Seasonal fluctuations of food intake and bodyweight in the dormouse Glis glis (author's transl)]

Cycles of body weight lasting a few weeks occurred in dormice fed ad libitum, throughout the year with the same food. The pattern of the fluctuations suggests an oscillation between an upper and a lower limit. When the lower limit is reached, compensatory mechanisms acting on the food intake are induced which cause an increase in body weight to the upper one; when this upper limit is reached, other mechanisms cause the body weight to decrease to the lower one. Thus, body weight and variations in food intake may well be controlled by the difference between the body weight and the limit it will reach. In a warm environment (23-25 degrees C) these fluctuations are smaller than in the cold (5-6 degrees C). They are also smaller during summer than during winter in animals placed in natural climatic conditions. In summer, the body weight stays near the upper limit; in this season, as in the warm environment, the lower limit approaches the upper one. Thus, the main circannual variation of body weight regulation in dormice may be the elevation during summer of the lower body weight limit.     

Ketoconazole, an antifungal agent, protects against adiposity induced by a cafeteria diet.

Ketoconazole, an anti-glucocorticoid agent, is widely used in humans as an antifungal agent. It inhibits ergosterol synthesis and reduces cortisol levels in the treatment of Cushing's Syndrome. The aim of this work was to study the drug's preventive potential against adiposity induced by a high-fat cafeteria diet in rats. Female Wistar rats were fed on standard pelleted diet or cafeteria diet during 42 days in the presence or absence of an oral treatment with ketoconazole (24 mg/kg of body weight). The cafeteria diet increased energy intake and body weight. In addition, this high-fat diet increased body-fat weight and adipose tissue depots analyzed. Interestingly, ketoconazole was able to protect against increased total body fat and adipose depot enlargement induced after cafeteria-diet feeding. Moreover, ex vivo isoproterenol-induced lipolysis was reduced in adipocytes from cafeteria-fed animals; this decrease was reverted by treatment with ketoconazole. Thus, ketoconazole was able to protect against adiposity induced by a cafeteria diet, revealing an interaction between fat intake and glucocorticoids on adipose deposition.     

Infradian cycles in dormice (Glis glis)

Summary Infradian cycles of body weight occur in captive dormice,Glis glis. The period of these cycles is often about 2 months but is highly variable both between and within individuals. These cycles can persist for at least 3 years. This paper describes a number of variables that change on an infradian basis along with body weight. These include: food and water intake, weight of the liver, adrenal and salivary gland weight, testes weight and spermatogenic condition, body temperature and wheel-running activity. Both the amount of running and its distribution over a 24 h period change. However, infradian cycles do not appear to be generated by the circadian system because they persist even in continuous bright light sufficiently intense to disrupt circadian organization. They also persist in LD 186, LD 1212, LD 618 and in naturally changing photoperiods. No evidence of photoperiodic effects on cycles was detected except that animals in long days have slightly higher moulting scores than those in short days. Moulting is more marked when body weight stays relatively stable. In dormice remaining stable in weight for several months testes have sperm present. The period of infradian cycles is temperature dependent: in a cool room animals that hibernate have longer cycles with periods varying from a few months to about a year. In a number of respects at least, infradian cycles appear to be accelerated circannual cycles. The adaptive value of a system that gives rise to infradian cycles probably relates to opportunism in an unpredictable environment. Infradian cycles in dormice may be a useful preparation for obtaining data on spontaneous physiological and behavioural changes in hibernators in less than a year.This work was supported by the Natural Sciences and Engineering Research Council of Canada and by an Ontario Graduate Scholarship to R.M. Many people have helped us in these experiments. We thank: Suzanne Hoy, Jenny Martin, Janice Farintosh, John Glover, Alex Joyner, Michael Juergensen, Harry Meyer, Yasmin Shah, Sara Shettleworth, Wendy Stewart, Vern Thiel, Patricia Williams, and Rae Weaver.     

