The data suggest that this type of cell but not olfactory neurons synthesize carnosine. The studies of carnosine biosynthesis in vitro demonstrated that the process is restricted to muscle cells, oligodendrocytes of brain and spinal cord, and ensheathing cells of the olfactory bulb, and the synthesis increases during differentiation of these cells. This fact puts forward the hypothesis that carnosine plays a role in mature tissue. Studies of its release as a response to stimulation could give an indication of its intra- or extracellular role. This phenomenon raises the question as to whether the release is always accomplished at a basal rate or whether it could be stimulated by neurotransmitters, receptor agonists, or elevated potassium concentration.
Oligodendrocytes provide a good model system for such investigations.
Based on our data, however, it seems unlikely that the release of carnosine from oligodendrocytes can be explained by such mechanisms. A century after the isolation of carnosine we have learned many details about carnosine and related dipeptides. Nevertheless, the biological functions of these peptides in different tissues remain obscure, and a unifying concept to answer this question has not yet emerged. A Dissection and Tissue Culture Manual of the Nervous System , Liss, N. Y., pp. A Dissection and Tissue Culture Manual of the Nervous System , Liss, N. Y., pp.