The role of piriform cortex adenosine A1 receptors on hippocampal kindling.
BACKGROUND
The hippocampus and piriform cortex have a critical role in seizure propagation. In this study, the role of adenosine A1 receptors of piriform cortex on CA1 hippocampal kindled seizures was studied in rats.


METHODS
Animals were implanted with a tripolar electrode in the right hippocampal CA1 region and two guide cannulae in the left and right piriform cortex. They were kindled by daily electrical stimulation of hippocampus. In fully kindled rats, N6- cyclohexyladenosine (CHA; a selective adenosine A1 receptors agonist) and 1,3-dimethyl-8-cyclopenthylxanthine (CPT a selective adenosine A1 receptor antagonist) were microinfused into the piriform cortex. The animals were stimulated at 5, 15 and 90 minutes (min) after drug injection.


RESULTS
Obtained data showed that CHA (10 and 100 microM) reduced afterdischarge duration, stage 5 seizure duration, and total seizure duration at 5 and 15 min after drug injection. There was no significant change in latency to stage 4 seizure. CPT at concentration of 20 microM increased afterdischarge duration, stage 5 seizure duration, and total seizure duration and decreased latency to stage 4 seizure at 5 and 15 min post injection. Pretreatment of rats with CPT (10 microM), 5 min before CHA (100 microM), reduced the effect of CHA on seizure parameters.


CONCLUSIONS
These results suggested that activity of adenosine A1 receptors in the piriform cortex has an anticonvulsant effect on kindled seizures resulting from electrical stimulation of the CA1 region of the hippocampus.
Department of Physiology, School of Medical Sciences, Tarbiat Modares University, Tehran, IR, Iran.
Simin
S
Namvar
Javad
J
Mirnajafi-Zadeh
Yaghoub
Y
Fathollahi
Maryam
M
Zeraati
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D004347:Drug Interactions; D004558:Electric Stimulation / Q000009:adverse effects; D004569:Electroencephalography; D018728:Entorhinal Cortex / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000503:physiopathology*; D007696:Kindling, Neurologic / Q000502:physiology* / Q000528:radiation effects; D008297:Male; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000502:physiology*; D012640:Seizures / Q000188:drug therapy / Q000209:etiology / Q000473:pathology*; D013997:Time Factors; D014970:Xanthines / Q000494:pharmacology
C112774:1,3-dimethyl-8-cyclopentylxanthine; D043682:Receptor, Adenosine A1; D014970:Xanthines; C027513:N(6)-cyclohexyladenosine; D000241:Adenosine