Factor affecting body mass of young fat dormics (Glis glis) at weaning and by hibernation

This paper describes the factors affecting body mass at weaning and by hibernation of young fat dormice (Glis glis) We studied a free-living population in 1991 and 1992 in a mixed forest where 100 nest-boxes were placed. In the two years, 128 females used the nest-boxes to give birth and rear their litters and more than 900 dormice have been individually marked. Body mass of young at weaning was positively correlated to body mass of the mother in both years and to birth date in 1991, while litter size was negatively correlated to body mass of the young in 1992 only, when birth took place about two weeks later than in 1991. On the contrary, by the time of hibernation, young born later weighed significantly less than those born earlier in the season, and heavier young at weaning remained heavier by hibernation, while maternal body mass and litter size did not significantly affect body mass of young at this stage. Body mass of the mother was negatively related to the date of parturition and early breeding females lost weight during lactation, while females that bred later did not. It seems, therefore, that early breeding carries a cost that only females in good condition can afford. It appears that females may follow two strategies: those in poor body condition will delay pregnancy so that lactation occurs when environmental feeding conditions are at their best; those in good condition will breed earlier, since they can afford to lose weight during lactation. Their young will have more time to grow before hibernation and the mothers themselves will have a longer period of time for restoring their fat reserves.     

Effects of adrenalectomy on energy balance, diet-induced thermogenesis and brown adipose tissue in adult cafeteria-fed rats

Feeding adult male rats a palatable cafeteria diet stimulated energy intake and expenditure but also raised body weight and energy gains. Bilateral adrenalectomy (ADX) had little effect on stock-fed animals, but prevented the development of obesity in cafeteria-fed rats by depressing food intake and energetic efficiency. Adrenalectomy also markedly increased the thermogenic activity of brown adipose tissue, and depressed insulin levels, particularly in the cafeteria group.     

Seasonal differences in the feeding ecology and behavior of male edible dormice (Glis glis)

Mammalian hibernators undergo dramatic seasonal changes of food intake and the use of their gastrointestinal tract. During several months of hibernation fat-storing hibernators do not use their intestinal tract for nutritional intake. However, during the rest of the year they have to increase their energy intake in order to compensate high reproductive investment and store sufficient body fat to survive the following hibernation period. Edible dormice (Glis glis) are obligate fat-storing hibernators which hibernate in Germany from September until June. Males incur high energetic costs during mating and as soon as reproduction is terminated they have to accumulate high quantities of fat to survive hibernation. In order to understand how fat-storing hibernators like edible dormice cope with these energetically demanding situations, we measured body mass changes of captured male edible dormice in the field and studied their feeding ecology. Furthermore, we measured seasonal changes in food ingestion and assimilation rates by feeding experiments carried out in captivity.Results of this study revealed that during the mating season males significantly lowered their body mass, while food ingestion and assimilation rates remained constant. The body mass reduction showed that they used their body fat reserves to pay at least part of the energetic costs of reproduction. During the pre-hibernation fattening period males increased their body mass but held their assimilation rates on a constant level. Nevertheless, they increased the amount of ingested food and subsequently the amount of energy intake. Furthermore, they changed their dietary spectrum in the field by turning to lipid-rich seeds. These behavioral adaptations enable them to restore their energy losses during reproduction and to accumulate sufficient body fat to survive hibernation.     

