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Timothy J. Bartness - One of the best experts on this subject based on the ideXlab platform.
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anti ghrelin spiegelmer inhibits exogenous ghrelin induced increases in Food intake hoarding and neural activation but not Food Deprivation induced increases
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2013Co-Authors: Brett J W Teubner, Timothy J. BartnessAbstract:Circulating concentrations of the stomach-derived “hunger-peptide” ghrelin increase in direct proportion to the time since the last meal. Exogenous ghrelin also increases Food intake in rodents and humans, suggesting ghrelin may increase post-fast ingestive behaviors. Food intake after Food Deprivation is increased by laboratory rats and mice, but not by humans (despite dogma to the contrary) or by Siberian hamsters; instead, humans and Siberian hamsters increase Food hoarding, suggesting the latter as a model of fasting-induced changes in human ingestive behavior. Exogenous ghrelin markedly increases Food hoarding by ad libitum-fed Siberian hamsters similarly to that after Food Deprivation, indicating sufficiency. Here, we tested the necessity of ghrelin to increase Food foraging, Food hoarding, and Food intake, and neural activation [c-Fos immunoreactivity (c-Fos-ir)] using anti-ghrelin Spiegelmer NOX-B11–2 (SPM), an l-oligonucleotide that specifically binds active ghrelin, inhibiting peptide-receptor interaction. SPM blocked exogenous ghrelin-induced increases in Food hoarding the first 2 days after injection, and foraging and Food intake at 1–2 h and 2–4 h, respectively, and inhibited hypothalamic c-Fos-ir. SPM given every 24 h across 48-h Food Deprivation inconsistently inhibited Food hoarding after refeeding and c-Fos-ir, similarly to inabilities to do so in laboratory rats and mice. These results suggest that ghrelin may not be necessary for Food Deprivation-induced foraging and hoarding and neural activation. A possible compensatory response, however, may underlie these findings because SPM treatment led to marked increases in circulating ghrelin concentrations. Collectively, these results show that SPM can block exogenous ghrelin-induced ingestive behaviors, but the necessity of ghrelin for Food Deprivation-induced ingestive behaviors remains unclear.
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arcuate nucleus destruction does not block Food Deprivation induced increases in Food foraging and hoarding
Brain Research, 2010Co-Authors: Megan J Dailey, Timothy J. BartnessAbstract:The mechanisms underlying the control of Food intake are considerably better understood than those underlying the appetitive ingestive behaviors of foraging and hoarding of Food, despite the prevalence of the latter across species including humans. Neuropeptide Y (NPY) and Agouti-related protein (AgRP), two orexigenic neuropeptides known to stimulate Food intake in a variety of species, applied centrally to Siberian hamsters increases foraging and especially hoarding with lesser increases in Food intake. Both are expressed in the arcuate nucleus (Arc) and their synthesis increases with Food Deprivation, a naturally-occurring stimulus that markedly increases foraging and hoarding in Siberian hamsters. Therefore, we tested whether destruction of Arc neurons blocks these ingestive behaviors. This was accomplished either by microinjecting NPY conjugated to saporin (NPY-SAP) bilaterally into the Arc to kill NPY receptor-bearing neurons or via neonatal monosodium glutamate (MSG) treatment. For both methods, Arc cresyl violet staining (cell density) and NPY and Y1 receptor-immunoreactivity (ir) were significantly decreased. Although baseline foraging and Food hoarding were not affected, Food Deprivation-induced increased Food hoarding was surprisingly exaggerated approximately 100% with both types of Arc destruction. We found a substantial amount of remaining NPY-ir fibers, likely emanating from the brainstem, and a significant up-regulation of Y1 receptors in Arc NPY projections areas (hypothalamic paraventricular nucleus and perifornical area) after Arc denervation and their activation may have accounted for the exaggerated increases. The converging evidence from both Arc destruction methods suggests an intact Arc is not necessary for Food Deprivation-induced increases in Food foraging and hoarding.
