Dietary proteins on reproductive performance in three consecutive generations of rats.

The cumulative effects of the long-term consumption of the Regional Basic Diet (RBD) of Northeast Brazil on gestational and lactational performances were assessed in three consecutive generations of Sprague Dawley rats (n = 1,334). The animals were distributed into three groups: RBD (8% predominantly vegetable-based proteins), Control (8% casein) and Standard (22% casein). Primiparous fertilized rats aged 120 days old and their offsprings made up generation 1. Consecutive generations were obtained by mating products from previous generations. Statistical differences between groups and generations were analysed by the method of Kruskal-Wallis. In comparison with their respective controls, data for RBD-fed groups were as follows: decreased conception rates, gradual declines in gestational body weight gains and reduction in the mean number of youngs per litter; the weight loss of lactating rats aggravated in consecutive generations; suckling rats had lower values for birthweight and weight gain, higher values for death rates (including soon after weaning) and severe immaturity at weaning (21 days). This dietary experimental model proved to be valid in terms of providing information for further studies about the relationship between quality and quantity of dietary proteins in order to allow decisions on supplementary feeding programmes for people now most in need.

Long-lasting Effects of Early Environmental Stimulation on Cortical Spreading Depression in Normal and Early Malnourished Adult Rats.

We investigated the effects of early environmental stimulation on spreading depression in the cerebral cortex of male Wistar adult (90 day old) well-nourished (23% protein diet) and early malnourished (8% protein) rats. Environmental stimulation was performed during the suckling period or after weaning. Control rats were housed in a standard environment. Environmental stimulation after weaning produced a reduction of body weights in well-nourished rats, and an increase in wet, but not dry brain weights, in malnourished rats. Environmental stimulation during suckling was associated with reduced spreading depression velocities in the malnourished, but not in the well-nourished group. In well-nourished rats stimulated during suckling, spreading depression velocities in the occipital and parietal regions of the same hemisphere were significantly different, the occipital area presenting lower values than the parietal region. The results indicate that environmental conditions prevailing during brain development can alter electrophysiological parameters of spreading depression of adult rats, the suckling period being more susceptible to such environmental conditions and the occipital cortex being more affected than the parietal region. Data also suggest that the nutritional status can influence brain spreading depression responses to environmental stimulation, malnourished rats being more effected than the well-nourished ones.

A New Dietary Supplement Based on Bovine Blood: Recovering Brazilian Children from Malnutrition.

Two compounds ("Prothemol" and "Plasmel"), based on bovine blood as source of high quality-protein, were tested as supplement for malnourished children. Prothemol is a powder containing desiccated bovine red cells, with 23.32 g% protein and 18.8 mg% iron, without any limiting amino acid. Plasmel (a syrup) contains 44.7% bovine plasma, 54.3% saccharose and 1500 IU% retinol. Children, 32-60 month old, from a day-nursery service in Recife, Brazil, received Prothemol + Plasmel for 90 (n = 14) or 180 days (n = 8). When compared to age-matched control children (n = 12 and n = 6, respectively), they presented significantly higher increments in weight and height, and in some haematological parameters. Clinical signs associated to malnutrition (faces suggesting suffering or sadness; brightnessless eyes; apathy; reduced mobility; reduced communication with their classmates and adults) were found in 12 treated children (85.7%) and in 9 controls (75%). Recovery from these signs begun after 51 ± 20.6 and 103.5 ± 14.6 days, for the treated and control groups, respectively (P < 0.05) and occurred in 100% of the treated children and in 67% (6 of 9 children) in the controls. We suggest that Prothemol + Plasmel is an effective dietary supplement to help treating malnutrition in children, recovering them from clinical signs indicative of improving neural functions.

[Longevity of malnourished rats fed with the regional basic diet (RBD) of the northeast of Brazil]. / Duración de la vida en ratas desnutridas, utilizando dieta básica del nordeste brasileño.

