EFFECT OF UNDERNUTRITION ON CELL FORMATION IN THE RAT BRAIN

Abstract— Rats were undernourished by approximately halving the normal food given from the 6th day of gestation throughout lactation. Growth of the foetuses was nearly normal, in marked contrast to the severe retardation caused by undernutrition during the suckling period. In comparison with controls the size and the DNA content of the brain were permanently reduced by undernutrition during the suckling period: this effect was relatively small, approx. 15 per cent decrease at 21 and 35 days. The rate of ¹⁴C incorporation into brain DNA at 30 min after administration of [2-¹⁴C] thymidine was taken as an index of mitotic activity; compared with controls there was severe reduction in mitotic activity (maximal decrease by about 80 per cent at 6 days in the cerebrum and by 70 per cent at 10 days in the cerebellum). The rate of acquisition of cells was calculated from the slopes of the logistic curves fitted to the estimated DNA contents. In normal animals the maximal slope was attained at 2·7 days and at 12·8 days after birth in cerebrum and cerebellum respectively; the daily acquisition of cells at these times was 4·8 × 10⁶ and 18 × 10⁶ cells respectively. The fractional increase in cell number at the maximum was 5·4 percent per day in the cerebrum and 15·2 per cent per day in the cerebellum. The rate of acquisition of cells relative to the rate of mitotic activity was higher in the brains of undernourished animals than in controls. One of the compensatory mechanisms for the severe depression of mitotic activity in the brain of undernourished animals Seems to involve a reduction in the normal rate of cell loss.     

Insulin secretion and GLUT-2 expression in undernourished neonate rats

In previous studies, we verified increased insulin sensitivity in adult male offspring of lactating rats readjusting to lack of insulin secretion reduction brought about by protein restriction during lactation. The present study aims to evaluate the effects of maternal protein undernutrition during lactation on glucose-induced insulin secretion and GLUT-2 expression in beta-cells of neonate male and female rats. Lactating Wistar rats were given a protein-free diet during the first 10 days and a normal diet (22% of protein) until weaning. The neonates were separated at birth by sex and diet and studied at 4, 8 and 21 days of lactation. Glucose-induced insulin secretion by pancreatic islets was analyzed by radioimmunoassay and GLUT-2 expression in beta-cells by Western blot. Glucose-induced insulin secretion of the undernourished groups was higher than in the control groups except among females. When comparing the male and female groups and the control and undernourished groups, female neonates showed significantly greater insulin secretion than the male group. Also it was noted that undernutrition induced greater GLUT-2 expression. For instance, comparing the undernourished male and female neonates there was an increase in female GLUT-2 expression on day 4. On the other hand, in undernourished male neonates a GLUT-2 expression increased later in lactation. In conclusion, during a short term, maternal undernutrition induces an increase of the glucose-induced insulin secretion only in male neonates and is associated with an increase in GLUT-2 expression in the beta-cell.     

Effect of undernutrition on some enzymes involved in the salvage pathway of purine nucleotides in different regions of developing rat brain

The effect of undernutrition on the activity of two key enzymes of purine salvage pathway, namely hypoxanthine-guanine phosphoribosyltransferase (HGPRTase) and adenine phosphoribosyltransferase (APRTase), in cerebral hemispheres, cerebellum and brain stem of rats at different days of postnatal development was studied. The activity of HGPRTase and of APRTase is significantly lower in all brain regions of undernourished animals at 5 days after birth; between 10 and 15 days of age there is a recovery of the enzymatic activity which is particularly evident in the cerebellum. Successively both enzymatic activities decrease reaching at 30 days of age values quite similar to those of controls. These results indicate that undernutrition during fetal and postnatal development, impairs and delays the activity of the enzymes of purine salvage pathway.     

