ATP-SENSITIVE POTASSIUM CHANNELS AND ENDOGENOUS ADENOSINE ARE INVOLVED IN SPINAL ANTINOCICEPTION PRODUCED BY LOCUS COERULEUS STIMULATION

• Published in: International journal of neuroscience 2004-08, Vol.114 (8), p.961-974
• Main Authors: HAN, BAO-FEN, ZHANG, CE, REYES-VAZQUEZ, CRUZ, QIAO, JIAN-TIAN, DAFNY, NACHUM
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Action Potentials - radiation effects; Adenosine - agonists; Adenosine - antagonists & inhibitors; Adenosine - physiology; Adenosine Triphosphate - metabolism; Adenosine-5'-(N-ethylcarboxamide) - pharmacology; Aminophylline - pharmacology; Animals; Behavioral psychophysiology; Biological and medical sciences; Drug Interactions; Electric Stimulation - adverse effects; Electric Stimulation - methods; Female; Fundamental and applied biological sciences. Psychology; Glyburide - pharmacology; Indoles - pharmacology; Intralaminar Thalamic Nuclei - cytology; Intralaminar Thalamic Nuclei - drug effects; Intralaminar Thalamic Nuclei - physiology; Intralaminar Thalamic Nuclei - radiation effects; Locus Coeruleus - physiology; Locus Coeruleus - radiation effects; Male; Neural Inhibition - drug effects; Neural Inhibition - radiation effects; Neurons - drug effects; Neurons - physiology; Neurons - radiation effects; Neurotransmission and behavior; Nociceptors - physiology; Phosphodiesterase Inhibitors - pharmacology; Potassium Channel Blockers - pharmacology; Potassium Channels - physiology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Wistar; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs
• ISSN: 0020-7454; 1563-5279; 1543-5245
• DOI: 10.1080/00207450490450136

The effects of locus coeruleus stimulation on nociceptive evoked discharges of thalamic parafascicular (PF) neurons were investigated in lightly urethane-anesthetized rats, aiming to study the mechanisms underlying these effects. Intrathecal (i.t.) administration of aminophylline (an adenosine antagonist), glibenclamide (an ATP-sensitive potassium [K+ATP] channels blocker), nicrorandil (Nico; an agonist of K+ATP channel and a K+ATP channel opener), and 5'-N-ethylcarboxamido-adenosine (NECA; an adenosine agonist) were used. The results showed that (1) locus coeruleus stimulation significantly inhibited the nociceptive evoked discharges of parafascicular neurons, (2) locus coeruleus stimulation-produced antinociception in PF neurons was blocked by both i.t. glibenclamide and i.t. aminophylline, (3) nociceptive discharges of PF neurons were also suppressed by both i.t. NECA and i.t. nicorandil, and (4) i.t. glibenclamide showed no effect on the suppression of nociceptive discharges induced by NECA, whereas aminophylline blocked the suppression of nociceptive discharges induced by nicorandil. These results suggest that (a) K+ATP channels and endogenous adenosine may be involved in the mediation of antinociception induced by norepinephrine, which is released in the dorsal horn by descending fibers originating from the locus coeruleus and (b) the opening of K+ATP channels may precede the release of endogenous adenosine in the process of suppressing nociceptive transmission at the spinal level.