Spinal antinociceptive effect of agmatine and tentative analysis of involved receptors: study in an electrophysiological model of rats.
The present study was designed to evaluate the antinociceptive effect of agmatine and the receptors involved at the spinal level by using an experimental model in which agmatine was intrathecally (i.t.) administered while the changes of nociceptively-evoked discharges in thalamic parafascicular (PF) neurons were monitored in anesthetized Wistar rats. The results showed that: (1) i.t. agmatine dose-dependently suppressed the nociceptive discharges of PF neurons induced by the tail pinch; (2) i.t. yohimbine did not block the agmatine-induced suppressive effect of nociceptive discharges in these neurons; and (3) the agmatine-induced suppression could be blocked significantly by i.t. idazoxan. The results suggest that agmatine suppresses the transmission of nociceptive inputs at the spinal level mainly through the activation of imidazoline receptors other than alpha(2)-adrenoceptors.
Hou
Shang-Wei
SW
Department of Neurobiology, Shanxi Medical University, Taiyuan, Shanxi 030001, China.
Qi
Jin-Shun
JS
Zhang
Yu
Y
Qiao
Jian-Tian
JT
D000200:Action Potentials / Q000187:drug effects; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000376:Agmatine / Q000494:pharmacology*; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology / Q000379:methods; D005260:Female; D019329:Idazoxan / Q000494:pharmacology; D007278:Injections, Spinal; D020646:Intralaminar Thalamic Nuclei / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology; D013623:Tail / Q000294:innervation; D015016:Yohimbine / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D000700:Analgesics; D015016:Yohimbine; D000376:Agmatine; D019329:Idazoxan