Santiago Santidrian

Osteopenia in rats with liver cirrhosis: beneficial effects of IGF-I treatment.

BACKGROUND/AIMS Liver cirrhosis is associated with osteopenia and also with low levels of IGF-I. This hormone has been reported to stimulate bone formation in states of undernutrition and low bone turnover. Our aims were to evaluate whether osteopenia develops in male Wistar rats with CCl4-induced cirrhosis and whether IGF-I is effective in the restoration of bone mass in these animals. METHODS Cirrhotic rats were distributed into two groups: group CI (n = 12) which received placebo and group CI + IGF (n = 12) which was treated with human recombinant IGF-I (2 microg/100 g bw/day, s.c., 21 days). Twelve normal animals which received placebo constituted the control group. On the 22nd day, the animals were sacrificed, and bone parameters were analyzed in femur and/or tibia. RESULTS Posterior-anterior and latero-medial diameters were similar in all groups. Also, no significant differences were observed in bone contents of calcium, total proteins, collagen and hydroxyapatite in CI rats as compared with controls. However, CI rats showed significant reductions in bone weight (-13.5%, p < 0.001), total bone density (-9.28%, p < 0.001), and increased perimedullar bone resorption and urinary levels of deoxypyridinoline (a marker of bone resorption). In CI + IGF rats these parameters improved significantly as compared with CI animals. CONCLUSIONS Osteopenia characterized by loss of bone mass and preserved bone composition is found in rats with CCl4-induced cirrhosis. This bone disorder is partially corrected by treatment with low doses of IGF-I. Since osteoporosis seems to be the predominant form of osteopenia in patients with cirrhosis, IGF-I should be considered as a possible therapy for this disorder.

Low doses of insulin-like growth factor-I improve nitrogen retention and food efficiency in rats with early cirrhosis

BACKGROUND/AIMS In order to ascertain whether malnutrition is an early-onset feature of liver cirrhosis and whether the anabolic hormone insulin-like growth factor I (IGF-I) could be useful in the treatment of this complication, we analyzed the nutritional alterations present in rats with early-stage liver cirrhosis and the effects of IGF-I on nutritional parameters in these animals. METHODS After a 24 h fast, a 15N-enriched diet was administered for 5 days to normal control rats and to cirrhotic rats receiving subcutaneous injections of vehicle (Group 1) or IGF-I, 2 micrograms.100 g bw-1.day-1, (Group 2) during the 5 experimental days. 15N, a stable N isotope, was measured in biological samples by mass spectrometry. RESULTS Compared with control rats, Group 1 animals showed significant reductions in N intake and food efficiency (p < 0.05, both). In addition, the weight of the gastrocnemius muscle, its total N content and the dietary N content of this muscle were significantly lower in Group 1 than in control animals (p < 0.05, all). In rats from Group 2, mean values of N intake, food efficiency, gastrocnemius N content and the amount of dietary N incorporated into this muscle were similar to those in control rats, and (with the exception of gastrocnemius N total content) significantly higher than those in non-treated cirrhotic rats (p < 0.05, all). CONCLUSIONS A variety of nutritional disturbances were detected in rats from the early stages of liver cirrhosis. Low doses of IGF-I were found to reverse most of these changes. These results stimulate further studies to determine whether IGF-I might be useful in the correction of the malnutrition present in patients with liver cirrhosis.

Antifibrogenic effect in vivo of low doses of insulin-like growth factor-I in cirrhotic rats.

Insulin-like growth factor-I (IGF-I) is produced mainly in the liver and it induces beneficial effects on the nutritional status, the liver function and oxidative hepatic damage in cirrhotic rats. The aim of this work was to analyze the effect of IGF-I on mechanisms of fibrogenesis in cirrhotic rats. Liver cirrhosis was induced by CCl(4) inhalation and phenobarbital in Wistar rats. Ten days after stopping CCl(4) administration (day 0), rats received either IGF-I (2 microg/100 g bw/day) (CI+IGF) or saline (CI) subcutaneously during 14 days. Animals were sacrificed on day 15. As control groups were used: healthy rats (CO) and healthy rats treated with IGF-I (CO+IGF). Liver histopathology, hydroxyproline content, prolyl hydroxylase activity, collagen I and III mRNA expression and the evolution of transformed Ito cells into myofibroblasts were assessed. Among the two control groups (CO+IGF), no differences were found in hydroxyproline content and these levels were lower than those found in the two cirrhotic groups. Compared with untreated cirrhotic rats, the CI+IGF-I animals showed a significant reduction in hydroxyproline content, prolyl hydroxylase activity and collagen alpha 1(I) and alpha1(III) mRNA expression. A higher number of transformed Ito cells (alpha-actin +) was observed in untreated cirrhotic animals as compared to CO and CI+IGF groups. In summary, treatment with IGF-I reduced all of the studied parameters of fibrogenesis. In conclusion, low doses of IGF-I induce in vivo an antifibrogenic effect in cirrhotic rats.

