Prenatal protein malnutrition alters response to reward in adult rats.
Developing rats were either malnourished or adequately nourished during the prenatal period by feeding their dams diets of 6% (low) or 25% (adequate) casein content 5 weeks prior to mating and throughout pregnancy. All pups received adequate nutrition from the day of birth onwards. In Experiment 1, male offspring aged 125 days were tested in a food-rewarded variable interval 2-min (VI 2') operant paradigm under three levels of body weight reduction (90%, 85% and 80% of their ad lib feeding weight). Previously malnourished rats showed significantly higher response rates than well-nourished controls at the 90% and 85% levels but not at the 80% level. In Experiment 2, behaviorally native male littermates aged 225 days were tested in a saccharin-solution-rewarded VI 2' operant task. The rate of receipt of reward within each daily session was found to differ in the two nutritional groups. Previously malnourished rats maintained a stable rate of reward throughout the session while the controls showed a rapid decline over the first 15-20 min. The higher rate of reward late in the session in Experiment 2 and the elevated response rate in the first two phases of Experiment 1 suggests that prenatal protein malnutrition increases subsequent responsiveness to reward.
Tonkiss
J
J
Center for Behavioral Development and Mental Retardation, Boston University School of Medicine, MA 02118.
Shukitt-Hale
B
B
Formica
R N
RN
Rocco
F J
FJ
Galler
J R
JR
D000818:Animals; D001070:Appetitive Behavior; D001835:Body Weight; D003216:Conditioning, Operant; D005260:Female; D005317:Fetal Growth Retardation / Q000523:psychology; D008297:Male; D009042:Motivation; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011502:Protein-Energy Malnutrition / Q000523:psychology*; D051381:Rats; D011919:Rats, Inbred Strains; D012201:Reward