Hymenolepis diminuta: lack of pathogenicity in the healthy rat host.

Whether Hymenolepis diminuta (Cestoda: Cyclophyllidea) might affect adversely the growth of its host under normal conditions was studied. Rats were divided into four experimental groups: (1) rats infected with the tapeworm and fed ad libitum, (2) uninfected rats fed ad libitum, (3) and infected rats fed isocalorically with (4) uninfected rats. Growth rates of infected rats did not differ from infected animals. Infected, meal fed rats limited to 15 g synthetic diet/day grew as rapidly as their uninfected counterparts, and infected rats fed ad libitum did not consume more food than the comparable infected group. There were no significant differences in consumption or in excrement produced between groups (1) and (2) and groups (3) and (4). Weights attained by the worms were not affected by mode of host feeding (ad libitum or meal fed), whether expressed as wet or dry weight. Since H. diminuta appears not to affect nutrient utilization or consumption in a healthy, unstressed host, at least on a gross level, it probably should be considered an endocommensal.     

Resveratrol supplementation restores high-fat diet-induced insulin secretion dysfunction by increasing mitochondrial function in islet

Resveratrol (RSV), a natural compound, is known for its effects on energy homeostasis. Here we investigated the effects of RSV and possible mechanism in insulin secretion of high-fat diet rats. Rats were randomly divided into three groups as follows: NC group (animals were fed ad libitum with normal chow for 8 weeks), HF group (animals were fed ad libitum with high-fat diet for 8 weeks), and HFR group (animals were treated with high-fat diet and administered with RSV for 8 weeks). Insulin secretion ability of rats was assessed by hyperglycemic clamp. Mitochondrial biogenesis genes, mitochondrial respiratory chain activities, reactive oxidative species (ROS), and several mitochondrial antioxidant enzyme activities were evaluated in islet. We found that HF group rats clearly showed low insulin secretion and mitochondrial complex dysfunction. Expression of silent mating type information regulation 2 homolog- 1 (SIRT1) and related mitochondrial biogenesis were significantly decreased. However, RSV administration group (HFR) showed a marked potentiation of glucose-stimulated insulin secretion. This effect was associated with elevated SIRT1 protein expression and antioxidant enzyme activities, resulting in increased mitochondrial respiratory chain activities and decreased ROS level. This study suggests that RSV may increase islet mitochondrial complex activities and antioxidant function to restore insulin secretion dysfunction induced by high-fat diet.     

Effect of Thyroid Hormone and Sex Difference on Liver Histidase Activity of Young Rats Fed a Histidine Imbalanced Diet

Histidase (l-histidine ammonia-lyase EC 4.3.1.3) activity of thyroidectomized rats was higher than that of intact animals. The levels of protein bound iodine (PBI) in plasma of rats fed a basal diet were higher than those of an imbalanced diet group under ad libitum condition, while if the food intake of a basal diet group was restricted to that of the imbalanced diet group, the levels of PBI of a paired fed group were practically the same as those of the imbalanced diet ad libitum group. Histidase activity of paired fed rats was twice as high as that of ad libitum fed animals, and was about 60% of that of the imbalanced ones. Thyroxine did not affect histidase activity in vitro.

Neither sex difference nor castration affected the activity of histidase of young rats fed the imbalanced diet.     

Underfeeding and exposure to short photoperiod alters rat pineal and Harderian gland lysosomal enzyme activities

Harderian gland (HG) weight and lysosomal enzyme activity were evaluated after 21-day-old female rats were singly caged in a long (LP; 14:10 LD) or short (SP; 8:16 LD) photoperiod and fed on one of two dietary regimens (fed ad libitum or 50% underfed) for 50 days; an additional fed and an underfed group of animals in LP were injected every afternoon with 100 micrograms melatonin. Absolute HG weights were significantly lower in all underfed groups compared to their respective fed controls or to the LP fed control group. Absolute HG weights of underfed rats in SP were significantly lower than the underfed rats in LP. Relative HG weights (mg/100 g body wt) were significantly higher in the underfed saline or melatonin-treated groups compared to their respective fed controls; however, HG of the underfed SP group were not different from SP-fed controls. No significant differences in HG acid phosphatase, hexosaminidase, and beta-glucuronidase activities were observed in any of the treatment groups maintained in LP. Acid phosphatase, hexosaminidase, and beta-glucuronidase activities were significantly elevated in HG of underfed animals maintained in SP compared to their respective fed controls or to the LP-underfed group. Both the underfed control and the underfed-melatonin treated groups had lower pineal protein values than their respective fed groups; underfed animals in 8:16 LD had similar pineal protein values compared to those of the fed control group in SP. Significant effects of photoperiod and underfeeding with no interaction between these variables were observed on pineal acid phosphatase. The fed group maintained in 8:16 LD had significantly higher acid phosphatase activity than the fed group kept in 14:10 LD. In conclusion, underfeeding resulted in severely reduced body weights and absolute Harderian gland weights. Increased activity in certain lysosomal enzymes occurred in both the pineal and Harderian gland and in some instances this was dependent upon the light cycle and dietary regimen to which the animals were exposed.     