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leptin inhibits Food Deprivation induced increases in Food intake and Food hoarding
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2008Co-Authors: Erin Keenrhinehart, Timothy J. BartnessAbstract:Food Deprivation stimulates foraging and hoarding and to a much lesser extent, Food intake in Siberian hamsters. Leptin, the anorexigenic hormone secreted primarily from adipocytes, may act in the periphery, the brain, or both to inhibit these ingestive behaviors. Therefore, we tested whether leptin given either intracerebroventricularly or intraperitoneally, would block Food Deprivation-induced increases in Food hoarding, foraging, and intake in animals with differing foraging requirements. Hamsters were trained in a running wheel-based Food delivery foraging system coupled with simulated burrow housing. We determined the effects of Food Deprivation and several peripheral doses of leptin on plasma leptin concentrations. Hamsters were then Food deprived for 48 h and given leptin (0, 10, 40, or 80 μg ip), and additional hamsters were Food deprived for 48 h and given leptin (0, 1.25, 2.5, or 5.0 μg icv). Foraging, Food intake, and hoarding were measured postinjection. Food Deprivation stimulated Food hoarding to a greater degree and duration than Food intake. In animals with a foraging requirement, intracerebroventricular leptin almost completely blocked Food Deprivation-induced increased Food hoarding and intake, but increased foraging. Peripheral leptin treatment was most effective in a sedentary control group, completely inhibiting Food Deprivation-induced increased Food hoarding and intake at the two highest doses, and did not affect foraging at any dose. Thus, the ability of leptin to inhibit Food Deprivation-induced increases in ingestive behaviors differs based on foraging effort (energy expenditure) and the route of administration of leptin administration.
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mtii attenuates ghrelin and Food Deprivation induced increases in Food hoarding and Food intake
Hormones and Behavior, 2007Co-Authors: Erin Keenrhinehart, Timothy J. BartnessAbstract:Food Deprivation triggers a constellation of physiological and behavioral changes including increases in peripherally-produced ghrelin and centrally-produced agouti-related protein (AgRP). Upon refeeding, Food intake is increased in most species, however hamsters primarily increase Food hoarding. Food Deprivation-induced increases in Food hoarding by Siberian hamsters are mimicked by peripheral ghrelin and central AgRP injections. Because Food Deprivation stimulates ghrelin as well as AgRP synthesis/release, Food Deprivation-induced increases in hoarding may be mediated by melanocortin 3 or 4 receptor (MC3/4-R) antagonism via AgRP, the MC3/4-R inverse agonist. Therefore, we asked: Can a MC3/4-R agonist block Food Deprivation- or ghrelin-induced increases in foraging, Food hoarding and Food intake? This was accomplished by injecting melanotan II (MTII), a synthetic MC3/4-R agonist, into the 3rd ventricle in Food deprived, fed or peripheral ghrelin injected hamsters and housed in a running wheel-based Food delivery foraging system. Three foraging conditions were used: a) no running wheel access, non-contingent Food, b) running wheel access, non-contingent Food or c) a foraging requirement for Food (10 revolutions/pellet). Food Deprivation was a more potent stimulator of foraging and hoarding than ghrelin. Concurrent injections of MTII completely blocked Food Deprivation- and ghrelin-induced increases in Food intake and attenuated, but did not always completely block, Food Deprivation- and ghrelin-induced increases in Food hoarding. Collectively, these data suggest that the MC3/4-R are involved in ghrelin- and Food Deprivation-induced increases in Food intake, but other neurochemical systems, such as previously demonstrated with neuropeptide Y, also are involved in increases in Food hoarding as well as foraging.
