Maternal protein deprivation during pregnancy or lactation in rats and the efficiency of food and nitrogen utilization of the progeny

Life history and bioeconomy of the house mouse

1. More is known about the western European house mouse, Mus (musculus) domesticus than any other non-human mammal. If laboratory and field information is combined, an extremely valuable understanding of the species' bioeconomy could be obtained. 2. The seven stages of mouse life-history are surveyed (up to birth, nest life, sex life, social structure, population statics and stability, senescence, and death), and the interactions between the changing phenotype and the environment are described. 3. These interactions can be used to build up a model of the opportunities and compromises which result in the fitness of individual mice. It is not yet possible to quantify such a model, but this should in principle be achievable.

Prenatal protein malnutrition alters response to reward in adult rats

Developing rats were either malnourished or adequately nourished during the prenatal period by feeding their dams diets of 6% (low) or 25% (adequate) casein content 5 weeks prior to mating and throughout pregnancy. All pups received adequate nutrition from the day of birth onwards. In Experiment 1, male offspring aged 125 days were tested in a food-rewarded variable interval 2-min (VI 2') operant paradigm under three levels of body weight reduction (90%, 85% and 80% of their ad lib feeding weight). Previously malnourished rats showed significantly higher response rates than well-nourished controls at the 90% and 85% levels but not at the 80% level. In Experiment 2, behaviorally native male littermates aged 225 days were tested in a saccharin-solution-rewarded VI 2' operant task. The rate of receipt of reward within each daily session was found to differ in the two nutritional groups. Previously malnourished rats maintained a stable rate of reward throughout the session while the controls showed a rapid decline over the first 15-20 min. The higher rate of reward late in the session in Experiment 2 and the elevated response rate in the first two phases of Experiment 1 suggests that prenatal protein malnutrition increases subsequent responsiveness to reward.

Effects of early rearing experience on feeding behavior in B6D2F2 mice

This work investigated putative factors contributing to the hyperphagia previously observed in mice which had been overfed during the preweaning period by rearing in small litters. In the first study, B6D2F2 mice, reared in small (Sm = 4), medium (Md = 8) and large (Lg = 12) litters, were subjected to a series of diets adulterated with varying concentrations of sucrose octa-acetate (1, 2, 4, and 8%). All animals reduced their food intake in response to the dietary adulteration, with evidence of a dose-response effect, but this response did not differ as a function of litter size. The second study addressed the involvement of the opioid system in the feeding response through the administration of a series of doses of naloxone (0.1, 0.25, 0.5, 1.0, 2.5, and 5.0 mg/kg, or 5, 7.5 and 10.0 mg/kg). Although naloxone treatment did reduce food intake, there was not a clear dose-response relationship. Again, there was no interaction with litter size. These results do not support effects of early rearing on the feeding response to dietary adulteration or to the effects of naloxone administration.

Refeeding after various times of ingestion of a low protein diet: effects on food intake and body weight in rats

Rats born of protein-deprived mothers were fed on a low protein (LP) diet (5% casein) from weaning. In each time sequence (0, 1, 3, 5, 8 and 16 weeks after weaning), 12 of them were refed on an isocaloric well-balanced diet (18% casein) for 2 weeks. Food intake, body and adipose tissue weights and protein efficiency ratio (PER) were measured in the refed rats as well as in 12 LP rats. At weaning and after one week, refed (RF) rats immediately increased their food intake. This increase was delayed at weeks 3, 5 and 8 occurred during the second week of refeeding only. At week 16, there was a significant decrease during the first week when compared with LP rats. Body weight increased regularly during each refeeding period without any significant augmentation of the proportion of adipose tissue. During all the experiment (except at week 16), PER in the RF group remained high (about 3 g body weight/g protein) during the first week of refeeding, and fell to 2.0-2.5 g/g during the second week. It was particularly significantly greater than that of the LP rats between week 3 and 5 where an important decrease was observed in this group (1.99 +/- 0.36 vs. 3.23 +/- 0.58 g body weight/g protein during the 1-3 weeks period). It appeared therefore that protein restriction during gestation and lactation in dams had no effect on the mechanisms controlling food intake of their offspring at weaning.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of early under-nutrition on dietary self-selection and relative carbohydrate- and protein-conditioned preferences

Rats were either under-nourished from birth to 45 days and thereafter well fed, or were well-nourished throughout. Such previously under-nourished rats (PU) had a body weight deficit in adulthood of about 15% when compared with the well-fed group (C). On four training days, rats were presented with a distinctively odourized solution of carbohydrate or protein, following a 5-h period of food deprivation. On the test day, under the same food deprivation conditions as occurred during training, identical solutions distinguished only by their odour were presented simultaneously to the rats for a period of 20 min. PU rats showed a conditioned preference for the carbohydrate-paired odour. Control animals showed a small preference for the protein-paired odour. The same rats were later allowed to self-select from three macronutrients for a period of 8 days. No differences in dietary self-selection patterns were found between PU and C rats.

