Behavioral development was studied in 2 groups of rats during the postweaning period. Pups were selected from litters nursed by dams fed either a standard protein (25% casein by weight) or a low protein diet (12% casein) during lactation. Two pups from each litter were housed together and fed the control diet throughout rehabilitation. Behavioral observations were made by repeated time-lapse photography at 5-day intervals. Differences in home cage behavior were observed at the onset of rehabilitation in the postnatally malnourished rats. Increased feeding behavior was observed during the 1st week of rehabilitation. Locomotor behavior was depressed during the rehabilitation period in the experimental animals. Climbing activity, however, was significantly greater. Self-grooming activity was elevated throughout rehabilitation in post-natally malnourished animals. During the course of rehabilitation, the behavioral differences between the 2 groups gradually disappeared.

Animals↗

PubMed1977

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.

Animals↗

PubMed1977

Effect of different postnatal periods of protein-energy malnutrition in young rats upon subsequent protein utilization.

Previously it had been shown that rat pups, malnourished during the 3-week suckling period and the nutritionally rehabilitated for about 30 weeks, showed an increase in the efficiency of dietary protein utilization of the protein was fed at a less than optimal level and if the protein was of poor nutritional quality (J. Nutr. 103, 273, 1973). The present study extends this observation to growing rats malnourished during the first 3 weeks of life and then rehabilitated with a 25% casein diet for 4 weeks. The test proteins were casein, fed at a level of 12%, and wheat gluten, at a level of 25%. Efficiency of nitrogen retention was greater for both proteins in rats previously malnourished than for control, non-malnourished rats. Malnutrition was then imposed on rats malnourished by feeding a low protein diet either during the first 4 weeks postweaning or from the 7th to 11th week of life. After these periods of malnourishment, the rats were rehabilitated for 4 weeks and efficiency of utilization measured for both casein and wheat gluten fed at 10% of the diet. No change in utilization was found for either protein fed to rats rehabilitated from either of these periods of malnutrition.

Animals↗

PubMed1977

Comparative contributions of dietary protein quality and quantity to growth during gestation, lactation and postweaning in the rat.

The growth promotion by feeding purified diets containing 25%, 12% or 7% of either casein or wheat gluten (W.G.) and the supplementation value of adding cystine to the low casein diets, and lysine or lysine plus threonine to the wheat gluten diets ascertained in rats by comparing the weight achieved at birth, after 3 weeks suckling or 4 weeks postweaning. Birth weight was depressed by 30% with 7% casein; by 20% with 7% W.G.; by 15% with 25% W.G. compared to controls and there was no change when lysine alone was added to 7% W.G. Addition of lysine plus threonine to 7% W.G., lysine to 25% W.G. and cystine to 7% casein increased birth weight. The weight gain of dams reflected birth weight of pups in most cases. Weaning weight was depressed by 60% with either 12% casein or 12% W.G., and by 40% with 25% W.G. compared to controls. Addition of cystine to 12% casein and lysine to 25% W.G. increased the weaning weight slightly. Addition of lysine, lysine plus threonine or lysine plus glutamic acid (G.A.) to 12% W.G. had no effect on weaning weight. Maternal weight loss was decreased by amino acid supplementation of the diet. Four-week postweaning body weight was equal to the control when cystine was added to 12% casein and lysine was added to 25% W.G. Addition of lysine to 12% W.G. improved the growth rate, and addition of lysine plus threonine further improved the growth rate. Food intake was not decreased by protein deficiency during gestation. Food intake was significantly lowered by protein deficiency during both lactation and postweaning, however, supplementation of amino acid partially restored food intake to normal levels.

Animal Nutritional Physiological Phenomena↗

PubMed1976

The effect of protein-energy undernutrition induced during the period of suckling on cholinergic enzyme activity in the rat brain stem.

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Acetylcholinesterase↗

PubMed1976

Effect of postnatal dietary protein and energy restriction on exploratory behavior in young pigs.

