Vitamin B₁ and Acetylcholine Formation in Isolated Brain

Abstract

WE have shown in earlier papers¹ that in the presence of glucose or of pyruvate and under aerobic conditions brain tissue, whether sliced or minced, synthesizes acetylcholine. In the absence of such substrates, little or no synthesis takes place. Since it is well known from the work of Peters and his colleagues that the presence of vitamin B1 (as cocarboxylase) is necessary for the oxidation of pyruvic acid in brain in vitro, it becomes of interest to discover whether the presence of vitamin B₁ has any influence on the rate of acetylcholine synthesis in isolated brain tissue. MacIntosh² investigated the acetylcholine contents of brains of polyneuritic pigeons and found these to be of the same order as those in the brains of normal pigeons. We have examined the abilities of intact brain slices, from normal and polyneuritic pigeons, to synthesize acetylcholine under suitable aerobic conditions in bicarbonate-Locke-pyruvate media containing eserine. (The eserine is added to prevent the decomposition of the acetylcholine by the choline esterase in the tissue.) We have found no appreciable difference between the rates of acetylcholine formation in normal or polyneuritic brain tissue examined under these conditions; nor have we found as a general rule that the addition of vitamin B₁ has any significant effect upon these rates. (On one occasion we found that the addition of vitamin B₁ definitely increased the rate of acetylcholine formation by polyneuritic pigeon brain in a phosphate-pyruvate medium.)