Effects Of Food Restriction Research Articles

Effects of starvation and refeeding cycles on spermatogenesis and sex steroids in the Nile tilapia Oreochromis niloticus

Food restriction is part of the life cycle of many fish species; however, nutritional deficiency may negatively influence gametogenesis and gonadal maturation. The aim of this study was to evaluate the effects of food restriction on the spermatogenesis of Nile tilapia. For this, adult males were submitted to starvation and refeeding cycles (alternating periods of starvation and feeding) for 7, 14, 21, and 28 days. After 7 days of starvation, glycaemic and lipid levels were significantly reduced, followed by reduction of plasma testosterone (T) and 11-ketotestosterone (11-KT). In addition, reduced proliferation of spermatogonia and increased apoptosis of spermatocytes, spermatids, and spermatozoa was observed in starvation groups. In the refeeding groups, the sex steroids and the proportion of germ cells had no significant alterations compared to the control group, except for spermatozoa. In this sense, the present study suggests that starvation after 7 days progressively reduces T and 11-TK, resulting in damage to the production of spermatogenic cells, while refeeding may delay spermatogenesis but does not lead to testicular impairment.

Augmentation of morphine-conditioned place preference by food restriction is associated with alterations in the oxytocin/oxytocin receptor in rat models

ABSTRACT Background Studies indicate that food restriction (FR) reinforces the effects of morphine. The exact mechanisms by which FR influences the reward circuitry of morphine have not yet been determined. Objectives We hypothesized that the effects of FR on the oxytocin (OXT) system and HPA axis can be associated with substance abuse disorders. In this study, the serum levels of OXT and corticosterone, and the expression of OXT/OXT receptor (OXTR), glucocorticoid receptor (GR), and brain-derived neurotrophic factor (BDNF) in the hippocampus, prefrontal cortex, and nucleus accumbens were investigated in an FR model. Methods First, the male rats (n = 8 per group) were subjected to FR for 3 weeks. Then, morphine-induced conditioned place preference (CPP) was observed using two doses of morphine (3 and 5 mg/kg). The serum concentrations of corticosterone and OXT were determined by ELISA and the expression of genes was examined by qPCR. Results FR induced an enhanced preference in the animals for the 5 mg/kg dose of morphine compared to the controls. Serum corticosterone levels increased after FR but OXT levels decreased. Meanwhile, FR actuated downregulation of GR, BDNF, and OXT genes, while inducing the overexpression of OXTR. Conclusion We propose the inclusion of OXT and OXTR alterations in the enhancement of morphine-induced CPP and addiction vulnerability following FR. Moreover, we conclude that altered BDNF levels and HPA axis activity may be the mechanisms involved in the effects of FR on morphine-induced behavior.

Nutritional Status in Spanish Children and Adolescents with Celiac Disease on a Gluten Free Diet Compared to Non-Celiac Disease Controls.

Patients who follow a gluten-free diet (GFD) may be prone to nutritional deficiencies, due to food restriction and consumption of gluten-free products. The aim was to assess nutritional status in celiac children and adolescents on a long-term GFD. A cross-sectional age and gender-matched study in 70 celiac and 67 non-celiac volunteers was conducted, using dietary, anthropometric, biochemical parameters, and assessing bone mineral density and physical activity. Adequacy of vitamin D intake to recommendations was very low, in both groups, and intakes for calcium and magnesium were significantly lower in celiac volunteers. Celiac children and adolescents may have a higher risk of iron and folate deficiencies. Both groups followed a high-lipid, high-protein, low fiber diet. Median vitamin D plasma levels fell below reference values, in celiac and non-celiac participants, and were significantly lower in celiac girls. Other biochemical parameters were within normal ranges. Anthropometry and bone mineral density were similar within groups. With the exception of some slightly lower intakes, children and adolescents following a GFD appear to follow the same trends as healthy individuals on a normal diet. No effect of food restriction or gluten-free product consumption was observed.

Impact of confinement and food access restriction on the three-spined stickleback (Gasterosteus aculeatus, L.) during caging: a multi-biomarker approach.

