MSH on LPS-induced iNOS and COX-2 mRNA levels was not observed in the presence of HS024, suggesting that MC4-R may be involved in the modulatory effect of alpha-MSH. None of these treatments produced any modifications in nNOS, eNOS and COX-1 expression in MBH. The increase in serum corticosterone levels induced by LPS was attenuated by alpha-MSH. Both LPS and alpha-MSH decreased serum LH and prolactin levels. HS024 failed to modify the inhibitory effects of LPS and alpha-MSH on prolactin release but reverted the effect of LPS on LH secretion, indicating that MC4-R activation may be involved in the effects of alpha-MSH on LH secretion in male rats. When we examined the in vitro effect of LPS (10 microg/ml) and LPS plus interferon-gamma (IFN-gamma, 100 ng/ml) on iNOS expression in MBH, an increase in iNOS mRNA levels was observed only in the presence of LPS + IFN-gamma. This stimulatory effect was attenuated in the presence of alpha-MSH (5 microM), which by itself had no effect. No changes were found in nNOS, eNOS, COX-1 or COX-2 expression. These results indicate that alpha-MSH reduces the induction of iNOS and COX-2 gene expression at the hypothalamic level during endotoxemia and suggest that endogenous alpha-MSH may exert an inhibitory tone on iNOS and COX-2 transcription via MC4 receptors acting as a local anti-inflammatory agent within the hypothalamus.
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PMID:Alpha-melanocyte-stimulating hormone through melanocortin-4 receptor inhibits nitric oxide synthase and cyclooxygenase expression in the hypothalamus of male rats. 1521 20

The melanocortin system is involved in regulation of food intake and energy balance. Melanocyte-stimulating hormone (alpha-MSH) is an endogenous melanocortin receptor (MC-R) agonist. It acts on MC3/4 receptors to reduce appetite and to increase energy expenditure. The production of alpha-MSH is reduced during food deprivation, but MC4-R density is increased. The net effect of reduced alpha-MSH production and increased receptor level is not clear. To address this question, responses of ventromedial hypothalamic (VMH) neurons to melanotan II (MTII; a synthetic analogue of alpha-MSH) were recorded in brain slices from fed and food-deprived rats. Responses to the highest dose MTII were observed in 61% of VMH neurons from fed rats but only 33% of VMH neurons from food-deprived rats. To assess a possible mechanism by which responsiveness to melanocortins is diminished even though receptor number is augmented during fasting, we examined the effect of agouti gene-related peptide (AGRP), an endogenous MC-R antagonist that stimulates food intake. The synthesis of AGRP increases during fasting. AGRP significantly reduced VMH responsiveness to MTII. Additionally, AGRP by itself evoked neuronal responses, in contrast to synthetic MC-R antagonists. AGRP (1 nM) induced a predominant inhibitory effect on VMH neurons in food-deprived rats but not in fed rats. In the presence of AGRP, MTII induced a significant inhibition of neuronal activity in deprived rats, but not in fed rats. Inhibition of VMH neurons reduces energy expenditure and the satiety signal. These findings suggest that although food deprivation increases MC4-R density, it nevertheless reduces the effectiveness of melanocortins on VMH neurons, possibly by the involvement of AGRP.
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PMID:Food deprivation decreases responsiveness of ventromedial hypothalamic neurons to melanocortins. 1526 29

The central melanocortin system is critical in the regulation of appetite and body weight, and leptin exerts its anorexigenic actions partly by increasing hypothalamic proopiomelanocortin (POMC) expression. The POMC-derived peptide alpha-melanocyte-stimulating hormone (alphaMSH) is a melanocortin 4 receptor agonist, and its potency in reducing energy intake is strongly increased by N-acetylation. The reason for the higher biological activity of N-acetylated alphaMSH (Act-alphaMSH) compared with that of N-desacetylated alphaMSH (Des-alphaMSH) is unclear, and regulation of acetylation by leptin has not been investigated. We show here that total hypothalamic alphaMSH levels are decreased in leptin-deficient ob/ob mice and increased in leptin-treated ob/ob and C57BL/6J mice. The increase in total alphaMSH occurred as soon as 3 h after leptin injection and was entirely due to an increase in Act-alphaMSH. Consistent with this observation, leptin rapidly induced the enzymatic activity of a N-acetyltransferase in the hypothalamus of mice. In 293T cells expressing the melanocortin 4 receptor, Act-alphaMSH is far more potent than Des-alphaMSH in stimulating cAMP accumulation, an effect caused by a dramatically increased stability of Act-alphaMSH. Moreover, Des-alphaMSH is rapidly degraded in the hypothalamus after intracerebroventricular injection in rats and was less potent in inhibiting energy intake. The results suggest that leptin activates a N-acetyltransferase in POMC neurons, leading to increased hypothalamic levels of Act-alphaMSH. Due to its increased stability, this posttranslational modification of alphaMSH may play a critical role in leptin action via the central melanocortin pathway.
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PMID:N-acetylation of hypothalamic alpha-melanocyte-stimulating hormone and regulation by leptin. 1528 May 41