The effects of a Regional Basic Diet (RBD) on life expectancy and growth were studied in 23 Sprague-Dawley rats from mothers fed RBD since fecundation. These animals were compared with 20 rats from mothers fed the balanced control diet (22% protein). At weaning, the animals were fed their mothers diet and the weight was recorded every week until death. Sex related differences were not detected among RBD-fed animals; the growth curve was similar for both sexes. The critical points of acceleration and deceleration of the growth rate were not defined for these rats. Survival for RBD-groups decreased until 75 d of age and was unchanged between 75 and 450 d of life. From the 459 th d to the 589 th d of life deaths occurred successively. Controls survived until the 860 th d of life. Data point out the need for improving the basic food pattern of the region to prevent, among other things, a low life expectancy for the northeastern population.

Malnutrition and brain function: experimental studies using the phenomenon of cortical spreading depression.

Depending on its intensity and duration, nutritional deficiency can disrupt the structure and function of the nervous system of humans and other mammals, with consequences more or less devastating for the whole organism, particularly in the early postnatal life, when body growth is very rapid and the need for proteins, calories and other nutrients is greatest. In this review, electrophysiological data are presented regarding the use of the phenomenon of cortical spreading depression (CSD) to study effects of malnutrition on the brain. Several conditions of clinical importance and that are known to alter brain function are shown also to influence CSD features in experimental animals. Some of these conditions, (e.g., pharmacological manipulation of neurotransmitter systems, dietary treatment with Lithium, acute hyperglycemia, hypothyroidism, aging and environmental stimulation) decrease CSD susceptibility, while other conditions increase it, as, for example, systemic reduction of extracellular chloride levels, deprivation of REM-sleep, acute hypoglycemia, treatment with diazepam, consumption of ethanol and malnutrition. Particular emphasis is laid on the effect of early environmental enrichment on CSD in normal and malnourished animals. Our results suggest that such effect is more evident in the malnourished brain, as compared to the well-nourished one. The data also show that malnutrition alters the brain responsivity to some CSD-facilitatory or inhibitory agents. The underlying mechanisms to explain the observed effects are discussed.

Effect of aging on cortical spreading depression.

The effects of aging on spreading depression (SD) were investigated in the Mongolian gerbil (G; age range 1.5 to 58 months; N = 35) and in albino rat (R; 2.5 to 24 months; N = 100). Two strains of rats were studied: Wistar (W; N = 35) and Sprague-Dawley (SDAW; N = 65). SDAW rats were divided into two groups: one group was fed a commercial lab chow diet (CD) containing 22% protein (N = 47), and the other was fed a 22% casein diet (CAS; N = 18). SD was elicited on the frontal cortical surface by 1-min application of 2% KCl and its appearance was recorded (ECoG and DC potential) at two points in the parieto-occipital area of the same hemisphere. SD propagation velocity was measured on the basis of the time spent for an SD "wave" to cross the distance between the two recording points. Within the age range studied, older animals displayed significantly lower SD velocities than the younger ones, independent of the species, strain or diet (velocity ranges, in mm/min: G, 2.22-5.99; W, 2.47-4.12; SDAW-CD, 2.32-4.42 and SDAW-CAS, 2.65-4.14). The correlation coefficients between age and SD velocity were: G. -0.78; W, -0.45; SDAW-CD, -0.68 and SDAW-CAS, -0.72 (P < 0.05 in all cases). As a rule, at each time point the gerbils presented higher SD velocities than the rats of the same age. In another set of experiments, in order to test the role of free radicals in SD, 7 gerbils (14-51 months old) and 13 W rats (3-24 months old) were fed a 22% casein diet free of the antioxidant vitamins C and E for 4-6 weeks before the experiments. No correlation was found between age and SD propagation in these animals fed a diet free of vitamins C and E, although gerbils displayed higher SD velocities than age-matched rats (velocities: G, 3.70-5.34; R, 3.25-4.44 mm/min; correlation coefficients: G; -0.39; W, -0/29; P > 0.05). These data indicate that gerbils have higher SD susceptibility than rats of the same age, and that this susceptibility decreases with aging in both species. The lack of correlation between age and SD velocity in the animals fed a diet free of antioxidant vitamins suggests a possible role of free radicals in cortical SD, in accordance with evidence from other laboratories obtained in the isolated retina.

