Interleukin-12 as a biomarker of the beneficial effects of food restriction in mice receiving high fat diet or high carbohydrate diet

The impact of food restriction (FR) during 56 days on serum levels of cytokines in mice fed a high-fat diet (HFD) or high-carbohydrate diet (HCD) were evaluated. The amount of food was reduced 50% for HFD-FR and HCD-FR groups compared to mice receiving free access to HFD (HFD group) or HCD (HCD group). We quantified the serum levels of basic fibroblast growth factor, granulocyte-macrophage colony-stimulating factor, inducible protein 10, interferon γ, interleukin 1α (IL-1α), IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, IL-17, keratinocyte chemoattractant, macrophage inflammatory protein-1α, monocyte chemotactic protein 1, monokine induced by IFN-γ, and tumor necrosis factor α. Only IL-12 levels were lower (P<0.05), for both HFD-FR (HFD-FR vs HFD) and HCD-FR (HCD-FR vs HCD). Therefore, IL-12 levels could be considered a biological marker of the beneficial effects of FR.

Influence of food restriction on lipid profile and spontaneous glucose levels in male rats subjected to paradoxical sleep deprivation

OBJECTIVES: The purpose of this study was to determine the paired consequences of food restriction and paradoxical sleep deprivation on lipid profile and spontaneous glucose levels in male rats. METHOD: Food restriction began at weaning, with 6 g of food being provided per day, which was subsequently increased by 1 g per week until reaching 15 g per day by the eighth week. At adulthood, both rats subjected to food restriction and those fed ad libitum were exposed to paradoxical sleep deprivation for 96 h or were maintained in their home-cage groups. RESULTS: Animals subjected to food restriction exhibited a significant increase in high-density lipoprotein levels compared to animals that were given free access to food. After the paradoxical sleep deprivation period, the foodrestricted animals demonstrated reduced concentrations of high-density lipoprotein relative to their respective controls, although the values for the food-restricted animals after sleep deprivation were still higher than those for the ad libitum group. The concentration of low-density lipoproteins was significantly increased in sleep-deprived animals fed the ad libitum diet. The levels of triglycerides, very low-density lipoproteins, and glucose in foodrestricted animals were each decreased compared to both ad libitum groups. CONCLUSION: These results may help to illustrate the mechanisms underlying the relationship between sleep curtailment and metabolism and may suggest that, regardless of sleep deprivation, dietary restriction can minimize alterations in parameters related to cardiovascular risk.

[Effects of short-term starvation on hematological parameters in cultured juvenile beluga]

This study examined the effect of different starvation periods on hematological parameters including hemoglobin[MCV], hematocrit [MCH], red and white blood cells count and corpuscle indices [MCHC], of cultured juvenile Beluga [Huso huso], with an initial body weight of 45 +/- 0.91g. After adaptation to a dry diet for 10 days group s, with 15 fish in each group, were used for this experiment. Each group was randomly distributed to twelve 500L fiberglass tanks. Each tank had a flow-through system. The fish were exposed to 4 different feeding regimes; Control Group [fed four times daily]; Group 1 [given 2 days of starvation]; Group 2 [given 4 days of starvation]; and, Group 3 [given 8 days of starvation]. Analysis was done at the end of each starvation period by collecting blood from the caudal vein and immediately transporting the samples to the laboratory. The results of the analysis indicated that the different starvation periods did not affect the red blood cell count. The hematocrit value in the Control Group was significantly lower [p<0.05] than the fish group starved for 8 days. MCHC value in the control group was significantly lower [p<0.05] than the fish group starved for 2 days. The hemoglobin concentration, MCV and MCH, did not show any significant difference between the treated groups and the Control Group. Those groups with longer starvation periods showed that the white blood cell count decreased significantly [p<0.05]. It could be concluded that short-term starvation periods weaken the immunological system of cultured juvenile Beluga

Efeito de um complexo homeopático “Homeobase Convert H®” em ovinos sob condições de restrição Alimentar / Effect of a homeopathic complex “Homeobase Convert H®” in sheep submited in feed restriction condictions

