Altered distribution and function of A2A adenosine receptors in the brain of WAG/Rij rats with genetic absence epilepsy, before and after appearance of the disease.
The involvement of excitatory adenosine A(2A) receptors (A(2A)Rs), which probably contribute to the pathophysiology of convulsive seizures, has never been investigated in absence epilepsy. Here, we examined the distribution and function of A(2A)Rs in the brain of Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats, a model of human absence epilepsy in which disease onset occurs 2-3 months after birth. In the cerebral areas that are mostly involved in the generation of absence seizures (somatosensory cortex, reticular and ventrobasal thalamic nuclei), A(2A)R density was lower in presymptomatic WAG/Rij rats than in control rats, as evaluated by immunohistochemistry and western blotting. Accordingly, in cortical/thalamic slices prepared from the brain of these rats, A(2A)R stimulation with the agonist 2-[4-(-2-carboxyethyl)-phenylamino]-5'-N-ethylcarboxamido-adenosine failed to modulate either cAMP formation, mitogen-activated protein kinase system, or K(+)-evoked glutamate release. In contrast, A(2A)R expression, signalling and function were significantly enhanced in brain slices from epileptic WAG/Rij rats as compared with matched control animals. Additionally, the in vivo injection of the A(2A)R agonist CGS21680, or the antagonist 5-amino-7-(2-phenylethyl)-2-(2-fuyl)-pyrazolo-(4,3-c)1,2,4-triazolo(1,5-c)-pyrimidine, in the examined brain areas of epileptic rats, increased and decreased, respectively, the number/duration of recorded spontaneous spike-wave discharges in a dose-dependent manner during a 1-5 h post-treatment period. Our results support the hypothesis that alteration of excitatory A(2A)R is involved in the pathogenesis of absence seizures and might represent a new interesting target for the therapeutic management of this disease.
D'Alimonte
Iolanda
I
Department of Biomedical Sciences, University of Chieti, Medical School, Chieti, Italy.
D'Auro
Mariagrazia
M
Citraro
Rita
R
Biagioni
Francesca
F
Jiang
Shucui
S
Nargi
Eleonora
E
Buccella
Silvana
S
Di Iorio
Patrizia
P
Giuliani
Patricia
P
Ballerini
Patrizia
P
Caciagli
Francesco
F
Russo
Emilio
E
De Sarro
Giovambattista
G
Ciccarelli
Renata
R
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D004195:Disease Models, Animal; D018450:Disease Progression; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D007150:Immunohistochemistry; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D010627:Phenethylamines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D013003:Somatosensory Cortex / Q000187:drug effects / Q000378:metabolism*; D013788:Thalamus / Q000187:drug effects / Q000378:metabolism*; D014230:Triazoles / Q000494:pharmacology
C098657:5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine; D010627:Phenethylamines; D011743:Pyrimidines; D043705:Receptor, Adenosine A2A; D014230:Triazoles; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D018698:Glutamic Acid; D000241:Adenosine