title: Additive effect of combined application of magnesium and MK-801 on analgesic action of morphine.
abstract: As previously reported, magnesium ions (Mg(2+)) administered in relatively low doses markedly potentiated opioid analgesia in neuropathic pain, in which the effectiveness of opioids is limited. Considering that Mg(2+) behaves like an N-methyl-D-aspartate receptor antagonist, the effect of this ion on the analgesic action of morphine was compared with that of MK-801. Acute pain was evoked by mechanical or thermal stimuli, whereas neuropathic hyperalgesia was induced by streptozotocin (STZ) administration. Magnesium sulphate (40 mg/kg i.p.) or MK-801 (0.05 mg/kg s.c.) administered alone did not modify the nociceptive threshold to acute stimuli or the streptozotocin hyperalgesia but significantly augmented the analgesic action of morphine (5 mg/kg i.p.). Furthermore, if these drugs (i.e. magnesium sulphate and MK-801) were applied concomitantly, a clear additive effect on the analgesic action of morphine occurred in both models of pain. Possible explanations of these observations are discussed.
authors.affiliation: Department of Pharmacodynamics, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bujalska-Zadrożny
authors.forename: Kamila
authors.initials: K
authors.lastname: Duda
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004195:Disease Models, Animal; D016291:Dizocilpine Maleate / Q000008:administration & dosage / Q000494:pharmacology*; D004357:Drug Synergism; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D006930:Hyperalgesia / Q000188:drug therapy / Q000503:physiopathology; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009437:Neuralgia / Q000188:drug therapy / Q000503:physiopathology; D010146:Pain / Q000188:drug therapy / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013311:Streptozocin / Q000633:toxicity
chemical_list: D000701:Analgesics, Opioid; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D013311:Streptozocin; D016291:Dizocilpine Maleate; D008278:Magnesium Sulfate; D009020:Morphine