Caging is an active biomonitoring strategy that employs a sentinel species, sometimes a species naturally absent from the studied site, in the surveillance of water bodies to verify whether biota may be at risk. The main advantage of caging is the possibility to standardize several biotic and abiotic parameters. However, little knowledge is available about the effects of confinement on physiology and metabolism of caged organisms. The aim of this study is to characterize confinement and food access restriction effects, induced via caging experiments using a multi-biomarker approach (biometric data, immunity, antioxidant, metabolic detoxication, and digestive enzymes). The study has been undertaken using the same experiment conducted in ecosystem conditions using three-spined stickleback (Gasterosteus aculeatus) during two different periods: one in April, corresponding to breeding season, and the other in October, outside breeding season. Fifteen fish were maintained for 21days in different conditions (caged or uncaged and with or without food supply). The main result was that confinement stress had little impact on the biological markers of sticklebacks. However, the stressors seemed to increase the negative effects of food restriction on these biomarkers, when sticklebacks needed more energy, that is, during their breeding period. Outside breeding period, most investigated biomarkers were not impacted by caging. This study showed a way to specify the conditions of application and interpretation of biomarkers during active monitoring to ensure an effective, reliable diagnosis of water body quality.

The effect of food restriction on the regulation of gonadotropin-releasing hormone in male house finches (Haemorhous mexicanus)

Seasonal activation of the vertebrate hypothalamic-pituitary-gonadal (HPG) axis and gonadal development is initiated by gonadotropin-releasing hormone-I (GnRH) release from the hypothalamus. In photoperiodic species, the consistent annual change in photoperiod is the primary environmental signal affecting GnRH cell activity, including changes in the synthesis and secretion of this neuropeptide. Non-photoperiodic environmental cues such as energy availability also influence HPG axis activity, but the mechanisms mediating this influence, in particular on the GnRH system, are unclear. Understanding how the neuroendocrine system integrates environmental information is critical in determining the plasticity and adaptability of physiological responses to changing environments. The primary objective of this study was to investigate GnRH-mediated changes in HPG axis activity and gonadal development in response to energy availability in a wild bird. We hypothesized that negative energy balance inhibits HPG axis activity by affecting GnRH secretion. Moderate food restriction for several weeks in male house finches, Haemorhous mexicanus, decreased body condition and inhibited photoinduced testicular growth compared to birds fed ad libitum. Food restriction did not affect plasma luteinizing hormone (LH; a correlate of GnRH release) or plasma testosterone, but it enhanced the plasma LH response to an injection of the glutamatergic agonist, N-methyl-D-aspartate (NMDA). Thus, food restriction may decrease photoinduced HPG axis activation by acting centrally, in particular by attenuating the release of accumulated GnRH stores.

Immediate and Delayed Effects of Food Restriction on Some Parameters of Brain Development in Rats.

The effects of 15-day restriction diet (from 1 to 1.5 months of age) on some parameters of brain development were studied in rats. The immediate and delayed (15 days after transfer to normal ration) effects were evaluated. The immediate effects included a significant decrease of the absolute weights of the brain and hemispheres. The relative weight of the brain was significantly higher. The thickness of the cortex of the parietal lobe proper and its layer I decreased. The absolute weights of the brain and hemispheres were less than in the control 15 days after the rats were transferred to ad libitum feeding, while the relative weight of the brain was higher than in controls. The thickness of the parietal and anterior parietal cortex and the numerical density of neurons in layers II and V did not differ from the control. In the neurons of layers II and V of the anterior parietal and parietal lobe proper the nuclei were larger, while the nucleoli were enlarged in the neurons of these locations and the hippocampus, the shifts being significant in the anterior parietal layer V. The concentrations of RNA in the parietal, anterior parietal, and hippocampal lobe neurons in different groups were similar directly and 15 days after the diet. Changes in the gravimetric and morphometric parameters of the brain were paralleled by the development of oxidative stress.

