Role of hypothalamic neuropeptide Y and orexigenic peptides in anorexia associated with experimental colitis in the rat.
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Neuropeptide Y (NPY) is thought to play a crucial role in the normal hypothalamic response to starvation. After a period of food restriction, increased release of NPY induces hunger and hyperphagia, and helps to restore body weight to its set point. Persistent anorexia in rats with experimental colitis implies failure of this adaptive feeding response. In vivo NPY release and regional hypothalamic NPY concentrations were measured in rats with trinitrobenzenesulphonic acid (TNBS)-induced colitis, healthy controls and animals pair-fed to match the food intake of the colitic group. Food intake in the colitic group was assessed after administration of NPY and two other potent orexigenic peptides: melanin-concentrating hormone (MCH) and hypocretin (orexin-A). Food intake was decreased by 30-80% below control values for 5 days in the colitic rats. In both the pair-fed and colitic groups, release of NPY in the paraventricular nucleus was significantly increased compared with free-feeding controls. Intraventricular or intrahypothalamic administration of NPY, MCH or hypocretin elicited a feeding response in healthy controls, but not in the colitic group. In summary, animals with TNBS-colitis and anorexia show an appropriate increase in hypothalamic NPYergic activity. However, the failure of NPY and other orexigenic peptides to increase feeding in the colitic group indicates suppression of feeding, either by inhibition of a common downstream hypothalamic neuronal pathway or by induction of one or more potent anorexigenic agents. (+info)
Uremic anorexia: a consequence of persistently high brain serotonin levels? The tryptophan/serotonin disorder hypothesis.
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Anorexia is a frequent part of uremic syndrome, contributing to malnutrition in dialysis patients. Many factors have been suggested as responsible for uremic anorexia. In this paper we formulate a new hypothesis to explain the appetite disorders in dialysis patients: "the tryptophan/serotonin disorder hypothesis." We review current knowledge of normal hunger-satiety cycle control and the disorders described in uremic patients. There are four phases in food intake regulation: (1) the gastric phase, during which food induces satiety through gastric distention and satiety peptide release; (2) the post absorptive phase, during which circulating compounds, including glucose and amino acids, cause satiety by hepatic receptors via the vagus nerve; (3) the hepatic phase, during which adenosine triphosphate (ATP) concentration is the main stimulus inducing hunger or satiety, with cytokines inhibiting ATP production; and (4) the central phase, during which appetite is regulated through peripheral (circulating plasma substances and neurotransmitters) and brain stimuli. Brain serotonin is the final target for peripheral mechanisms controlling appetite. High brain serotonin levels and a lower serotonin/dopamine ratio cause anorexia. Plasma and brain amino acid concentrations are recognized factors involved in neurotransmitter synthesis and appetite control. Tryptophan is the substrate of serotonin synthesis. High plasma levels of anorectics such as tryptophan (plasma and brain), cholecystokinin, tumor necrosis factor alpha, interleukin-1, and leptin, and deficiencies of nitric oxide and neuropeptide Y have been described in uremia; all increase intracerebral serotonin. We suggest that brain serotonin hyperproduction due to a uremic-dependent excess of tryptophan may be the final common pathway involved in the genesis of uremic anorexia. Various methods of ameliorating anorexia by decreasing the central effects of serotonin are proposed. (+info)
Molecular mechanisms in the brain involved in the anorexia of branched-chain amino acid deficiency.
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The anterior piriform cortex (APC) of the rat is thought to be the site of indispensable amino acid (IAA) chemosensation in the brain. The branched-chain amino acids, including leucine, are among the IAA that are recognized in the APC. The behavioral outcome of IAA deficiency is an anorectic response. The specific transduction mechanisms by which IAA deficiency and repletion activate the APC are not fully understood, but clearly phosphorylation of proteins, increases in intracellular calcium, and expression of the immediate early gene c-fos, which are among the earliest events occurring after the initial drop in the concentration of the limiting IAA, cause stimulation in the APC. Subsequently, several neurotransmitter systems, including those for norepinephrine, GABA, serotonin, dopamine and nitric oxide, are activated in the APC of rats that have consumed an IAA-imbalanced diet. These systems appear to modulate the output cells from the APC, glutamatergic pyramidal cells that send neural signals to activate subsequent relays in the brain. Ultimately, the feeding circuits of the brain carry out the anorectic response. Continued consumption of a diet containing an IAA imbalance causes a conditioned taste aversion to the diet in all animals that have been studied. Such learning involves synaptic reorganization, requiring both degradation and synthesis of protein, along with alterations in genomic activity. (+info)
A disease resembling inclusion body disease of boid snakes in captive palm vipers (Bothriechis marchi).