DNA polymerase and thymidine kinase activities in different regions of rat brain during postnatal development: Effect of undernutrition

The effect of undernutrition on the activity of two key enzymes for DNA synthesis, namely DNA polymerase and thymidine kinase, in developing rat brain has been investigated. Both enzymatic activities in cerebral hemispheres and in brain stem are lower in undernourished animals than in controls at the 5th day after birth; succesively, from 5 to 30 days, they decrease in both groups of animals, however the decrease is less drastic in undernourished rats than in controls. At 30 days of age the specific activity of both enzymes is quite similar in the two groups of animals. In the cerebellum, DNA polymerase and thymidine kinase activities increase after 5 days of age showing a peak at around 9 days in controls and at about 13 days in undernourished animals, decreasing thereafter in both groups, although less drastically in undernourished animals, and reaching quite similar values at 30 days. The results obtained show that both enzymatic activities are impaired at 5 days and delayed thereafter, in agreement with the changes of DNA synthesis previously observed.     

EFFECTS OF UNDER NUTRITION AND PROTEIN DEFICIENCY ON GLUTAMATE DEHYDROGENASE AND DECARBOXYLASE IN RAT BRAIN

Abstract— Studies were made on the effects of undernutrition at different ages during the neonatal period and of the comparative effects of postweaning protein and calorie deficiencies in neonatally undernourished or normally reared animals. Neonatal undernutrition resulted in deficits in body wt, brain wt and the activities of brain glutamate dehydrogenase and glutamate decarboxylase. Percentage deficits in brain wt were maximum in the first week of life but those in brain enzymes were greater in the second week. Rehabilitation of neonatally undernourished animals reversed the deficits in brain wt and brain enzymes. Post-weaning protein deficiency produced similar deficits in brain enzymes in both neonatally undernourished and normally reared animals. With post-weaning undernutrition, however, these deficits were found only in animals subjected to neonatal undernutrition as well.     

The effect of normal development and of undernutrition on the exchange of [32P]orthophosphate with bone powder in vitro

1. The effect of age and undernutrition on the exchange of phosphate in the cortical bone powder of pigs with [(32)P]orthophosphate was investigated in vitro. 2. The extent of exchange fell steadily from birth to old age. 3. The bones of animals undernourished for 1 year behaved like those of animals 3(1/2) years old.     

EFFECTS OF PRE-WEANING AND POST-WEANING UNDERNUTRITION ON ACETYLCHOLINE LEVELS IN RAT BRAIN

Abstract— Studies were made of the effects of undernutrition during the neonatal period and also protein deficiency and undernutrition during the post-weaning period on brain acetylcholine. Rats undernourished from birth to 4 weeks so as to result in a body wt deficit of 43 per cent had an associated deficit in brain wt of 14 per cent, but the concentration of acetylcholine in the brain was not affected. In the case of post-weaning undernutrition, acetylcholine concn was found to be affected in protein deficiency as well as in severe calorie restriction.     

Early Undernutrition and [3H]γ-Aminobutyric Acid Binding in Rat Brain

The effect of early undernutrition and dietary rehabilitation on [3H]gamma-aminobutyric acid ([3H]GABA) binding in rat brain cerebral cortex and hippocampus was examined. Undernourished animals were obtained by exposing their mothers to a protein-deficient diet during both gestation and lactation. Saturation analysis of [3H]GABA binding in the cerebral cortex and hippocampus revealed high- and low-affinity components in the undernourished group, whereas control animals possessed only a low-affinity site. The concentration of low-affinity binding sites was greater in the undernourished animals. Rehabilitation of undernourished animals completely abolished the binding site differences. Treatment of brain membranes with Triton X-100 yielded two binding components in both the undernourished and control animals, although the concentration of lower affinity sites was still greater in the undernourished group. Neither the efficacy nor the potency of GABA to activate benzodiazepine binding in cerebral cortex was modified by undernutrition. These data suggest that early undernourishment modifies the characteristics of [3H]GABA binding, perhaps by reducing the brain content of endogenous inhibitors of the higher affinity binding site. The lack of effect on GABA-activated benzodiazepine binding suggests the possibility that neither the high- nor the low-affinity GABA binding sites are coupled to this receptor component.     