The human melanocortin 4 receptor (MC4r) was successfully expressed in Sf9 cells using the baculovirus infection system. N- and C-terminally His-tagged receptors generated B(max) values of 14 and 23 pmol receptor/mg membrane protein, respectively. The highest expression level obtained with the C-terminally His-tagged MC4r corresponded to 0.25mg active receptor/litre culture volume. Addition of a viral signal peptide at the N-terminus of the His-tagged MC4r did not improve the expression level. Confocal laser microscopy studies revealed that both the N- and C-terminally tagged MC4r did not accumulate intracellularly and were mainly located in the plasma membrane. The recombinant receptors showed similar affinity for the agonist NDP-MSH (Kd = 11 nM) as to MC4r expressed in mammalian cells. Functional coupling of the highest expressed C-terminal tagged receptor to endogenous Galpha protein was demonstrated through GTPgammaS binding upon agonist stimulation of the receptor. Ki values for the ligands MTII, HS014, alpha-, beta-, and gamma-MSH are comparable to the values obtained for MC4r expressed in mammalian cells.
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PMID:Overexpression and functional characterisation of the human melanocortin 4 receptor in Sf9 cells. 1535 70

Maintaining a stable body weight set-point is assumed to rely on a homeostatic central nervous system (CNS) regulation of body fat with the particular involvement of hypothalamic pathways. The peripheral adiposity signals insulin and leptin convey information on the amount of energy stored as body fat to the arcuate nucleus of the hypothalamus, where anabolic/orexigenic and catabolic/anorexigenic pathways interact to regulate food intake and energy expenditure. One of the most prominent orexigenic messengers is neuropeptide Y (NPY), whereas melanocortins, including alpha-melanocyte-stimulating hormone (alpha-MSH), are essential for inducing anorexigenic effects. The melanocortin receptor 4 (MC4-R) plays the most important role in mediating catabolic effects of alpha-MSH. In this review, we present a series of own studies on NPY, insulin and MSH/ACTH4-10, an MC4-R agonist. The studies were all based on the intranasal route of administration which enables a direct access of the peptides to hypothalamic functions. NPY acutely attenuated electrocortical signs of meal-related satiety. Prolonged intranasal administration of insulin as well as of MSH induced weight loss in healthy human subjects. However, overweight subjects did not lose body fat after MSH administration. The results corroborate in humans the significance of all three messengers for the central nervous regulation of adiposity and might contribute to the future development of medical strategies against body-weight-related disorders.
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PMID:Manipulating central nervous mechanisms of food intake and body weight regulation by intranasal administration of neuropeptides in man. 1550 91

Obesity is increasing in severity and prevalence in the United States and represents a major public health issue. No effective pharmacologic treatment leading to sustained weight loss currently exists. The growing interest in the regulation of food intake stems from the current drug treatments for obesity, almost all of which interfere with the monoamine system. Our knowledge of potential interactions between the orexigenic and anorexigenic pathways is limited and fragmented, making the development of targeted drug therapy for obesity difficult. The present review of the interaction of neuropeptides and monoamines emphasizes the complexity of the central mechanisms that regulate feeding behavior. Two main systems are implicated in food intake regulation: neuropeptide Y (NPY) and pro-opiomelanocortin. alpha-Melanocyte-stimulating hormone is a tridecapeptide cleaved from pro-opiomelanocortin that acts to inhibit food intake. The predominant NPY orexigenic receptors are NPY-Y1 and NPY-Y5, and the two anorexigenic melanocortin receptors involved in hypothalamic food intake control are MC3-R and MC4-R. Both neuropeptides interact with monoamines in the hypothalamus to control physiologic states such as hunger, satiation, and satiety. Serotonin suppresses food intake and body weight, acting mainly through the serotonin 1B receptor. Dopamine regulates hunger and satiety by acting in specific hypothalamic areas, through the D1 and D2 receptors. Noradrenaline activation of alpha1- and beta2-adrenoceptors decreases food intake, and stimulation of the alpha2-adrenoceptor increases food intake. A better understanding of the detailed mechanisms underlying the pathogenesis of hyperphagia and hypophagia is needed to develop new therapeutic approaches to obesity.
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PMID:Neuropeptide Y, alpha-melanocyte-stimulating hormone, and monoamines in food intake regulation. 1572 58

