Modulatory effects of inosine, guanosine and uridine on lipopolysaccharide-evoked increase in spike-wave discharge activity in Wistar Albino Glaxo/Rijswijk rats.

We showed previously that the number of spike-wave discharges (SWDs) was increased after intraperitoneal (i.p.) injection of lipopolysaccharide (LPS), inosine (Ino) and muscimol alone whereas i.p. guanosine (Guo), uridine (Urd), bicuculline, theophylline and (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801) alone decreased the SWD number in Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. These drugs may exert their effects on absence epileptic activity mainly via proinflammatory cytokines-evoked increase in cortical excitability (such as LPS), GABAergic system (LPS, Ino, Urd, muscimol and bicuculline), glutamatergic system (LPS, Guo and MK-801) and adenosinergic system (LPS, Ino, Guo, Urd and theophylline). Both GABAergic system and glutamatergic system are involved in the pathomechanism of absence epilepsy, the LPS-evoked increase in absence epileptic activity and the pro- or antiepileptic effects of non-adenosine (non-Ado) nucleosides Ino, Guo and Urd. Moreover, Ino, Guo and Urd have modulatory effects on inflammatory processes. Thus, we investigated whether Ino, Guo and Urd have also modulatory influence on LPS-evoked increase in SWD number using two different concentrations of each nucleoside in WAG/Rij rats. We demonstrated that Ino dose-dependently aggravated whereas Guo and Urd attenuated the LPS-evoked increase in SWD number. Our results suggest that different nucleosides have diverse effects on LPS-induced changes in absence epileptic activity.