Effects Of Food Restriction Research Articles

Effects of food restriction during puberty and pregnant period on the maternal rats and growth of progeny

Effects of food restriction during puberty and pregnant period on the maternal rats and growth of progeny

Food Restriction Alters N′-Propyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine dihydrochloride (Pramipexole)-Induced Yawning, Hypothermia, and Locomotor Activity in Rats: Evidence for Sensitization of Dopamine D2 Receptor-Mediated Effects

Food restriction enhances sensitivity to the reinforcing effects of a variety of drugs of abuse including opiates, nicotine, and psychostimulants. Food restriction has also been shown to alter a variety of behavioral and pharmacological responses to dopaminergic agonists, including an increased sensitivity to the locomotor stimulatory effects of direct- and indirect-dopamine agonists, elevated extracellular dopamine levels in responses to psychostimulants, as well as suppression of agonist-induced yawning. Behavioral and molecular studies suggest that augmented dopaminergic responses observed in food-restricted animals result from a sensitization of the dopamine D2 receptor; however, little is known about how food restriction affects dopamine D3 receptor function. The current studies were aimed at better defining the effects of food restriction on D2 and D3 receptor function by assessing the capacity of N'-propyl-4,5,6,7-tetrahydrobenzothiazole-2,6-diamine dihydrochloride (pramipexole) to induce yawning, penile erection (PE), hypothermia, and locomotor activity in free-fed and food-restricted rats. Food restriction resulted in a suppression of pramipexole-induced yawning, a sensitized hypothermic response, and an enhanced locomotor response to pramipexole, effects that are suggestive of an enhanced D2 receptor activity; no effect on pramipexole-induced PE was observed. Antagonist studies further supported a food restriction-induced enhancement of the D2 receptor activity because the D2 antagonist 3-[4-(4-chlorophenyl)-4-hydroxypiperidin-l-yl]methyl-1H-indole (L741,626) recovered pramipexole-induced yawning to free-fed levels, whereas yawning and PE were suppressed following pretreatment with the D3 antagonist N-{4-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-trans-but-2-enyl}-4-pyridine-2-yl-benzamide hydrochloride (PG01037). The results of the current studies suggest that food restriction sensitized rats to the D2-mediated effects of pramipexole while having no effect on the D3-mediated effects of pramipexole.

Food restriction and simulated microgravity: effects on bone and serum leptin

Leptin is responsible for linking energy metabolism to bone mass. Because astronauts are commonly in negative energy balance during spaceflight, this study was designed to assess individual and combined effects of food restriction and simulated microgravity on bone mass and serum leptin. Six-month-old male Sprague-Dawley rats were randomly assigned to four groups (n = 12 each): two hindlimb-unloading (HU) groups fed 100% (HU100) and 70% (HU70) and two cage-activity control (CC) groups fed 100% (CC100) and 70% (CC70) of their baseline food requirement. After 28 days, CC100 rats gained body weight, whereas all other groups lost body weight; this loss was greater in HU70 than in CC70 and HU100 rats. Serum leptin decreased in CC70 and HU100 (-60% and -27%, respectively) and was not detectable in HU70 animals. Percent osteoid surface in CC70 and HU100 was lower than that of CC100 (7.80%, 8.60% vs. 10.70%, respectively), and this decrease was more pronounced in HU70 animals (4.38%). Mineral apposition rate of CC70, HU100, and HU70 rats was lower than that of CC100 (1.5, 1.6, and 1.5 vs. 2.1 mum/day, respectively). Bone formation rate of CC70, HU100, and HU70 rats was lower than that of CC100 (13.4, 13.1, and 12.2 vs. 40.8 mm(3).mm(-2).day(-1), respectively). The change in bone formation rate was correlated with the change in serum leptin value over 28 days (r(2) = 0.69, P = 0.0007). We conclude that moderate caloric restriction may cause bone loss at susceptible bone sites to a similar degree as does the unloading effect of microgravity; serum leptin may be an important endocrine regulator contributing to this change in skeletal integrity.