Metabolic, cognitive, and environmental factors processed in the forebrain modulate food intake by changing the potency of direct controls of meal ingestion in the brain stem. Here, we behaviorally and anatomically test the role of the hypothalamic proopiomelanocortin (POMC) system in mediating some of these descending, indirect controls. Melanotan II (MTII), a stable melanocortin 4 receptor (MC4R) and melanocortin 3 receptor (MC3R) agonist injected into the fourth ventricle near the dorsal vagal complex, potently inhibited 14-h food intake by decreasing meal size but not meal frequency; SHU9119, an antagonist, increased food intake by selectively increasing meal size. Furthermore, MTII injected into the fourth ventricle increased and SHU9119 tended to decrease heart rate and body temperature measured telemetrically in freely moving rats. Numerous alpha-melanocyte-stimulating hormone-immunoreactive axons were in close anatomical apposition to nucleus tractus solitarius neurons showing c-Fos in response to gastric distension, expressing neurochemical phenotypes implicated in ingestive control, and projecting to brown adipose tissue. In retrograde tracing experiments, a small percentage of arcuate nucleus POMC neurons was found to project to the dorsal vagal complex. Thus melanocortin signaling in the brain stem is sufficient to alter food intake via changing the potency of satiety signals and to alter sympathetic outflow. Although the anatomical findings support the involvement of hypothalamomedullary POMC projections in mediating part of the descending, indirect signal, they do not rule out involvement of POMC neurons in the nucleus tractus solitarius in mediating part of the direct signal.
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PMID:Brain stem melanocortinergic modulation of meal size and identification of hypothalamic POMC projections. 1595 61

Alpha melanocyte-stimulating hormone (alpha-MSH) is an agonist at the melanocortin 3 (MC3-R) and melanocortin 4 (MC4-R) receptors. Alpha-MSH stimulates corticosterone release from rat and human adrenal cells. Patients with Cushing's syndrome have elevated levels of serum alpha-MSH. Agouti related protein (AgRP) is an endogenous antagonist at the MC3-R and MC4-R and is expressed in the rat adrenal cortex. AgRP antagonises alpha-MSH-induced corticosterone release from rat and bovine adrenal cells. This suggests that AgRP may have an inhibitory paracrine role in the adrenal gland. We measured adrenal AgRP mRNA expression and circulating AgRP in 2 patients with Cushing's syndrome and controls. Adrenal AgRP mRNA expression and plasma AgRP were higher in the patients with Cushing's syndrome compared to controls. Plasma AgRP in the patients with Cushing's syndrome following bilateral adrenalectomy and hydrocortisone replacement were similar to the levels seen in controls. Our results suggest that AgRP may have a novel inhibitory paracrine role in the human adrenal gland.
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PMID:Agouti related protein (AgRP) is upregulated in Cushing's syndrome. 1632 Jan 60

The proinflammatory cytokine interleukin-1beta (IL-1beta) influences neuroendocrine activity and produces other effects, including fever and behavioral changes such as anxiety. The melanocortin neuropeptides, such as alpha-melanocyte-stimulating hormone (alpha-MSH), antagonize many actions of IL-1, including fever, anorexia and hypothalamic-pituitary-adrenal (HPA) axis activation through specific melanocortin receptors (MC-R) in the central nervous system. The objective of the present study was to establish the effect of MSH peptides on IL-1beta-induced anxiety-like behavior and the melanocortin receptors involved. We evaluated the effects of intracerebroventricular (i.c.v.) administration of IL-1beta (30 ng) and melanocortin receptor agonists: alpha-MSH, an MC3/MC4-R agonist (0.2 microg) or gamma-MSH, an MC3-R agonist (2 microg) or HS014, an MC4-R antagonist (2 microg), on an elevated plus-maze (EPM) test. Injection of IL-1beta induced an anxiogenic-like response, as indicated by reduced open arms entries and time spent on open arms. The administration of alpha-MSH reversed IL-1beta-induced anxiety with co-administration of HS014 inhibiting the effect of alpha-MSH. However, the associated treatment with gamma-MSH did not affect the anxiety response to IL-1beta. These data suggest that alpha-MSH, through central MC4-R can modulate the anxiety-like behavior induced by IL-1beta.
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PMID:Anxiety-like behavior induced by IL-1beta is modulated by alpha-MSH through central melanocortin-4 receptors. 1632 4

Hypothalamic neuronal histamine and its H(1) receptor (H(1)-R) form part of the leptin signaling pathway in the brain, and regulate body weight and adiposity by affecting food intake and energy expenditure. The pro-opiomelanocortin (POMC)-melanocortin 4 receptor (MC4-R) is also important for leptin signaling. We investigated whether and how these two neuronal pathways interact in regulating energy metabolism. From studies of agouti yellow (A(y)/a) obese mice, a model of a defect in POMC-MC4-R signaling, we concluded that the histamine H(1)-R signaling pathway is independent of the POMC-MC4-R complex in regulating food intake, energy metabolism, and adiposity.
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PMID:The neuronal histamine H(1) and pro-opiomelanocortin-melanocortin 4 receptors: independent regulation of food intake and energy expenditure. 1634 92


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