Avaliou-se o efeito de um complexo homeopático em ovinos distribuídos em quatro grupos: sem homeopatia e com restrição alimentar (A1B2); com homeopatia e com restrição alimentar (A2B2);com homeopatia e sem restrição alimentar (A2B1) e sem homeopatia e sem restrição alimentar (A1B1). Com 30 dias de restrição alimentaro grupo A2B2 apresentou nível sérico de cortisol semelhante (p>0,05)aos dos grupos A2B1 e A1B1, o que se observou no grupo A1B2 somente com 75 dias. Aos 15 dias após primovacinação todos os grupos possuíam anticorpos acima do nível mínimo de proteção de 0,5UI/mL. As concentrações médias de anticorpos atingiram níveis abaixo do mínimo de proteção aos 30 dias em alguns animais de todos os grupos e, somente o grupo A2B2 manteve a média acima deste nível durante os 90 dias de avaliação. O indicativo de diferença(p=0,054) entre a média da titulação de anticorpos do grupo A2B2 e os demais grupos, seis dias pós-vacinação, sugere que a proteção neste grupo ocorreu em menor tempo do que nos demais grupos. Os modelos de regressão estimam concentrações séricas de anticorpos maiores para os grupos A2B1 e A2B2, em relação aos grupos A1B2 eA1B1, obtendo-se, aos 15; 30 e 45 dias pós-vacinação, indicativos de diferenças entre as suas médias (p=0,067; p=0,091 e p<0,05 respectivamente). Conclui-se que complexo homeopático, ministrado a ovinos sob restrição alimentar, possui efeito sobre o estresse, reduzindo a concentração sérica de cortisol e promovendo uma maior concentração sérica de anticorpos.

It was evaluated the effect of a homeopathic complex in sheep distributed in four groups: without homeopathy and with alimentary restriction (A1B2); with homeopathy and alimentary restriction (A2B2); with homeopathy and without alimentary restriction (A2B1), and without homeopathy and without alimentary restriction (A1B1). After 30 days of alimentary restriction, the group with homeopathy (A2B2) had already presented an average serum level of cortisol similar (p>0,05) to the groups without restriction (A2B1 and A1B1). It was observed in the group without homeopathy (A1B2) only after 75 days. After 15 days post-vaccination all the groups had antibodies above the minimum level of protection of 0,5UI/mL. The medium concentrations of antibodies reached levels below the minimum of protection to the 30 days in some animals of all groups and, only the group A2B2 kept on average above this level during the 90 days of evaluation. The indicative of difference (p=0,054) between the titration average of antibodies from the group A2B2 and the other groups, six days after vaccination, suggests that the protection in this group occurred in smaller time than in the other groups. Regression models estimate higher serum concentrations of antibodies for the groups A2B1 and A2B2, regarding the groups A1B2 and A1B1, obtaining indicators of differences between their averages (p=0,067;p=0,091 and p<0,05 respectively) 15, 30 and 45 days after vaccination. It was concluded that the homeopathic administered to ovine under alimentary restriction, has effect on stress, reducing the serum concentration of cortisol which can cause a higher rise in the serum concentration of antibodies.

Associação de POMC, NPY e IRS2 hipotalâmicos com padrões de comportamento alimentar em ratos Wistar normais e sobrepeso / Association of POMC, NPY and hypothalamic IRS2 with patterns of eating behavior in overweight and normal Wistar rats

O comportamento alimentar de uma espécie é determinado por um conjunto de características filogenéticas, ontogenéticas, e epigenéticas, e regulado por fatores internos e externos ao organismo. Os fenômenos naturais que regem a vida no nosso planeta são periódicos em sua maioria, e a oferta de alimentos não é exceção. Cada safra é seguida de uma entressafra, e este ritmo sincroniza diversos outros ritmos, exógenos e endógenos, capazes de determinar a sobrevivência de espécies. Uma das estratégias adaptativas mais primitivas e bem sucedidas na dinâmica oscilatória da natureza, é o acúmulo de reservas. Nossa espécie, nos últimos 50 anos, vive uma situação de grande oferta de alimentos, período este extremamente pequeno, se visto sob a ordem de grandeza da evolução humana. Este fenômeno tem sido determinante na prevalência do depósito de energia e em decorrência, do surgimento da obesidade e suas consequentes patologias. O hipotálamo está intimamente associado à homeostase energética e ao comportamento alimentar. No núcleo arqueado hipotalâmico encontram-se populações neuronais orexigênicas e anorexigênicas, dentre as quais, as que expressam os neuroreceptores POMC, NPY e o substrato de receptor de insulina IRS2. A modificação da expressão destas proteínas tem sido associada à alterações do comportamento alimentar, bem como à impressão e programação metabólica, capazes de induzir obesidade em ratos adultos. A correlação desta circuitaria neuronal com o comportamento alimentar, porém, ainda não está suficientemente compreendida. A detecção do estado de fome-saciedade nos ratos, fundamental no estudo da neurofisiologia relacionada ao comportamento alimentar, vem sendo obtida via de regra, por meio de procedimentos complexos de observação comportamental. O presente estudo contribui para o conhecimento de padrões de alimentação determinados por condições nutricionais, e sua relação com a expressão neurofisiológica hipotalâmica dos neurônios POMC, NPY e IRS2 ...