Effect of Agricultural Countermeasures on Ingestion Dose Following a Nuclear Accident

Background: Management of an agricultural food product system following a nuclear accident is indispensable for reducing radiation exposure due to ingestion of contaminated food. The present study analyzes the effect of agricultural countermeasures on ingestion dose following a nuclear accident. Materials and Methods: Agricultural countermeasures suitable for domestic farming environments were selected by referring to the countermeasures applied after the Fukushima accident in Japan. The avertable ingestion doses that could be obtained by implementing the selected countermeasures were calculated using the Korean Agricultural Countermeasure Analysis Program (K-ACAP) to investigate the efficiency of each countermeasure. Results and Discussion: Of the selected countermeasures, the management of crops was effective when radionuclide deposition occurred during the growing season of plants. Treatment by soil additive and topsoil removal was effective when deposition occurred during the nongrowing season of plants. The disposal of milk was not effective owing to the small contribution of milk to the overall ingestion dose. Clean feeding of livestock was effective when deposition occurred during the growing season of fodder plants such as pasture and rice-straw. Finally, the effect of food restriction increased with the soil deposition density of radionuclide. The practical effect of countermeasures was very small when the avertable ingestion dose was absolutely low. Conclusion: The agricultural countermeasures selected to reduce the radionuclide ingestion dose after a nuclear accident must be made appropriate by considering the accident situation, such as the soil deposition density of the radionuclide and the deposition date in relation to farming cycles.

Differential regulation of thyrotropin-releasing hormone mRNA expression in the paraventricular nucleus and dorsomedial hypothalamus in OLETF rats

Thyrotropin-releasing hormone (TRH) plays an important role in the regulation of energy balance. While the regulation of TRH in the paraventricular nucleus (PVN) in response to changes of energy balance has been well studied, how TRH is regulated in the dorsomedial hypothalamus (DMH) in maintaining energy homeostasis remains unclear. Here, we assessed the effects of food restriction and exercise on hypothalamic Trh expression using Otsuka Long-Evens Tokushima Fatty (OLETF) rats. Sedentary ad lib fed OLETF rats (OLETF-SED) became hyperphagic and obese. These alterations were prevented in OLETF rats with running wheel access (OLETF-RW) or food restriction in which their food was pair-fed (OLETF-PF) to the intake of lean control rats (LETO-SED). Evaluation of hypothalamic gene expression revealed that Trh mRNA expression was increased in the PVN of OLETF-SED rats and normalized in OLETF-RW and OLETF-PF rats compared to LETO-SED rats. In contrast, the expression of Trh in the DMH was decreased in OLETF-SED rats relative to LETO-SED rats. This alteration was reversed in OLETF-RW rats as seen in LETO-SED rats, but food restriction resulted in a significant increase in DMH Trh expression in OLETF-PF rats compared to LETO-SED rats. Strikingly, while Trh mRNA expression was decreased in the PVN of intact rats in response to acute food deprivation, food deprivation resulted in increased expression of Trh in the DMH. Together, these results demonstrate the differential regulation of Trh expression in the PVN and DMH in OLETF rats and suggest that DMH TRH also contributes to hypothalamic regulation of energy balance.

Effects of food restriction on energy metabolism in male Apodemus chevrieri from Hengduan mountain region of China

To investigate the relationship between the energy strategies in response to food restriction and the levels of metabolism in small mammals, body mass, resting metabolic rate (RMR), nonshivering thermogenesis (NST) and cytochrome c oxidase (COX) activity were measured in Apodemus chevrieri that were subjected to different levels of food restriction (FR). The results showed that cold-exposed group had significantly increased RMR and NST, but decreased body mass and survival rate after being restricted to 80% of ad libitum food intake compared with their counterparts maintained at room temperature. A. chevrieri with higher RMR consumed higher food intake than individuals with lower RMR, whereas no differences were observed in body mass and survival rate between two groups after being restricted to 80% of ad libitum food intake. The results suggest that A. chevrieri characterized by higher levels of metabolism are sensitive to periods of FR, providing a support for the “metabolism switch hypothesis”.