Effect of aging on cortical spreading depression

The effects of aging on spreading depression (SD) were investigated in the Mongolian gerbil (G; age range 1.5 to 58 months; N = 35) and in the albino rat (R; 2.5 to 24 months; N = 100). Two strains of rats were studied: Wistar (W; N = 35) and Sprague-Dawley (SDAW; N = 65). SDAW rats were divided into two groups: one group was fed a commercial lab chow diet (CD) containing 22 per cent protein (N = 47), and the other was fed a 22 per cent casein diet (CAS; N = 18). SD was elicited on the frontal cortical surface by 1-min application of 2 per cent KCl and its appearance was recorded (ECoG and DC potential) at two points in the parieto-occipital area of the same hemisphere. SD propagation velocity was measured on the basis of the time spent for an SD "wave" to cross the distance between the two recording points. Within the age range studied, older animals displayed significantly lower SD velocities than the younger ones, independent of the species, strain or diet (velocity ranges, in mm/min: G, 2.22-5.99; W, 2.47-4.12; SDAW-CD, 2.32-4.42 and SDAW-CAS, 2.65-4.14). The correlation coefficients between age and SD velocity were: G, -0.78; W, -0.45; SDAW-CD, -0.68 and SDAW-CAS, -0.72 (P<0.05 in all cases). As a rule, at each time point the gerbils presented higher SD velocities than the rats of the same age. In another set of experiments, in order to test the role of free radicals in SD, 7 gerbils (14-51 months old) and 13 W rats (3-24 months old) were fed a 22 per cent casein diet free of the antioxidant vitamins C and E for 4-6 weeks before the experiments. No correlation was found between age and SD propagation in these animals fed a diet free of vitamins C and E, although gerbils displayed higher SD velocities than age-matched rats (velocities: G, 3.70-5.34; R, 3.25-4.44 mm/min; correlation coefficients: G, -0.39; W, -0.29; P>0.05). These data indicate that gerbils have higher SD susceptibility than rats of the same age, and that this susceptibility decreases with aging in both species. The lack of correlation between age and SD velocity in the animals fed a diet free of antioxidant vitamins suggests a possible role of free radicals in cortical SD, in accordance with evidence from other laboratories obtained in the isolated retina.

Intestinal protein absorption in malnourished mice with acute schistosomiasis mansoni.

Intestinal protein absorption was studied in undernourished albino Swiss mice with acute schistosomiasis mansoni. Undernutrition was induced by feeding mice with the Regional Basic Diet (RBD) ingested by human populations in Northeast Brazil, an experimental model previously developed in our laboratory. Weaning mice were infected with 40 cercariae and compared to undernourished non-infected mice and/or to infected mice fed a balanced control diet. Apparent and True Protein Absorption Coefficients were determined by nitrogen balance during five consecutive days ending at the 63rd day of the trial (acute phase of murine schistosomiasis). Fecal metabolic nitrogen (FMN) was determined after administration of a non-protein diet and was also calculated through linear regression. Our results showed a reduced protein absorption in non-infected RBD-fed mice as compared to mice fed a casein control diet. Infection with Schistosoma mansoni had apparently no effect on intestinal protein absorption in well-nourished mice. However, infection seemed to interfere with protein absorption in under-nourished animals, since the lowest absorption ratios have been detected among RBD-fed infected mice. A brief discussion is made on the advantages of using the method of linear regression for the determination of FMN.

Rat models of protein and protein-energy malnutrition.

