A single session of the food conditioning in rats entailed an increase of labelled phenylalanine incorporation into the proteins of the nuclei and, particularly, of the cytoplasm of CA3 hippocampal neurons. In the trained animals, as compared with active control group, a session repeated in 3 days returned the turnover of neuronal proteins to the control level, while the same session in 6 days of decreased the protein turnover below the control level. No changes occurred in the course of the experiment in the perineuronal neuroglial cells. Predominant involvement of neuronal protein metabolism is outlined in the metabolic reconstruction within the whole neuron-neuroglia unit in the course of conditioning.