The effect of developmental temperature on morphology, energy metabolism, growth hormone and thyroid stimulating hormone in Long-Evans rats

Abstract

Long-Evans rats were raised from birth tq eight weeks of age at 5°C, 20°C and 30°c. Blood was taken from animals two to eight weeks of age and assayed for growth hormone and thyroid stimulating hormone.The 30°C reared rats were found to have the 1ongest ear, tail and found to be related to weekl.y obtained serum levels of growth hormone and thyroid stimulating hormone. Foo<l consumption was greatest for the 5°C reared rats followed by the 20°c reared rats. The 5°C reared rats were found to have the lowest routine metabolic rate in the s 0 c chamber.The 20°c reared rats were found to have the lowest routine metabolic rate in both the 20°c and 30° C chamber.When 30°c and 20°c reared rats were put in the s 0 c chamber with the sec reared rats, they initially lost mass, however after three weeks in the s 0 c chamber they began to gain mass. The 30°C reared rats gained mass at a greater rate than did the 20°c reared rats. The s 0 c reared rats continued to gain mass throughout this period. While in the 5°C chamber the total food consumption of the 20°c reared rats was the greatest, whereas the s 0 c and 30°c reared rats consumed similar amounts of food.