Influence of Physical Exercise and Food Restriction on the Biomechanical Properties of the Femur of Ageing Male Rats

Background: Voluntary running in wheels as well as food reduction increase the life spans of rats. Disparate parameters such as the collagen biomarker of ageing and the development of kidney pathologies are decreased by voluntary exercise. There are few reports on the influence of physical exercise and food restriction on the skeleton of male rats. Most investigations initiated rather short-term interventions in 4- to 5-week-old animals and thus studied more the influence of growth than the influence of ageing on the skeleton. Objective: To compare the effects of physical exercise and food restriction on the biomechanical properties of bone tissue of ageing male rats with the interventions starting at the age of 5 months with the end point at 23 months. This enables the study of the influence of these interventions on the ageing of the skeleton. Methods: Five groups of male Sprague-Dawley rats were used: baseline (BL), voluntarily running in wheels (RW), food restriction to attain pair weight with RW animals (PW), forced running in treadmills (TM), and sedentary controls (SE). The biomechanical properties of femoral neck, diaphysis, and distal metaphysis were measured. Results: While the body weights and fat-free mass increased from BL to SE group, the occiput-sacrum length did not increase and the length of the femur increased marginally. These lengths were slightly retarded in RW and PW groups compared to the SE group. The strength of the distal femoral metaphysis decreased from BL to SE group. This decrease was counteracted by physical exercise (RW and TM groups) as well as by food restriction (PW group). In contrast, the strength of the femoral mid-diaphysis did not differ between BL and SE groups. Conclusions: The distal metaphysis in the male rat femur is more prone to decreasing biomechanical strength than the diaphysis during ageing. Physical exercise, when started at the age of 5 months, when the skeleton has reached its adult size, is somewhat effective in counteracting these changes. There is also some retarding effect of food restriction.

Chronic food restriction differentially affects NPY mRNA level in neurons of the hypothalamus and in neurons that innervate liver

Neuropeptide Y (NPY) is found in neurons of the brain and in the neurons that innervate abdominal organs including liver. Major biological function of hypothalamic NPY is regulation of appetite and body weight homeostasis. In the periphery, biological function of NPY varies, depending on the organ/tissue. Increased hypothalamic NPY mRNA level in response to chronic caloric restriction is a well documented phenomenon. The effect of food restriction on NPY mRNA level in neurons that innervate liver has not been published so far. To evaluate how chronic food restriction affects liver (and other abdominal organs) NPY mRNA level, we compared NPY mRNA abundance in liver, kidney cortex, perirenal white adipose tissue and in hypothalamus of rats maintained on chronic restricted diet. Data presented in this paper indicate that chronic food restriction: (a) caused the increase of NPY mRNA level in the hypothalamus, (b) caused the decrease of NPY mRNA level in the liver, and (c) was without effect on NPY mRNA level in kidney cortex and perirenal white adipose tissues. Moreover, rats maintained on restricted diet displayed lower serum NPY, leptin and insulin concentrations and higher serum corticosterone concentration. Together, these data suggest that hypothalamus and liver (and other abdominal organs) NPY gene expression is differentially regulated by caloric restriction. It seems that liver NPY gene expression in contrast to the hypothalamus NPY gene expression is not suppressed by leptin.