Sedentary behavior during postnatal life is determined by the prenatal environment and exacerbated by postnatal hypercaloric nutrition

The discovery of a link between in utero experience and later metabolic and cardiovascular disease is one of the most important advances in epidemiology research of recent years. There is now increasing evidence that alterations in the fetal environment have long-term consequences on metabolic and endocrine pathophysiology in adult life. This process has been termed "fetal programming," and we have shown that undernutrition of the mother during gestation leads to obesity, hypertension, hyperphagia, hyperinsulinemia, and hyperleptinemia in offspring. Using this model of maternal undernutrition throughout pregnancy, we investigated whether prenatal influences may lead to alterations in postnatal locomotor behavior, independent of postnatal nutrition. Virgin Wistar rats were time mated and randomly assigned to receive food either ad libitum (ad libitum group) or at 30% of ad libitum intake (undernourished group). Offspring from UN mothers were significantly smaller at birth than AD offspring. At weaning, offspring were assigned to one of two diets [control or hypercaloric (30% fat)]. At ages of 35 days, 145 days, and 420 days, voluntary locomotor activity was assessed. At all ages studied, offspring from undernourished mothers were significantly less active than offspring born of normal birth weight for all parameters measured, independent of postnatal nutrition. Sedentary behavior in programmed offspring was exacerbated by postnatal hypercaloric nutrition. This work is the first to clearly separate prenatal from postnatal effects and shows that lifestyle choices themselves may have a prenatal origin. We have shown that predispositions to obesity, altered eating behavior, and sedentary activity are linked and occur independently of postnatal hypercaloric nutrition. Moreover, the prenatal influence may be permanent as offspring of undernourished mothers were still significantly less active compared with normal offspring at an advanced adult age, even in the presence of a healthy diet throughout postnatal life.     

Photoperiodic time measurement is maintained in undernourished lambs with delayed puberty

Beginning at 42 weeks of age undernourished females that had been maintained outdoors were exposed to long days (15L:9D) or short days (9L:15D). After 6 weeks, both groups were placed on short days, and ad-libitum feeding was begun. Rapid 'catch-up' growth occurred similarly in both groups. However, the response to oestradiol negative feedback regulation of LH secretion differed greatly. Short-day lambs remained hyperresponsive to oestradiol inhibition, and circulating LH remained low, a condition that typifies immaturity of the system governing LH secretion. In the females exposed to the long-day-short-day sequence, circulating LH began to increase 10 weeks after the end of long days; this change is characteristic of the neuroendocrine alteration that occurs during puberty. These findings indicate that the growth-retarded lamb can differentiate long days from short days, and can therefore continue to accumulate photoperiod information during prolonged periods of undernutrition.     

Effects of Gestational Maternal Undernutrition on Growth,Carcass Composition and Meat Quality of Rabbit Offspring

An experiment was conducted in order to evaluate the effects of gestational undernutrition of rabbit does on growth, carcass composition and meat quality of the offsprings. Thirty primiparous non lactating rabbit does were artificially inseminated and randomly divided in three treatment groups: Control (C; fed to 100% of maintenance requirements throughout gestation, n = 10), early undernourished (EU; fed to 50% of maintenance requirements during days 7–19 of gestation, n = 10) and late undernourished (LU; fed to 50% of maintenance requirements during days 20-27 of gestation, n = 10). During the 4^th week of the gestation period, LU does significantly lost weight compared to C and EU groups (P<0.05). At kindling, C does produced litters with higher proportions of stillborn kits (P<0.05) while the total litter size (alive and stillborn kits) was not different among groups (10.7, 12.8 and 12.7 kits in C, EU and LU groups, respectively). Kit birth weight tended to be lower in the LU group. During fattening, body weight and feed intake were not different among offsprings of the three experimental groups. Moreover, the maternal undernutrition did not have any impact on carcass composition of the offsprings in terms of carcass parts and internal organs weights as well as meat quality of L. lumborum muscle (pH24, colour, water holding capacity and shear values) at slaughter (70 days of age). Therefore, it can be concluded that the gestational undernutrition of the mother does not have detrimental effects on the productive and quality traits of the offsprings.     