The feeding behavior of a specie is determined by a group of phylogenetic, ontogenetic, and epigenetic features, and regulated by internal and external factors to the organism. The natura phenomena that govern life in our planet are mainly periodic, and the food stocks is not an exception. Each harvest is followed by a time between harvests, and this rhythm synchronizes other several exogenous and endogenous rhythms, capable of determining the survival of species. One of the most primitive strategies of adaptative evolution of species, and what usually happens regarding the oscillatory dynamics of nature, is the reserve accumulation. Our species, in the last 50 years, has been living a situation of great food offer, such period is exremely small if analysed under the greatness order of the human evolution. This phenomenon has been decisive in the prevalence of the energy deposit and, in consequence, determining the appearance of obesity and its consequent pathologies. The hypothalamus is intimately associated to the energy homeostasis and the feeding behavior. In the arcuate nucleous are orexigenic and anorexigenic neuronal populations, that express the neuroreceptors POMC, NPY and insulin receptor substratum IRS2. The modification of these proteins expression, has been associated to alterations of the feeding behavior, as well as to the metabolic imprinting and programming, capable to induce obesity in adult rats. The correlation of this neuronal circuits with the alimentary behavior, however, it is not yet sufficiently understood. The detection of the hunger-satiation state in the rat, crucial in the neurophysiology studies related to the alimentary behavior, has been obtained through complex procedures of behavioral observation. The present study contributed to the knowledge of certain feeding patterns for nutritional conditions, and its relationship with the neurophysiological expression of POMC, NPY and IRS2 neurons. Using the metabolic programming ...

Influence of food restriction on the reproduction and larval performance of matrinxã, Brycon amazonicus (Spix and Agassiz, 1829) / Influência da restrição alimentar no desempenho reprodutivo e larval do matrinxã, Brycon amazonicus (Spix e Agassiz, 1829)

This work evaluated the effect of food restriction and refeeding of matrinxã females, Brycon amazonicus, on their reproductive performance and on the growth and survival of the progeny. Broodstocks were distributed in 8 earthen tanks (15 fish/tank) and fish from 4 tanks were fed daily (G1) while fish from the other 4 tanks were fed for 3 days and not fed for 2 days (G2) during 6 months prior to artificial spawning. Among the induced females, 57 percent in G1 group and 45 percent in G2 group spawned and the mean egg weights were 208.1 g (G1) and 131.6 g (G2). Oocytes of G2 fish were smaller (1.017 ± 0.003 mm) than oocytes of G1 fish (1.048 ± 0.002 mm). Fertilization (71.91 ± 12.6 percent and 61.18 ± 13.7 percent) and hatching (61.28 ± 33.9 percent and 67.50 ± 23.4 percent) rates did not differ between G1 and G2 fish. Larvae were collected at hatching and at 24, 48 and 72 hours of incubation and fixed for growth measurement. After incubation, fry were transferred to aquaria and sampled 1, 5, 9 and 15 days later. G1 and G2 larvae had similar weight (1.51 ± 0.15 and 1.46 ± 0.07 mg) but the G2 length was significantly higher (6.26 ± 0.13 and 6.74 ± 0.14 mm). By the ninth day of rearing, G2 fry had higher weight (13.6 ± 0.26 and 18.9 ± 0.07 mg) and length (11.8 ± 0.09 and 14.5 ± 0.04 mm) but by the fifteenth day, G1 fry had higher weight (90.2 ± 1.19 and 68.6 ± 0.77 mg) and length (18.8 ± 0.16 and 18.5 ± 0.04 mm) than G2 fry. By the ninth day of rearing, when fry are recommended to be transferred to outdoor tanks, G2 fry were larger and after 15 days, fry produced by restricted-fed females showed higher survival. The survival rate of G2 progeny by the fifteenth day was significantly higher (24.7 ± 2.07 percent) than that of G1 progeny (19.2 ± 1.91 percent). The ration restriction (35 percent reduction) imposed on matrinxã broodstock during 6 months prior to spawning reduced the number of spawned females and the egg amount, but it did not affect...