Effects of Food Restriction on Phenotypes of TALLYHO/JngJ Mouse

Background: Food restriction has been reported to ameliorate diabetes and obesity. In this study, we examined the effects of the food restriction on phenotypes of TALLYHO/JngJ (TH) mouse, a recently developed diabetic model animal. Methods: 3 week-old TH mice were divided into 2 groups (n = 20 each for food-restricted (THR) and free-fed (THF)) and THR mice were fed the same amount of food as normal control mice (C57BL/6, n = 20). Body weight was weekly monitored till 14 weeks of age. The half of animals were sacrificed at 8 weeks of age, and liver, kidney, and fat weight were measured. The histopathology of liver and brown fat tissues and mRNA expression of leptin in adipose tissue were analyzed. The oral glucose tolerance test and insulin resistance test was done at 14 weeks of age. The plasma concentrations of glucose, free fatty acid, triglyceride, cholesterol and leptin were analyzed. Results: The THR mice had lower body weights than the THF mice, similar to C57BL/6 mice, with reduced fat deposition in liver and brown fat tissue. The plasma levels of glucose, triglyceride and free fatty acid were decreased in the THR group. The THR mice, however, carried more fat than normal mice, with increased plasma leptin concentration and leptin mRNA expression in fats and no alteration in plasma cholesterol levels. Furthermore, the THR mice revealed glucose intolerance with impaired after-meal insulin secretion and slight insulin resistance Conclusion: The food restriction apparently ameliorated the obesity and di abetic phenotypes of TH mice. However, plasma concentration of cholesterol were not improved in THR mice with increased adiposity index and glucose intolerance, suggesting the genetically prone tendency of obesity and diabetes development in TH mice possibly with an impairment in cholesterol metabolism. (KOREAN DIABETES J 32:304-316, 2008)

CrossRef Listing of Deleted DOIs

The etiology of amenorrhea in exercising women is linked to a mismatch between caloric intake and high levels of exercise energy expenditure that results in a chronic energy deficit. This in turn stimulates compensatory mechanisms such as weight loss, metabolic hormone alterations, or energy conservation that subsequently causes a central suppression of reproductive function and concomitant hypoestrogenism. This suppression of reproductive function is associated with stress fractures, loss of bone mineral density, the failure to achieve peak bone mass, osteopenia, and osteoporosis. It has generally been accepted that the chronic hypoestrogenism is the major cause of bone loss in exercising women. However, the effects of food restriction and energy deficiency on bone mineral density likely represents an estrogen-independent mechanism for bone loss that involves some of the metabolic-related hormones altered with exercise-associated amenorrhea. These hormones (IGF-1 and leptin) play an important role in modulating bone turnover and bone mineral density in these women.

Effects of Food Restriction during Puberty and Pregnant Period on the Maternal Body and Growth of Offspring in Rats

Effects of Food Restriction during Puberty and Pregnant Period on the Maternal Body and Growth of Offspring in Rats

Increase in Ghrelin Levels After Weight Loss in Obese Zucker Rats is Prevented by Gastric Banding

Gastric banding is thought to decrease appetite in addition to the mechanical effects of food restriction, although this has been difficult to demonstrate in human studies. Our aim was to investigate the changes in orexigenic signals in the obese Zucker rat after gastric banding. Obese Zucker rats (fa/fa) were submitted to gastric banding (GBP), sham gastric banding fed ad libitum (sham), or sham operation with food restriction, pair-fed to the gastric banding group (sham-PF). Lean Zucker rats (fa/+) were used as additional controls. Body weight and food intake were daily recorded for 21 days after surgery when epididymal fat was weighed and fasting ghrelin and hypothalamic NPY mRNA expression were measured. Gastric banding in obese Zucker rats resulted in a significant decrease of cumulative body weight gain and food intake. Furthermore, gastric banded rats were leaner than Sham-PF, as expressed by a significantly lower epididymal fat weight. Ghrelin levels of gastric banded rats were not increased when compared to sham-operated animals fed ad libitum and were significantly lower than the levels of weight matched sham-PF rats (1116.9 +/- 103.3 g GBP vs 963.2 +/- 54.3 g sham, 3,079.5 +/- 221.6 sham-PF and 2,969.9 +/- 150.9 g lean rats, p < 0.001); hypothalamic NPY mRNA expression was not increased in GBP when compared to sham-operated rats. In obese Zucker rats, GBP prevents the increase in orexigenic signals that occur during caloric deprivation. Our data support the hypothesis that sustained weight loss observed after gastric banding does not depend solely on food restriction.