Two animal models of infantile malnutrition were produced where some aspects of carbohydrate metabolism can be studied: protein-depleted (PD, "kwashiorkor") rats, fed a protein-free diet for 18 days, starting 3 days before weaning, and chronically malnourished animals during suckling (PED, "marasmus") where 20-22 pups were fed by the same dam. PED and PD rats were sacrificed at 21 and 36 days of age, respectively. Body weight was 35% in PD, and 50% in PED groups when compared to their age-matched controls. After an overnight fast, some of the PD animals presented with low blood glucose levels, and the levels of lactic and pyruvic acids were depressed in PED, while lactic acid was increased in PD animals. Blood glucose utilization was reduced in PED, and increased in PD rats, while the opposite was true for the kidney gluconeogenic capacity. When compared to the respective control values, muscle glycogen was high in both groups, while the level of liver glycogen was unchanged. The rate of muscle glycolysis was decreased in both groups. These results are in agreement with clinical observations, suggesting that these models may be used to study some of the metabolic changes brought about by infantile malnutrition.

A regional basic diet from northeast Brazil as a dietary model of experimental malnutrition.

The nutritional potentiality of the "Regional Basic Diet" (RBD) was assessed in albino rats. The diet, which was prepared according to data from food consumption surveys and was similar--in terms of quality and quantity--to those consumed by human populations in Northeast Brazil, was compared to a balanced diet (22% casein). The centesimal composition, aminogram, minerals content, NDpCal% and GCal%/PCal% ratio were determined. Vitamin contents were calculated from data in the literature. The RBD was shown to be imbalanced and poor in certain nutrients, mainly protein (7.8%). The growth curve of the RBD group was severely impaired; the naturally occurring sex-related differences in body weight were not detected. For fetuses and suckling pups, the weights of the liver and diaphragm paralleled body weight; brain weights were about 20% lower than those of controls, and its ratio was higher. RBD pregnant females presented, despite their higher food and energy intakes, lower weight gain as compared to the controls. During lactation food and energy intakes of RBD dams were lower than those of controls. The mortality rate among RBD pups was 24%. Our data indicate that RBD produces in the rat a type of malnutrition similar to that prevalent among children from Northeast Brazil, namely an association to nutritional dwarfism with some clinical signs of marasmus. RBD is considered to be a useful experimental model for studies on human malnutrition in countries where basic food patterns are similar to those in RBD-consuming regions.

Enhanced rate of cortical spreading depression due to malnutrition: prevention by dietary protein supplementation.

The enhanced propagation rate of cortical spreading depression, observed previously in rats rendered malnourished by the regional basic diet that is typical of the daily fare of many of the inhabitants of the northeastern region of Brazil, was not prevented by raising the quantity of dietary protein to the normal level without changing its quality. Dietary supplementation with casein, a protein of good quality, however, abolished the effect on spreading depression. These data indicate that the quality, and not the quantity, of the dietary protein is the critical factor in reversing the effects of regional basic diet malnutrition on spreading depression.

Enhanced rate of cortical spreading depression due to malnutrition: prevention by dietary protein supplementation

The enhanced prpagation rate of cortical spreading depression, observed previously in rats rendered malnourished by the region basic diet that is typical of the daily fare of many of the inhabitants of the northeastern region of Brazil, was not prevented by raising the quantity of dietary protein to the normal level without changing its quality. Dietary supplementation with casein, a protein of good quality, however, abolished the effect on sprteading depression. These data indicte that the quality, and not the quantity, of the dietary protein is the criticañ factor in reversing the effects of regional basic diet malnutrition on spreading depression

Effect of dietary lithium on cortical spreading depression.

The influence of lithium administration on cortical spreading depression (SD) was investigated in rats whelped by dams fed a diet containing lithium (1.5 g/kg) during the gestation or the lactation periods. Velocity of SD propagation was measured when the rats became adults and was similar to that of rats raised on a normal diet. A third group of adult rats received lithium during the three weeks preceding SD recordings and presented a significant reduction in SD velocity as compared to control rats. These data suggest that in adult rats a brief treatment with lithium impairs SD propagation, whereas much earlier treatment does not.

