ABSTRACT
Malnourished pups were obtained by increasing litter size to 20 pups/dam VS 10 pups/dam in controls. Rehabilitation was started when the pups were 17 days old. The normalized growth rate (% body weight increase/day) of the malnourished pups was significantly lower than that of controls at 10-17 days of age. After starting ad libitum feeding, the normalized growth rate became the same as that of control when both groups were at 17-23 and 23-34 days of age. The body weight of the previously malnourished pups was still lower than that of controls at 34 days of age. Serum growth-promoting activity (GPA) in malnourished and control rat pups was determined by measuring the degree of stimulation of thymidine incorporation into lymphocytes treated with low dose of phytohemagglutinin (PHA). The serum GPA in malnourished pups was lower than that of controls at 17 days old. When malnourished pups were weaned onto laboratory chow ad libitum starting at 17 days, their serum GPA at 23 and 34 days of age was found to be similar to that of control pups of the same age. We conclude that immediate postnatal malnutrition is associated with reduction of serum GPA and reduced growth.
ABSTRACT
Serum growth-promoting activity (GPA) in rats was determined by measuring the degree of stimulation of thymidine incorporation into lymphocyts treated with low dose of phytohemagglutinin (PHA). GPA in rat serum was found to be low at birth (193% of that stimulation with PHA alone), increased slightly (224%) at 5 days of age and then increased rapidly to peak at 10 days of age (450%). Thereafter, GPA decreased gradually, reaching an adult level (which was similar to that of the newborn) at 60 days of age. A significant correlation was found between the level of GPA and normalized growth rate (% body weight increase/day) in rats.