Role of Lipids in Regulation of Neuroglial Interactions

Lipids comprise an extremely heterogeneous group of compounds that perform a wide variety of biological functions. Traditional view of lipids as important structural components of the cell and compounds playing a trophic role is currently being supplemented by information on the possible participation of lipids in signaling, not only intracellular, but also intercellular. The review article discusses current data on the role of lipids and their metabolites formed in glial cells (astrocytes, oligodendrocytes, microglia) in communication of these cells with neurons. In addition to metabolic transformations of lipids in each type of glial cells, special attention is paid to the lipid signal molecules (phosphatidic acid, arachidonic acid and its metabolites, cholesterol, etc.) and the possibility of their participation in realization of synaptic plasticity, as well as in other possible mechanisms associated with neuroplasticity. All these new data can significantly expand our knowledge about the regulatory functions of lipids in neuroglial relationships.

[THE ROLE OF HEME-CONTAINING GLOBINS IN HYPOXIC NO-SIGNALING OF VERTEBRATE CELLS]

Nitric oxide is one of the most important signaling molecule of living organisms. It may be produced by two ways: from arginine by means of NO-syntases and from nitrite by means of nitrite reductases. The last way is realized mostly at hypoxic state of organisms and heme-containing globins of vertebrates (hemoglobin, myoglobin, cytoglobin, neuroglobin) mediate the transformation of NO2 into NO by means of their nitrite reductase activities. Hypoxic NO-signaling depends on oxygen concentration and is important for exercise, vascular hypoxic vasodilation, myocardial preconditioning and angiogenesis. Data of scientific literature of last 15 years show that the nitrite-reductase activity of heme-containing globins was used for oxygen sensing and ROS/RNS defence at early stages of life evolution.

A study of the 18O-exchange reactions catalyzed by cardiac myosin and its subfragment 1

Isotope-exchange reactions (H2(18)O in equilibrium with KH2PO4) during ATP hydrolysis catalyzed by myosin and its subfragment 1 from rabbit, dog, and human cardiac muscle were studied. All preparations of myosin and subfragment 1 in the presence of Mg2+ catalyzed two types of 18O-exchange reactions similar to those of skeletal muscle: intermediate and direct 18O exchange. The dependences of both reactions on divalent metals and nucleotides were studied. Data on 18O exchange of subfragment 1 from rabbit, dog, and human cardiac muscle were obtained for the first time. They indicate the similarity of molecular mechanisms of ATP energy use in cardiac and skeletal muscle contraction.