Correlation of the S100 brain protein with behavior

The brain-specific acidic protein S100 in the pyramidal nerve cells of the hippocampus was investigated as a possible correlate to learning during transfer of handedness in rats. The amount of S100 increased during training. Intraventricular injection of antiserum against the S100 protein during the course of training prevented the rats from further learning but did not affect motor function in the animals. Antibodies against the S100 protein could be localized after the injection to hippocampal structures by immunofluorescence, penetrating presumably through slight ependymal lesions caused by the injection. By contrast, control animals subjected to the same training and injected with S100 antiserum absorbed with S100 protein or with other antisera against γ-globulins showed no decrease in their ability to learn. The conclusion is that the brain-specific protein S100 is linked to the learning process within the training used.