A longitudinal study of leptin during development in the male rhesus monkey: the effect of body composition and season on circulating leptin levels

The objective of this study was to examine longitudinal changes in serum leptin concentrations during development and to correlate those changes with sexual development in male rhesus monkeys housed under natural environmental conditions. Blood samples were drawn from 8 control animals approximately every other month from 10 to 30 mo of age and thereafter monthly through 80 mo of age. Leptin levels declined through the juvenile period until the onset of puberty and were negatively correlated with body weight. Seven of the eight animals became sexually mature during the breeding season of their fourth year of life. Puberty was delayed in the other animal until the subsequent breeding season. There were no significant fluctuations in leptin levels prior to or in association with the pubertal rise in LH and testosterone (T) secretion. During the peripubertal period, levels of leptin varied between 2 and 3 ng/ml. The animal that exhibited delayed puberty had the lowest body weight and highest leptin levels during this period. With the achievement of sexual maturity, leptin levels varied seasonally, with peak levels in the late winter (Jan-Mar) and a nadir in the late summer (Aug-Sept). A late winter rise in leptin was also evident in most of the animals during Years 2 and 3, but not during Year 4. In the fall of Years 5 and 6, the seasonal rise in leptin concentrations lagged 3-4 mo behind the seasonal increase in LH and T. In the fall of Year 5, but not thereafter, leptin levels were positively related to percent body fat and negatively correlated with lean body mass. The data do not support the hypothesis that increasing leptin concentrations trigger the onset of puberty in the male rhesus monkey. During the juvenile period and after sexual maturation, but not during the peripubertal period, leptin secretion varied with season in the animals; but the environmental factors that cue or drive this rhythm remain to be determined.     

Seasonal changes in liver size in edible dormice (Glis glis): non-invasive measurements using ultrasonography

We used non-invasive ultrasonography to investigate seasonal changes in liver size of an obligate hibernator; the edible dormouse (Glis glis). We repeatedly measured liver size in dormice at two study sites, (1) an enclosure-housed colony and (2) a free-ranging population. We observed a significant increase in transverse liver size throughout the active season; however, this effect was most pronounced in animals with low body mass early in the active season. Ultrasonography imaging revealed that the content of fat in the liver (distributed in an unexpected pattern of discrete focal areas) visibly increased at the end of the active season both in the field and enclosure. Thus, the observed increase in liver size of dormice seems mainly related to fat accumulation. We found no principal differences in the time courses of transversal liver size between the two study sites. Our results support the view that non-invasive ultrasonography is an accurate method to study internal organ sizes, such as liver, in the laboratory and in the field.     

Positive correlation of skeletal muscle UCP3 mRNA levels with overweight in male,but not in female,rats

The objective of this study was to investigate the sex-dependent regulation of skeletal muscle uncoupling protein (UCP)3 mRNA expression in response to overweight and its relationship with serum levels of free fatty acids, leptin, and insulin. Two obesity models were used: rats made obese by feeding them with a cafeteria diet for 14 wk, and postcafeteria overweight rats fed a chow diet for 10 wk after consuming the cafeteria diet for 14 wk. The effects of 24-h fasting were studied in postcafeteria rats and their age-matched controls. The cafeteria rats ate a high-fat diet and attained an excess body weight that was higher in females (+59%) than in males (+39%). A trend to higher induction of abdominal muscle UCP3 mRNA in male rats than in females after cafeteria diet was apparent (+116% increase vs. +26% increase). Postcafeteria male but not female rats still showed the tendency to have increased UCP3 mRNA levels relative to their age-matched controls. A linear regression analysis showed a significant positive correlation of the UCP3 mRNA levels with overweight and with serum levels of leptin and insulin in males, but not in females, and no correlation with serum free fatty acid levels. A subsequent correlation analysis and a multiple linear regression analysis showed that overweight was the only parameter actually related to UCP3 mRNA levels in males. Fasting-induced upregulation of muscle UCP3 mRNA levels was higher in males (5- to 7-fold) than in females (3- to 4-fold). Our results point to the existence of sex-associated differences in the control of muscle UCP3 expression in response to overweight and fasting, with an impaired induction in female rats under both conditions. The correlation of abdominal muscle UCP3 mRNA expression with overweight in males could be related to their relative resistance to gain weight after chronic overeating of a cafeteria diet, by the purported role of UCP3 in the regulation of lipid utilization.     