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diet self selection and Food hoarding after Food Deprivation by siberian hamsters
Physiology & Behavior, 1999Co-Authors: Diane E Day, Eric M Mintz, Timothy J. BartnessAbstract:Abstract Siberian hamsters ( Phodopus sungorus ) increase Food hoarding, but not Food intake, after a fast. Because the physiological mechanisms underlying these changes in Food hoarding are virtually unknown, we sought insight into these mechanisms by allowing hamsters to self-select their diet from Food sources varying in macronutrient composition and caloric density (“dietary wisdom”). Therefore, the effects of Food Deprivation length on diet self-selection were tested in adult female hamsters after adaptation to three composite diets: sunflower seeds (SS), pellet chow (PC), and rabbit chow (RC). One group initially was fasted for 32 h, the other for 56 h, and then each was refed. The remaining nonexperienced fast was instated after prefast body mass, Food intake, and hoarding were recovered. Food hoarding, but not Food intake, was increased regardless of fast length or sequence; moreover, the largest increase in Food hoarding was on the first day of refeeding and was primarily reflected as increased SS hoarding. When the longer fast occurred first body mass loss was greater and the increased Food hoard size was maintained for more days than when the longer fast came second. The order of Food intake and hoarding preferences was not changed after a fast (SS > PC > RC), but the degree of Food hoarding preference for SS was exaggerated. Collectively, these results support the notion that Food hoarding increases with decreases in lipid stores, and show that when internal lipid stores are decreased, external lipid stores are preferentially increased.
Matthew J Will - One of the best experts on this subject based on the ideXlab platform.
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central amygdala opioid transmission is necessary for increased high fat intake following 24 h Food Deprivation but not following intra accumbens opioid administration
Behavioural Brain Research, 2014Co-Authors: Kyle E Parker, Howard W Johns, Ted G Floros, Matthew J WillAbstract:Previous research has demonstrated a dissociation of certain neural mediators that contribute to the increased consumption of a high-fat diet that follows intra-accumbens (Acb) administration of μ-opioid receptor agonists vs. 24-h Food Deprivation. These two models, both which induce rapid consumption of the diet, have been shown to involve a distributed corticolimbic circuitry, including the amygdala. Specifically, the central amygdala (CeA) has been shown to be involved in high-fat feeding within both opioid and Food-Deprivation driven models. The present experiments were conducted to examine the more specific role of CeA opioid transmission in mediating high-fat feeding driven by either intra-Acb administration of the μ-opioid agonist d-Ala2-NMe-Phe4-Glyol5-enkephalin (DAMGO) or 24-h home cage Food Deprivation. Injection of DAMGO into the Acb (0.25 μg/0.5 μl/side) increased consumption of the high-fat diet, but this feeding was unaffected by administration of opioid antagonist, naltrexone (5 μg/0.25 μl/side) administered into the CeA. In contrast, intra-CeA naltrexone administration attenuated high-fat intake driven by 24-h Food Deprivation, demonstrating a specific role for CeA opioid transmission in high-fat consumption. Intra-CeA naltrexone administration alone had no effect on baseline feeding levels within either feeding model. These findings suggest that CeA opioid transmission mediates consumption of a palatable high-fat diet driven by short-term negative-energy balance (24-h Food Deprivation), but not intra-Acb opioid receptor activation.
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basolateral amygdala opioids contribute to increased high fat intake following intra accumbens opioid administration but not following 24 h Food Deprivation
Pharmacology Biochemistry and Behavior, 2010Co-Authors: Kyle E Parker, Jordan G Mccall, Matthew J WillAbstract:Abstract Previous research has demonstrated that administration of μ-opioid receptor agonists into the nucleus accumbens increases high-fat diet consumption in sated rats and has shown a role of basolateral amygdala (BLA) activity in mediating this response. The present experiments were conducted to examine the role of BLA opioid transmission in mediating high-fat feeding driven by either intra-accumbens opioid activation or 24-h home cage Food Deprivation. Injection of the μ-opioid agonist, d -Ala2-NMe-Phe4-Glyol5-enkephalin (DAMGO) into the nucleus accumbens (0.25 μg/0.5 μl/side) increased consumption of a high-fat diet, and this effect was attenuated by pre-treatment with the opioid antagonist, naltrexone (5 μg/0.25 μl/side) administered into the BLA. In contrast, intra-BLA naltrexone administration had no influence on the increase in high-fat intake following 24-h Food Deprivation. These findings suggest that BLA opioid transmission is an important mediator of palatability-driven feeding as modeled by intra-accumbens opioid activation, while BLA opioid transmission has no significant influence on the increase in high-fat feeding driven by short-term negative-energy balance.
Petteri Nieminen - One of the best experts on this subject based on the ideXlab platform.