Effect of dietary lithium on cortical spreading depression

The influence of lithium administration on cortical spreading depression (SD) was investigated in rats whelped by dams fed a diet containing lithium (1.5 g/kg) during the gestation or the lactation periods. Velocity of SD propagation was measured when the rats became adults and was similar to that of rats raised on a normal diet. A third group of adult rats received lithium during the three weeks preceding SD recordings and presented a significant reduction in SD velocity as compared to control rats. These data suggest that in adult rat a brief treatment with lithium impairs SD propagation, whreas much earlier treatment does not

Sciatic nerve conduction velocity of malnourished rats fed the human "basic regional diet" of the northeast of Brazil.

1. Rats were fed the "basic regional diet" (BRD) utilized by some human populations in northeastern Brazil, which contains only 7.8% protein (mainly from beans), to produce a form of malnutrition. The effects of chronic malnutrition on nerve impulse conduction velocity was studied in the sciatic nerve of young (121-143 days) and old (420-540 days) rats. 2. BRD rats presented a 50% reduction in sciatic nerve conduction velocity compared to controls fed a diet containing 22% casein. 3. Rats chronically fed a commercially available diet (CD group) containing an intermediate level of protein (14%) presented conduction velocities intermediate between values obtained from control and BRD rats (62% to 76% of the control values). 4. The conduction velocities of animals belonging to the same nutritional group were independent of sex, body weight or age. 5. Nutritional restriction imposed only in adult life by increasing the number of rats per cage in the casein group did not have any effect on the conduction velocity of nerve impulses. 6. The severity of the effects observed in the malnourished rats may be related to the quantity and quality of protein in the diet. In this respect, the present data agree with those reported in the literature on human and animal experiments. 7. The present results justify the use of the foods ingested by malnourished human populations for the development of experimental animal models of malnutrition.

Does dietary tryptophan play a role in the control of convulsive activity?

The convulsive response to pentylenetetrazol was investigated in rats receiving different dietary tryptophan inputs. In the first experiment the animals were fed either a corn or a corn-supplemented diet. In the second one they received either a control diet supplemented with tryptophan, a low-protein/high-carbohydrate diet, or a low-protein/high-carbohydrate tryptophan-supplemented diet. The control groups for both experiments were fed a diet containing 22% milk protein. The corn diet facilitated seizures; the low-protein/high-carbohydrate/tryptophan diet prevented seizures. These results suggest that the brain serotonin levels determined by dietary tryptophan, or tryptophan by itself, could play a role in the convulsive response.

Lasting effects of acute dehydration and post-weaning undernourishment on cortical spreading depression in adult rats.

Acute dehydration (D) early in life made adult rats less susceptible to cortical spreading depression (SD) than control (C) rats. Post weaning undernourished (U) rats tended to be more susceptible than controls. The association of D and U (DU group) made rats more susceptible to SD than U-rats. It is suggested that this association gives rise to a more complex pathological state than that which would result from the summation of the effects of its components.

Learned and emotional behavior in chronically malnourished rats.

Weanling male and female Wistar rats, whose mothers received low protein diet (6.8%) during pregnancy and lactation, were fed on the same diet of their mothers and trained in an active avoidance situation at the ages of 60, 90 or 120 days. Control animals fed on a 20% protein diet of the same age groups were submitted to similar training. The consolidation and performance of the conditioned avoidance response and other behavioral reactions were studied. The malnourished animals showed delay of consolidation and lower frequency of conditioned avoidance responses, escape responses and holdings as well as higher frequency of anticipatory reactions, vocalization, riddance attempts and touching of surroundings. The results show that chronic malnutrition impairs the active avoidance response. They also show that chronic malnutrition affects the emotional behavior more markedly than early malnutrition. Chronic malnutrition also enhances the exploratory activity, in contrast to early malnutrition, and this is attributed to an alimentary drive-dependent mechanism.