Food restriction in pregnant and lactating rats induces anemia and increases plasma lipid peroxidation in their progeny

This study was designed to investigate the effects of food restriction in female rats during pregnancy and lactation periods on hematologic parameters in their progeny. Twelve pregnant Wistar rats were randomly divided into 2 groups: a control (C) group with free access to a standard diet and a food-restricted group with alternating 24 hours of fasting and nonfasting from day 14 of pregnancy to day 14 of lactation. Food restriction reduced the number of red blood cells, hemoglobin concentration, and hematocrit values in mothers and their pups. In dams, plasma iron and folate levels were respectively reduced by 27% (P < .04) and 46% (P < .01) compared with the C group, whereas plasma copper and vitamin B12 levels were unchanged. In pups, plasma iron, copper, and vitamin B12 levels were decreased by 50%, 23%, and 16%, respectively, compared with those in the C group, whereas folate levels were unchanged. Blood glutathione levels were significantly decreased in mothers and pups compared with those in the C group. Erythrocyte osmotic fragility decreased, and plasma thiobarbituric acid–reactive substance (TBARS) levels increased only in pups. The results of the present study suggest that food restriction in rats provoked alterations in erythrocyte parameters in mothers, probably as a consequence of disturbance in the iron status. In pups, these changes might be pronounced by an increase in TBARS levels and erythrocyte osmotic fragility, which suggests involvement of lipid peroxidation, causing alteration of erythroid cells.

Food restriction markedly increases dopamine D2 receptor (D2R) in a rat model of obesity as assessed with in‐vivo μPET imaging ([11C] raclopride) and in‐vitro ([3H] spiperone) autoradiography

Dopamine (DA) regulates food intake by modulating food reward and motivation but its involvement in obesity is much less understood. Recent evidence points to the involvement of leptin in the DA-related modulation of food intake. Here we assess DA D2 receptors (D2R) in a genetic rodent obesity model characterized by leptin-receptor deficiency and assess the influence of food restriction on these receptors. We compared D2R levels between Zucker Obese (fa/fa) and Lean (Fa/Fa) rats at 1 and 4 months of age and in two different feeding conditions (restricted and unrestricted food access) using in-vivo muPET imaging ([11C] raclopride, which is a method sensitive to competition with endogenous DA) and in-vitro ([3H] spiperone washed to ensure no competition with endogenous DA) autoradiography (ARG). Both ARG and muPET showed that D2R were higher at 1 month than at 4 months of age and that food restricted animals had higher D2R than unrestricted animals. However there were significant differences in the results obtained at 4 months between ARG and muPET. ARG showed that at 1 month and at 4 months unrestricted lean rats (Le U) had significantly higher D2R binding than obese unrestricted rats (Ob U) but showed no differences between restricted obese (Ob R) and restricted lean rats (Le R). It also showed that D2R decline between 1 and 4 months of age was significantly attenuated in food restricted rats [both obese and lean]. In contrast, muPET showed that at 4 months of age, Ob U showed greater D2R availability than Le U rats but like ARG showed no differences between Ob R and Le R rats. The lower D2R binding in Ob U than Le U rats observed with ARG most likely reflects decreases in striatal D2 receptors levels whereas the increased availability observed with muPET is likely to reflect reduced DA release (resulting in decreased competition with endogenous DA). Lack of a significant difference between Ob R and Le R suggests that the differences in dopamine activity and D2R levels between Ob and Le Zucker rats are modulated by access to food. The ARG finding of an attenuation of the age-related loss of D2R binding corroborates previous studies of the salutary effects of food restriction in the aging process. Because [11C] raclopride is sensitive to competition with endogenous DA, the higher D2R binding in obese rats with raclopride despite the lower D2R levels shown with spiperone could reflect lower extracellular DA in the Ob rats and merits further investigation.

Conservative maternal care in an iteroparous mammal: a resource allocation experiment

When resources are limited, life history theory predicts a trade-off between growth, reproduction and survival. In summer, lactating females of temperate large herbivores such as the white-tailed deer (Odocoileus virginianus) normally have access to abundant forage but also face the high energetic needs of lactation and recovery from winter mass loss. At high population density, however, females may face a trade-off between allocating resources for maintenance and for reproduction. To simulate the effects of increased intra-specific competition at high density, we measured for 2 years how an experimental food restriction of approximately 20% affected current reproduction and body mass changes of adult females and their fawns during the fawning and lactation periods. Fawn survival decreased 35%, and fawn growth decreased 26% in the food-restricted treatment. There was no effect of food restriction on female mass. Irrespective of treatment, however, lactating females gained 30 g/day less than non-lactating females, and females that had weaned a fawn the previous year gained 20 g/day less than females that had not. We conclude that when resources were scarce, females adopted a conservative strategy favouring their own survival, mass recovery and future reproductive potential over their current reproduction, probably to maximise their lifetime reproductive success.

