Kynurenic acid enhances electroacupuncture analgesia in normal and carrageenan-injected rats

摘要: Abstract The interaction between electroacupuncture (EA) and an intrathecally administered wide-spectrum excitatory amino acid (EAA) receptor(s) antagonist, kynurenic (KYNA) on carrageenan-induced thermal hyperalgesia spinal Fos expression was investigated. Intrathecal (i.t.) injection of 0.1, 1, 10, 100 nmol KYNA markedly dose-dependently increased the latency paw withdrawal (PWL) carrageenan-injected paw. While PWLs non-injected normal saline (NS)-injected paws were not obviously affected by application at doses tested. 0.1 significantly potentiated anti-nociception induced EA stimulation contralateral ‘Zu-San-Li’ ‘Kun-Lun’ acupoints either in carrageenan- or NS-injected rats. Three hours after intraplantar (i.pl.) carrageenan, number Fos-like immunoreactive (Fos-LI) neurons all layers ipsilateral cord L4–L5 with higher density laminae I–II V–VI. Intrathecally pre-administered (10 nmol) reduced total Fos-LI more apparent reduction IV–V. Pre-coapplication 10 bilateral acupoints, numbers V–VI further reduced. level carrageenan lower compared that i.t. alone. These results demonstrated EAA antagonist could enhance EA-induced anti-hyperalgesia.