Total parenteral nutrition induces sustained hypomethylation of DNA in newborn guinea pigs

Abstract

Background: Neonatal total parenteral nutrition (TPN) is associated with animals with low glucose tolerance, body weight, and physical activity at adulthood. The early life origin of adult metabolic perturbations suggests a reprogramming of metabolism following epigenetic modifications induced by a change in the pattern of DNA expression. We hypothesized that peroxides contaminating TPN inhibit the activity of DNA methyltransferase (DNMT), leading to a modified DNA methylation state. Methods: Three groups of 3-d-old guinea pigs with catheters in their jugular veins were compared: (i) control: enterally fed with regular chow; (ii) TPN: fed exclusively with TPN (dextrose, amino acids, lipids, multivitamins, contaminated with 350 ± 29 μmol/l peroxides); (iii) H 2 O 2 : control + 350 μmol/l H 2 O 2 intravenously. After 4 d, infusions were stopped and animals enterally fed. Half the animals were killed immediately after treatments and half were killed 8 wk later (n = 4-6 per group) for hepatic determination of DNMT activities and of 5′-methyl-2′-deoxycytidine (5MedCyd) levels, a marker of DNA methylation. results: At 1 wk, DNMT and 5MedCyd were lower in the TPN and H 2 O 2 groups as compared with controls. At 9 wk, DNMT remained lower in the TPN group, whereas 5MedCyd was lower in the TPN and H 2 O 2 groups. conclusion: Administration of TPN or H 2 O 2 early in life in guinea pigs induces a sustained hypomethylation of DNA following inhibition of DNMT activity. t otal parenteral nutrition (TPN) may be required in neonates with impaired oral feeding capability following intestinal surgery or in premature newborns with immature gastrointestinal tract. Even if this mode of nutrition enables sustained growth and development, its contamination by oxidant molecules such as peroxides (1) is associated with oxidative stress (2). The neonatal impacts of this stress have been demonstrated in an animal model of TPN (3) as well as in premature neonates (2). An oxidative stress early in life is also suspected to modulate the health status into adulthood (4,5).Administration of TPN or H 2 O 2 during the first week of life in guinea pig pups has been shown to induce, 3 mo later, a modification in energy metabolism that was associated with a phenotype of energy deficiency (6). As compared with orally fed controls, animals receiving TPN had a lower body weight, weaker spontaneous physical activity, and poorer glucose tolerance. These characteristics are also reported in young adults 20 y of age who were born very low birth weight (7-9) and in whom the use of TPN was a frequent occurrence. This early life origin of adult metabolic perturbations suggests a reprogramming of metabolism following epigenetic modifications induced by a change in the pattern of DNA expression. We suspect that this might take place through a permanent effect of TPN on DNA methylation.Metabolic activities are dependent of the expression of genes. Transcription of genes is dependent on their availability to interact with transcription factors and other componen...

Neonatal Vitamin C and Cysteine Deficiencies Program Adult Hepatic Glutathione and Specific Activities of Glucokinase, Phosphofructokinase, and Acetyl-CoA Carboxylase in Guinea Pigs’ Livers

“…The relationship between the redox potential of glutathione and DNA methylation in the liver of one-week-old guinea pigs has been previously reported. Oxidation of redox potential strongly correlated with increased methylation [59,60], while the methylation of the glucokinase gene promoter was increased with age and associated with the risk of metabolic disease [61,62]. If this relationship could explain our observation, it also suggests that methylation of DNA during neonatal period may not be permanent.…”

Relationship between redox potential of glutathione and DNA methylation level in liver of newborn guinea pigs

“…Animals on PN were nourished through a catheter inserted in the jugular vein under anaesthesia with a ketamine/xylazine cocktail on the third day of life, as previously described [ 9 , 15 , 16 ]. PN solutions, freshly prepared daily, consisted of two separate bags.…”

“…The analysis of DNMTs activity was performed in the nuclear extract with a modified method adapted from previous studies [ 9 , 49 , 50 ]. Briefly, approximately 200 mg of liver was homogenized in a high concentration sucrose (1.8 M) – glycerol (9%) buffer, pH 7.6 (containing 10 mM Hepes, 25 mM KCl, 0.15 mM spermine and 0.5 mM spermidine, 1 mM EDTA, 0.1 mM phenylmethylsulfonyl fluoride, and 1 mM dithiothreitol) by using a dounce homogenizer, then centrifuged at 79 000 g for 30 min.…”

Neonatal parenteral nutrition affects the metabolic flow of glucose in newborn and adult male Hartley guinea pigs’ liver

“…Supplemental oxygen and peroxides from PN are two independent factors leading to the development of bronchopulmonary dysplasia 11,12 . Thus, oxidative stress, caused by oxygen supplement or by peroxides, is suspected to cause the metabolic reprogramming because of its impact on epigenetic metabolism [13][14][15] and its direct implication in causing diseases of the premature newborns 9,15,16 . In addition, a disruption of the hepatic lipid metabolism is reported in an animal model, [17][18][19] where a modification of the activities of key enzymes 18 as well as the deposition of fat 17 was associated with the presence of these peroxides.…”