Feed intake and performance of growing lambs raised on concentrate-based diets under cafeteria feeding systems

Two trials were undertaken to study the effects of cafeteria feeding systems on the feed intake, animal performance and carcass characteristics of growing lambs. Trial 1 was designed to compare conventional and cafeteria feeding systems in terms of the growth of individually reared lambs. For this assay, 26 weaned Merino lambs (15.5 ± 0.20 kg live weight) were assigned to three dietary treatment groups: (1) a control group fed barley straw and commercial concentrate under a conventional feeding system, (2) group W100S, fed soya-bean meal, whole barley grain and a mineral-vitamin supplement under a cafeteria feeding system, and (3) group W100S-T, fed as in the W100S treatment but allowing the lambs an initial training period so they could learn to identify a number of feeds. The feeding system had no significant effect ( P>0.05) on either average daily live-weight gain, carcass weight, or carcass conformation. The food conversion ratio was lower ( P < 0.05) for the cafeteria-reared animals (2.9 ± 0.16 v. 2.5 ± 0.08 g dry-matter intake per g average daily gain) than those of the control group. This might be related to the higher crude protein intake seen in the cafeteria groups (150 ± 5.6 v. 208 ± 12.5 g per animal per day; P < 0.001).In trial 2, cafeteria and conventional feeding system were compared in terms of the growth of feedlot lambs. Two hundred weaned Merino lambs (13.1 ± 0.10 kg) were divided into two experimental groups: (1) a control group, offered commercial concentrate and barley straw, and (2) a cafeteria group fed the same diet as W100ST in trial 1. The average daily gain (282 ± 5.8 and 309 ± 6.5; P < 0.01) was greater in the cafeteria than in the control group. Whereas neither carcass conformation nor fatness were affected by the feeding system, the dressing percentage was slightly higher ( P>0.001) in the conventional than in the cafeteria system lambs.The use of cafeteria systems for fattening lambs can improve the feed conversion efficiency and body growth rate over those achieved with conventional feeding systems, although the crude protein intake in these systems seems to be in excess of requirements.     

An investigation of tolerance to the actions of leptogenic and anorexigenic drugs in mice

This study compared the effects of chronic administration of anorexigenic drugs on weight loss in mice. Tolerance to the effects of peripheral anorexigenic peptides, viz. cholecystokinin-octapeptide and bombesin, developed rapidly. Morphine, cocaine and dehydroepiandrosterone-sulfate caused weight loss and appeared similar to d-amphetamine in mechanisms of action. A high dose of fluoxetine (25 mg/kg) proved to be a potent leptogenic agent but was also associated with death in some animals. A lower dose of fluoxetine (5 mg/kg) was associated with the development of tolerance. Calcitonin, a potent anorexigenic agent, did not produce weight loss and tolerance to its anorectic effect had developed by 10 days. Animals varied widely in their individual responsiveness to a given drug. Peripheral administration of peptide YY caused weight loss. We conclude that acute or chronic effects of agents on food intake do not necessarily predict effects on body weight. However, neurotransmitters that enhance feeding centrally appear to cause weight loss when administered peripherally.     

Relationship between seasonal energy economy and thyroid activity in farm-raised raccoon dogs

1. The levels of thyroid hormones (T3, T4), total lipids and urea in blood serum of adult farmed raccoon dogs (Nyctereutes procyonoides Gray 1834) were monitored year-round, and compared with seasonal changes in body weight and feed consumption during intense, maintenance and restricted fasting feeding. 2. Thyroid hormone levels tended to be low during winter whereas during the rest of the year no marked seasonal differences were observed. That thyroid hormone levels were influenced by altering feed intake suggests the hypothesis that the winter hypothyroidism observed was a result of a decreased level of voluntary feed intake. 3. The colder the temperature was during winter, the less the animals consumed the feed supplied. 4. Neither season nor feed intake level affected serum levels of total lipids or urea. 5. Marked seasonal changes in body weight of the animals were found. From maximum values occurring in early winter their body weight generally dropped about 30% reaching the minimum values in mid-summer. This marked seasonal change was mainly the result of changes in subcutaneous fat reserves.     