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Between April 1998 and June 1999, 8 palm vipers (Bothriechis marchi) were diagnosed with a disease similar to inclusion body disease (IBD) of boids. Six palm vipers were captive bred, and 2 were wild caught. All of the vipers were adults at the time of death. Three palm vipers were found dead with no premonitory clinical signs, and 5 had anorexia plus possibly 1 of the following clinical signs: regurgitation, paresis, and dehydration. Histologically, all snakes had intracytoplasmic, round to oval, single to multiple eosinophilic inclusion bodies in hepatocytes and renal tubular epithelial cells. Inclusion bodies were distributed among other organs with varying frequency. Common concurrent histologic lesions were urate nephrosis, septic thrombi, and hepatocellular degeneration. Ultrastructurally, inclusions had features similar to inclusions in boid snakes with IBD. (+info)
Fumonisin B(1) is hepatotoxic and nephrotoxic in milk-fed calves.
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Fumonisins are a group of mycotoxins that alter sphingolipid biosynthesis and induce leukoencephalomalacia in horses and pulmonary edema in pigs. Experimental administration of fumonisin induces hepatotoxicity in all species, including cattle, as well as nephrotoxicity in rats, rabbits, and sheep. We investigated the hepatotoxicity and nephrotoxicity of fumonisin B(1) to calves. Ten milk-fed male Holstein calves aged 7 to 14 days were instrumented to obtain blood and urine. Treated calves (n = 5) were administered fumonisin B(1) at 1 mg/kg, iv, daily and controls (n = 5) 10 ml 0.9% NaCl, iv, daily until euthanized on day 7. Fumonisin B(1)-treated calves were lethargic and had decreased appetite from day 4 onward, serum biochemical evidence of severe liver and bile duct injury, and impaired hepatic function. Treated calves also had biochemical evidence of renal injury that functionally involved the proximal convoluted tubules. Sphinganine and sphingosine concentrations in liver, kidney, lung, heart, and skeletal muscle were increased in treated calves. Sphinganine, but not sphingosine, concentration was increased in brains of treated calves. In fumonisin B(1)-treated calves, hepatic lesions were characterized by disorganized hepatic cords, varying severity of hepatocyte apoptosis, hepatocyte proliferation, and proliferation of bile ductular cells. Renal lesions in treated calves consisted of vacuolar change, apoptosis, karyomegaly, and proliferation of proximal renal tubular cells, as well as dilation of proximal renal tubules, which contained cellular debris and protein. This is the first report of fumonisin B(1)-induced renal injury and organ sphingolipid alterations in cattle. (+info)
High-dose progestins for the treatment of cancer anorexia-cachexia syndrome: a systematic review of randomised clinical trials.
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BACKGROUND: The aim of the present study was to summarise evidence from scientific studies on cancer anorexia-cachexia syndrome in order to assess and highlight the efficacy of high-dose progestins (megestrol acetate and medroxyprogesterone acetate) compared with placebo in patients with hormone-independent tumors. MATERIALS AND METHODS: A systematic review of published randomised clinical trials was carried out by an extensive electronic and hand search through databases, relevant journals and books, congress, proceedings, reference lists, without any language or year of publication restriction. The research was conducted by two independent operators who collected the data in a form specifically designed for this review. Among the several possible outcomes, appetite and body weight were chosen. RESULTS: Fifteen randomised clinical trials (more than 2000 patients) were retrieved for the review. There was a statistically significant advantage for high-dose progestins as regards improved appetite: pooled odds ratio (OR) = 4.23, 95% confidence interval (CI): 2.53-7.04. Although the effect of high-dose progestins on body weight was less impressive, statistical significance was also reached for this outcome: pooled OR = 2.66, 95% CI: 1.80-3.92. Treatment morbidity was very low, due to the brief period of the treatment in most of the studies. CONCLUSIONS: The effects of high-dose progestins on appetite and body weight were clearly demonstrated. However, further studies are undoubtedly warranted to investigate other aspects of progestin activity, especially as regards dosage, duration and timing with best therapeutic index. (+info)
Cytokine and cyclooxygenase-2 protein in brain areas of tumor-bearing mice with prostanoid-related anorexia.