Effects of food restriction and/or aerobic exercise on the GLUT4 in type 2 diabetic male rats.

Background:The aim of present study was to compare the effects of negative energy balance with food restriction and/or aerobic exercise on the glucose, insulin, and GLUT4 levels in diabetic male rats.Methods:Fifty-six 10-week old male Wistar rats were randomly assigned to seven groups: a non-diabetic (ND) group and six diabetic groups. After an infusion of type 2 diabetes, the diabetic groups were given labels as well, namely diabetic control (DC) group, exercise (Ex) group, food restriction with standard diet (FRSD) group, food restriction with low-carbohydrate diet (FRLCD) group, food restriction with standard diet combination in exercise (FRSDE) group, and food restriction with low-carbohydrate diet combination in exercise (FRLCDE) group. Further, to induce caloric restriction (CR), food intake was reduced by 20% and given to food restriction consists of both of (FRSD and FRLCD). Hundred percent food consumption for the Ex group was fixed, but instead, 20% of their energy intake in exercise was calculated, and time of daily exercise was determined. Finally, a combination of reduced food intake (10%) and exercise (10%) was applied in each group FRSDE and FRLCDE for 8 weeks.Results:The results showed that type 2 diabetes inductions had reduced glucose, insulin, and GLUT4 gene expression compared to the ND group (P = 0.001). However, there were significant differences in GLUT4 gene expression between groups after 8 weeks of intervention (P = 0.001). A post hoc least significant difference test show that compared to DC group, GLUT4 gene expression level of Ex, FRSDE, and FRLCDE groups was significantly increased 47% (P = 0.004), 60% (P = 0.001), and 65% (P = 0.001), respectively after 8 week of intervention, but it was not significant or with any other diabetic groups (P > 0.05). Moreover, glucose levels were significantly higher in the FRLCDE, FRLCD, FRSD, FRSDE, Ex groups compared with the DC group in the same period (P = 0.0.01).Conclusions:It was concluded that FRSD and FRLCD combination in regular exercise was elevated of GLUT4 gene expression in type 2 diabetes. These results may help to develop new methods for the treatment of obesity and type 2 diabetes mellitus.

Adipose tissue is less responsive to food restriction anti-inflammatory effects than liver, muscle, and brain in mice.

High caloric intake promotes chronic inflammation, insulin resistance, and chronic diseases such as type-2 diabetes, which may be prevented by food restriction (FR). The effect of FR on expression of pro-inflammatory and anti-inflammatory genes in adipose tissue, liver, muscle, and brain was compared. Male Swiss mice were submitted to FR (FR group) or had free access to food (control group) during 56 days. The liver, gastrocnemius muscle, brain, and epididymal white adipose tissue (WAT) were collected for analysis of gene expressions. FR attenuated inflammation in the liver, brain, and gastrocnemius muscle but did not markedly change inflammatory gene expression in epididymal WAT. We concluded that adipose tissue was less responsive to FR in terms of gene expression of pro-inflammatory and anti-inflammatory genes.

Bone callus formation is highly disrupted by dietary restriction in growing rats sustaining a femoral fracture

Purpose To evaluate the effects of food restriction on fracture healing in growing rats. Methods Sixty-eight male Wistar rats were assigned to two groups: (1) Control and (2) Dietary restriction. After weaning the dietary restricted animals were fed ad libitum for 42 days with 50% of the standard chow ingested by the control group. Subsequently, the animals underwent bone fracture at the diaphysis of the right femur, followed by surgical stabilization of bone fragments. On days 14 and 28 post-fracture, the rats were euthanized, and the fractured femurs were dissected, the callus was analyzed by dual-energy X-ray absorptiometry, micro-computed tomography, histomorphometry, mechanical tests, and gene expression. Results Dietary restriction decreased body mass gain and resulted in several phenotypic changes at the bone callus (a delay in cell proliferation and differentiation, lower rate of newly formed bone and collagen deposition, reductions in bone callus density and size, decrease in tridimensional callus volume, deterioration in microstructure, and reduction in bone callus strength), together with the downregulated expression of osteoblast-related genes. Conclusion Dietary restriction had detrimental effects on osseous healing, with a healing delay and a lower quality of bone callus formation.