Este estudo avaliou o efeito da restrição alimentar e realimentação na reprodução de fêmeas e no crescimento inicial e sobrevivência de larvas de matrinxã, Brycon amazonicus. Matrizes distribuídas em 8 viveiros (15 peixes/tanque) foram alimentadas diariamente (em 4 tanques - G1) e alimentados em ciclos de 3 dias de alimentação seguidos de 2 dias de restrição (em 4 tanques - G2) por 6 meses antes da desova. Na indução à desova, 57 por cento das fêmeas no G1 e 45 por cento no G2 desovaram. Os pesos médios dos oócitos foram 208,1 g (G1) e 131,6 g (G2), sendo os oócitos G2 menores (1,017 ± 0,003 mm) que os oócitos de G1 (1,048 ± 0,002 mm). As taxas de fertilização (71,9 ± 12,6 por cento e 61,2 ± 13,7 por cento) e de eclosão (61,3 ± 33,9 por cento e 67,5 ± 23,4 por cento) entre os G1 e G2 não diferiram. Larvas foram coletadas na eclosão e às 24, 48 e 72 horas de incubação para medida do crescimento e as restantes transferidas para aquários e amostradas 1, 5, 9 e 15 dias depois. Na transferência, as larvas G1 e G2 tinham pesos similares (1,5 ± 0,15 e 1,46 ± 0,07 mg), mas o comprimento das larvas G2 era maior (6,2 ± 0,13 e 6,7 ± 0,14 mm). Ao 9° dia, quando é recomendada a transferência dos juvenis para tanques externos, os juvenis G2 tinham peso (13,6 ± 0,26 e 18,9 ± 0,07 mg) e comprimento (11,8 ± 0,09 e 14,5 ± 0,04 mm) maiores, mas no 15º dia os juvenis G1 eram maiores em peso (90,2 ± 1,19 e 68,6 ± 0,77 mg) e comprimento (18,8 ± 0,16 e 18,5 ± 0,04 mm). Aos 15 dias, a prole das fêmeas submetidas à restrição alimentar apresentou sobrevivência mais alta que a prole das fêmeas alimentadas diariamente (24,7 ± 2,07 por cento e 19,2 ± 1,91 por cento). A restrição alimentar imposta às fêmeas de matrinxã, apesar de reduzir o número de fêmeas que desovaram e a quantidade de oócitos extrusados, não afetou a fertilização e eclosão das larvas e melhorou a sobrevivência final das larvas.

Programação do processo fome-saciedade de animais desnutridos no início da lactação: papel do NPY/AgRP e POMC / Programming hunger-satiety process of malnourished animals in early lactation: role of NPY/AgRP and POMC

A modulação do processo fome-saciedade é um fator determinante para o crescimento normal dos sistemas metabólicos. Tem sido demonstrado que variações nutricionais nos períodos pré e pós-natal induzem modificações nas projeções e/ou contatos dos circuitos neuronais hipotalâmicos, gerando uma "reprogramação" deste sistema que envolve mecanismos de interação da ação primária de hormônios como leptina em neurônios orexigênico (NPY/AgRP) anorexigênicos (POMC) no núcleo arqueado, para regular o comportamento alimentar. O objetivo deste trabalho foi estudar a programação do processo fome-saciedade no núcleo arqueado hipotalâmico, em curto e longo prazos, em animais que foram desnutridos no início da lactação. Para isso, utilizamos ratos Wister desnutridos nos primeiros 10 dias de lactação com a utilização de dieta materna com 0% de proteína e que foram submetidos a novo período de desnutrição protéica na fase adulta (60 dias de idade) por 3 dias. Para o estudo do processo fome-saciedade, as variáveis avaliadas foram peso corporal, razão peso corporal / consumo alimentar, conteúdos de receptores de leptina (Ob-Rb) e de neuropeptídeos hipotalâmicos (NPY/AgRP e POMC). Observamos que ao final de 10 dias de desnutrição na lactação, os animais desnutridos apresentaram menor peso corporal (FD - fêmea desnutrida, 50% e MD - macho desnutrido, 53%) e aumento dos conteúdos de Ob-Rb (FD: 121,67% e MD: 132,73%), NPY/AgRP (FD: 32,31% e MD: 115,62%) e POMC (FD: 71,2% e MD: 26,58%). Aos 60 dias de vida, os animais desnutridos apresentaram maior razão peso corporal / consumo alimentar e não evidenciamos diferença nos conteúdos de Ob-Rb, NPY/AgRP e POMC (p<-0,05). Aos 63 dias de vida, fêmeas (FDD) e machos desnutridos (MDD), após um segundo episódio de desnutrição, apresentaram redução de peso corporal (FDD: 12,4% e MDD: 10,75%) e consumo alimentar (FDD: 57,5% e MDD: 39,88%). O conteúdo dos neuropeptídeos orexigênicos (NPY/AgRP)...