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body temperature rhythms in microtus voles during feeding Food Deprivation and winter acclimatization
Journal of Mammalogy, 2013Co-Authors: Petteri Nieminen, Esa Hohtola, Anne-mari MustonenAbstract:Abstract Arvicoline voles do not possess sophisticated mechanisms to tolerate prolonged fasting and can starve to death in less than 24 h. Two experiments were performed to determine if the common vole (Microtus arvalis) and the tundra vole (M. oeconomus) have thermoregulatory adaptations to enhance survival during Food Deprivation or in winter, and to reveal the possible presence of ultradian body temperature (Tb) rhythms. Laboratory-bred voles (n = 5–6 for both species) were equipped with intra-abdominal data loggers that registered Tb every 10 min and were subjected to 12-h fasting periods during photophase and scotophase. In addition, 10 animals of both species were placed in outdoor cages at natural ambient temperature (Ta) and their Tb was registered at 3-h intervals between October and June. Fasted voles did not enter torpor, but the average 24-h Tb decreased by 0.2–0.5°C in winter, yielding modest energy savings. The decrease in the Tb correlated with Ta but not photoperiod and could, thus, be int...
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Rapid Development of Fasting-Induced Hepatic Lipidosis in the American Mink (Neovison vison): Effects of Food Deprivation and Re-Alimentation on Body Fat Depots, Tissue Fatty Acid Profiles, Hematology and Endocrinology
Lipids, 2010Co-Authors: Kirsti Rouvinen-watt, Anne-mari Mustonen, Rebecca Conway, Catherine Pal, Lora Harris, Seppo Saarela, Ursula Strandberg, Petteri NieminenAbstract:Hepatic lipidosis is a common pathological finding in the American mink ( Neovison vison ) and can be caused by nutritional imbalance due to obesity or rapid body weight loss. The objectives of the present study were to investigate the timeline and characterize the development of hepatic lipidosis in mink in response to 0–7 days of Food Deprivation and liver recovery after 28 days of re-feeding. We report here the effects on hematological and endocrine variables, body fat mobilization, the development of hepatic lipidosis and the alterations in the liver lipid classes and tissue fatty acid (FA) sums. Food Deprivation resulted in the rapid mobilization of body fat, most notably visceral, causing elevated hepatosomatic index and increased liver triacylglycerol content. The increased absolute amounts of liver total phospholipids and phosphatidylcholine suggested endoplasmic reticulum stress. The hepatic lipid infiltration and the altered liver lipid profiles were associated with a significantly reduced proportion of n-3 polyunsaturated FA (PUFA) in the livers and the decrease was more evident in the females. Likewise, re-feeding of the female mink resulted in a more pronounced recovery of the liver n-3 PUFA. The rapid decrease in the n-3/n-6 PUFA ratio in response to Food Deprivation could trigger an inflammatory response in the liver. This could be a key contributor to the pathophysiology of fatty liver disease in mink influencing disease progression.
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selective fatty acid mobilization from adipose tissues of the pheasant phasianus colchicus mongolicus during Food Deprivation
Physiological and Biochemical Zoology, 2009Co-Authors: Anne-mari Mustonen, Juha Asikainen, Reijo Kakela, Petteri NieminenAbstract:Abstract Avian response to fasting has been examined intensively in penguins (Aptenodytes spp.) adapted to long‐term Food Deprivation but less in species experiencing shorter fasts. Thus, the selectivity in (i) incorporating different fatty acids (FA) from diet into total lipids of white adipose tissue (WAT) and liver and (ii) mobilizing FA from these tissues was examined in pheasants Phasianus colchicus mongolicus fed or fasted for 4 d. Dietary FA were selectively incorporated into intra‐abdominal and subcutaneous WAT having a similar composition. The WAT lipids contained higher proportions of saturated and monounsaturated FA and less polyunsaturated FA (PUFA) than the dietary profile. However, the isomers of 20:1 and 22:1 were incorporated inefficiently into the WAT lipids. The essential C18 PUFA precursors having smaller percentages in the pheasant tissues than in the diet were likely converted into longer‐chain derivatives probably utilized to a great extent for structural lipids of muscles and organs...
