Holger Hydén

Protein Synthesis in the Hippocampal Pyramidal Cells of Rats during a Behavioral Test

Protein synthesis was studied in the pyramidal nerve cells of the CA3 region in the hippocampus of rats uring a behavioral test involving transfer of handedness. A new electrophoretic technique was used for separation of 10-7 to 10-9 gram of protein and radiometric determination of the various protein fractions. After interventricular administration of 3H-leucine, protein synthesis of two fast-moving fractions was significantly higher bilaterally in the hippocampus of the trained rats. There was also a trend to lateralization of the highest protein synthesis to the learning side.

Correlation of the S100 brain protein with behavior

Abstract 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.

Micro-electrophoretic determination of protein and protein synthesis in the 10−9 to 10−7 gram range

Abstract A procedure is described of electrophoretic separation of 10−7 to 10−9 g of proteins on polyacrylamide gel in 200 μ or 400 μ diameter glass capillaries. Specific activities of tritium-labeled protein fractions are determined by a combustion technique in combination with interferometry. To be able to compare protein specific activities in identical structures of the same organism or of different animals, a procedure is described to correct for variations in the concentration of the precursor amino acid. An application of this method to a neurobiological problem is described.

Do Specific Biochemical Correlates to Learning Processes Exist in Brain Cells

The present paper will deal mainly with the biochemical changes observed in neurons during three different learning experiments. First, however, some experiments showing differences in the protein composition of nerve and glia cells will be described. Of the learning experiments, the first is a case of instrumental learning in rats, in which changes in the synthesis of three acidic neuronal proteins and in the RNA base composition of neurons occurred; the arguments that these changes are specifically related to the training and that they are an expression of increased gene activation will be presented. In the next study, the protein changes observed in brain cells during simple sensory conditioning in rats will be described, and it will be argued that these are due to an increased level of attention rather than to learning per se.

Enzyme Changes in Neurons and Glia during Barbiturate, Sleep

During barbiturate sleep of rabbits, the succinoxidase activity in isolated neurons and glia from the caudal part of the reticular formation was lower than that during physiological sleep. No rhythmical, inverse enzyme changes were detected in barbiturate sleep in the neuron-glia unit, such as were found in physiological sleep.