The modulation of the hunger-satiety process is a determining factor for the normal growth of the metabolic systems. It has been demonstrated that nutritional variations during pre- and postnatal lead to modifications in projetions and/or contacts of hypothalamic neuronal circuits generating a "reprogramation" of this system, which involves mechanisms of interation of primary action of hormone as leptin in NPY/AgRP and POMC neurons in the arcuate nucleus, to regulate eating behavior. Our aim was to study the programation in the hunger-satiety process in the arcuate nucleus, in the short and long terms, in animals that were malnourished during the early lactation period. In the present study we used Wistar rats that were malnourished during the first 10 days of lactation (0% protein maternal diet) and that were submitted to new a period of malnutrition at adulthood (60 days-old) for 3 days. To study the hunger-satiety process, the variables evaluated were: body weight, body weight/food intake ratio, hypothalamic content of the leptin receptor (Ob-Rb) and the orexigenic NPY/AgRP and anorexigenic POMC neuropeptides. We observed at the end of 10 days of malnutrition during lactation, that the malnourished animals had lower body weight (MF - malnourished female, 50% and MM - malnourished male, 53%) and higher content of Ob-Rb (MF: 121,67% and MM: 132,73%), NPY/AgRP (MF: 32,31% e MM: 115,62%) and POMC (MF: 71,2% e MM: 26,58%). At 60 days, the malnourished animals had higher body weight/food intake ratio and showed no change in the Ob-Rb, NPY/AgRP and POMC content (p<-0,05). At 63 days of life, malnourished female and male after a second episode of malnutrition, had lower body weight (MMF: 12,4% and MMM: 10,75%) and food intake (MMF: 57,5% and MMM: 39,88%). The content of neuropeptides (NPY/AgRP) was significantly lower (MMF: 22,6% and MMM: 26,58%), while the content of Ob-Rb (MMF: 92,27% and MMM: 28%) and POMC neuropeptide (MMF: 22,34% and MMM:27,27%)...

Down-regulation of the cardiac sarcoplasmic reticulum ryanodine channel in severely food-restricted rats

We have shown that myocardial dysfunction induced by food restriction is related to calcium handling. Although cardiac function is depressed in food-restricted animals, there is limited information about the molecular mechanisms that lead to this abnormality. The present study evaluated the effects of food restriction on calcium cycling, focusing on sarcoplasmic Ca2+-ATPase (SERCA2), phospholamban (PLB), and ryanodine channel (RYR2) mRNA expressions in rat myocardium. Male Wistar-Kyoto rats, 60 days old, were submitted to ad libitum feeding (control rats) or 50 percent diet restriction for 90 days. The levels of left ventricle SERCA2, PLB, and RYR2 were measured using semi-quantitative RT-PCR. Body and ventricular weights were reduced in 50 percent food-restricted animals. RYR2 mRNA was significantly decreased in the left ventricle of the food-restricted group (control = 5.92 ± 0.48 vs food-restricted group = 4.84 ± 0.33, P < 0.01). The levels of SERCA2 and PLB mRNA were similar between groups (control = 8.38 ± 0.44 vs food-restricted group = 7.96 ± 0.45, and control = 1.52 ± 0.06 vs food-restricted group = 1.53 ± 0.10, respectively). Down-regulation of RYR2 mRNA expressions suggests that chronic food restriction promotes abnormalities in sarcoplasmic reticulum Ca2+ release.

Seasonal variation and food deprivation in common vampire bats (Chiroptera: Phyllostomidae)

The aim of this study was to investigate the effects of seasonal variation and fasting on fat reserves of the common vampire bat Desmodus rotundus. Plasma free fatty acids (FFA), along with lipid content of the liver and muscles, and fatty acids from the carcass were obtained from bats fed bovine blood and from whom food was subsequently withheld for 24 and 48 h. Animals were caught during both dry and rainy seasons. In general, fat tissue stores were not significantly influenced by seasonal variation. Lipid content of liver, muscles, and carcass decreased during some food deprivation periods, although the concomitant increase expected in plasma FFA was not observed. Lipid metabolism is hypothesized as being continued by the tissues themselves. In addition, free access to food sources (e.g., domestic livestock) throughout the year is believed to contribute to the low seasonal variations in fat reserves observed in the common vampire bat.

Os efeitos da variação sazonal e do jejum sobre as reservas lipídicas do morcego vampiro comum (Desmodus rotundus) foram investigadas a fim de se estabelecer o padrão do metabolismo de lipídios da espécie e possíveis alterações sazonais. Foram determinadas as concentrações de Acidos Graxos Livres (AGL) e o conteúdo lipídico no fígado, músculos e na carcaça de animais alimentados (sangue bovino) e jejuados por 24 e 48 h, capturados durante as estações seca e chuvosa. Em geral, os depósitos lipídicos teciduais não apresentaram variações significativas em resposta às diferentes estações. As reservas de gordura diminuíram, no entanto, em resposta ao jejum, apesar de não ter sido observado nenhum aumento simultâneo dos AGL no plasma, aumento que normalmente indica mobilização lipídica. O metabolismo lipídico nestes tecidos parece importante para as necessidades energéticas dos próprios tecidos. Fatores como abundância e facilidade de acesso às presas (bovinos) podem estar contribuindo para a baixa variabilidade sazonal das reservas lipídicas teciduais.