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selective fatty acid mobilization in the american mink mustela vison during Food Deprivation
Comparative Biochemistry and Physiology B, 2006Co-Authors: Petteri Nieminen, Reijo Kakela, Teija Pyykonen, Anne-mari MustonenAbstract:Abstract The mobilization of fatty acids (FAs) during Food Deprivation is a selective process in laboratory rodents and humans. The site-specific differences in adipose tissue functions – e.g. energy storage versus insulation – should also affect the use of different FAs. To study this, 16 female minks were randomly assigned into the control group or fasted for 5 days. Preferential mobilization of n-3 polyunsaturated FAs (PUFAs) during fasting caused a decrease in the n-3/n-6 PUFA ratio in fat and liver. In addition, the minks utilized short-chain FAs efficiently in all fat depots, but long-chain FAs – 20:0, 20:1n-11, 20:1n-9, 22:1n-11 and 24:1n-9 – were preserved. The number of double bonds in the FA chain correlated positively with mobilization rate in the retroperitoneal fat. The observed negative correlation between mobilization rate and the location of the first double bond from the methyl end may be due to peroxisomal chain-shortening of long-chain FAs and not the double bond position per se. As a result, minks are able to preserve a low melting point and fluidity of the subcutaneous fat depots, which would be essential to a Northern semi-aquatic mammal.
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seasonal reproductive endocrine profile of the raccoon dog nyctereutes procyonoides effects of melatonin and Food Deprivation
Journal of Experimental Zoology Part A: Comparative Experimental Biology, 2003Co-Authors: Juha Asikainen, Heikki Hyvärinen, Anne-mari Mustonen, Petteri NieminenAbstract:The raccoon dog (Nyctereutes procyonoides, Canidae, Carnivora) is a middle-sized omnivore with excessive autumnal fattening and winter sleep. We studied adaptations of the species to boreal climate and photoperiod by following the plasma reproductive and thyroid hormone concentrations of farm-bred raccoon dogs (n=32) for 12 months. On August 16, 2000, and February 8, 2001, half of the raccoon dogs received continuous-release melatonin implants (the MEL group). The other half was sham-operated (the SHAM group). Between November 27, 2000, and January 25, 2001, half of the animals of both groups were fasted. The plasma testosterone concentrations of the MEL males peaked in February, a month earlier than in the SHAM males. Autumnal melatonin treatment also advanced the gestation period reflected by the plasma progesterone concentrations by seven weeks. Food Deprivation in winter seems to accentuate the sex steroid response during the mating as the fasted males had higher testosterone concentrations than the fed males in February and March.
Kyle E Parker - One of the best experts on this subject based on the ideXlab platform.
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central amygdala opioid transmission is necessary for increased high fat intake following 24 h Food Deprivation but not following intra accumbens opioid administration
Behavioural Brain Research, 2014Co-Authors: Kyle E Parker, Howard W Johns, Ted G Floros, Matthew J WillAbstract:Previous research has demonstrated a dissociation of certain neural mediators that contribute to the increased consumption of a high-fat diet that follows intra-accumbens (Acb) administration of μ-opioid receptor agonists vs. 24-h Food Deprivation. These two models, both which induce rapid consumption of the diet, have been shown to involve a distributed corticolimbic circuitry, including the amygdala. Specifically, the central amygdala (CeA) has been shown to be involved in high-fat feeding within both opioid and Food-Deprivation driven models. The present experiments were conducted to examine the more specific role of CeA opioid transmission in mediating high-fat feeding driven by either intra-Acb administration of the μ-opioid agonist d-Ala2-NMe-Phe4-Glyol5-enkephalin (DAMGO) or 24-h home cage Food Deprivation. Injection of DAMGO into the Acb (0.25 μg/0.5 μl/side) increased consumption of the high-fat diet, but this feeding was unaffected by administration of opioid antagonist, naltrexone (5 μg/0.25 μl/side) administered into the CeA. In contrast, intra-CeA naltrexone administration attenuated high-fat intake driven by 24-h Food Deprivation, demonstrating a specific role for CeA opioid transmission in high-fat consumption. Intra-CeA naltrexone administration alone had no effect on baseline feeding levels within either feeding model. These findings suggest that CeA opioid transmission mediates consumption of a palatable high-fat diet driven by short-term negative-energy balance (24-h Food Deprivation), but not intra-Acb opioid receptor activation.