Sustained NPY Overexpression in the PVN Results in Obesity via Temporarily Increasing Food Intake

Increasing neuropeptide Y (NPY) signaling in the paraventricular nucleus (PVN) by recombinant adeno‐associated virus (rAAV)‐mediated overexpression of NPY in rats, results in hyperphagia and obesity in rats. To determine the importance of hyperphagia in the observed obesity phenotype, we pair‐fed a group of AAV‐NPY‐injected rats to AAV‐control‐injected rats and compared parameters of energy balance to ad libitum fed AAV‐NPY‐injected rats. For 3 weeks, AAV‐NPY‐injected rats, received the same amount of food as ad libitum‐fed rats injected with control rAAV They did not gain more body weight than these controls. When allowed access to food ad libitum, these AAV‐NPY‐injected rats increased food intake, which subsequently decreased when rats reached the same body weight as AAV‐NPY‐injected rats that were fed ad libitum for the entire study. These data indicate that overexpression of NPY in the PVN results in obesity by increasing food intake until a certain body weight is achieved.     

The effect on growth of feeding supplemental milk or baby food to the suckling rat

Suckling rats were fed synthetic rat milk or baby food as dietary supplements amounting to 10% of their total expected daily caloric intake from day 10 to day 16 of life. On day 17, their body lipid levels were significantly higher than those of control pups, and they remained high throughout a 6-week postweaning period of ad libitum food intake. Protein content (at 17 and 60 days of age) was similar in experimental and control groups. Seventeen-day-old pups that had been fed supplemental baby food showed a small but significant increase in DNA levels but no accompanying increase in lean body mass. Rats that received supplemental milk weighed more than either those that received baby food or controls at 17 days of age; however, both experimental groups weighed considerably more at weaning (21 days) than controls. At 60 days of age, their weights were again similar to those of control rats.     

Lactational performance, consummatory behavior, and suppression of estrous cyclicity in rats suckling underfed pups

The role of pups' appetite in the regulation of maternal consummatory behavior (food intake of nursing mothers), lactational performance and postpartum diestrus was studied over a period of 45 days postpartum in rats chronically exposed to either underfed or normally fed pups. Experimental rats (n = 10) daily received 5 pups, 4-10-days-old, that had been deprived of food for the preceding 24 h while under the care of nonlactating foster mothers. Control rats (n = 10) received normally fed pups obtained daily from lactating foster mothers. Throughout the experimental period, the daily milk yield (estimated by litter weight gain), the intake of food and water by the mother, as well as the ratio of litter weight gain to mother's intake of food and water were all markedly higher in rats nursing underfed pups than in rats nursing normally fed pups. After a peak in lactation around Day 15 postpartum, experimental rats produced the same amount of milk during extended lactation as they did in the beginning of lactation, while control rats produced only half the amount of milk during extended lactation as they did in early lactation. Regardless of the nutritional state of the suckling pups, maternal body weight increased progressively over the first four weeks of lactation and remained unchanged during the time of extended lactation. The postpartum diestrus and the subsequent diestrous phase in the time of extended lactation were considerably longer in duration in rats that nursed underfed pups. On Day 45 of lactation, prolactin levels were higher and the adrenal glands were larger in experimental rats than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunohistochemical identification of aquaporin 2 in the kidneys of young beef cattle

Aquaporin 2 (AQP2) is a small, integral tetrameric plasma membrane protein that is expressed in mammalian kidneys. The specific constitution of this protein and its selective permeability to water means that AQP2 plays an important role in hypertonic urine production. Immunolocalization of AQP2 has been studied in humans, monkeys, sheep, dogs, rabbits, rats, mice and adult cattle. We analyzed the expression of AQP2 in kidneys of 7-month-old Polish-Friesian var. black and white male calves. AQP2 was localized in the principal cells of collecting ducts in medullary rays penetrating the renal cortex and in the collecting ducts of renal medulla. AQP2 was expressed most strongly in the apical plasma membrane, but expression was observed also in the intracellular vesicles and basolateral plasma membrane. Our study provides new information concerning the immunolocalization of AQP2 in calf kidneys.     