Adrenalectomy Abolishes Fasting-induced Down-regulation of NADPH-diaphorase in the Rat Paraventricular Nucleus

This study was conducted to define the molecular mechanism of fasting-induced down-regulation of neuronal nitric oxide synthase (nNOS) expression in the hypothalamic paraventricular nucleus (PVN). Rats were adrenalectomized (ADX), and then either underwent food deprivation or received varying doses of dexamethasone for 48 h. The brain tissues were processed for NADPH-diaphorase (NADPH-d) staining, a histochemical marker of nNOS enzyme activity. Both the ADX and the sham operated rats showed a significant weight loss after 48 h of food deprivation. Food deprivation decreased the number of NADPH-d containing cells in the PVN of sham rats, however, not in the ADX rats. Dexamethasone dose- dependently decreased NADPH-d cells in the PVN of ADX rats. The effect of ADX or dexamethasone was limited to the parvocellular subdivision of PVN. These results suggest that the adrenal glucocorticoids may down-regulate nNOS expression in the PVN during food deprivation.

Blocking of enhanced sensitivity to behavioral effects of naloxone induced by narcotic agonists in rats.

The present experiment evaluated whether prior treatment with naloxone could block the sensitization to opiate antagonist induced by single dose administration of pure agonist (morphine) or mixed agonist (buprenorphine). Food deprived male Wistar rats were trained to respond for food on a multiple-trial, fixed-interval 3 min schedule. Reinforcement was contingent upon a response within a 10-s limited hold period following a fixed-interval of 3 min. A trial consisted of three fixed interval of 3 min separated by a 10 min timeout period during which responses were not reinforced. The rate decreasing effects of the opioid antagonist naloxone was determined by cumulative dosing. Pretreatment with morphine (0.3 mg/ kg, SC) and buprenorphine (0.03 mg/kg, SC) resulted in an increase sensitivity to the rate decreasing effect of naloxone compared to saline pretreatment. Administration of naloxone (0.3 mg/kg) 10 min prior to pretreatment doses of buprenorphine (0.03 mg/kg; 1.0 mg/kg) and morphine (0.3 mg/kg) increased sensitization to naloxone. However, greater sensitization was observed at low dose of buprenorphine. The increased sensitivity was partially blocked at high dose of buprenorphine (1.0 mg/ kg) by naloxone pretreatment. These results suggest that the doses of naloxone used to block opioid induced sensitization might be different from those required in animals with normal sensitivity to opioid antagonists. Further agonist-induced sensitization to behavioral effects of opioid antagonist appears to be opioid receptor specific.

Morphometric alterations in hepatocytes and ultrastructural distribution of liver glycogen in pacu (Piaractus mesopotamicus Holmberg, 1887) during food restriction and refeeding

The morphometric alterations in hepatocytes and the ultrastructural distribution of tissue glycogen in pacu (Piaractus mesootamicus) were studied following food restriction and refeeding. Fish (200-300g) were allocated to control and experimental groups. The experimental group was sampled after 0, 2, 7, 30 and 60 days of food restriction and after 7 and 30 days of refeeding. The control group, which was fed daily, was sampled on the same days. The morphometric results were analyzed by ANOVA in a 2x7 (feeding x days) factorial design and the averages compared by the Tukey test. Transmission electron microscopy showed liver glycogen mobilization during food restriction. The levels of glycogen did not return to normal after up to 30 days of refeeding. There was a decrease in the cytoplasmic area and volume after seven days without food whereas changes in the nuclear area and volume appeared after two days of food restriction. Recovery of the nuclear and cytoplasmic area and volume occurred after 7 days and 30 days of refeeding, respectively. These results indicate tha liver glycogen supplies at least part of the energy requirement during food restriction in juvenile pacu. Thirty days of refeeding were not enough to re-establish the pre-restriction carbohydrate levels, probably because of the extra energy demand associated with the high metabolic rate that occurred during the compensatory process of refeeding at elevated ambient temperatures. However, the recovey seen in the morphometric parameters of the hepatocytes indicated a functional re-adjustment of the liver stimulated by the restored food supply.

