ESPE Abstracts

Background: Neonatal over-nutrition (NON) can increase the propensity to become overweight and develop associated metabolic disturbances in later life. Moreover, some of these long-term effects are sexually dimorphic.

Objective and hypotheses: We aimed to determine how NON affects body weight (BW), body composition and triglyceride (TG) and non-esterified fatty acids (NEFA) levels. We hypothesized that the effects would be both age and sex dependant.

Method: At birth, Wistar rats were organized into litters of four (NON) or 12 (CT) pups (equal number males (M)/females (F)) and killed on postnatal days (P) 10, 50 or 150. BW, subcutaneous adipose tissue (SCAT) and visceral adipose tissue (VAT) mass and serum levels of TG and NEFA were measured.

Results: At P10, BW was greater in NON rats of both sexes (P<0.0001), continuing until approximately P50. This effect on BW then dissipated and reappeared at P90, but only in M (P<0.0001). At P10 and until weaning (P21) SCAT was increased by NON, with F more affected than M (P<0.0001). At P150, NON M again had increased SCAT. At weaning NON increased VAT (P<0.001) and M had more VAT than F (P<0.0001). Serum levels of TG were unaffected by NON at P10 and P50, but were increased at P150, with NON M having higher levels than NON F (P<0.03). Serum NEFA levels were unchanged at PND10. At P50, NON F had lower levels than CT F and NON M, while NON M tended to have increased NEFA levels compared to CT M. At P150, NEFA were increased in NON M compared to CT M (P<0.05).

Conclusions: i) Early over nutrition affects males and females differently, even prepubertally. ii) The long-term effects of neonatal overnutrition are both age and sex dependant. iii) Neonatal overnutrition could possibly affect the aging of metabolic homeostasis.