Effect of pentoxifylline on nitrogen balance and 3-methylhistidine excretion in parenterally fed endotoxemic rats

Haematological and febrile response to Escherichia coli lipopolysaccharide in 12-week-old cockerels of genetically diverse layer lines fed diets with increasing L-arginine levels

Due to its decisive function in the avian metabolic, endocrine and immune system L-arginine (Arg) is dietary indispensable for chickens. In 12-week-old cockerels of two high- and two low-performing purebred layer lines, the effects of increasing dietary Arg on the haematological and febrile response were studied over 48 h after single lipopolysaccharide (LPS) injection. The offered diets contained Arg equivalent to 70%, 100% and 200% of recommended supply. Pathophysiological alterations in weight gain, feed intake, body temperature and differential blood count were examined in comparison with their physiological initial values. Within the first 24 h after LPS injection, cockerels reduced feed intake and lost body weight subsequently. Thereby, low-performing genotypes lost body weight to a lesser extent than high-performing ones. The loss of body weight was further intensified by deficient dietary Arg. Within the following 24 h, cockerels recovered by improving feed intake and weight gain. Furthermore, LPS induced genotype-specific fever response: both brown genotypes showed initial hypothermia followed by longer lasting moderate hyperthermia, whereas the white genotypes exhibited biphasic hyperthermia. Fever response was accompanied by significant changes in differential blood counts. Characterized by lymphopenia and heterophilia, a severe leucopenia was observed from 4 to 8 h after LPS injection and replaced by a marked leucocytosis with longer lasting monocytosis up to 48 h after LPS injection. Under given pathophysiological conditions, deficiently Arg-supplied cockerels showed higher total leucocyte counts than adequately and excessively Arg-supplied cockerels. However, deficient and surplus dietary Arg tended to cause higher ratios between heterophils and lymphocytes. To conclude, present results confirmed that LPS induced numerous immunological changes in 12-week-old cockerels and emphasized that chicken's genotype is a source of variation to be considered for immunological studies. Deficient dietary Arg intensified acute changes in differential blood counts and weight gain during LPS-induced inflammation.

Evaluation of a glycine-rich amino acid solution for parenteral nutrition in endotoxemic rats

OBJECTIVE

It has been shown recently that high amounts of glycine might have some pharmacologic effects (reduction of injury and mortality in endotoxemic rats), but its effects on the nutritional status and protein metabolism during injury are still unknown. The aim of this study was to compare the nutritional effects of a glycine-rich amino acid solution for parenteral nutrition (AFD) with a standard one (Vintene) (glycine, 15 vs. 9 g/L) in endotoxemic rats.

DESIGN

Laboratory investigation.

SETTING

University laboratory.

SUBJECTS

Male Wistar rats (198 +/- 11 g).

INTERVENTIONS

Rats were operated to receive total parenteral nutrition (250 kcal/kg/day, 2 g N/kg/day) with amino acids supplied by either AFD (n = 9) or Vintene (V, n = 6). One day after surgery, corresponding to day 0 of the experiment and to the first day of full-strength total parenteral nutrition, the AFD and V group rats received an endotoxemic shock by intraperitoneal injection of lipopolysaccharide (Escherichia coli, 8 mg/kg). The rats were then studied over 3 days and compared with a healthy ad libitum-fed group (AL, n = 10).

MEASUREMENTS AND MAIN RESULTS

The rats were weighed and urine was collected daily to determine nitrogen balance and 3-methylhistidine excretion. On day 3, the thymus, spleen, liver, intestinal mucosa, and muscles were weighed, and amino acids from plasma and tissues were analyzed. Lipopolysaccharide caused the classic endotoxemic shock, of similar intensity in the V and AFD groups (V and AFD not equal AL, p < .05): no weight gain, decreased nitrogen balance (day 3, AL 558 +/- 21, V 83 +/- 28, AFD 123 +/- 25 mg N/day), increased urinary 3-methylhistidine/creatinine excretion (day 3, AL 51 +/- 2, V 91 +/- 13, AFD 87 +/- 14 mumol/mmol), soleus (V -15% and AFD -26 % vs. AL) and thymus atrophy (V -36% and AFD -33%), and spleen hypertrophy (V 51% and AFD 83%). Compared with V solution, AFD has a reduced content of some essential amino acids and proline and an elevated content of glycine, aspartate, and glutamate. These differences were not reflected in tissue or plasma amino acids, except for plasma glycine, which in the AFD group was restored to the level of the AL group (AL 426 +/- 12 and AFD 379 +/- 50 vs. V 251 +/- 31 mumol/L, p < .05).