Esquema de restriçäo alimentar altera a resposta celular à insulina em ratos diabéticos / Scheme of food restriction change the cellular response to insulin in rats

A resistência à insulina é um elemento chave na gênese de várias alterações fisiopatológicas. O esquema de restrição alimentar meal-feeding (MF) consiste na oferta de uma única refeição diária de 2h, sem, contudo, limitar a quantidade de alimento durante esse período. Este esquema determina várias adaptações morfo-metabólicas, algumas sugerindo maior sensibilidade à insulina. No presente estudo investigou-se, em adipócitos isolados, a sensibilidade à insulina de ratos submetidos a treinamento alimentar e tornados diabéticos (MFD) comparando-os com ratos em livre curso alimentar diabéticos (FFD). A curva dose resposta da captação de 2-deoxi-D-glicose estimulada por insulina sugeriu maior sensibilidade, enquanto a captação máxima foi significativamente maior (p<0,05) nos ratos MFD. Esta maior responsividade à insulina refletiu-se nometabolismo dos adipócitos que mostraram aumento (p<0,05) na capacidade máxima de oxidar glicose a CO 2 e incorporar glicose em triacilglicerol. O aumento da resposta celular à insulina em ratos MFD refletiu-se in vivo em menor (p<0,05) insulinemia e maior (p<0,05) índice glicose/insulina (G/I). Em conjunto, os resultados indicam que o treinamento alimentar melhora a resposta à insulina em ratos diabéticos, o que pode representar uma abordagem alternativa no tratamento do diabetes mellitus.

Effects of stress and food deprivation on catfish, Heteropneustes fossilis (Bloch).

No significant changes in plasma cortisol and plasma osmolarity (the indicators of primary and secondary response respectively) were observed when the blood samples were obtained from unanaesthetized, anaesthetized and stressed catfish, H. fossilis. The results suggest that the catfish is fairly hardy and not easily susceptible to stress by routine laboratory handling. The sustained plasma glucose levels and decreased liver and muscle glycogen concentrations during cessation of feeding of the catfish suggest that during period of food deprivation, it draws its energy through glycogenolysis. Hence, in any study dealing with carbohydrate metabolism, the catfish needs to be fed during acclimation and experimental periods.

Effect of microinjections of 5-hydroxytryptamine and adrenaline in central grey on pain responsiveness during acute food deprivation in conscious rats.

To study the effects of microinjections of 5 hydroxytryptamine and adrenaline in central grey on pain responsiveness during acute food deprivation, experiments were conducted in nine male rats. Microinjections of 5 HT (10 micrograms/microliter) and adrenaline (10 micrograms/microliter) were given in central grey before and at the end of 6, 12, 18 and 24 hr food deprivation and the effects on pain threshold, cardiorespiratory parameters and body temperature were noted. Observations showed that 5 HT increased the pain threshold (antinociception) significantly (P < 0.05) with no change in cardiorespiratory response and body temperature, adrenaline did not alter pain threshold with no change in cardiorespiratory response and body temperature. The observations suggest the possible existence of two types of monoaminergic receptors or pathways in the central grey.

Stud male protection of implantation in food-deprived mice: evaluation of status of ovarian hormones

A falha de implantaçäo em camundongos recém-inseminados induzida por privaçäo alimentar de 48 horas, iniciada às 9 horas no quarto dia após o coito, é evitada pela exposiçäo aos machos. Na presente investigaçäo, estudou-se o efeito da privaçäo alimentar, bem como a influência da presença dos machos durante a privaçäo alimentar nos esteróides ovarianos. Estudos radioimunológicos revelaram que estradiol e testosterona näo foram alterados significativamente nas fêmeas privadas de alimento, independente da presença ou ausência do macho, o que foi comparável ao visto em fêmeas sem privaçäo alimentar. No entanto, o nível sérico de progesterona nas fêmeas privadas foi significativamente reduzido. Por outro lado, näo houve reduçäo no nível de progesterona nas fêmeas privadas de alimento quando em presença dos machos, como ocorreu nas fêmeas controles, i.e., sem jejum. Os resultados suportam a hipótese de que a liberaçäo de prolactina hipofisária, com conseqüente diminuiçäo no desenvolvimento de corpo lúteo funcional, seja o fator endócrino primário na falha de implantaçäo em camundongos com estresse nutricional. Além disso, estes resultados indicam que a presença dos machos contrapöe o fator acima nas fêmeas privadas de alimento.

Ethanol elimination by rats as a function of reproductive state, gender and nutritional status

Alcohol elimination was studied in rats of different ages, reproductive states and nutritional deprivation, with the following results: 1) blood levels of ethanol 180 min after a single dose of 1.5 g/kg, ip were significantly higher in adult male (74 days old, N=5) than in young male rats (34 days old, N = 5): 92.4 ñ 8.4 vs 6.8 + 3.4 mg/lOO ml, means ñ SD, respectively; 2) when male rats were given a low protein diet for 48 h, blood ethanol levels after a single dose were significantly increased in young males (38.6 ñ 14.6 mg/l00 ml) but no effect after a single dose was found in the same animals at an older age (93.2 ñ 5.0 mg/l00 ml); 3) blood levels in female rats were higher than in young males both in the virgin and pregnant states, but during lactation a significant drop in blood levels of ethanol was observed. Blood levels of ethanol (mg/l00 ml) 180 min after a single dose of 1.5 g/kg, ip, in females, were: virgin (N=6): 44.9 ñ 16. 1, pregnant (N = 5): 40.0 ñ 10.4, lactant (N = 5): 8.8 5.8. This difference between virgin and pregnant and lactant rats was not related to changes in ADH activity which did not differ between groups. The present study indicates that in male rats the effect of a short-term protein deprivation on ethanol elimination is dependent on the age of the animal. In females, reproductive state is an important factor in determining ethanol elimination.

