Metabolic effects of different protein intakes after short term undernutrition in artificially reared infant rats.
BACKGROUND
Early postnatal nutrition is involved in metabolic programming. Small for gestational age and premature babies commonly receive insufficient dietary protein during the neonatal period due to nutrition intolerance, whereas high protein formulas are used to achieve catch up growth. Neither the short term, nor the long term effects of such manipulation of protein intake are known.


OBJECTIVE
We hypothesized that high or low protein intake during infancy would induce metabolic alterations both during early-life and in adulthood.


METHODS
Gastrostomized neonatal rat pups received either 50% (P50%), 100% (P100%), or 130% (P130%) of the normal protein content in rat milk from the 7th to the 15th day of life (D7 to D15), when they were either sacrificed or placed with mothers for the long term study. Glucose tolerance tests (GTT) were performed at D230. Long term rats were sacrificed at D250.


RESULTS
At D15, weight of P50% pups was lower than P100% and P130% pups. Neither liver and kidney mass, nor islet beta-cell areas were altered. Brain weight (adjusted to body weight) was higher in P50% vs. P130% (p<0.05). Insulin/glucose ratio was lower in P50% vs. P130%. Expression of GLUT4 on adipocyte cell membrane and GLUT2 in liver cytosol was significantly enhanced in P50% vs. P130%. Long term, neither GTT results nor body nor organ weights differed between groups.


CONCLUSIONS
In neonatal rats, higher protein intakes via the enteral route led to enhanced short term weight gain, insulin resistance, and modified expression of glucose transporters. However, these differences were not sustained.
des Robert
Clotilde
C
University of Nantes, INRA, UMR PhAN, Nantes, France.
Li
Nan
N
Caicedo
Ricardo
R
Frost
Susan
S
Lane
Robert
R
Hauser
Nicholas
N
Neu
Josef
J
D052242:Adiponectin / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D015153:Blotting, Western; D001835:Body Weight; D017931:DNA Primers; D004044:Dietary Proteins / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005951:Glucose Tolerance Test; D007150:Immunohistochemistry; D020738:Leptin / Q000378:metabolism; D044342:Malnutrition / Q000378:metabolism*; D009929:Organ Size; D011247:Pregnancy; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D052242:Adiponectin; D017931:DNA Primers; D004044:Dietary Proteins; D020738:Leptin