Energy or information? The role of seed availability for reproductive decisions in edible dormice

The edible dormouse is a specialized seed predator which is highly adapted to the fluctuations of food availability caused by mast seeding of beech and oak trees. Dormice produce young just in time with maximum food availability, and can completely skip reproduction in years with a lack of seeding. Because their decision to reproduce or not in any particular year is made long before the ripe seeds are available, it seems that dormice can anticipate the upcoming mast situation. We tested the hypothesis that the presence of high caloric food in spring affects their reproductive decision. Therefore, we supplementary fed dormice in a field experiment from spring to early summer with sunflower seeds, which also contain a high amount of energy. Supplemental feeding caused significant increases in the proportion of reproducing females and reproductively active males. These results suggest that edible dormice may use the occurrence of an energy rich food resource to predict the autumnal mast situation. Further, our data indicate that the decision to reproduce was not the result of an increased body mass due to the consumption of surplus food, but that sufficient seed abundance acts as an environmental signal to which dormice adjust their reproduction.     

Influence of Feeding Inorganic Vanadium on Growth Performance,Endocrine Variables and Biomarkers of Bone Health in Crossbred Calves

The nutritional essentialities of transition element vanadium (V) as micro-nutrient in farm animals have not yet been established, though in rat model, vanadium as vanadate has been reported to exert insulin-mimetic effect and shown to be needed for proper development of bones. The objective of this study was to determine the effect of V supplementation on growth performance, plasma hormones and bone health status in calves. Twenty-four crossbred calves (body weight 72.83 ± 2.5 kg; age 3–9 months) were blocked in four groups and randomly assigned to four treatment groups (n = 6) on body weight and age basis. Experimental animals were kept on similar feeding regimen except that different groups were supplemented with either 0, 3, 6 or 9 ppm inorganic V/kg DM. Effect of supplementation during 150-day experimental period was observed on feed intake, body weight gain, feed efficiency, body measures, endocrine variables, plasma glucose and biomarkers of bone health status. Supplementation of V did not change average daily gain (ADG), dry matter intake (DMI), feed efficiency and body measures during the experimental period. During the post-V supplementation period plasma insulin-like growth factor-1 (IGF-1), triiodothyronine (T₃) and thyroxin (T₄) concentrations were increased and observed highest in 9 mg V/kg DM fed calves; however, levels of insulin, glucose, parathyroid hormone (PTH) and calcitonin hormones remained similar among calves fed on basal or V-supplemented diets. Bone alkaline phosphatase (Bone-ALP) concentration was increased (P < 0.05); however, plasma protein tyrosine phosphatase (PTP) level decreased (P < 0.05) in 6 and 9 mg V/kg DM supplemented groups. Plasma hydroxyproline (Hyp) and tartrate-resistant acid phosphatase (TRAP) concentration were unchanged by V supplementation. Blood V concentration showed positive correlation with supplemental V levels. These results suggest that V may play a role in modulation of the action of certain endocrine variables and biomarkers of bone health status in growing crossbred calves.     