Gut DYSBIOSIS and altered barrier function precedes the appearance of metabolic syndrome in a rat model of nutrient-induced catch-up growth

Nutritional restriction early in life followed by catch-up growth has been associated with increased risk of metabolic syndrome in adulthood. To elucidate whether altered gut colonization underlies the mechanisms responsible of this predisposition gut microbiome was studied before or afterwards catch-up growth. Offspring of dams fed ad libitum (C) or undernourished during pregnancy and suckling (U), were weaned onto high-fat diet (HFD) for 22 weeks (CHF and UHF, respectively) or continued on their diet. HF-feeding induced glucose intolerance (P<.05), insulin resistance (P<.001), and white adipose tissue inflammation (P<.001) in UHF rats compared to CHF. Analyses of gut microbial composition before catch-up growth revealed reduced F/B ratio and significant expansion of the mucolytic genera Akkermansia (P<.05) and Desulfovibrio (P<.05) in U pups. Although relative abundance of Akkermansia remained elevated to adulthood in U rats, HFD normalized its levels to C and CHF. Food-restriction increased intestinal permeability causing disorganization on the tight-junction proteins of colonic epithelium, Zonula Occludens-1 (ZO-1) and occludin, and reducing the mucus thickness layer in U adult rats. The levels of ZO-1 and occludin were not recovered in U rats after HF-feeding. This event was correlated with increased circulating levels of bacterial lipopolysaccharides in both U and UHF adult rats. Even more, serum lipopolysaccharides were already elevated in U rats compared to C group (P<.001) at weaning. Thus, gut dysbiosis and chronic endotoxemia observed in U rats, even before catch-up growth, might anticipate a pro-inflammatory milieu promoting metabolic diseases when fed hyperlipidic diets.     

Implications of maternal nutrient restriction in transgenerational programming of hypertension and endothelial dysfunction across F1-F3 offspring

AimsAn extensive variety of prenatal insults are associated with an increased incidence of metabolic and cardiovascular disorders in adult life. We previously demonstrated that maternal global nutrient restriction during pregnancy leads to increased blood pressure and endothelial dysfunction in the adult offspring. This study aimed to assess whether prenatal exposure to nutritional insult has transgenerational effects in F₂ and F₃ offspring.Main methodsFor this, female Wistar rats were randomly divided into two groups on day 1 of pregnancy: a control group fed standard chow ad libitum and a restricted group fed 50% of the ad libitum intake throughout gestation. At delivery, all animals were fed a standard laboratory chow diet. At 11 weeks of age, one female and one male from each restricted litter were randomly selected and mated with rats from another restricted litters in order to generate the F₂ offspring. The same procedure produced F₃ generation. Similarly, the rats in the control group were bred for each generation.Key FindingsOur findings show that the deleterious effects of maternal nutrient restriction to which the F₀ mothers were exposed may not be limited to the male first generation. In fact, we found that elevated blood pressure, an impaired vasodilatory response to acetylcholine and alterations in NO production were all transferred to the subsequent males from F₂ and F₃ generations.SignificanceOur data show that global nutrient restriction during pregnancy results in a specific phenotype that can be passed transgenerationally to a second and third generation.     

Lipoprotein lipase and lipogenic enzyme activities in adipose tissue from rats fed different lipid sources

This work was designed to study the effect of different lipid sources on the activities of lipoprotein lipase and lipogenic enzymes in adipose tissue from rats fedad libitum or energy-controlled diets. Male Wistar rats were fed diets containing 40% of energy as fat (olive oil, sunflower oil, palm oil or beef tallow), for 4 wk. Underad libitum feeding no differences were found among dietary fat groups in final body weight, adipose tissue weights and total body fat. Under energy-controlled feeding, despite isoenergetic intake, rats fed the beef tallow diet gained significantly less weight than rats fed the other three diets. Beef tallow fed rats showed the lowest values for adipose tissue weights and total body fat. When rats had free access to food no effect of dietary lipid source on lipogenic enzyme activities was found. In contrast, under energy-controlled feeding rats fed the beef tallow diet showed significantly higher activities of glucose-6-phosphate dehydrogenase and fatty acid synthase than rats fed the other three diets. Heparin-releasable lipoprotein lipase activity in perirenal and subcutaneous adipose tissues was not different among rats fed olive oil, safflower oil, palm oil or beef tallow. When comparing both adipose tissue anatomical locations, significantly higher activities were found in subcutaneous than in perirenal fat pad independently of dietary fat. In conclusion, under our experimental protocol, lipogenesis in rat adipose tissue does not seem to be affected by dietary fat type.     