Physiological effects of copper in the euryhaline copepod Acartia tonsa: Waterborne versus waterborne plus dietborne exposure

The physiological effects of waterborne and waterborne plus dietborne copper exposure were determined in the euryhaline copepod Acartia tonsa at different salinities (5, 15 and 30 ppt). Copepods were exposed (48 h) to a reported 48-h LC50 for copper (CuCl 2), which had been previously determined under the same experimental conditions. Whole body copper accumulation, ion concentrations (Na +, Cl −, Mg 2+), and Na +, K +-ATPase activity were the endpoints measured in all experimental groups. Feeding rate was also measured in fed experimental groups. In copper-exposed copepods, whole body copper accumulation was dependent on salinity, decreasing as salinity increased. However, it was similar in copepods exposed to waterborne and waterborne plus dietborne copper, irrespective the salinity tested. Waterborne copper exposure induced a disturbance of the whole body Na + concentration in all salinities tested. This effect was characterized by an increased whole body Na + concentration in seawater (salinity 30 ppt) and a decreased whole body Na + concentration at lower salinities (5 and 15 ppt). The ionoregulatory imbalance in low salinity (5 ppt) was associated with an inhibition of the whole body Na +, K +-ATPase activity, as observed in freshwater fish and crustaceans. When copepods were exposed to waterborne plus dietborne copper, the physiological effects described were only observed at a low salinity (5 ppt) and were associated with a marked inhibition of the feeding rate. Taken altogether, the data suggest that the physiological effects induced by waterborne copper exposure in A. tonsa acclimated to higher salinities (15 and 30 ppt) are due to a combined effect of food restriction and copper exposure. Differential physiological responses to waterborne and waterborne plus dietborne copper cannot be ascribed to differences in whole body copper burden.

The timing of nutrient restriction during rat pregnancy/lactation alters metabolic syndrome phenotype

Modulation of growth of intrauterine growth restricted (IUGR) newborns causes either adult obesity or normalization of body weight and fat. We investigated the impact of rapid versus delayed catch-up growth of IUGR offspring on glucose and lipid profiles. From 10 days to term gestation and through lactation, control pregnant rats received ad libitum food, whereas study rats were 50% food restricted. Cross-fostering techniques were used to examine effects of food restriction during pregnancy and/or lactation periods. Glucose and lipid profiles were determined in offspring at ages 1 day, 3 weeks, and 9 months. Food restriction during pregnancy produced hypoglycemic IUGR pups. Those permitted rapid catch-up growth demonstrated adult obesity with insulin resistance (hyperglycemia/hyperinsulinemia) and hypertriglyceridemia. Conversely, IUGR exhibiting delayed catch-up growth demonstrated normal adult body weight and insulin deficiency (hyperglycemia/hypoinsulinemia) and elevated cholesterol levels as compared with controls. However, these adult offspring had higher glucose though similar insulin levels as control offspring nursed by food restricted dam. The timing and the rate of IUGR newborn catch-up growth causes markedly altered adult phenotypes. Although delayed newborn catch-up growth may be beneficial in the prevention of adult obesity, there may be significant adverse effects on pancreatic function.