Sodium vanadate toxicity in adult and developing rats

The toxic effect of vanadium (sodium metavanadate) during pregnancy and lactation was studied by feeding vanadium to pregnant, Sprague-Dawley rats at levels of 1 (control) or 75 μg V/g diet through d 21 postpartum, at which time they were killed. Vanadium-fed dams had lower food intakes and weight gains than controls during pregnancy. Survival until d 21 postpartum was significantly lower in the vanadium pups compared to controls. In addition, the surviving pups gained less weight than control pups, despite similar birth weights. On a relative body weight basis, vanadium pups had larger livers, brains, and testes than controls, suggesting that these animals were developmentally delayed. Vanadium dams and pups had higher concentrations of hepatic vanadium than controls. Vanadium pups also had higher concentrations of hepatic zinc than control pups. Maternal hepatic zinc concentrations were not affected by diet. Also, no significant differences in hepatic iron, copper, or manganese concentrations were observed for either dams or pups. Hepatic thiobarbituric acid reactivity was higher in whole cell and isolated mitochondria for vanadium dams and pups than for control dams and pups, indicating that these animals may have had higher levels of lipid peroxidation. This idea was supported by the observation of lower concentrations of reduced glutathione in the livers of vanadium pups compared to controls. In contrast, kidney and brain glutathione levels were not affected by diet. In conclusion, animals during periods of rapid growth are susceptible to vanadium toxicity, and increased lipid peroxidation may be one factor underlying this toxicity.     

Seasonal changes in thyroid-gonadal interactions in the edible dormouse,Glis glis

Summary This study was conducted to determine changes in thyroid-gonadal interaction in the edible dormouse during the phase of the annual cycle that corresponds to the end of the breeding season (from June to September). We evaluated intra-hypothalamic luteinizing hormone-releasing hormone (LHRH) content, and plasma concentrations of luteinizing hormone (LH), testosterone, thyroid-stimulating hormone (TSH) and thyroxine (T4) in three groups of dormice: (1) controls; (2) dormice receiving sufficient T4 supplementation to maintain June levels in control animals until September, thus counteracting the seasonal reduction of T4 that normally begins in July; and (3) thyroidectomized dormice. The effect of thyroidectomy was only detectable in June, when plasma T4 concentration in the control group was maximal, and consisted of a significant decrease in plasma testosterone levels. This provides strong support for the hypothesis that thyroid function positively influences gonadal function during the breeding season. The T4 supplementation resulted in a decrease in hypothalamic LHRH concentration, suggesting that an increased LHRH release led to the observed stimulated hypophyseal secretion of LH in June and September and the increased circulating testosterone levels in September. There was no detectable effect in July and August. These results show that thyroid axis activation of the hypothalamic-pituitary-gonadal system is only possible during certain phases of the annual cycle, particularly evidenced here during the breeding season. They also reinforce our conclusions drawn from the thyroidectomy results. Conversely, the summer testicular regression which normally occurs after the breeding season is no longer controlled by plasma T4 levels. Even though the sensitivity of the gonadal axis to the thyroid axis appears to reappear at the end of the summer, results of previous studies indicate that this resumption is only temporary.Abbreviations LH luteinizing hormone - LHRH luteinizing hormone-releasing hormone - RIA radioimmunoassay - T4 thyroxine - TSH thyroid-stimulating hormone     

Effects Of A Post-Weaning Cafeteria Diet In Young Rats: Metabolic Syndrome,Reduced Activity And Low Anxiety-Like Behaviour

Among adolescents, overweight, obesity and metabolic syndrome are rapidly increasing in recent years as a consequence of unhealthy palatable diets. Animal models of diet-induced obesity have been developed, but little is known about the behavioural patterns produced by the consumption of such diets. The aim of the present study was to determine the behavioural and biochemical effects of a cafeteria diet fed to juvenile male and female rats, as well as to evaluate the possible recovery from these effects by administering standard feeding during the last week of the study. Two groups of male and female rats were fed with either a standard chow diet (ST) or a cafeteria (CAF) diet from weaning and for 8 weeks. A third group of males (CAF withdrawal) was fed with the CAF diet for 7 weeks and the ST in the 8th week. Both males and females developed metabolic syndrome as a consequence of the CAF feeding, showing overweight, higher adiposity and liver weight, increased plasma levels of glucose, insulin and triglycerides, as well as insulin resistance, in comparison with their respective controls. The CAF diet reduced motor activity in all behavioural tests, enhanced exploration, reduced anxiety-like behaviour and increased social interaction; this last effect was more pronounced in females than in males. When compared to animals only fed with a CAF diet, CAF withdrawal increased anxiety in the open field, slightly decreased body weight, and completely recovered the liver weight, insulin sensitivity and the standard levels of glucose, insulin and triglycerides in plasma. In conclusion, a CAF diet fed to young animals for 8 weeks induced obesity and metabolic syndrome, and produced robust behavioural changes in young adult rats, whereas CAF withdrawal in the last week modestly increased anxiety, reversed the metabolic alterations and partially reduced overweight.     