Effects of maternal marginal zinc deficiency on myelin protein profiles in the suckling rat and infant rhesus monkey

In the current study, the effects of marginal Zn deficiency on myelin protein profiles in neonatal rats and rhesus monkeys were investigated. Following mating, rats were fed a Zn-adequate diet,ad libitum (50 μg Zn/g; 50 Zn AL), or a marginal Zn diet (10 μg Zn/g) from day 0 (10 Zn d0) or day 14 (10 Zn d14) of gestation to day 20 postnatal. An additional group of dams was restricted-fed the control diet to the food intake of the 10 Zn d0 group (50 Zn RF). Day 20 pup plasma and liver Zn concentrations in the 10 Zn groups were lower than in the 50 Zn groups. In a parallel experiment, rhesus monkeys were fed a Zn-adequatead libitum diet (100 μg Zn/g) or a marginal Zn diet (4 μg Zn/g diet; MZD) throughout gestation and lactation. Day 30 monkey infant plasma and liver Zn levels were similar in the MZD and control groups. Rat brain and monkey brain cortex weights were similar among the dietary groups. The amount of myelin recovered (mg protein/g brain) from day 20 rat pups from the 10 Zn groups was lower than that recovered from the 50 Zn rat pups. Myelin recovery from the MZD and control monkey infants was similar. When myelin protein profiles were characterized, it was found that the percentages of high-molecular-weight (HMW) proteins and Wolfgram protein were higher, whereas the percentages of small and large basic proteins were lower in myelin from the 10 Zn d0 and 50 Zn RF pups compared to the distribution in the 50 Zn AL rat pups. Results for the 10 Zn d0 and 10 Zn d14 pups were similar for all of the parameters studied. The percentage of HMW proteins was higher and that of basic protein lower in myelin from MZD monkey infants compared to the percentage of these proteins in myelin from controls. Although the interpretation of the rat data is complicated because of the anorexia associated with the Zn deficiency, the observed changes in monkey myelin protein profiles provide strong evidence that maternal Zn deficiency affects myelination in the offspring.     

Involvement of the GHSR in the developmental programming and metabolic disturbances induced by maternal undernutrition

The mismatch between maternal undernutrition and adequate nutrition after birth increases the risk of developing metabolic diseases. We aimed to investigate whether the hyperghrelinemia during maternal undernourishment rewires the hypothalamic development of the offspring and contributes to the conversion to an obese phenotype when fed a high-fat diet (HFD). Pregnant C57BL/6 J, wild type (WT) and ghrelin receptor (GHSR)^−/− mice were assigned to either a normal nourished (NN) group, or an undernutrition (UN) (30% food restricted) group. All pups were fostered by NN Swiss mice. After weaning, pups were fed a normal diet, followed by a HFD from week 9. Plasma ghrelin levels peaked at postnatal day 15 (P15) in both C57BL/6 J UN and NN pups. Hypothalamic Ghsr mRNA expression was upregulated at P15 in UN pups compared to NN pups and inhibited agouti-related peptide (AgRP) projections. Adequate lactation increased body weight of UN WT but not of GHSR^−/− pups compared to NN littermates. After weaning with a HFD, body weight and food intake was higher in WT UN pups but lower in GHSR^−/− UN pups than in NN controls. The GHSR prevented a decrease in ambulatory activity and oxygen consumption in UN offspring during ad libitum feeding. Maternal undernutrition triggers developmental changes in the hypothalamus in utero which were further affected by adequate feeding after birth during the postnatal period by affecting GHSR signaling. The GHSR contributes to the hyperphagia and the increase in body weight when maternal undernutrition is followed by an obesity prone life environment.     

