| Abstrakt: |
We have previously shown that runt miniature pigs demonstrate compensatory growth and develop early indicators of obesity, heart disease and hypertension, compared to large littermates. The mechanism for this programming is probably associated with methylation of DNA using methyl groups generated by sulfur amino acid (SAA) metabolism. In this study, we hypothesized that hepatic SAA metabolic enzyme capacity is different in runts. Runt piglets (850±130g) were paired with the largest littermate (1360±210g) and killed at 3 d of age (N=12). Relative (g/kg body weight) organ weights were similar between groups for liver, kidney, colon and small intestine. Specific activities of BHMT and CGL were 30% and 20% lower in runts, respectively (P<0.05, paired t-test) and not different for MAT, MS, MTHFR and CBS. Runts also had lower total liver activities for all enzymes (P<0.05). Plasma total cysteine (Cys) was lower in runts (P<0.05), consistent with lower flux through the transsulfuration pathway which includes CGL. However, total methionine (Met) and homocysteine (Hey) were not different in plasma. The lower BHMT and CGL activities in runts suggest lower remethylation (Hey to Met) and transsulfuration (Met to Cys) capacities, respectively. During compensatory growth, less Met is available for maintenance reactions which will alter methyl supply and possibly lead to epigenetic alterations in runts. [ABSTRACT FROM AUTHOR] |
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