Food restriction decreases BMR, body and organ mass, and cellular energetics, in the Chinese Bulbul (Pycnonotus sinensis)

BackgroundFood is an important environmental factor that affects animals’ energy metabolism and food shortage has significant effects on animals’ behavior, physiology and biochemistry. However, to date few studies have focused on the thermogenesis and its effects on the body condition of birds. In this study, we examined the effects of food restriction on the body mass, basal metabolic rate (BMR) and body composition, and several physiological, biochemical and molecular markers potentially related to thermogenesis, in the Chinese Bulbul (Pycnonotus sinensis).MethodsBirds in the control group were provided with food ad libitum whereas those in the food restriction group were provided with one-half of the usual quantity of food for 12 days. Oxygen consumption was measured using an open-circuit respirometry system. Mitochondrial state 4 respiration and cytochrome c oxidase (COX) activity in the liver and pectoral muscle were measured with a Clark electrode. Avian uncoupling protein (avUCP) mRNA expression was determined in pectorals muscle with quantitative Real-time PCR.ResultsChinese Bulbuls in food restriction group decreased in body mass, BMR and internal organ (heart, kidneys, small intestine and total digestive tract) mass compared with the control group over the 12-day period of food restriction. Bulbuls in the food restriction group also had lower levels of state-4 respiration, COX activity in the liver and muscle, and mitochondrial avUCP gene expression in muscle compared to the control group. BMR was positively correlated with body mass, state 4 respiration in the liver and COX activity in the muscle.ConclusionsOur data indicate that Chinese Bulbuls not only sustain food shortage through simple passive mechanisms, such as reducing body and organ mass and energy expenditure, but also by reducing energetic metabolism in the liver and muscle.

Both Low Temperature and Shorter Duration of Food Availability Delay Testicular Regression and Affect the Daily Cycle in Body Temperature in a Songbird.

Photoperiodic control of reproduction in birds is based on two processes, a positive effect leading to gonadal maturation and an inhibitory effect subsequently inducing regression. Nonphotoperiodic cues can modulate photoperiodic control, particularly the inhibitory process. In previous studies of common starlings (Sturnus vulgaris), (1) restriction of food availability to 8 h after dawn had little effect on testicular maturation but dramatically delayed subsequent regression and (2) lower ambient temperature also had little effect during maturation but delayed regression. Could the effects of food restriction and temperature share a common underlying mechanism? Four groups of starlings were kept on a simulated natural cycle in photoperiod in a 2 × 2 factorial experimental design. Two groups were held under an ambient temperature of 16°C, and the other two were held under 6°C. One of each of these groups had food provided ad lib., and in the other two groups access to food was denied 7 h after dawn. In both the ad lib. food groups and the food-restricted groups, lower temperature had little effect on testicular maturation but delayed subsequent regression and molt. In both the 16°C groups and the 6°C groups, food restriction had no effect on testicular maturation but delayed regression and molt. The daily cycle in body temperature was recorded in all groups when the photoperiod had reached 12L∶12D, the photoperiod at which regression is initiated. In both 6°C groups, nighttime body temperature was lower than in the 16°C groups, a characteristic of shorter photoperiods. In the two ad lib. food groups high daytime temperature was maintained until dusk, whereas in the two food-restricted groups body temperature began to decrease after food withdrawal. Thus, both lower temperature and food restriction delayed regression, as if the photoperiod was shorter than it actually was, and both resulted in daily cycles in body temperature that reflected cycles under shorter photoperiods. This implies that the daily cycle in body temperature is possibly a common pathway through which nonphotoperiodic cues may operate.

