ISSN 0012-4966, Doklady Biological Sciences, 2012, Vol. 444, pp. 1–5. © Pleiades Publishing, Ltd., 2012. Original Russian Text © I.A. Malakhin, A.F. Achkasov, A.S. Ratushnyak, T.A. Zapara, A.L. Markel, E.V. Boldyreva, V.V. Boldyrev, 2012, published in Doklady Akademii Nauk, 2012, Vol. 444, No. 5, pp. 567–571. 1 At the present time the problem of different biolog- ical activity of polymorphic modifications of the same compounds are actively discussed in the literature though the nature of observed distinctions remains generally ambiguous [1]. One of interesting systems is the elementary amino acid, glycine (Gly). It is known several polymorphic modifications of Gly sharply dif- ferent in their physical properties [2]. Exogenous Gly is widely used for correction of excitatory and inhibi- tory disbalance of neuronal activity, but exclusively in the form of α-polymorphic modification. The biological effect of γ-polymorphic modifica- tions has been investigated for the first time in work [3]. It is shown, that it possesses much higher biologi- cal potency, than α- the form, concerning influence on behaviour of rats of the line with genetic predispo- sition to catalepsy. Such rats are used as a biological model for the investigation of some forms of patholog- ical behavior, which are typical for negative symptom- atology of schizophrenics. Intake γ-Gly results in a sharp reduction of time of cataleptic reactions, the reduction of fear reaction in new conditions, and the enhancement of research motivation. The reasons of these new and earlier uninvestigated distinctions of biological activity of polymorphic modifications of Gly remain ambiguous. In work [3] glycine (in the crystal form) was introduced into an organism of ani- mals with food. It was absolutely ambiguous whether the distinctions of a biological activity of polymorphic modifications of Gly will remain after preparation of their solutions, and how these distinctions of activity will show it not on organismic but at cellular (neural) level. In order to answer these questions, we have used a widespread method based on the registration of inte- gral characteristic of neurons in the hippocampal slices. The influences of the solutions prepared from two forms of glycine on activity of pyramidal neurons of ÑÀ1 field of mice hippocampal slices (ICR) have been compared. The fundamentally important results were obtained. They have shown that the differences in bio- logical activity of two glycine polymorphs are pre- served after dissolving these two forms, and these dif- ferences manifest themselves on the cell level, and are not a consequence of the metabolic modifications in the organism. Glycine of firms Sojuzhimreaktiv (a mixture of α- and γ-forms) was re-crystallized to obtain α- and γ- polymorphic modifications pure in the phase attitude. γ-Glycine was obtained by two alternative tech- niques—using ammonia [4], or malic acid [5]. The samples were characterized by X-ray diffraction (Bruker D8-GADDS diffractometer, CuK α -radiation, Different Effects of α- and γ-Glycine on the Aberrant Activity of Pyramidal Neurons of Hippocampal Slices 1 I. A. Malakhin, A. F. Achkasov, A. S. Ratushnyak, T. A. Zapara, A. L. Markel, E. V. Boldyreva, and Academician V. V. Boldyrev Presented by Academician D.S. Pavlov February 20, 2012 Received February 20, 2012 Abstract—Experiments in vitro on hippocampal slices of mouse have shown that solutions prepared from polymorphic modifications α- and γ-glycine have different effect on the aberrant activity of neurons. In the presence of @-glycine the excitability of these neurons decreased more slowly, prolonging its modulating effect on NMDA type glutamate receptors. This effect agrees with higher biological activity of @- polymor- phic modifications (as compared with that of the @-form) that previously observed with respect to behavior of mice from the line with genetic diathesis to catalepsy, which were used as a biological model for investiga- tion of some pathological behavior forms. DOI: 10.1134/S0012496612030179 Institute of Cytology and Genetics Siberian Branch of the Russian Academy of Sciences Novosibirsk Institute of Design and Technology of Digital Techniques, Siberian Branch of the Russian Academy of Sciences, Novosibirsk Novosibirsk State University Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 1 The article was translated by the authors. PHYSIOLOGY