EFFECTS OF HYPOTHYROIDISM AND UNDERNUTRITION ON DNA CONTENT AND THYMIDINE KINASE ACTIVITY DURING CEREBELLAR DEVELOPMENT IN THE RAT1,2

—The effects of hypothyroidism and several degrees of undernutrition on the development of cerebellar weight, DNA, and thymidine kinase activity were studied in young rats ranging in age from 2 to 22 days. Early propylthiouracil treatment caused a delayed cerebellar cell multiplication. The activity of cerebellar thymidine kinase was suppressed at ages 2 and 5 days and was in excess of control values on days 15 and 22, thus resulting in a delay in the developmental spectrum for thymidine kinase, and extending the time span of activity beyond that of controls. Undernutrition led to varying degrees of reduced cell proliferation at experimental ages 5, 12, and 19 days. Cerebella from the most undernourished animals showed significant differences from controls in thymidine kinase activity at ages 5 and 12 days. Comparisons between sub-groups from within the oversized litters at 5 and 12 days suggested that changes in thymidine kinase activity relate to the degree of undernutrition to which the sub-group is subjected and that during development there may be a critical degree of undernutrition at which a particular essential enzyme becomes affected. This study emphasizes the biochemical similarities and differences between neonatal hypothyroidism and undernutrition, while pointing out the difficulties which exist in biochemical separation of components of the two conditions. Further evidence is presented that thymidine kinase is responsive to hormonal stimuli during cerebellar development and may play an important role in the regulation of DNA biosynthesis in brain as well as other organs.     

Effects of prolonged undernutrition on structure and function of the diaphragm

The present study examined the effect of prolonged undernutrition on diaphragmatic structure and force-generating ability. Studies were performed on 58 Syrian hamsters in which the feed was reduced by 33% for a 4-wk period. Sixty animals fed a similar diet ad libitum served as controls. Diaphragm muscle structure was assessed from its mass (wet and dry weight), thickness, fiber composition, and fiber size. Isometric force produced in vitro by isolated muscle strips in response to electrical stimulation of the phrenic nerve was examined over a range of muscle lengths (length-tension relationship). In undernourished animals, body weight decreased 25 +/- 5%. Diaphragm wet and dry weight, muscle thickness, and the cross-sectional area of fast-glycolytic (FG) and fast-oxidative (FO) fibers were significantly less in undernourished than control animals and correlated with reductions in body weight. The cross-sectional area of slow-oxidative (SO) fibers was the same in the two groups. The percentage of FG fibers in undernourished animals was decreased slightly and the percentage of SO fibers increased. Maximum isometric tension was reduced in undernourished animals as compared with controls, but the position and shape of the length-tension relationship was the same in the two groups. Reductions in muscle force appeared to be explained by decreases in muscle mass, since tension corrected for cross-sectional area or tissue weight was the same in the two groups. Therefore muscle mechanical efficiency appeared to be unaffected by undernutrition. These data indicate that prolonged undernutrition causes deleterious changes in diaphragm muscle structure that impair its ability to generate force.     

Muscle growth during neonatal undernutrition and subsequent rehabilitation in the rat

The growth of the rat calf muscle has been followed radiographically during neonatal undernutrition and subsequent catch-up. The following observations were made: (1) The mean calf muscle width of rats reared in litters of 16 was 20% less than that of those reared in litters of 8. (2) There was no significant difference between the sexes in the degree of growth retardation brought about by suckling the pups in large litters. (3) By the end of the experiment, females had caught up in both muscle width and muscle length, the males had caught up in muscle length (identical to tibia length) but not in muscle width. (4) In male pups during undernutrition the muscle diameter was greater than in normally fed animals of the same weight (but younger). This difference was not seen in females. (5) During recovery, until a weight of about 160 g was reached, the muscle width of the neonatally undernourished rats of both sexes was less than controls of the same body weight.     