Systemic lupus erythematosus onset in lupus-prone B6.MRL/lpr mice Is influenced by weight gain and Is preceded by an increase in neutrophil oxidative burst activity

In this study, we assessed whether weight gain influenced the systemic lupus erythematosus (SLE) onset and/or outcome, and examined the role that reactive oxygen species (ROS) production by neutrophils played in the SLE onset and/or outcome. Female control (C57BL/6) and lupus-prone B6.MRL/lpr mice (CM and LPM, respectively) at 4 weeks old were fed standard diet or standard diet plus cafeteria diet during 12 weeks. SLE diagnosis relied on the presence of both antinuclear antibodies (ANA) and renal abnormalities. We found that the percentage of weight gain in CM and LPM increased as a function of the length of cafeteria diet feeding period, but it was not associated with energy intake. Cafeteria diet-fed CM and LPM at 8 and 12 weeks old were overweight, while CM and LPM at 16 weeks old were obese. Compared with standard diet-fed CM and LPM, cafeteria diet-fed CM and LPM exhibited elevated glucose and total cholesterol levels, and diminished triglycerides levels. Standard diet-fed 16-week-old LPM and cafeteria diet-fed 12-week-old LPM had nephritis, characterized by the increased interstitial infiltration of leukocytes. Cafeteria diet-induced weight gain rose the frequency of homogeneous and speckled ANA staining patterns in the 12- and 16-week-old LPM groups. Together, these results indicated that weight gain anticipated the SLE onset. In addition, neutrophils from cafeteria diet-fed 8-week-old LPM exhibited augmented ROS production capacity; in standard diet-fed LPM, such rise occurred only in the 16-week-old group. Thus, the neutrophil ROS production capacity was increased before the SLE onset and during its outcome. Overweight and obese CM and LPM displayed elevated levels of kidney, liver, heart, and spleen lipid peroxidation. In conclusion, cafeteria diet-induced weight gain is associated with the increased production of ANA and neutrophil-derived ROS, which may contribute to accelerate the SLE onset.     

Modulatory role of food, feeding regime and physical exercise on body weight and insulin resistance

Energy intake and expenditure is a highly conserved and well-controlled system with a bias toward energy intake. In times of abundant food supply, individuals tend to overeat and in consequence to increase body weight, sometimes to the point of clinical obesity. Obesity is a disease that is not only characterized by enormous body weight but also by rising morbidity for diabetes type II and cardiovascular complications. To better understand the critical factors contributing to obesity we performed the present study in which the effects of energy expenditure and energy intake were examined with respect to body weight, localization of fat and insulin resistance in normal Wistar rats. It was found that a diet rich in fat and carbohydrates similar to "fast food" (cafeteria diet) has pronounced implication in the development of obesity, leading to significant body weight gain, fat deposition and also insulin resistance. Furthermore, an irregularly presented cafeteria diet (yoyo diet) has similar effects on body weight and fat deposition. However, these rats were not resistant to insulin, but showed an increased insulin secretion in response to glucose. When rats were fed with a specified high fat/carbohydrate diet (10% fat, 56.7% carbohydrate) ad lib or at the beginning of their activity phase they were able to detect the energy content of the food and compensate this by a lower intake. They, however, failed to compensate when food was given in the resting phase and gained more body weight as controls. Exercise, even of short duration, was able to keep rats on lower body weight and reduced fat deposition. Thus, inappropriate food intake with different levels of energy content is able to induce obesity in normal rats with additional metabolic changes that can be also observed in humans.