CONCLUSIONS

In endotoxemic rats, the nutritional effects of a glycine-rich AFD solution are similar to those of a standard amino acid solution for parenteral nutrition.

Effects of an immune-enhancing diet in endotoxemic rats

OBJECTIVE

This work compared the nutritional efficiency of a recently available enteral formula enriched with arginine, omega-3 fatty acids, and antioxidants and supplied nitrogen as peptides (Crucial, Nestle Clinical Nutrition) with that of a standard polymeric formula (Sondalis HP, Nestle Clinical Nutrition) in endotoxemic rats.

METHODS

Male Wistar rats (209 +/- 2 g) underwent catheter gastrostomy and received Sondalis HP until they recovered their preoperative weight. At that time (day 0), an endotoxemic shock was induced by an intraperitoneal injection of lipopolysaccharide (Escherichia coli, 8 mg/kg) and rats then received 290 kcal x kg(-1) x d(-1) and 3.29 g of nitrogen x kg(-1) x d(-1) in the form of Crucial (IED group, n = 7) or Sondalis HP (S group, n = 6) for 3 d. Another group underwent no treatment and was fed ad libitum (AL group). Rats were killed on day 3. Results are presented as mean +/- standard error of the mean (analysis of variance and Newman-Keuls test).

RESULTS

The endotoxemic shock induced a weight loss in group S on days 1 and 2 and a weight gain in group IED (-3.5 +/- 1.3 g in group S versus +6.0 +/- 2.2 g in group IED, P < 0.05). In the same way, atrophy of extensor digitorum longus muscle was observed in group S, whereas wasting was limited in group IED (102 +/- 4 mg in group IED versus 90 +/- 3 mg in group S versus 119 +/- 3 mg in group AL, P < 0.05). Muscular atrophy was associated with muscular glutamine depletion and correlated with hyperphenylalaninemia (R = 0.60), with the latter being blunted in group IED (57 +/- 1 microM/L in group AL versus 77 +/- 4 microM/L in group S versus 66 +/- 2 microM/L in group IED, P < 0.05). No difference was observed between the experimental groups of endotoxemic rats with respect to nitrogen balance, urinary excretion of 3-methyl histidine, or total tissue protein content.

CONCLUSION

Crucial counteracts injury-mediated weight loss, extensor digitorum longus muscle atrophy, and hyperphenylalaninemia in endotoxemic rats.

Pentoxifylline reduces acute lung injury in chronic endotoxemia

BACKGROUND

Pentoxifylline (PTX) attenuates end-organ injury in models of sepsis and hemorrhage. PTX is thought to act by inhibiting phosphodiesterase, thus increasing cAMP and decreasing tumor necrosis factor-alpha (TNF-alpha) synthesis. The effects of PTX on neutrophil and endothelial cell adhesion molecules and, ultimately, organ injury in a chronic endotoxemia model have not been studied. We hypothesized that continuous infusion of PTX reduces acute lung injury (ALI) caused by chronic lipopolysaccharide (LPS) exposure.

MATERIALS AND METHODS

Male Sprague-Dawley rats were given continuous infusion of LPS, PTX + LPS combined, or saline (sham) by implantable pumps. Neutrophil CD11b expression, lung histopathology, lung intercellular adhesion molecule-1 (ICAM-1) expression assessed by immune staining, serum TNF-alpha, serum interleukin-6 (IL-6), and bronchoalveolar lavage (BAL) IL-8 were evaluated at different time points. Lung injury was graded in a blinded fashion from 0 (normal) to 4 (severe) for interstitial inflammation, neutrophil infiltration, congestion, and edema. Total lung injury score (TLIS) was calculated by adding listed categories. White cell count in the peripheral blood and in the BAL was also performed.