Food deprivation and hypothermia in desynchronized sleep-deprived rats

Reports of the effect of desynchronized sleep (DS) deprivation on body temperature (Tb) of rats in the literature are contradictory. Since conspicuous body weight loss is common in such deprivation, the effect of food plus DS deprivation on Tb of adult male Wistar rats was studied. DS deprivation carried out by the small platform method with food ad libitum (N = 8) induced hyperthermia (Tb above 38.5 degrees Celsius) in 1 to 3 rats daily until the 8th day, when a case of discrete hypothermia (Tb below 36.9 degrees Celsius) appeared. Food deprivation alone started to induce hypothermia on the third day in one (20 percent) out of five rats. Fasting imposed from the 5th to the 8th day of DS deprivation (N = 12) caused hypothermia in 33 percent and 67 percent of the animals on the second and third day of starvation, respectively. DS compensatory manifestations in 6 starved rats intensified (N = 2) or precipitated (N = 2) hypothermia after the end of sleep deprivation. It is concluded that the hypothermia is not a primary effect of DS deprivation, and this state of sleep seems to have its particular functional role which is independent of thermoregulation.

Reduced renal sodium excretion in walker-256 tumor-bearing rats

Subcutaneous inoculation of Walker-256 tumor is followes by an asymptomatic period which is widely variable in duration, after which, paraneoplastic effects appear suddenly in the form of progressive and rapidy changing homeostatic alterations. Multifocal inoculation of tumor cells in each animal, was carried out with data averaging in each (sub-clinical [SubC], moderate [mCP] and grave [gCP] clinical phases and compared to foodrestrieted FR. The renal sites involved were studied in awake unrestrained animals by measure of sodium, cratinine and lithium clearance. Results indicated an initial increase of both absolute proximal (mCP:21.4+1.7 vs FR: 16.0+1.1 mmol/min/100 g.b.w., p<0.05) and postproximal (mCP:11.1+0.4 vs FR:6.6+0.4 mmol/min/100g g.b.w., p<0.001) Na+ reabsorption, which were partially compensated by a rise in glomerular filtration rate (mCP:213+11.4 vs FR: 162+10.2p1/min/100 g.b.w., p<0.01) and by fell of fractional proximal Na+ reabsorption (mCP:62.8+ vs FR: 70.1+1.7 per cent, p<0.05), despite this a significant Na+ and fluid retention was observed. Additionally, this study shows that terminal phase of the illness (gCP) culminated with a marked decrease in the creatinine clearance suggesting a significant fall of the renal function.

Energy balance of rats subjected to continuous and intermittent food restriction

Data from our laboratory have demonstrated that food restriction leads to alterations in energy balance such as reduced energy expenditure as an energy conservation mechanism. Food restriction may be imposed on the animals in different ways. The most common is to give equal daily amounts of restricted food. Alternatively, food may be given once every two or three days so that the food intake is not constant with the animal tending to eat more on the first day and be very restricted during the subsequent days of period. The former model may elicit habituation to the low food intake-while the latter may decrease the habituatiuon stimulus since the food intake is not constant. Energy balance was determined in 3 groups of female rats weighing 206,7 + or - 2.0 g (N=6 each): control (C), which, received food ad libitum; continuosly food restricted (CR), which received 8 g of food daily, and intermittently food restricted (IR), which received 24 g of food every 3 days. On the 21st day of treatment, the animals from both food-restricted groups showed a similar reduction of body weight (-47,9 + or - 5,1 and -55.8 + or - 4.0 g for CR and IR, respectively) and body energy (-501.0 + or - 65.5 and -427.0 + or - 82.1 for CR and IR, respectively), and they had similar energy expenditure (2643 + or - 72 and 2518 + or - 97 for CR and IR, respectively) which was different from ad libitum controls (4.6 + or - 2.9 body weight gain, 277,3 + or - 42.5 body energy gain and 4574 + or - 290 energy expenditure). Body weight decreased continuously in the CR group while in the IR group it followed the pattern of food intake with up-and-down shifts. We conclude that the energy balance pattern presented by food restricted animals in the same regardless of the form of food restriction imposed