Hyperhomocysteinaemia induced by dietary folate restriction causes kidney oxidative stress in rats.

Diet is the most common cause of mild hyperhomocysteinaemia (HHcy), which occurs in approximately 5-7 % of the general population. Since HHcy causes endothelial damage by oxidative stress in different organs, the present study was designed to examine whether HHcy might be involved in renal oxidative stress. Twenty-five male Wistar rats were randomly divided into two groups: one (n 13) was fed ad libitum a folate-free diet (FF) and the other (n 12) was fed the same diet supplemented with folic acid (control, CO). After 8 weeks the animals were killed and kidneys removed. Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured in plasma and kidney homogenates. Renal tissue sections were analysed by indirect immunostaining with the primary antibody against oxidatively modified LDL receptor (LOX-1). A marked HHcy was confirmed in the FF group. As compared with CO animals, MDA levels in plasma and kidney homogenate were significantly higher in FF rats (P < 0.05). Similarly, renal GPx and SOD activities were significantly higher in the FF group (P < 0.001). No differences were found in LOX-1 immunohistochemical expression, which in the two groups was displayed in tubular cells. The present study provides evidence that HHcy does produce renal oxidative stress mediated by lipid peroxidation, and that the increased kidney MDA displayed by FF animals may enhance kidney antioxidant activity and thereby attenuate both kidney damage and expression of LOX-1.

Local (gut) and systemic metabolism of rats is altered by consumption of raw bean (Phaseolus vulgaris L. var. athropurpurea )

The composition of the raw legume Phaseolus vulgaris L. var. athropurpurea (PhVa) and its effects on the metabolism of young growing rats have been evaluated. The levels of protein, unsaturated fatty acids, carbohydrate, fibre and bioactive factors present in PhVa were comparable with those in other Phaseolus vulgaris varieties. However, the lectins of PhVa were predominantly of the leucoagglutinating type, and concentrated in the albumin protein fraction. Rats fed a diet (110 g total protein, 16.0 MJ/kg) in which PhVa meal provided about half of the protein excreted high levels of N in faeces and urine, and grew more slowly, than rats fed a high-quality control diet (ad libitum or pair-fed). Small intestine, large intestine and pancreas weights were increased (by almost 100 %, P<0.05), whilst skeletal muscle, thymus and spleen weights were reduced. Blood insulin (16.20 v. 0.50 mU/l, P<0.05, thyroxine, glucose, protein (60.5 v. 48.3 g/l, P<0.05) and LDL-cholesterol were lowered, whilst glucagon (155.3 v. 185.4 ng/l, P<0.05), triiodothyronine and urea were elevated, as were urinary urea, creatinine and glucose. These changes in the local (gut) and systemic metabolism of rats were probably mediated primarily by lectins in PhVa, which were concentrated in the albumin protein fraction, whereas in many other Phaseolus vulgaris lines they are distributed across the globulin and albumin fractions.

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.

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.

Influence of feeding a raw kidney bean diet (Phaseolus vulgaris L.) on the immune function of growing chickens

Abstract A significant impairment in growth rate, protein efficiency rate and relative weight of bursa of Fabricius, thymus and spleen was exhibited in growing chickens fed a raw kidney bean ( Phaseolus vulgaris L.) diet. Total IgM and IgG titers in primary and secondary immune response against killed Brucella abortus , as well as total number of white blood cells and absolute lymphocytes, were significantly reduced in legume-fed birds. An involution of bursal follicles was observed in these animals. In another experiment, in which legume-fed birds were challenged with a live culture of B. abortus , total antibody, IgG levels and relative weight of lymphoid organs were again significantly reduced in legume-fed birds; survival of B. abortus in spleen significantly increased in these animals. These data suggest that feeding a raw kidney bean diet impairs the immune function of growing chickens.

Liver and muscle proteolytic activity in male growing rats fed a field bean (Vicia faba L.) diet.

Total liver cathepsin A and D and gastrocnemius acid proteolytic activities have been evaluated in male growing rats fed ad libitum over periods of 15 and 30 days on 20%-protein diets containing either casein or raw field bean (Vicia faba L.) as protein sources. It has been found that, compared to the control casein-fed rats, those fed the legume diet exhibited a marked reduction (p less than 0.05) in the rate of growth and protein efficiency rate; liver proteolytic activity increased with ageing in the two dietary treatments and was found to be significantly higher (p less than 0.05) in the legume-fed rats. However, muscle proteolytic activity decreased with ageing and proved significantly increased (p less than 0.05) in the legume-fed rats.