EN
Gap junction (GJ) channels provide an aqueous pathway for the passage ions current and small molecules between cell cytoplasms. It has been demonstrated that various physiological stimuli, experimental treatments and chemical agents can modulate activity of those structures. In our previous studies we showed that intrahippocampal injection of carbenoxolone (GJ blocker) abolished local recorded theta rhythm in anesthetized rats. However, intrahippocampal formation (HPC) administration of trimethylamine (GJ opener) evoked an opposite effect i.e. well synchronized theta activity. The similar fi ndings were also obtained in many experiments carried out on awake animals and in studies conducted in in vitro conditions. In the present studies, performed on anesthetized rats, the interaction between GJ blocker and opener, separately injected into HPC on locally registered theta rhythm, were established. When diminishing effect of HPC injection of carbenoxolone (100 μg/1 μl) on theta rhythm amplitude and power was observed, trimethylamine (30 μg/1 μl) was locally administered. Trimethylamine was found to alleviate blocking effect on spontaneous HPC theta rhythm. In the next experiment, all rats pretreated with trimethylamine were injected with carbenoxolone. GJ blocker was found to prevent facilitating effect of trimethylamine on theta rhythm. The mechanism underlying GJ involvement in theta rhythm generation in vivo is discussed. These studies were supported by grant MNiSzW NN 401 2811 33.