Segmental expression of the bradykinin type 2 receptor in rat efferent ducts and epididymis and its role in the regulation of aquaporin 9

Water and solute transport in the efferent ducts and epididymis are important for the establishment of the appropriate luminal environment for sperm maturation and storage. Aquaporin 9 (AQP9) is the main water channel in the epididymis, but its regulation is still poorly understood. Components of the kinin-kallikrein system (KKS), leading to the production of bradykinin (BK), are highly expressed in the lumen of the male reproductive tract. We report here that the epididymal luminal fluid contains a significant amount of BK (2 nM). RT-PCR performed on epididymal epithelial cells isolated by laser capture microdissection (LCM) showed abundant BK type 2 receptor (Bdkrb2) mRNA expression but no type 1 receptor (Bdkrb1). Double-immunofluorescence staining for BDKRB2 and the anion exchanger AE2 (a marker of efferent duct ciliated cells) or the V-ATPase E subunit, official symbol ATP6V1E1 (a marker of epididymal clear cells), showed that BDKRB2 is expressed in the apical pole of nonciliated cells (efferent ducts) and principal cells (epididymis). Triple labeling for BDKRB2, AQP9, and ATP6V1E1 showed that BDKRB2 and AQP9 colocalize in the apical stereocilia of principal cells in the cauda epididymidis. While uniform Bdkrb2 mRNA expression was detected in the efferent ducts and along the epididymal tubule, marked variations were detected at the protein level. BDKRB2 was highest in the efferent ducts and cauda epididymidis, intermediate in the distal initial segment, moderate in the corpus, and undetectable in the proximal initial segment and the caput. Functional assays on tubules isolated from the distal initial segments showed that BK significantly increased AQP9-dependent glycerol apical membrane permeability. This effect was inhibited by BAPTA-AM, demonstrating the participation of calcium in this process. This study, therefore, identifies BK as an important regulator of AQP9.     

Influence of zinc depletion and zinc status on serum growth hormone levels in rats

In a preceding trial, the growth hormone concentrations in the serum of zinc-deficient rats were greatly reduced compared to thead libitum- fed control animals. The same reduction, however, was also noted in the case of the pair-fed control animals with strongly diminished feed intake. Therefore, it was not possible to distinguish between the effects of zinc deficiencyper se and the effects resulting from restricted feed intake. A new study with 136 young male Sprague-Dawley rats showed again that zinc deficiency as well as strongly restricted feed intake reduced the growth hormone content in the serum. But in a marginal zinc deficiency status, when feed intake was only slightly or not reduced, there were lowered serum growth hormone levels in comparison to pair-fed control rats. A 1-wk zinc repletion did not increase the serum growth hormone content of the rats to a normal level, although the serum zinc concentration was normalized.     

Estrogen- and Satiety State-Dependent Metabolic Lateralization in the Hypothalamus of Female Rats

Hypothalamus is the highest center and the main crossroad of numerous homeostatic regulatory pathways including reproduction and energy metabolism. Previous reports indicate that some of these functions may be driven by the synchronized but distinct functioning of the left and right hypothalamic sides. However, the nature of interplay between the hemispheres with regard to distinct hypothalamic functions is still unclear. Here we investigated the metabolic asymmetry between the left and right hypothalamic sides of ovariectomized female rats by measuring mitochondrial respiration rates, a parameter that reflects the intensity of cell and tissue metabolism. Ovariectomized (saline injected) and ovariectomized+estrogen injected animals were fed ad libitum or fasted to determine 1) the contribution of estrogen to metabolic asymmetry of hypothalamus; and 2) whether the hypothalamic asymmetry is modulated by the satiety state. Results show that estrogen-priming significantly increased both the proportion of animals with detected hypothalamic lateralization and the degree of metabolic difference between the hypothalamic sides causing a right-sided dominance during state 3 mitochondrial respiration (St3) in ad libitum fed animals. After 24 hours of fasting, lateralization in St3 values was clearly maintained; however, instead of the observed right-sided dominance that was detected in ad libitum fed animals here appeared in form of either right- or left-sidedness. In conclusion, our results revealed estrogen- and satiety state-dependent metabolic differences between the two hypothalamic hemispheres in female rats showing that the hypothalamic hemispheres drive the reproductive and satiety state related functions in an asymmetric manner.     

Effects of feeding programme on the performance and energy balance of nulliparous rabbit does

