The antiepileptogenic effect of electrical stimulation at different low frequencies is accompanied with change in adenosine receptors gene expression in rats

Purpose:   Previous studies have shown that the anticonvulsant effects of low-frequency stimulation (LFS) can be affected by activation of adenosine receptors. In the present study, the effect of LFS at different frequencies on kindling rate and adenosine receptors gene expression was investigated.
Methods:   Animals were kindled by perforant path stimulation in a rapid kindling manner. LFS (0.5, 1, and 5 Hz) was applied after termination of each kindling stimulation. Seizure severity was measured according to behavioral and electrophysiologic parameters. At the end of the experiments, adenosine A₁ and A_2A receptor gene expression were measured.
Results:   The inhibitory effect of LFS on kindling acquisition was observed at all frequencies. In addition, the inhibitory action of LFS on enhancement of field excitatory postsynaptic potential slope and population spike amplitude during kindling acquisition was not affected by the LFS frequency. However, the effects of LFS on paired-pulse recordings were greater at frequency of 5 Hz. Application of LFS during kindling acquisition also prevented the kindling induced decrease in the A₁ receptor gene expression and attenuated the level of A_2A receptor gene expression in the dentate gyrus. These effects were also greater at the frequency of 5 Hz.
Discussion:   According to these data, it may be suggested that the antiepileptogenic effects of LFS, developed through inhibition of synaptic transmission in the dentate gyrus, is mediated somehow through preventing the decrease of A₁ receptor and through attenuating the A_2A receptor gene expression. These effects might be dependent on the frequency of LFS.