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basolateral amygdala opioids contribute to increased high fat intake following intra accumbens opioid administration but not following 24 h Food Deprivation
Pharmacology Biochemistry and Behavior, 2010Co-Authors: Kyle E Parker, Jordan G Mccall, Matthew J WillAbstract:Abstract Previous research has demonstrated that administration of μ-opioid receptor agonists into the nucleus accumbens increases high-fat diet consumption in sated rats and has shown a role of basolateral amygdala (BLA) activity in mediating this response. The present experiments were conducted to examine the role of BLA opioid transmission in mediating high-fat feeding driven by either intra-accumbens opioid activation or 24-h home cage Food Deprivation. Injection of the μ-opioid agonist, d -Ala2-NMe-Phe4-Glyol5-enkephalin (DAMGO) into the nucleus accumbens (0.25 μg/0.5 μl/side) increased consumption of a high-fat diet, and this effect was attenuated by pre-treatment with the opioid antagonist, naltrexone (5 μg/0.25 μl/side) administered into the BLA. In contrast, intra-BLA naltrexone administration had no influence on the increase in high-fat intake following 24-h Food Deprivation. These findings suggest that BLA opioid transmission is an important mediator of palatability-driven feeding as modeled by intra-accumbens opioid activation, while BLA opioid transmission has no significant influence on the increase in high-fat feeding driven by short-term negative-energy balance.
Juan Miguel Mancera - One of the best experts on this subject based on the ideXlab platform.
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the influence of stocking density and Food Deprivation in silver catfish rhamdia quelen a metabolic and endocrine approach
Aquaculture, 2015Co-Authors: Charlene Menezes, Ignacio Ruizjarabo, Juan Antonio Martossitcha, Joseânia Salbego, Alexssandro Geferson Becker, Gonzalo Martinezrodriguez, Cândida Toni, Vania Lucia Loro, Juan Miguel ManceraAbstract:Abstract The influence of stocking density and Food Deprivation on energy metabolism, stress processes and the pituitary endocrine system of silver catfish (Rhamdia quelen) was investigated after a period of 14 days, in which plasmatic and hepatic parameters and the mRNA expression of prolactin (PRL), growth hormone (GH) and somatolactin (SL) were assessed. The fish were subjected to four experimental conditions: (1) fed under high stocking density (32 kg/m3, HSD); (2) fed under mean stocking density (16 kg/m3, MSD); (3) fed under low stocking density (8 kg/m3, LSD); and (4) Food-deprived under low stocking density (8 kg/m3, LSD-FD). After 14 days, plasma and liver samples were obtained to analyze the metabolite levels and enzymatic activities related to metabolism, and pituitary glands were obtained to analyze hormone expression (PRL, GH and SL). Liver weight and the hepato-somatic index (HSI) revealed that specimens maintained at HSD and/or MSD had higher hepatic stores, which were observed in the triglyceride and glycogen levels in this tissue, than animals submitted to the LSD and LSD-FD groups. Triglyceride levels in the plasma and liver revealed the consumption of fatty acid reserves in the fasting group. Enzymatic activities, such as glutamate dehydrogenase (GDH), phosphorylase (GPase), pyruvate kinase (PK), aspartate transaminase (AST) and glycerol-3-phosphate dehydrogenase (G3PDH), indicated an increase in gluconeogenic pathways in the HSD group and an increase in glycolitic metabolism in the LSD groups. The expression of PRL was not affected by stocking density and/or Food Deprivation and GH decreased with increased density and increased in fasting conditions. A negative effect of density and fasting was observed on the expression of SL. Overall, the data suggested that juvenile silver catfish reared at stocking densities of 16 to 32 kg/m3 were better maintained than those maintained at the lowest density.