Behavioral and biochemical effects of various food-restriction regimens in the rats

In this paper we describe the effects of six different food restriction (FR) regimens on amphetamine (AMPH)-induced locomotor and nonlocomotor activities in male rats. Changes in serum corticosterone (CORT), insulin and glucose levels were also examined. Each regimen was implemented through different daily food allowance (50%, 25% and 12.5% of the daily food intake, referred to as 50%, 75% and 87.5% FR groups, respectively) and by a specific feeding regimen — either every day (ED) or every other day (EOD). AMPH injection led to a significant increase of locomotor activity in all rats subjected to FR compared to ad libitum fed rats. A significant increase of nonlocomotor activity was observed only in the 75% FR and 87.5% FR groups. The serum CORT levels were significantly elevated and the serum insulin and glucose levels were significantly decreased in all of the FR groups in comparison to the AL rats. The results presented in this paper suggest that the ED regimens produced changes in motor activity and biochemical parameters, which were more-or-less dependent on the degree of FR. In contrast, the EOD regimens induced very similar changes irrespective of the degree of FR degree. Our data support the possible mechanistic roles of CORT and insulin in the effect of FR on locomotor activity, since the most pronounced increase of serum CORT and more pronounced decrease in serum insulin concentration was observed in the groups that also exhibited the highest locomotor activities.

Deleterious effects of food restrictions in yellowtail kingfish Seriola lalandi during early development

The effects of delayed first feeding and food deprivation on the structure and function of the digestive system in yellowtail kingfish Seriola lalandi larvae and juveniles were studied through histological examinations and enzymatic analyses. The experimental design included a conventional feeding regime with initial feeding from 3 days after hatching (DAH) as a control, delayed first feeding until 5 DAH, a first 3-d food deprivation from 12 to 15 DAH, and a second 3-d food deprivation from 33 to 36 DAH. Fish samples for histological and enzymatic analyses were taken on 5, 15, and 36 DAH, respectively. The delay of first feeding and a 3-d food deprivation on 15 DAH significantly reduced the height of enterocyte cells in the midgut, but a 3-d food deprivation on 36 DAH did not significantly reduce the cell height. Lipid vacuoles and supranuclear vacuoles disappeared from the epithelial cells after the fish had experienced the delay of first feeding or a 3-d food deprivation on 15 DAH. Total and specific activities of trypsin and amylase were reduced by the delay of first feeding. The 3-d food deprivation on 15 DAH reduced specific activities of trypsin, amylase and alkaline phosphatase, and total activity of amylase, but the 3-d food deprivation on 36 DAH only reduced the amylase activity. This study indicates that yellowtail kingfish larvae are more vulnerable to starvation in the first 2 weeks after the start of first feeding but fish become more tolerant to a short-term starvation after 33 DAH. Therefore, any delay of feeding during the first 2 weeks may impair histological structure and cause malfunction of the digestive system in yellowtail kingfish larvae. Our data also suggest that the enterocyte morphology, the number of supranuclear vacuoles in the intestine and the activity of digestive enzymes can be used as indicators of the nutritional condition of fish larvae.

Effect of maternal food restriction during gestation on early development of F1 and F2 offspring in the rat-like hamster ( Cricetulus triton)

Maternal food restriction (FR) may have strong and long-term effects on body weight, brain and behavior development of offspring. However, it is still not well understood whether such an effect is carried over to the next generation. Our objective was to examine the differences of maternal behavior, body growth, cranial growth and early development of F1 and F2 offspring of rat-like hamsters between a FR group and a control group. Results show that FR has a significant influence on maternal gathering behavior. The body weight of F1 offspring was significantly lower in the food-restricted group compared with that of the control animals, while the body weight of food-restricted F2 offspring was not significantly different from that of the control group. The physical development and neurodevelopment of food-restricted F1 and F2 offspring were significantly delayed compared to the controls. These results suggest that FR in female rat-like hamsters affected negatively the body growth of F1 offspring, and the physical and neurodevelopment of both F1 and F2 offspring. The effect of maternal FR on F2 offspring was smaller than that on F1 offspring. These factors may, in turn, play an important role in the population regulation of this species.

