Calcium Content And Conformational-Changes Of S-100 Protein In Hippocampus During Training

The relationship between S-100 and calcium changes in the hippocampus of rats was studied during a behavioral experiment (transfer of handedness). Changes in the S-100 brain-specific protein in the CA3 region during the training were estimated from electrophoretic separations on polyacrylamide gels. The Ca, K and Na contents of the same brain region were determined with ultramicro flame photometric techniques. The training resulted in a slight increase in the amount of S-100; and at the same time a marked difference in the electrophoretic pattern of the total S-100 protein occurred, resulting in the appearance of a faster migrating fraction. The training also resulted in an increased Ca content in the CA3 region without any changes in K or Na. The training gave rise to an increased cellular Ca content and the appearance of an S-100 fraction of a different conformation to that of the bulk of the S-100. It is assumed that the training induces the formation or synthesis of S-100 protein of a different conformation, a conformation that is stabilized by Ca. It is suggested that the conformationally changed S-100 protein appearing during training may play a role in the regulation of cellular activity and the establishment of new behavior.