Does pharmacological dose of parenteral arginine have beneficial effect in rats with sub-acute peritonitis?

Peritonitis is a life-threatening condition that may occur as a sequela of intra-abdominal infection. The management of peritonitis includes surgical intervention, antimicrobial therapy, and nutritional support. Arginine has been reported to have beneficial and adverse effects in subjects with inflammation, which might be related to the dose, time, and route of supplementation and the disease severity. So far, the optimal doses of parenteral arginine are not known. In this study, we investigated dose effects of parenterally supplemented arginine on anabolism and arginine-derived metabolites in sub-acute inflammation.

Male Wistar rats underwent modified cecal puncture procedure for induction of peritonitis were infused with total parenteral nutrition solutions for 7 days, which contained conventional, low, medium, and high doses of arginine, i.e., 1.61, 2.85, 4.08, and 6.54% of calories from arginine. Healthy, orally fed rats were included as references.

On day 7, peritonitic rats had significantly decreased body weight, declined serum albumin, and increased serum nitric oxide (NO) and tumor-necrosis factor-alpha compared to references (ANOVA, P < 0.05). There were no dose effects of parenteral arginine on body weight, nitrogen retention, and serum blood urea nitrogen and creatinine in peritonitic rats. In contrast, plasma arginine, proline, and ornithine, and urinary urea nitrogen were significantly increased, whereas serum NO and plasma glutamine were significantly decreased in dose-dependent manners with parenteral arginine. Pharmacological dose of parenteral arginine may increase the synthesis of ornithine, urea, and proline instead of citrulline and NO in peritonitic rats.

These results suggest that high dose of parenteral arginine may facilitate ureagenesis and proline conversion without causing augmentation of NO production in sub-acute inflammation. Therefore, pharmacological dose of parenteral arginine may not have benefits in anabolism but does not cause adverse effect in rats with sub-acute inflammation.