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high density and Food Deprivation affect arginine vasotocin isotocin and melatonin in gilthead sea bream sparus auratus
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2008Co-Authors: Juan Miguel Mancera, Gonzalo Martinezrodriguez, Agnieszka Kleszczynska, Luis Vargaschacoff, Hanna Kalamarz, Angel Garcialopez, Ewa KulczykowskaAbstract:Abstract Arginine vasotocin (AVT) and isotocin (IT) levels in plasma and pituitary, and melatonin (MEL) levels in plasma were determined in gilthead sea bream ( Sparus auratus ) subjected to two different types of stress: i) high density (HD) and ii) Food Deprivation (NF: non-fed). Fishes were randomly assigned to one of 4 treatments that lasted for 14 days: 1) fed fish under normal low density (ND, 4 kg m − 3 ); 2) non-fed (NF) fish under ND; 3) fed fish under high density (HD, 70 kg m − 3 ); and 4) non-fed fish under HD. Ten fish from each tank were anaesthetized, weighed and plasma and pituitary samples were taken. Plasma and pituitary AVT and IT content were determined by HPLC, while plasma MEL was assayed by RIA. Plasma AVT and IT values were enhanced in all fish kept at high density. The response of AVT was much stronger than that of IT. The highest pituitary AVT and IT levels were shown in NF fish kept at normal density. The significantly higher plasma MEL levels were measured in fed fish kept at HD. These results suggest a role of AVT, IT and MEL in response of sea bream to a common stress factor, high density. Although Food Deprivation does not influence AVT and IT plasma levels, it seems to affect hypothalamic synthesis of nonapeptides. Further studies are required to elucidate the complex role of AVT, IT and MEL in the sea bream's response to different stress stimuli.
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interactive effects of high stocking density and Food Deprivation on carbohydrate metabolism in several tissues of gilthead sea bream sparus auratus
Journal of Experimental Zoology Part A: Comparative Experimental Biology, 2005Co-Authors: Susana Sangiaoalvarellos, Juan Miguel Mancera, Jose M Guzman, Raul Laizcarrion, Jesus M Miguez, Maria Del Pilar Martin Del Rio, Jose L SoengasAbstract:The influence of high stocking density (HSD) and Food Deprivation was assessed on carbohydrate metabolism of several tissues of gilthead sea bream Sparus auratus for 14 days. Fish were randomly assigned to one of four treatments: (1) fed fish under normal stocking density (NSD) (4 kg m 3 ); (2) fed fish under HSD (70 kg m 3 ); (3) Food-deprived fish under NSD; and (4) Food- deprived fish under HSD. After 14 days, samples were taken from the plasma, liver, gills, kidney and brain for the assessment of plasma cortisol, levels of metabolites and the activity of several enzymes involved in carbohydrate metabolism. HSD conditions alone elicited important changes in energy metabolism of several tissues that in some cases were confirmatory (5-fold increase in plama cortisol, 20% increase in plasma glucose, 60% decrease in liver glycogen and 20% increase in gluconeogenic potential in the liver) whereas in others provided new information regarding metabolic adjustments to cope with HSD in the liver (100% increase in glucose phosphorylating capacity), gills (30% decrease in capacity for phosphorylating glucose), kidney (80% increase in the capacity of phosphorylating glucose) and brain (2.5-fold increase in ATP levels). On the other hand, Food Deprivation alone resulted in increased plasma cortisol, and metabolic changes in the liver (enhanced gluconeogenic and glycogenolytic potential of 13% and 18%, respectively) and brain (10% increase in glycolytic capacity), confirmatory of previous studies, whereas new information regarding metabolic adjustments during Food Deprivation was obtained in the gills and kidney (decreased lactate levels in both tissues of 45% and 55%, respectively). Furthermore, the results obtained provided, for the first time in fish, information indicating that Food Deprivation increased the sensitivity of gilthead sea bream to the stress induced by HSD compared with the fed controls, as demonstrated by increased plasma cortisol levels (50% increase vs. fed fish) and a further increase in the capacity to export glucose mobilized from liver glycogen stores (70% decrease vs. fed fish). These results lend support for a cumulative effect of both stressors on plasma cortisol and parameters assessed on carbohydrate metabolism in the present experiments, and provide information regarding reallocation of metabolic energy to cope with simultaneous stressors in fish. J. Exp. Zool. 303A:761-775, 2005. r 2005 Wiley-Liss, Inc.