42 



METABOLISM IN CHANGED CEREBRAL ACTIVITY 



weight were made by Fries et al. (1940) and Fries and Chaikoff 

 (1941). Thus, radioactivity in lipids from the forebrain was twice 

 as great in the 1 -day-old rat as in the 7-day-old rat and some 10-20 

 times as great as in the 30-day-old rat. Similar decreases in phos- 

 phorus incorporation were found with the lipids from the cere- 

 bellum, medulla and spinal cord. In the cat radioactive phosphate 

 was found to enter the phospholipids of the foetal brain some 3-4 

 times more rapidly than the maternal brain (Stern and Marshall, 



- 006 



002 



o £ 



.5 1 



10 20 30 40 50 60 70 

 Days after feeding or injecting radioactive phosphate 



Fig. 9. The incorporation and retention of radioactive phosphate 

 into the phospholipids of whole brain in the infant and adult rat. 

 Infant rats were initially selected when 38 g body weight. 

 Ordinate A, data from Changus et al. (1938); O = infant rat; 

 A = adult rat. Ordinate B, data from Davison and Dobbing 

 (1958): • = infant rat. 



1951). Similar measurement in the rabbit (Bakay, 1953) showed 

 that here also the foetal brain accumulated more of a dose of radio- 

 active phosphorus in a given period than did the adult brain. 



During development the entry into the brain of many ions 

 such as phosphate, chloride, glutamate and thiocyanate is decreased, 

 though the mechanism underlying the change is obscure (Bakay, 

 1953; Himwich and Himwich, 1955; Lajtha, 1957). Such changes 

 are generally ascribed to the development of the blood-brain 

 barrier but a decreased uptake of a substance by an organ may also 

 reflect a change in the metabolic pattern of that organ. Difficulties 



