[Evolution of the neuroprotection concept]

Abstract

Although the modern concept of neuroprotection has been formulated quite recently, the basis of this approach was laid about four decades ago when Zakusov initiated the study of mechanisms involved in the neuroprotector action of GABA shunt metabolites (in particular, alpha-hydroxybutyric acid and succinic semialdehyde) during hypoxia. It was suggested to consider these agents as a system of endogenous neuroprotectors. The interest of Zakusov in endogenous regulators (including oligopeptides) had stimulated research in this direction and gave impact to the investigations of A. P. Skoldinov and T. A. Gudasheva initiated in the early 1980s. Proceeding from the original concept of the possibility of imitation of the action of neurotropic agents by their structural-conformational oligopeptide analogs, a number of biologically active stable dipeptides were obtained, based on pyroglutamate and proline, and high specific bioaccessibility of these dipeptides for the brain was established. Our investigations showed that these compounds not only possess nootropic activity (in a dose 1000 times lower than that of piracetam), but produce a pronounced neuroprotector action as well. Most thoroughly studied in this respect were substituted acyl-prolyl dipeptides, in particular, the drug noopept exhibiting a combined neuroprotector effect both in vitro and in vivo. Noopept decreases the extent of necrotic damage caused by photoinduced thrombosis of cortical blood vessels. It was established that the neuroprotector effect of noopept is related to its action upon the well-known "triad", whereby the drug reduces neurotoxic effects of excess extracellular calcium, glutamate, and free radicals. Two additional components of the neuroprotector action of noopept are related to the antiinflammatory and antithrombotic activity. The prospects of using direct and indirect action upon neurotrophin system for neuroprotection purposes are considered. Taking into account common secondary mechanisms of the neuronal damage, it is possible to provide for pleotrophic brain protection with dipeptides in a broad spectrum of pathological states, including strokes, cerebral traumas, neurodegenerative processes, epilepsy, and schizophrenia.