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Evidence suggests that cytokines in the central nervous system are mediators behind anorexia in tumor-bearing hosts. We have therefore evaluated, by immunohistochemical image analyses, time course changes of interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, IL-6 receptor (gp130), IL-1 receptor I, and cyclooxygenase (Cox)-2 protein in brain cortex, hippocampus and the ventromedial hypothalamic nucleus (VMH) in tumor-bearing mice with prostanoid-related anorexia. Pair-fed non-tumor-bearing mice were used as controls. Prostaglandin E(2) was provided systemically to freely fed, non-tumor-bearing mice to confirm a role for prostanoids in modulation of brain cytokines and food intake. Time course changes of IL-1beta were significantly different between tumor-bearing mice and pair-fed controls in the hippocampus but not in the VMH. TNF-alpha in the hippocampus and VMH did not show any significant difference between tumor-bearing mice and pair-fed controls, whereas TNF-alpha showed a small increase over time in brain VMH. IL-6 content did not show any significant alterations among tumor-bearing and pair-fed mice but increased significantly over time in both the study and control group. Cox-2 in brain hippocampus and VMH showed a statistically significant rise in both tumor-bearing and pair-fed controls, with no difference between animal groups. Systemic provision of exogenous PGE(2) to non-tumor-bearing mice altered brain cytokines significantly in the hippocampus and VMH with associated changes in food intake. Our results demonstrate that some differences (IL-1beta) occurred in brain cytokines comparing tumor-bearing and pair-fed, non-tumor-bearing mice but within unexpected decreased levels in brain tissue from tumor-bearing mice. Surprisingly, many time course changes in brain cytokines were similarly altered in tumor-bearing and pair-fed mice. Our observations do not support that up-regulation of brain cytokines explains or promotes anorexia in cancer disease. Rather, cytokine and Cox-dependent alterations in brain tissue seemed to be secondary to a decline in food intake and related to subsequent stress hormone activities. (+info)
Phase I trial of gemcitabine combined with radiation for the treatment of locally advanced pancreatic adenocarcinoma.
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Gemcitabine has modest activity in the treatment of advanced pancreatic cancer and is a potent radiosensitizer. We conducted a Phase I trial to determine the maximum tolerated dose of weekly gemcitabine delivered concurrently with radiation therapy for the treatment of locally advanced adenocarcinoma of the pancreatic head and to assess the treatment-related toxic effects associated with such a regimen. Eighteen patients with pathologically proven, locally advanced adenocarcinoma of the pancreatic head were enrolled in this study. Patients received seven weekly doses of gemcitabine with 3000 cGy of external beam radiation therapy delivered during the first 2 weeks of therapy. Six patients received gemcitabine at 350 mg/m(2)/week, nine at 400 mg/m(2)/week, and three at 500 mg/m(2)/week. Grade 3-4 hematological toxicity was observed in over half the patients treated. Nonhematological toxicities were significant and included fatigue, anorexia, nausea, vomiting, and dehydration. Forty-four % of the patients required admission to the hospital for management of nausea/vomiting and dehydration. The risk of hospitalization appeared to be dose-related; all of the three patients treated at 500 mg/m(2)/week required hospital admission during treatment. Seventeen patients were evaluated for response, and eight patients (47%) had evidence of a local anticancer effect. Four of these eight patients (24%) had a partial response to therapy. The median survival for the entire group was 6 months. The 1-year survival rate for patients with an objective response to therapy was 66%. The clinical responses observed in this group of patients suggest gemcitabine is a clinically relevant radiosensitizer in patients with pancreatic adenocarcinoma. However, the toxic effects are significant, suggesting that until dose and scheduling issues are explored further, concomitant administration of gemcitabine and radiation therapy should still be considered investigational. (+info)