caa a22 4500 469078871 CHVBK 20180323132943.0 cr unu---uuuuu 170328e19920101xx s 000 0 eng 10.1007/BF00175474 doi (NATIONALLICENCE)springer-10.1007/BF00175474 Comparison of the effects of losigamone and its isomers on maximal electroshock induced convulsions in mice and on three different patterns of low magnesium induced epileptiform activity in slices of the rat temporal cortex [Elektronische Daten] [C. Zhang, S. Chatterjee, U. Stein, U. Heinemann] Summary: Losigamone (AO-33) is a recemate of a tetronic acid derivative. The effects of losigamone and its three isomers (AO-242, AO-294 and AO-23) were compared on maximal electroshock (MES) induced convulsions in mice and on different patterns of extracellularly recorded, low Mg 2+ induced epileptiform activity in slices of the rat temporal cortex. Lowering Mg 2+ induced recurrent short discharges in areas CA3 and CA1 while ictaform events that lasted for many seconds were induced in the entorhinal cortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the entorhinal cortex changed their characteristics after one to two hours to recurrent discharges of 0.8 to 10 s. Afterdischarges and interictal events were absent. 50 μM AO-242 showed a similar efficacy to 50 μM AO-33 in reducing and blocking epileptiform discharges in areas CA1 and CA3 while 50 μM AO-294 and 50 μM AO-23 had weaker effects than 50 μM AO-33. Concentrations of 50 μM and 100 μM AO-242 showed a similar efficacy to AO-33 on ictaform events in the entorhinal cortex. Late recurrent discharges were also blocked by AO-33 and AO-242 although at higher concentrations (300 μM). The in vitro observations are with respect to order of efficacy in accordance with the in vivo data obtained in the maximal electroshock test in mice. The order of potency in the MES test was AO-242>AO-33≫AO-294≫ AO-23. The results show that the erythro-isomer AO-23, although active, is much less potent than AO-33. Of the two optical isomers of losigamone the (+) isomer AO-242 is more active than the (−) form AO-294. Springer-Verlag, 1992 Entorhinal cortex nationallicence Isomers nationallicence Low magnesium epilepsy nationallicence Losigamone nationallicence Maximal electroshock test nationallicence Mice nationallicence Rat nationallicence Zhang C. Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut Chatterjee S. Dr. Willmar Schwabe Arzneimittel, Willmar Schwabestrasse 4, W-7500, Karlsruhe 41, Federal Republic of Germany aut Stein U. Dr. Willmar Schwabe Arzneimittel, Willmar Schwabestrasse 4, W-7500, Karlsruhe 41, Federal Republic of Germany aut Heinemann U. Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/1(1992-01-01), 85-92 0028-1298 345:1<85 1992 345 210 https://doi.org/10.1007/BF00175474 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00175474 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhang C. Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut NATIONALLICENCE 700 1- Chatterjee S. Dr. Willmar Schwabe Arzneimittel, Willmar Schwabestrasse 4, W-7500, Karlsruhe 41, Federal Republic of Germany aut NATIONALLICENCE 700 1- Stein U. Dr. Willmar Schwabe Arzneimittel, Willmar Schwabestrasse 4, W-7500, Karlsruhe 41, Federal Republic of Germany aut NATIONALLICENCE 700 1- Heinemann U. Institut für Neurophysiologie, Zentrum für Physiologie und Pathophysiologie, Universität zu Köln, Robert-Koch-Strasse 39, W-5000, Köln 41, Federal Republic of Germany aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 345/1(1992-01-01), 85-92 0028-1298 345:1<85 1992 345 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer