Jesús Larralde

Nutritional outcome and immunocompetence in mice fed on a diet containing raw field beans (Vicia faba, var. minor) as the source of protein

Feeding growth mice on diets containing raw field beans (Vicia faba var. minor) as the only source of protein brought about an impairment in growth, muscle mass and liver weight. No changes in food consumption were observed, but the food intake:weight gain ratio was increased in those animals. Plasma protein, triacylglycerols and cholesterol values were not affected by the dietary treatment although serum glucose and zinc levels fell after legume intake as well as the number of circulating erythrocytes. The relative enlargement of thymus and spleen in the legume-fed mice was apparently accompanied by a reduction in the cell number and an increase in cell size, while the protein synthesis capacity followed differentiated patterns in both tissues when assessed through protein, DNA and RNA determinations. The haemagglutination titres and the number of rosette-forming cells were lower in those animals fed on the field bean diet as well as the splenic lymphocyte responses to phytohaemagglutinin, Concanavalin A or lipopolysaccharide mitogens used to evaluate the functional status of T and B lymphocytes. The present study describes, apparently for the first time in mice, the involvement of field bean intake in some immunological disturbances affecting both humoral- and cell-mediated aspects of the immune response.

Response of Muscle, Liver and Whole-Body Protein Turnover to Two Different Sources of Protein in Growing Rats

A significant impairment in growth rate, food efficiency and weight of the gastrocnemius muscle was observed in rats fed a raw legume as the source of protein compared to casein-fed animals. No appreciable differences in chemical composition of the carcass were found. The source of dietary protein did not influence the ratio protein/DNA, DNA concentration or protein-synthesizing capacity (RNA/protein). The slower weight gain of animals fed the legume diet was attributed to a lower muscle protein synthesis, mediated by a depression of muscle RNA activity (grams protein synthesized/gram RNA) rather than changes in myofibrillar protein breakdown. In contrast liver protein synthesis appeared to be slightly increased in the legume-fed animals.

Effect of Raw Field Bean (Vicia faba) on Amino-Acid-Degrading Enzymes in Rats and Chicks

The effects of Vicia faba diet on urinary nitrogenous compounds and on enzyme activities of pathways directly associated with amino acid metabolism were studied in rats and chicks. The urea and creatinine excretion of rats fed on V. faba was approximately 90% more than that of control rats. The V.-faba-fed rats had increased activities of liver arginase (EC 3.5.3.1), argininosuccinate synthetase (EC 6.3.4.5) and alanine aminotransferase (EC 2.6.1.2). The chicks fed on V. faba also showed increased activity of xanthine dehydrogenase (EC 1.2.3.2). The possible nature of these altered amino-acid-degrading enzyme activities is discussed.

Homeorhetic Actions on Tissue Protein Metabolism After the Administration of Rat Growth Hormone to Normal Rats

An acute treatment with rat growth hormone (1 microgram/g) to intact female rats produced immediate changes in muscle and bone protein synthesis as well as in muscle protein breakdown, while glucose and glutamate-piruvate transaminase plasma levels were not altered. These effects, apparently, are not mediated by systemic insulin-like growth factor I. Also a long-term treatment with somatotropin (0.1 microgram/g/d) for 22 days was performed, in which protein synthesis rates in muscle, liver and bone remained unchanged. However, the growth hormone long-term treatment induced a decrease in muscle proteolytic activity and an increase in tibia weight. In this context, this experiment describes, apparently for the first time, the systemic effect of growth hormone in entire female rats. Data suggest that a single dose of rat growth hormone produces immediate changes in tissue protein metabolism, through a direct effect of growth hormone. These effects were not observed after the long-term growth hormone treatment, although these animals showed an increased in tibia proportions.

Guanidinoacetate methyltransferase activity in growing male rats fed on a raw field bean (Vicia faba L.) diet.

A significant reduction (p less than 0.01) in both the rate of growth and liver protein was found in growing male rats fed ad libitum over a 5-week period on a diet containing raw field bean (Vicia faba L.) as the sole source of protein, as compared to casein-fed rats. The activity of the hepatic enzyme guanidinoacetate methyltransferase (EC 2.1.1.2) as well as the urinary output of total nitrogen and creatinine were also significantly increased (p less than 0.01) in the legume-fed rats. The addition of methionine to the legume diet did not improve the antinutritive effect caused by the raw field bean. The possible nature of these effects is discussed.

Growth, hormonal status and protein turnover in rats fed on a diet containing peas (Pisum sativum L.) as the source of protein

The inclusion of peas (Pisum sativum L.) as the source of protein in the diet of growing rats brings about a reduction in growth rate as well as the impairment in the liver, muscle and spleen weights as compared with casein fed controls. Also, a fall in plasma glucose, triglycerides and protein was observed in the legume fed animals, while no changes in cholesterol levels were found. Furthermore, the rats fed on the diet containing peas showed lower levels of plasma insulin, corticosterone, IGF-I and T4 as compared with casein controls. Liver and muscle total protein (mg) and total DNA (mg) were markedly decreased in the legume fed animals, but DNA/g, protein/DNA and RNA/protein ratios were similar in both dietary groups. Likewise, liver and muscle fractional synthesis rates were similar in the casein and legume groups, while the whole body protein synthesis is assumed to be lower in the legume fed animals due to differences in body weights. It is concluded that animals fed on a diet containing peas (Pisum sativum L.) as the only source of protein showed less adverse effects than those found with other legumes such asVicia faba L. orPhaseolus vulgaris L., in which protein quality, antinutritional factors and nutrient availability could be involved.

Insulin-like growth factor I (IGF-I) affects plasma lipid profile and inhibits the lipolytic action of growth hormone (GH) in isolated adipocytes.

The actions of insulin-like growth factor I (IGF-I) and growth hormone (GH) on lipid metabolism have been investigated in hormonally intact rats. The subcutaneous injection of IGF-I (100 micrograms) and GH (100 micrograms) lowered total cholesterol plasma levels. The in vitro assays on isolated rat adipocytes showed an antilipolytic effect of IGF-I on GH induced lipolysis. All these data support an important role for IGF-I and GH on the regulation of lipid metabolism.

Evidence of a short-term effect of growth hormone on in vivo bone protein synthesis in normal rats

The growth of skeletal tissue is influenced by growth hormone (GH), whose effects are believed to be mediated, at least in part, by somatomedins or insulin-like growth factors (IGFs). This report describes an action of GH by increasing bone protein synthesis. This effect was not accompanied by changes in circulating IGFs. It is concluded that this experiment shows apparently for the first time in intact animals a short-term effect on bone turnover of GH.

Development-related nutritional utilization and immune function in mice fed on two different protein sources

Young (recently weaned) and adult male mice were fed on diets containing casein or peas as the source of protein. Animals fed on the legume diet showed a retardation in growth as compared with their respective casein fed controls, which was more marked in the younger mice. Also, serum levels of different nutrients showed changes in relation to diet and developmental stage, particularly proteins, lipids and minerals. The recently weaned animals showed a significant increase in immunoglobulins and Ig G after legume intake. The percentage of the splenic T cells and helper T cells was significantly increased by the legume diet in both developmental stage, while no variations in the percentage of splenic cytotoxic/suppressor T cells were observed. Neither the B lymphocyte distribution and the macrophage/monocyte subpopulation showed statistically significant differences between experimental groups. Splenocyte proliferative response to phytohaemagglutinin (PHA), Concanavalin A, Escherichia coli lipopolysaccharide S (LPS) and pokeweed (PWM) was significantly lower in adult mice than in younger mice. The current study shows that feeding mice on a diet containing peas as the source of protein induces a reduction in the utilization of diferent nutrients and a impairment in growth performance that may be associated to an immune mechanism. These effects are more marked in young than in adult animals, which could be attributted to a lower maturity of the immune system.

Intestinal absorption of D-galactose in the presence of extracts fromPhaseolus vulgaris hulls

The relatively low nutritional value of protein from legume seeds has been attributed to the occurrence of some antinutritional factors and the poor content in sulphur aminoacids, which leads to undesirable physiological and biochemical alterations. However, the intimate nature of these processes remains unclear. In order to evaluate the influence of naturally occurring substances of legume constituents on nutrient utilization, the intestinal absorption of D-galactose in the presence of aqueous or alcoholic extracts, obtained fromPhaseolus vulgaris hulls, has been measured by use of thein vivo successive absorption technique.Aqueous extracts inhibited significantly (p<0.01) the uptake of D-galactose at different times of exposure, while no changes in sugar transport were observed with the alcoholic solutions. Polyamide treatment (a polyphenolic complexing agent) of the aqueous extracts decreased its ability to inhibit sugar uptake. Kinetic studies showed that the aqueous fractions modifyVmax values for D-galactose absorption and alsoKT data. This inhibition appeared to be reversible after short periods of exposure, affecting mainly the active component of transport. Therefore, it can be suggested that some substances, contained in aqueous extracts ofPhaseolus vulgaris reduce sugar absorption. Furthermore, our studies seem to indicate that polyphenols are, at least partly, involved in this phenomenon.