Abstract
The light exposure of parenteral nutritive solutions generates peroxides such as H2O2 and ascorbylperoxide. This absence of photo-protection is associated with higher plasma triacylglycerol concentration (TG) in premature infants and, in animals, with oxidative stress and a H2O2 independent hepatic steatosis. We hypothesized that ascorbylperoxide is the active agent leading to high TG. The aim was to investigate the role of ascorbylperoxide on glucose and lipid metabolism in an animal model of neonatal parenteral nutrition. Three day-old guinea pigs received, through a catheter in jugular, solutions containing dextrose+ 0, 90, 225 or 450 μM ascorbylperoxide. After 4 days, blood and liver were sampled and treated for determinations of TG, cholesterol, markers of oxidative stress (redox potential of glutathione & F2α-isoprostane) and activities & protein levels of acetylCoA carboxylase (ACC), glucokinase and phosphofructokinase (PFK). Ascorbylperoxide concentration was measured in urine of the last day. Data were compared by ANOVA, p<0.05. Plasma TG and cholesterol as well as hepatic PFK activity increased (200% of control), whereas ACC activity decreased (66% of control), in function of amount of ascorbylperoxide infused. Both markers of oxidative stress were higher in animals receiving the highest ascorbylperoxide. The logarithmic relations between urinary ascorbylperoxide and plasma TG (r2=0.69) and hepatic PFK activity (r2=0.26) were positive, whereas it was negative with ACC activity (r2=0.50). In conclusion, the ascorbylperoxide contaminating the parenteral nutrition stimulates glycolysis allowing higher availability of substrates for lipid synthesis. The logarithmic relation between urinary ascorbylperoxide and plasma TG suggests a very low efficient concentration.
- acetylCoA carboxylase
- ascorbylperoxide
- parenteral nutrition
- phosphofructokinase
- triacylglycerol
- vitamin C
Footnotes
- Received January 20, 2010.
- Revision received March 18, 2010.
- Accepted April 5, 2010.
- The American Society for Pharmacology and Experimental Therapeutics