Circulating leptin concentrations are positively related to leptin messenger RNA expression in the adipose tissue of fetal sheep in the pregnant ewe fed at or below maintenance energy requirements during late gestation

We have investigated the effects of maternal undernutrition during late gestation on maternal and fetal plasma concentrations of leptin and on leptin gene expression in fetal perirenal adipose tissue. Pregnant ewes were randomly assigned at 115 days of gestation (term = 147 +/- 3 days [mean +/- SEM]) to either a control group (n = 13) or an undernourished group (n = 16) that received approximately 50% of the control diet until 144-147 days of gestation. Maternal plasma glucose, but not leptin, concentrations were lower in the undernourished ewes. A significant correlation was found, however, between mean maternal plasma leptin (y) and glucose (x) concentrations (y = 2.9x - 2.4; r = 0.51, P < 0.02) when the control and undernourished groups were combined. Fetal plasma glucose and insulin, but not fetal leptin, concentrations were lower in the undernourished ewes, and no correlation was found between mean fetal leptin concentrations and either mean fetal glucose or insulin concentrations. A positive relationship, however, was found between mean fetal (y) and maternal (x) plasma leptin concentrations (y = 0.18x + 0.45; r = 0.66, P < 0.003). No significant difference was found in the relative abundance of leptin mRNA in fetal perirenal fat between the undernourished (0.60 +/- 0.09, n = 10) and control (0.70 +/- 0.08, n = 10) groups. Fetal plasma concentrations of leptin (y) and leptin mRNA levels (x) in perirenal adipose tissue were significantly correlated (y = 1.5x +/- 0.3; r = 0.69, P < 0.05). In summary, the capacity of leptin to act as a signal of moderate maternal undernutrition may be limited before birth in the sheep.     

Early and Long-term Undernutrition in Female Rats Exacerbates the Metabolic Risk Associated with Nutritional Rehabilitation

Human studies have suggested that early undernutrition increases the risk of obesity, thereby explaining the increase in overweight among individuals from developing countries who have been undernourished as children. However, this conclusion is controversial, given that other studies do not concur. This study sought to determine whether rehabilitation after undernutrition increases the risk of obesity and metabolic disorders. We employed a published experimental food-restriction model. Wistar female rats subjected to severe food restriction since fetal stage and controls were transferred to a moderately high-fat diet (cafeteria) provided at 70 days of life to 6.5 months. Another group of undernourished rats were rehabilitated with chow. The energy intake of undernourished animals transferred to cafeteria formula exceeded that of the controls under this regime and was probably driven by hypothalamic disorders in insulin and leptin signal transduction. The cafeteria diet resulted in greater relative increases in both fat and lean body mass in the undernourished rats when compared with controls, enabling the former group to completely catch up in length and body mass index. White adipose tissues of undernourished rats transferred to the high-lipid regime developed a browning which, probably, contributed to avoid the obesigenic effect observed in controls. Nevertheless, the restricted group rehabilitated with cafeteria formula had greater accretion of visceral than subcutaneous fat, showed increased signs of macrophage infiltration and inflammation in visceral pad, dyslipidemia, and ectopic fat accumulation. The data indicate that early long-term undernutrition is associated with increased susceptibility to the harmful effects of nutritional rehabilitation, without causing obesity.     

Influence of intrauterine undernutrition on the development of hypercholesterolemia in an animal model

A low birth weight is a new risk factor for the development of premature atherosclerosis. The effect of intrauterine undernutrition on hypercholesterolemia in later life was studied in an experimental model using the Prague Hereditary Hypercholesterolemic (PHHC) rat. Compared to animals in the control group (Wistar rats), animals with an increased sensitivity to high-cholesterol diet (PHHC rats) display hypercholesterolemia. Only in PHHC animals, individuals undernourished in their intrauterine life (hypotrophic group, HG) had a significantly higher total cholesterol, compared with individuals without food restriction in pregnancy (eutrophic group, EG). Restricted food intake in pregnancy led to smaller nests and a decreased number of pups in each litter. We found no significant diferences in birth weight between HG and EG. In spite of similar birth weights in PHHC and Wistar rats, intrauterine undernutrition caused an increase in cholesterolemia in the HG group of the PHHC rats. The effect of intrauterine undernutrition on the development of hypercholesterolemia will most likely play a role in individuals with geneticaly determined increased susceptibility to a high-cholesterol diet. The use of this model of intrauterine undernutrition for the study of hypercholesterolemia has proved to be feasible.     