Efecto de la restricción de alimento y posterior realimentación sobre algunas variables fisiológicas y metabólicas en yamú (Brycon amazonicus)

The effect of food restriction and refeeding on some physiological variables in yamú (Brycon amazonicus) was evaluated using 1115 juveniles (initial weight 217.75 g ± 14.74 g), distributed in three ponds. The groups were randomly assigned one of the following treatments: 1) Control (C), fed every day; 2) Moderate restriction (MR), restriction during two days and refeeding during three; and 3) Severe restriction (SR), total restriction during five weeks and refeeding from week 6 to 12. Blood samples from 7 animals from each treatment were taken on days 1, 35, 42, 56, 70, and 84 to determine hematocrit, proteins, glucose, lactate, triglycerides, cholesterol, cortisol, T3, and insulin. The animals were sacrificed and their livers removed to calculate the hepatic glycogen. The experimental design used was a fixed effects mixed model of 3 treatments and 6 samples, with sampling nesting in the treatments. A variance analysis was performed to analyze the data; the Tukey-Kramer test a variance analysis was used in the cases with significant differences. No significant differences (p˃ 0.05) were found for hematocrit, protein, glucose, cortisol, and lactate. The insulin and T3 showed differences among treatments on day 35, but not on day 84, the same as cholesterol and hepatic glycogen. Triglycerides showed differences throughout the study, SR showed the lowest levels on day 84. The results allow us to conclude that, despite the partial feed restriction, there were no adverse effects on the metabolism of Brycon amazonicus.

The Short and Long‐Term Effects of Food Restriction on Body Composition and the Renin Angiotensin System

IntroductionIndividuals who experience severe food restriction (FR) diet are at increased risk for developing cardiovascular disease during the FR period and also long term well after the FR period has ended. Abnormalities in the heart, vascular system and kidneys including hypotension, bradycardia and mitral valve prolapse are common problems in individuals who have experienced a FR. Unfortunately, the long‐term risk for cardiovascular and renal disease due to earlier exposure to FR is an understudied problem and there are no known therapeutic strategies designed to prevent the increased risk after recovery from the FR period(s). The goal of this study was to determine the short and long term consequences of a severe FR diet on body composition and sodium and potassium balance.MethodsFour month old (mo) female Fischer rats were divided into a control (CT) group that had access to food ad libitum and a FR group that received 40% of the normal daily food intake. After 2 weeks, the FR rats received chow ad libitum for 1 month. The FR group were placed in metabolic cages on day 1 through day 4 and on day 14 of the restricted diet through day 4 of the recovery phase to collect urine and to determine the sodium & potassium balance.ResultsAfter 2 weeks, the FR group had an 18% reduction in body weight (BW) and a 50% reduction in water intake compared to the CT rats. In addition, plasma volume (p=0.03), blood pressure (p=0.03), heart rate (p=0.03), kidney weight, and kidney protein were all reduced and angiotensin (Ang) II (p<0.05) and angiotensinogen (p<0.001) were increased in the plasma. No differences were observed in plasma aldosterone and potassium or in urine protein. The plasma sodium concentration was increased in the FR rats. While the FR animals remained in sodium balance during the first 4 days of the diet, these animals were in negative balance for potassium (p<0.05) returning to balance on the 2nd day. The estrous cycle was disrupted after 3 days on the diet with the animals remaining in diestrus and returning to the ovulatory phase only after 7 days into the recovery period. The ad libitum diet also caused a positive balance for potassium during the 1st day without any effect on sodium balance. The rats did not recover their normal BW until 21 days into the recovery phase. Body fat recovered within 1 week while the % lean body mass did not recover until 28 days of the recovery phase.ConclusionSevere FR causes major changes in the renin angiotensin system, potassium balance, endocrine status and body composition. These effects are long lasting and likely contribute to the long term adverse consequences of exposure to a single period of severe food restriction.Support or Funding InformationTL1‐TR001431 (AVP), UL1‐TR001409 (KS) and R01‐HL119380 (KS, HJ).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Is omphalocele a non-specific malformation in New Zealand White rabbits?

