Metabolism in Different Parts of the Brain, Especially in the Epiphysis, Measured with Radioactive Phosphorus

Abstract

This investigation constitutes an attempt to divide the brain into anatomically well defined regions and to compare the phosphate metabolisms of the latter by means of radioactive P. The highest phosphate content expressed in per cent of wet weight was found in the epiphysis, the lobus anterior and posterior of the hypophysis, the plexus chorioideus and the substantia perforata. Measurements with radioactive phosphorus suggested that a division of the parts of the brain into two groups was possible, viz. an active group with a lively phosphate metabolism and a less active group with a slow phosphate metabolism. The former group includes the epiphysis, the lobus anterior and posterior of the hypophysis and the plexus chorioideus, whereas the latter consists of the lobi olfactorius, parietalis and occipitalis, the thalamus, the anterior part of tuber cinereum, the posterior part of tuber cinereum, the corpus mamillare, the cerebellum, the pons, the corpora quadrigemina and the medulla oblongata. The substantia perforata has an intermediate position, but seems in the majority of cases to belong to the group with a lower phosphate metabolism. The activities were measured in relation to that of the cerebellum, which was taken as 100. The radioactive phosphorus accumulates 40 minutes after injection in the epiphysis to about 65 % in form of acidsoluble phosphate esters, in about 25 % in form of free phosphate and in about 10 % in compounds insoluble in trichloracetic acid. The activity of the epiphysis is generally higher than that of the hypophysis. The phosphate metabolism in this part was often twice or three times as vigorous as that of the lobus anterior hypophysis. It is therefore most probable that the epiphysis has an important function. Experiments are being carried out to investigate the function of this organ by the method described in this paper. The most active brain components, following immediately after the epiphysis, are the plexus chorioideus and the lobus anterior and posterior of the hypophysis. Owing to the considerable quantities of blood contained in the plexus chorioideus, particular conditions prevail in that organ. Those conditions are discussed in some detail. The average phosphate metabolism of these parts of the brain is four to five times that of the cerebellum. Other parts of the brain tested exhibit, generally speaking, the same metabolism as the cerebellum. It seems to be significant that the anterior part of the tuber cinereum exhibits a somewhat livelier activity than the majority of the brain components belonging to this group. We owe thanks to Docent J. MÖLLERSTRÖM for having placed his laboratory facilities at our disposal and for the interest he payed to our investigations and to Prof. MANNE SIEGBAHN for having provided us with the radioactive phosphorus necessary for this work.