Interaction between pre-weaning undernutrition and post-weaning environmental enrichment on somatic development and behaviour in male and female rats

Male and female rats were undernourished from birth to 30 days by restricting access to the lactating mother, and then fed ad libitum. At weaning, underfed and normally suckled controls were permanently housed either in pairs in standard cages or in groups of 10 in 1 m³ cages containing ladders, ropes etc. Severe undernutrition during suckling followed by 4 months of refeeding, produced some changes in sexual behaviour in adult males (increased ejaculation frequency) but had no effect on behaviour in open field, dark preference or passive avoidance. Differential post-weaning environment produced significant differences in behaviour, irrespective of previous feeding conditions. Enriched animals were more active and exploratory. Females differed from males in the same direction as enriched from standard, and were more responsive to social and housing conditions.     

Effects of undernutrition during suckling and of training on the hypothalamic beta-endorphin of young and adult rats

The involvement of the hypothalamic beta-endorphinergic system in behavioral processes has previously been studied in adult rats. In the present report, we studied the effects of undernutrition and of inhibitory avoidance training on the hypothalamic beta-endorphin-like immunoreactivity of 21-day-old and adult rats. Rats were undernourished by feeding their dams an 8% protein diet from the day of delivery until weaning (21 days of age). The beta-endorphin-like immunoreactivity was measured by radioimmunoassay. In adult rats, undernutrition decreased the basal level hypothalamic beta-endorphin. Avoidance training decreased the content of beta-endorphin in the hypothalamus of well-nourished adults, but had no effect on the levels of previously undernourished rats. In 21-day-old rats, neither undernutrition nor avoidance training altered the levels of beta-endorphin. These results suggest that the hypothalamic beta-endorphinergic system of weaning rats is not yet functional in relation to the parameters analyzed. Probably, other developmental factors are necessary for the emergence of the effects of undernutrition found in adult rats and for the emergence of the response of this system to training (novelty).     

Effects of Undernutrition and Thyroid State on the Ontogenetic Changes of D1, D2, and D3 Brain-Specific Proteins in Rat Cerebellum

Abstract: Disturbances in metabolic balance brought about by alterations in thyroid state and undernutrition during early life had a marked effect on the concentrations of the brain-specific proteins, D1, D2, and D3 in the developing rat cerebellum. In normal rats, the concentrations of D1 and D3 increased and that of D2 decreased during the first 3 weeks after birth. In the hyperthyroid state a small but consistent advancement was observed in the developmental curves of these proteins. The hypothyroid state caused a marked retardation in the maturational pattern of D1 and D2 but not of D3. In undernutrition, at 6 days the concentrations of D1 and D3 proteins were higher than in controls, but thereafter the developmental increase was markedly delayed for D1 only. The concentration of D2 was normal at 6 days, but after the first week a marked retardation was observed in the maturational pattern of this protein in undernourished rats. In addition, the "anodic-immature"form of D2 predominated in 6-day-old controls, but this was gradually replaced by a "cathodic-mature"form which progressively became the dominant form of D2 in 35-day-old rat cerebellum. The developmental switch in terms of the two forms was also advanced in hyperthyroidism and retarded in thyroid deficiency and undernutrition. Furthermore, daily treatment of hypothyroid rats with physiological doses of thyroxine from birth restored the concentrations of D1 and D2 to normal, but that of D3 was increased above control levels, indicating differences between the proteins in their sensitivity to mechanisms of control by thyroid hormone. Also, the overall effects of undernutrition were markedly different from those of hypothyroidism.