Adenosine A1 receptors mediate the presynaptic inhibition of calcitonin gene-related peptide release by adenosine in the rat spinal cord.
Electrical field stimulation evoked a reproducible outflow of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) from the dorsal half of the rat spinal cord, an effect which was abolished by prior application of capsaicin, tetrodotoxin or removal of extracellular Ca2+. Adenosine (EC50 3.2 microM) and the selective adenosine A1 receptor agonist N6-cyclohexyladenosine (EC50 8.2 nM) inhibited evoked CGRP-LI outflow, while the selective adenosine A2 receptor agonist CGS-21680 was ineffective up to 10 microM. The action of adenosine was prevented by the adenosine A1 receptor selective antagonist 8-cyclopentyl-1,3-dipropylxanthine (30 microM), which did not affect CGRP-LI release on its own.
Santicioli
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Pharmacology Department, A. Menarini Pharmaceuticals, Florence, Italy.
Del Bianco
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Maggi
C A
CA
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects*
D011983:Receptors, Purinergic; D015740:Calcitonin Gene-Related Peptide; D000241:Adenosine