Age-related deficit in behavioural extinction is counteracted by long-term ethanol consumption: Correlation between 5-HIAA/5HT ratio in dorsal raphe nucleus and cognitive parameters

We investigated age-related changes in learning and memory performance and behavioural extinction in the water maze; and in endogenous levels of serotonin (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in the neocortex, hippocampus, thalamus and dorsal raphe nucleus of Wistar rats. Another aim was to assess the correlation between behavioural and biochemical parameters, which were measured in rodents of two different ages: 5 months (adults) and 16 months (middle-aged). The middle-aged subjects succeeded in learning the behavioural task, albeit with significantly worse performance when compared to adult animals. Aging also had significant main effects on memory and extinction. An age-dependent decrease in 5-HIAA levels was observed in both hippocampus and dorsal raphe nucleus (DRN). The decrease in DRN 5-HIAA was paralleled by a decrease in 5-HIAA/5-HT ratio in this brain area, which was significantly correlated to the animals’ spatial memory performance and behavioural extinction. In addition, using middle-aged rats, a 2 × 2 factorial study was carried out to examine the effects of food restriction and chronic ethanol consumption on rat's performance in a spatial behavioural task and on central serotonergic parameters. None of these two treatments had a significant effect on the behavioural and biochemical parameters assessed, with the exception of extinction index, which was significantly affected by ethanol consumption. Long-term ethanol ameliorated the impairment in behavioural flexibility caused by aging. In conclusion, long-term ethanol consumption may have a role in protecting against age-related deficit in behavioural extinction. Moreover, the present results also indicate that DRN serotonergic system is involved in spatial memory and behavioural extinction.

The effects of food restriction on some biochemical parameters and certain bacterial groups in the cecum in Sprague Dawley rats

Objective: Moderate food restriction, such as a 20-40% reduction of the ad libitum intake without causing malnutrition, delays or prevents morphological and functional changes related to aging and overnutrition. This study was performed to evaluate the effects of moderate to severe food restriction (20%, 40%, and 60% of ad libitum intake) for 28 days on some bacterial groups in the cecum and certain biochemical variables in male Sprague Dawley rats. Materials and methods: One group was allowed free access to food (control), while the others were given food restricted to 20%, 40%, and 60% of the ad libitum consumption for 28 days. At the end of the experiment control and food-restricted animals were sacrificed and cecum weight, pH of cecal contents, and counts of total anaerobes, total aerobes, lactobacilli, and coliform bacteria in cecal contents were determined. Metabolic effects of food restriction were evaluated by analyzing some biochemical parameters in plasma and serum. Results : The effect of 60% restriction was severe; three animals died before the 28th day of experiment in this group. In general, biochemical variables did not change in 20% and 40% food-restricted groups. Although lactobacilli counts of the 20% and 40% restricted groups were significantly increased when compared with the 60% restricted group, none of the three groups were differed from the control group. Furthermore, the total aerobe bacteria counts of the 20% restricted group were significantly lower than those of the 60% restricted group. Conclusion: The results of this study suggest that restriction of food by 20% and 40% may affect cecal microbiota beneficially without causing considerable changes in the metabolism of the host, while 60% restriction causes dietary stress. Key words: food restriction, starvation, malnutrition, rat, cecal microbiota, biochemical variables

The role of food restriction on CCl 4-induced cirrhosis model in rats

Effects of food restriction on susceptibility to the toxic effect of some chemicals are controversial. In order to identify an exposure model that could maximize cirrhosis and minimize mortality rate, this study aimed to evaluate the effect of food restriction on tetrachloride carbon (CCl 4)-induced cirrhosis model in rats. Fifty-three male Wistar rats received CCl 4 0.25 ml/kg weekly intragastrically once a week. Thirty-three had 44% food restriction (group 1); 10 rats had 25% food restriction (group 2); and 10 rats received ad libitum food (group 3). After 10 weeks, the animals were sacrificed and liver sections were collected for histology. Of the 53 animals enrolled for the study, 22 (41.5%) died before completing 10-week CCl 4. Mortality rate was significantly higher in group 1 compared to other groups ( p<0.05). Cirrhosis was significantly more prevalent in group 1 than in group 3 ( p<0.01), but without significant difference between groups 1 and 2 ( p=0.624). We concluded that food restriction is an important issue to be considered when establishing a CCl 4-induced cirrhosis model in rats. Moreover, there is an ideal range of food intake that predisposes to liver damage without increasing mortality leading to a more effective model.