The role of adenosine A(1) receptors in mediating the inhibitory effects of low frequency stimulation of perforant path on kindling acquisition in rats.
Low frequency stimulation (LFS) has an inhibitory effect on rapid perforant path kindling acquisition. In the present study the role of adenosine A(1) and A(2A) receptors in mediating this inhibitory effect was investigated. Rats were kindled by perforant path stimulation using rapid kindling procedures (12 stimulations per day). LFS (0.1 ms pulse duration at 1 Hz, 200 pulses, and 50-150 muA) was applied to the perforant path immediately after termination of each rapid kindling stimulation. 1,3-Dimethyl-8-cyclopenthylxanthine (CPT; 50 muM), a selective A(1) antagonist and ZM241385 (ZM, 200 muM), a selective A(2A) antagonist were daily microinjected into the lateral ventricle 5 min before kindling stimulations. LFS had an inhibitory effect on kindling development. Pretreatment of animals with CPT reduced the inhibitory effect of LFS on kindling rate and suppressed the effects of LFS on potentiation of population EPSP during kindling acquisition. In addition, CPT was able to antagonize the effects of LFS on kindling-induced increase in early (10-50 ms intervals) and late (300-1000 ms intervals) paired pulse depression. ZM pretreatment had no effect on antiepileptogenic effects of LFS in kindling acquisition. In addition, LFS prevented the kindling-induced elevation of cyclic AMP (cAMP) levels in kindled animals. Based on these results, we suggest that the antiepileptogenic effects of LFS on perforant path kindling might be mediated through activation of adenosine A(1), but not A(2A) receptors. Moreover, modulation of cAMP levels by LFS may potentially be an important mechanism which explains the anticonvulsant effects of LFS in kindled seizures.
Mohammad-Zadeh
M
M
Department of Physiology, School of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran.
Mirnajafi-Zadeh
J
J
Fathollahi
Y
Y
Javan
M
M
Jahanshahi
A
A
Noorbakhsh
S M
SM
Motamedi
F
F
D058916:Adenosine A1 Receptor Antagonists; D058917:Adenosine A2 Receptor Antagonists; D000704:Analysis of Variance; D000818:Animals; D001703:Biophysics; D000242:Cyclic AMP / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007696:Kindling, Neurologic / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D019580:Perforant Pathway / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D043682:Receptor, Adenosine A1 / Q000502:physiology*; D012640:Seizures / Q000378:metabolism / Q000503:physiopathology; D013997:Time Factors; D014227:Triazines; D014230:Triazoles; D014970:Xanthines / Q000494:pharmacology
C112774:1,3-dimethyl-8-cyclopentylxanthine; D058916:Adenosine A1 Receptor Antagonists; D058917:Adenosine A2 Receptor Antagonists; D043682:Receptor, Adenosine A1; D014227:Triazines; D014230:Triazoles; D014970:Xanthines; C097270:ZM 241385; D000242:Cyclic AMP