Three-week-old pigs were subjected to dietary energy or protein restriction so as to prevent weight gain over a period of 8 weeks. During the last week of restriction their responses to a novel object introduced into an exploratory test situation were measured. The malnourished pigs exhibited indifference to the object, taking longer to make contact with it, spending less time playing with it, but not showing evidence of fear or avoidance of the object or the area in which it was located. Following 6 weeks of nutritional rehabilitation, the previously malnourished pigs again displayed less approach behavior to the novel object than controls, but the effect was substantially reduced. These observations are interpreted to support our hypothesis that a major mechanism through which early malnutrition produces long-term effects on behavior is by disturbing those behaviors required for gathering information from the environment.

Animals↗

PubMed1976

Dual role of environmental deprivation and malnutrition in retarding intellectual development. A. G. Hogan Memorial Lecture.

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Animals↗

PubMed1976

Maternal protein malnutrition during gestation alone and its effects on plasma insulin levels of the pregnant pig, its fetuses and the developing offspring.

The effects of restricting protein intake on plasma insulin were studied in pregnant pigs, fetuses and the developing offspring. Pregnant pigs were fed diets containing 18%, 3% or 0.5% protein throughout the gestation period. At 10, 13 and 15 weeks of gestation, fetuses were removed from the uterus after bleeding the dam. Plasma samples were used for insulin determination by a radioimmunoassay procedure. At week 15 of gestation, plasma insulin levels were significantly higher in pregnant pigs fed 18% protein and also in their fetuses than in the other two groups. There was a high correlation between fetal insulin level and fetal growth rate (r = 0.84). Two-day-pld pigs from another set of pregnant pigs fed the diet containing 18%, 3%, or 0.5% protein during gestation were cross-fostered to control nursing dams and weaned at 4 weeks of age to a standard diet. Plasma smaples obtained at regular intervals were used for insulin determination. Offspring of pigs fed 0.5% protein during gestation had consistently low insulin levels in postnatal life in spite of cross-fostering and standard feeding after weaning. It appears that one of the stimuli which control maternal insulin secretion and placenta transfer is the maternal protein intake while severe maternal protein restriction might contribute to the low levels of insulin in the progeny during postnatal life.

Animals↗

PubMed1976

Plasma insulin levels in weaned pigs fed protein or energy restricted diets.

Two experiments were conducted with pigs to investigate changes in plasma insulin levels during protein-energy malnutrition. Three or four week old pigs were fed a control diet (18% protein), an energy-restricted diet (19% protein) or a low protein diet (6% protein) for 8 weeks. Energy restriction was achieved by feeding the control diet in amounts that allowed some growth, but only to an extent equal to the low protein diet. At the end of the restriction period, all pigs were fed the control diet for another 8 weeks. Blood samples from the superior vena cava were collected at intervals throughout the experimental period. Plasma samples were analyzed for insulin by radioimmunoassay. Protein restriction after weaning resulted in persistently low insulin levels during depletion and rehabilitation periods, while high levels of plasma insulin were observed in energy-restricted pigs only during the depletion period compared to pigs fed the control diet.

Animals↗

PubMed1976

Decreased dietary protein or energy intake and plasma growth hormone levels of the pregnant pig, its fetuses and developing progeny.

The effects of low protein diets on plasma growth hormone were studied in pregnant pigs, fetuses and the developing progeny. Pregnant pigs were fed 18%, 3% or 0.5% protein diet throughout the gestation period. At 10, 13 and 15 week of gestation, fetuses were removed from the uterus after the dam had been bled to death. Plasma samples were used for growth hormone determinations. In a second experiment, 2-day old pigs from another set of pregnant pigs fed the diet containing 18%, 3% or 0.5% protein during gestation were cross-fostered to control nursing dams and weaned at 4 weeks of age to a standard diet. Plasma obtained at regular intervals was used for growth hormone determination. Plasma growth hormone was significantly higher in dams fed 0.5% protein after week 13 of gestation. High growth hormone (ten times the dam GH level) was observed in all fetuses irrespective of maternal dietary manipulation. Offspring of severely protein deprived pits (0.5% protein) had significantly elevated growth hormone levels up to 12 weeks of age in spite of cross fostering to a control dam after birth. The data suggest that there is little or no effect of maternal protein restriction on fetal growth hormone levels but the persistent high growth hormone levels in the progeny of severely malnourished pigs indicate a possible impairment of the production, release or catabolism of growth hormone and/or its releasing factor.

Animals↗