A total of 190 rabbit females were used to evaluate five feeding programmes from 9 weeks of age to the first parturition: CAL, fed ad libitum with a control diet (C: 11.0 MJ digestible energy (DE) and 114 g digestible protein (DP)/kg dry matter (DM)) until first parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until first parturition; F, fed ad libitum with a low-energy, high-fibre diet (F: 8.7 MJ DE and 88 g DP/kg DM) until first parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until first parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until first parturition. The rabbits were artificially inseminated at 18 weeks of age. CAL group had a higher mortality rate compared with the other groups between 9 and 12 weeks of age (34% v. 3%; P < 0.05) and during the last 3 weeks of first pregnancy (14% v. 3%; P < 0.05). The CAL and FC females presented higher BW and perirenal fat thickness (PFT) than CR females at 11 days of pregnancy (+0.41 kg and +0.6 mm; P < 0.05), with F females showing medium values. The type of feeding procedure did not affect the fertility rate of young females at first artificial insemination. Differences in BW disappeared at parturition, when only CAL females presented a greater PFT than CR and FC females (+0.3 mm; P < 0.05). In comparison with FCF, CAL females had smaller and thinner live born litters (−2.5 kits and −139 g, respectively; P < 0.05), with CR, F and FC females showing medium values. The low number of kits born alive for CAL females was because of their lesser total number of kits born (−1.7 kits; P < 0.05) and the greater mortality of their litters at birth (+13.9%; P < 0.05) compared with FCF females. Non-esterified fatty acid was higher in the blood of females fed C diet (CAL and CR) than in others at partum day (on average +0.15 mmol/l; P < 0.05). In conclusion, the ad libitum use of diets for lactating rabbit does throughout the rearing period could lead young rabbit females to present a higher risk of early death and smaller litter size at first parturition. Feed restriction or earlier use of suitably fibrous diets led females to achieve the critical BW and fat mass at first mating to ensure reproduction.     

Consequences of rearing feeding programme on the performance of rabbit females from 1st to 2nd parturition

To evaluate how rearing programmes could affect resources allocation and reproductive performance of primiparous rabbit females, a total of 118 rabbit females were used to evaluate the effects of five rearing feeding programmes on their performance from 1st to 2nd parturition: CAL, fed ad libitum C diet (11.0 MJ digestible energy (DE), 114 g digestible protein (DP) and 358 g NDF/kg dry matter (DM) until 1st parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until 1st parturition; F, fed ad libitum with F diet (8.7 MJ DE, 88 g DP and 476 NDF/kg DM) until 1st parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until 1st parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until 1st parturition. From 1st parturition, C diet was ad libitum offered to all the experimental groups until 2nd parturition. CAL females presented lower feed intake than females of F, FC and FCF groups in the 1^st week of lactation (on av. −16.6%; P<0.05). During 1st lactation, the perirenal fat thickness change in CAL females was not different from 0 (+0.02 mm), while in the other four groups it increased (on av. +0.44 mm; P<0.05). Plasma of females fed with F diet during rearing (F, FC and FCF) had lower non-esterified fatty acids content than those exclusively fed with C diet (–0.088 and –0.072 mmol/l compared to CAL and CR, respectively; P<0.05). FCF litters had higher weight than F litters at day 21 of lactation (+247 g; P<0.05), but FCF litter had significantly lower weight than FC litters at weaning (+170 g; P<0.05). CR females had the shortest average interval between the 1st and 2nd parturition (49 days) and FCF females the longest (+ 9 days compared to CR; P<0.05). At 2nd parturition, liveborn litters of F females were larger and heavier than litters of FCF females (+2.22 kits and +138 g; P<0.05), probably due to the lower mortality at birth of F litters (–16.5 percentage points; P<0.05). In conclusion, rearing females on fibrous diets seems to increase the ability of primiparous rabbit females to obtain resources, especially at the onset of lactation.     

Fatty acid oxidation and fatty acid synthesis in energy restricted rats

The importance of fat oxidation and fatty acid synthesis were examined in rats fed approximately one half their ad libitum food intake for a period of 13 days followed by 7 days of ad libitum feeding (refed rats). This study was undertaken because previous reports demonstrated that refed rats rapidly accumulated body fat. Our results confirmed this observation: refed rats accrued body fat and body weight at rates that were approximately 3 times higher than controls. Evidence for a period of increased metabolic efficiency was demonstrated by measuring the net energy requirement for maintenance over the refeeding period: refed rats had a reduced metabolic rate during the period of energy restriction (approximately 30% lower than control) and this persisted up to 2 days after the reintroduction of ad libitum feeding. The major factor responsible for the rapid fat gain was a depressed rate of fatty acid oxidation. Calculations of protein and carbohydrate intake over the refeeding period showed that the simplest explanation for the decrease in fatty acid oxidation is fat sparing. This is possible because of the large increase in dietary carbohydrate and protein intake during the refeeding period when metabolic rates are still depressed. The increased carbohydrate and protein may adequately compensate for the increasing energy requirements of the ER rats over the refeeding period affording rats the luxury of storing the excess dietary fat energy.