We evaluated the incidence of omphalocele, a malformation that occurs sporadically in many studies. We assembled data on external malformations using all treatment groups from every study published in three major journals over the past 35 years using New Zealand White rabbits. Fifty-eight papers were included: 4905 litters and 36,977 fetuses. Omphalocele was reported in 43% and was among the most common defects, occurring at a rate of 1.10% (litter) and 0.16% (fetus). The defect did not appear to be treatment-related, although it may have been in two studies, based on rate and dose-responsiveness. Removing these two studies from the analysis, the defect was still prevalent (0.77% litter, 0.11% fetal incidence). Three studies evaluated the effects of food restriction and omphalocele was observed with food restriction in two of them, suggesting that decreased maternal weight gain or food consumption may be causal. Otherwise, it appears to be spontaneous and common.

Effects of food restriction on the expression of genes related to acetaminophen-induced liver toxicity in rats.

It is well known that fasting substantially affects the metabolism of drugs and chemicals. Food restriction also affects drug kinetics, such as absorption, metabolism, and excretion, and therefore, it can potentially modulate the onset of chemical toxicity or drug-induced adverse reactions. In the present study, the expression of drug-metabolizing enzyme genes and total glutathione content in the liver, which are related to toxicity induced by overdose of the hepatotoxic drug acetaminophen (N-acetyl-p-aminophenol; APAP), were examined in rats reared under different feeding conditions: ad libitum feeding, 16-h fasting, and food restriction (fed 70% of the average intake of ad libitum feeding for 10 days) conditions. The rats under food restriction conditions as well as fasted rats showed significantly higher expression of Cyp2e1, the gene encoding the enzyme that metabolizes APAP to its toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). They also had lower levels of liver total glutathione, which detoxifies NAPQI. In contrast, the gene expression of UDP-glucuronosyltransferase 1A6 (Ugt1a6), sulfotransferase 1A1 (Sult1a1), and glutathione S-transferase M1 (Gstm1) was not affected by food restriction or fasting. When APAP was administered (800 mg/kg), histopathological changes were not observed in rats fed ad libitum, while hepatocellular necrosis was observed in most of the rats treated with APAP after fasting or food restriction. Taken together, these results suggest that not only fasting but also food restriction exacerbate APAP-induced acute liver injury, probably by the induction of CYP2E1 and the reduction of liver glutathione contents, in rodents.

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.

Enhancement of a visual reinforcer by D-amphetamine and nicotine in adult rats: relation to habituation and food restriction.

Nicotine and D-amphetamine can strengthen reinforcing effects of unconditioned visual stimuli. We investigated whether these reinforcement-enhancing effects reflect a slowing of stimulus habituation and depend on food restriction. Adult male rats pressed an active lever to illuminate a cue light during daily 60-min sessions. Depending on the experiment, rats were challenged with fixed or varying doses of D-amphetamine (0.25-2mg/kg IP) and nicotine (0.025-0.2mg/kg SC) or with the tobacco constituent norharman (0.03-10μg/kg IV). Experiment 1 tested for possible reinforcement-enhancing effects of D-amphetamine and norharman. Experiment 2 investigated whether nicotine and amphetamine inhibited the spontaneous within-session decline in lever pressing. Experiment 3 assessed the effects of food restriction. Amphetamine (0.25-1mg/kg) and nicotine (0.1mg/kg) increased active lever pressing specifically (two- to threefold increase). The highest doses of nicotine and amphetamine also affected inactive lever responding (increase and decrease, respectively). With the visual reinforcer omitted, responding was largely extinguished. Neither drug appeared to slow habituation, as assessed by the within-session decline in lever pressing, and reinforcement-enhancing effects still occurred if the drugs were given after this decline had occurred. Food restriction enhanced the reinforcement-enhancing effect of amphetamine but not that of nicotine. Responding remained goal-directed after several weeks of testing. Low doses of D-amphetamine and nicotine produced reinforcement enhancement even in free-feeding subjects, independent of the spontaneous within-session decline in responding. Reinforcement enhancement by amphetamine, but not nicotine, was enhanced by concurrent subchronic food restriction.