The Role of Adrenergic and Cholinergic Receptors on the Antinociception of Korean Red Ginseng in the Spinal Cord of Rats / 대한통증학회지

BACKGROUND: Experimental evidence indicates that ginseng modulate the nociceptive transmission. Authors examined the role of adrenergic and cholinergic receptors on the antinociceptive action of Korean red ginseng against the formalin-induced pain at the spinal level. METHODS: Catheters were inserted into the intrathecal space of male Sprague-Dawley rats. Fifty microl of 5% formalin solution was injected to the hindpaw for induction of pain and formalin-induced pain (flinching response) was observed. The role of spinal adrenergic and cholinergic receptors on the effect of Korean red ginseng was assessed by antagonists (prazosin, yohimbine, atropine and mecamylamine). RESULTS: Intrathecal Korean red ginseng produced a dose-dependent suppression of the flinching response in the rat formalin test. All of prazosin, yohimbine, atropine and mecamylamine antagonized the antinociception of Korean red ginseng. CONCLUSIONS: Spinal Korean red ginseng is effective against acute pain and facilitated pain state evoked by formalin injection. All of alpha 1, alpha 2, muscarinic and nicotinic receptors may play an important role in the antinociceptive action of Korean red ginseng at the spinal level.

Assessment for the Role of Serotonin Receptor Subtype 3 for the Analgesic Action of Morphine at the Spinal Level / 대한통증학회지

BACKGROUND: Serotonin 3 receptor is involved in the modulation of nociceptive transmission in the spinal cord. The serotonin 3 receptor antagonist has been used for the management of opioid-induced nausea and vomiting. The aim of this study was to examine whether the analgesic effect of morphine is antagonized by serotonin 3 receptor antagonists at the spinal level. METHODS: Rats were implanted with lumbar intrathecal catheters. For nociception, a formalin solution (5%, 50microliter) was injected into the hind paw of male Sprague-Dawley rats. To determine whether the effect of intrathecal morphine was mediated via serotonin 3 receptors, serotonin 3 receptor antagonists were intrathecally administered 10 min prior to the morphine delivery. Following the formalin injection, formalin-induced nociceptive behavior (flinching response) was observed for 60 min. RESULTS: Intrathecal morphine produced a dose-dependent suppression of the flinches in both phases during the formalin test. The analgesic action of morphine was not reversed by serotonin 3 receptor antagonists (LY-278, 584, ondansetron), which had little per se effect on the formalin-induced nociception. CONCLUSIONS: Spinal serotonin 3 receptors may not be involved in the analgesia of morphine on a nociceptive state evoked by a formalin stimulus.