Endogenous adenosine A1 receptor activation underlies the transient post-ischemic rhythmic delta EEG activity.
OBJECTIVE
Emergence of slow EEG rhythms within the delta frequency band following an ischemic insult of the brain has long been considered a marker of irreversible anatomical damage. Here we investigated whether ischemic adenosine release and subsequent functional inhibition via the adenosine A(1) receptor (A(1)R) contributes to post-ischemic delta activity.


METHODS
Rats were subjected to episodes of non-injuring transient global cerebral ischemia (GCI) under chloral hydrate anesthesia.


RESULTS
We found that a GCI lasting only 10s was enough to induce a brief discharge of rhythmic delta activity (RDA) with a peak frequency just below 1 Hz quantified as an increase by twofold of the 0.5-1.5 Hz spectral power. This post-ischemic RDA did not occur following administration of the A(1)R antagonist 8-cyclopentyl-1,3-dipropylxanthine. Nevertheless, a similar RDA could be induced in rats not subjected to GCI, by systemic administration of the A(1)R agonist N(6)-cyclopentyladenosine.


CONCLUSIONS
Our data suggest that A(1)R activation at levels that occur following cerebral ischemia underlies the transient post-ischemic RDA.


CONCLUSIONS
It is likely that the functional, thus potentially reversible, synaptic disconnection by A(1)R activation promotes slow oscillations in the cortical networks. This should be accounted for in the interpretation of early post-ischemic EEG delta activity.
Center for Excellence in Neuroscience, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
Alexandra Oana
AO
Constantinescu
Andrei
A
Ilie
Dragos
D
Ciocan
Ana-Maria
AM
Zagrean
Leon
L
Zagrean
Mihai
M
Moldovan
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D058916:Adenosine A1 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D003700:Delta Rhythm / Q000187:drug effects / Q000502:physiology*; D004195:Disease Models, Animal; D004562:Electrocardiography / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D043682:Receptor, Adenosine A1 / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
D058916:Adenosine A1 Receptor Antagonists; D043682:Receptor, Adenosine A1; D014970:Xanthines; C027513:N(6)-cyclohexyladenosine; C031433:8-(4-sulfophenyl)theophylline; C051360:1,3-dipropyl-8-cyclopentylxanthine; D013806:Theophylline; D000241:Adenosine