The influence of protein nutrition in early life on growth and development of the pig. 1. Effects on growth performance and body composition

The effects of feeding either a high-protein (HP) diet or a low-protein (LP) diet between 1.8 and 15 kg live weight (LW) and a low-energy (LE) or a high-energy (HE) intake but at the same protein intake subsequent to 15 kg LW on the performance and body composition of pigs growing to 75 kg LW were investigated. During the LW period 1.8-15 kg, pigs given the LP diet exhibited poorer growth performance (P less than 0.01) and at 15 kg contained more fat (P less than 0.01) in their empty bodies than pigs given the HP diet. On the LE treatment subsequent to 15 kg LW, pigs previously given the LP diet deposited protein at a faster rate and exhibited more rapid and efficient growth to 60 kg LW than those given the HP diet before 15 kg. However, on the HE treatment, pigs previously given the LP diet deposited protein at a slower rate and exhibited poorer growth performance (P less than 0.05) between 15 and 45 kg LW but grew at a faster rate between 45 and 60 kg LW than pigs previously given the HP diet. On the LE treatment subsequent to 15 kg LW the differences in body composition between the two protein groups were no longer significant at 45 kg. However, on the HE treatment, pigs previously given the LP diet remained fatter (P less than 0.05) to 60 kg LW than those previously given the HP diet. The results suggested that restricting protein intake between 1.8 and 15 kg LW reduced, temporarily, the upper limit of protein retention and growth performance during subsequent development. This finding is discussed in relation to the effects of protein nutrition in early life on the hyperplasic development of muscle tissue.

Hoarding behaviour and the defence of body weight in adult rats, following undernutrition during different periods of early development

In Experiment I, male rats, previously undernourished by underfeeding their mothers during lactation, weighed less as adults than progeny of mothers underfed during gestation, or than normally-nourished control rats. Daily 16 h food deprivation of the adults induced weight loss and elicited hoarding of food pellets. Deprivation-induced weight losses at criterion for hoarding did not differ significantly among the groups, and the critical weight at which hoarding began was thus significantly lower in the lactationally-undernourished group than in the controls. Thus adult rats, previously undernourished during their suckling period, appear to defend their body weights in a manner similar to controls, although at a lower level. Lactationally-undernourished rats also hoarded significantly fewer pellets than controls. Similar results were obtained when the rats were partially satiated before hoarding tests, suggesting that hoarding scores were unlikely to have been significantly affected by competition with feeding. Foetal undernutrition had weaker, and less consistent effects than lactational undernutrition on the ad libitum weight of the adult, and on the critical weight for hoarding. In Experiment II, severe undernutrition after weaning did not affect adult body weight, the weight loss necessary to induce hoarding, or the number of pellets hoarded. It is concluded that the pre-weaning period is specifically sensitive to the effects of undernutrition on body weight regulation and on hoarding. The data on hoarding do not support the view that a period of undernutrition at any time in early life increases the rat's responsiveness towards food.

Relationship of zinc and copper concentrations in maternal and cord blood and birth weight

Twenty and 30 Nigerian women who delivered infants weighing 1500 gm-2500 gm and more than 2500 gm, respectively, were studied. Cord and maternal blood samples collected at delivery were analyzed by atomic absorption spectrophotometry for zinc and copper content. The mean plasma zinc in maternal and cord blood was significantly lower and the mean plasma copper was significantly higher in the low-birth-weight group than in the control group. The zinc level in cord blood was higher than that in maternal blood in both groups. However, the copper level in both groups was lower in cord than in maternal blood.

Growth and the development of dietary obesity in adulthood of rats which have been undernourished during development

1. The effect of feeding a highly-palatable and varied diet on growth and body composition was assessed in male rats, some of which had undergone a period of undernutrition early in their development. 2. Undernutrition during gestation had no effects on weight, length or fat content of offspring in adulthood. Rats underfed during the first 3 weeks of postnatal life were shorter, lighter and more lean as adults than controls which had been well nourished through life. 3. Feeding the palatable diet from weaning led to increases in length and fat-free mass, and to comparable extents of obesity in all groups, irrespective of whether they had suffered either period of undernutrition. Access of palatable food for 30 d in adulthood also led to obesity, but to increases in length and fat-free mass in only the groups undernourished during suckling. 4. Withdrawal of the palatable diet led to some initial weight loss in all groups, irrespective of whether they had been undernourished during development; and 100 d following the replacement of the palatable with stock diet, there were no longer differences in weight between groups which had received palatable food, and those given stock diet throughout. 5. Nevertheless, those rats which had been undernourished during the suckling period and subsequently fed on the palatable diet still showed increased length and fat-free mass relative to their controls fed on the stock diet throughout. 6. All groups which had received the palatable diet, whether from weaning or as adults, and irrespective of early nutrition, were significantly less fat 100 d after its withdrawal than were those rats fed on the stock diet throughout life.