RESULTS

Animals treated with PTX + LPS showed a significant reduction in lung injury score, a marked decrease in ICAM-1 expression, and a significant decrease in IL-8 levels in the BAL and serum IL-6 levels when compared with LPS-treated animals.

CONCLUSIONS

Continuous infusion of PTX reduces ALI caused by chronic endotoxemia. The effect seems to be a result of decreased expression of endothelial and epithelial ICAM-1 and modulation of proinflammatory cytokine synthesis.

The effect of sepsis during parenteral nutrition on hepatic microsomal function in rats

STUDY OBJECTIVE

To investigate the effect of sepsis during parenteral nutrition on hepatic cytochrome P450 (CYP) activity in rats.

DESIGN

Prospective, randomized, controlled study.

SETTING

University-based animal research laboratory.

ANIMALS

Twenty adult male Sprague-Dawley rats.

INTERVENTION

The animals were cannulated intravenously and randomized to receive parenteral nutrition (PN), intravenous live Escherichia coli 4 x 10(8) colony-forming units/100 g body weight for 2 consecutive days with PN (PNEC), or chow (CH).

MEASUREMENTS AND MAIN RESULTS

Both PN alone and PNEC resulted in a progressive decline in hepatic CYP concentration compared with CH (0.53 +/- 0.10, 0.41 +/- 0.17, and 0.35 +/- 0.14 nmol/mg microsomal protein, respectively, p < 0.05). Parenteral nutrition alone was associated with a 57% decrease in isoenzyme ethoxycoumarin-O-deethylase activity (ECOD) compared with CH, but sepsis did not further decrease ECOD activity any more than PN alone (0.103 +/- 0.049, 0.044 +/- 0.018, and 0.050 +/- 0.020 nmol/mg microsomal protein/min, respectively, p < 0.05).

CONCLUSION

Hepatic CYP concentration declines with PN and is further decreased when compounded by sepsis. The disproportional decrease in ECOD activity relative to CYP concentration with PN is unchanged by sepsis, indicating a selective alteration in hepatic isoenzymes by PN.

Endotoxin-mediated hepatic lipid accumulation during parenteral nutrition in rats

OBJECTIVE

To assess the effect of endotoxemia on hepatic lipid content during parenteral nutrition (PN) in rats.

METHODS

Twenty male Sprague-Dawley rats (185-230 gm) were randomized to receive PN (n=9) or PN plus a continuous infusion of E. coli 026:B6 lipopolysaccharide (LPS; n= 11). All animals received isocaloric (170 kcal/kg/day), isonitrogenous (1.1 g N/kg/day), glucose-based PN for the next 78 hours. After 30 hours of adaptation to TPN, the animals were randomized to receive PN or PN plus LPS at 6 mg/kg/day for the remaining 48 hours of study. The animals were euthanized and the livers were harvested.

RESULTS

Liver weight increased significantly (by 60%) from 7.5+/-0.6 g to 12.1+/-2.4 g (p < or = 0.01) in the animals who received PN versus LPS, respectively. The proportion of liver water remained the same for PN and LPS groups (72.9+/-3.2% versus 72.3+/-3.8%, respectively, p = N.S.). However, liver fat increased disproportionately (by about 130%) from 0.20+/-0.05 g to 0.46+/-0.20 g (p < or = 0.01) total fat weight or from 9.6+/-1.8% to 13.6+/-4.1% (p < or = 0.02) lipid content (g/g) of the dry liver weight for the PN and LPS groups, respectively.

CONCLUSION

Endotoxin, when given concomitantly with parenteral nutrition, increases hepatic lipid accumulation and thus augments the development of parenteral nutrition-associated fatty liver in rats.