Sparing of the brain in neonatal undernutrition: amino acid transport and incorporation into brain and muscle

Rates of tyrosine and lysine transport and incorporation into protein were measured in control and undernourished weanling rats. Undernutrition was induced by feeding lactating dams a low protein diet (12 percent casein) from birth to day 21. At weaning, body and brain weights of undernourished rats were 50 percent and 88 percent, respectively, of control values. Lysine and tyrosine transport rates into skeletal muscle were reduced by over 75 percent, more than twice the reduction seen in brain. Rates of amino acid incorporation into muscle protein were reduced by approximately 50 percent; the change in rate of incorporation into brain protein was not statistically significant. These data indicate that, in spite of marked retardation of amino acid transport into brain, the brain seems fully capable of maintaining normal rates of protein synthesis.

Effect of protein-bound lysinoalanine, N epsilon-DL-(2-amino-2-carboxyethyl)-L-lysine on fetal and neonatal rats

Diets containing 5% to 30% of an alkali-treated isolated soybean protein (ATSP) containing 1% lysinoalanine (LAL) were fed to female Sprague-Dawley rats during gestation and lactation to provide 500, 1,000, 2,000, or 3,000 ppm LAL in the diet. An isolated soybean protein containing no LAL was used as control. No teratological effects were observed. No significant differences in birth weight, mortality, live births/litter, or number of pups/litter was found at any LAL level fed. However, significantly decreased weight gains were observed in pups from dams fed either 2,000 or 3,000 ppm LAL. No LAL was found in the milk, and protein content of all milks was similar. The decreased weight gains appeared to be due to reduced milk production in dams fed high levels of ATSP.

Effects of undernutrition in neonatal rats on physical development and food and water regulation

The effects of neonatal undernutrition in rats on food and water regulation, external indices of development, and long-term regulatory behavior were investigated. Undernutrition produced retardation in some external indices of development. The ability to eat, drink, and maintain body weight at weaning were not seriously affected by the undernutrition. Longer term deficiencies in feeding efficiency, osmotic regulation, prandial drinking, and activity were found for experimental subjects. The involvement of peripheral-systemic factors as well as neurological retardation in producing feeding and drinking deficits following undernutrition are discussed.

Protein malnutrition induced during gestation: its effect on pup development and maternal behavior

Repeated time-lapse photographic observations were used to examine the ontogeny of behavioral development in prenatally malnourished rat pups following birth. Pups born to dams receiving a low protein diet (7% casein by weight) were fostered at birth to well-nourished dams and behavioral observations were made at 4-day intervals. Dams nursing gestationally malnourished pups were observed to spend more time in the nesting area with their pups towards the end of lactation. Moreover, the behavioral development (locomotion, feeding, and rearing and climbing activity) of gestationally malnourished offspring was depressed when compared to their controls. The results indicate that prenatal undernutrition alters the behavioral development of the offspring and maternal behavior of the dam in a manner which reduces the exposure of the pup to the immediate environment.

Increased thirst and hunger in adult rats undernourished as infants: an alternative explanation

1. Rats were undernourished in early life by feeding their mothers a restricted quantity of a good-quality diet throughout lactation. Their undernutrition continued postweaning from 25 to 42 d of age, after which they were fed ad lib. Control rats were well nourished at all times. 2. Behavioural assessment of thirst was carried out on adult males. These were deprived of water for 23 h/d throughout the period of testing. Compared to control rats, previously-undernourished (PU) rats pressed a lever at a higher rate in a Skinner box to gain a water reward, drank more frequently during their first 5 min in an unfamiliar cage, and tended to run more quickly down an alleyway for water. PU rats also drank more (/kg body-weight 0-75) of a quinine solution (I g/l) when this was available to them ad lib. as their only source of fluid. 3. A second group of rats was growth-retarded during gestation and the suckling and early postweaning periods. The rats had free access to food from 42 d of age. In adulthood their ad lib. food and water consumption was measured. PU males ate and drank more (/kg body-weight 0-75) than control males. 4. These results indicate that adult rats which have been undernourished in early life display increased thirst. An attempt is made to explain this finding, together with their previously-demonstrated enhanced hunger drive, purely in terms of gross anatomical and physiological differences.