title: Modification of morphine analgesia by venlafaxine in diabetic neuropathic pain model.
abstract: BACKGROUND
  The purpose of this study was to investigate the influence of single or chronic (21 days) administration of the serotonin and noradrenaline reuptake inhibitor, venlafaxine, on the antinociceptive action of the opioid receptor agonist, morphine, in streptozotocin (STZ)-induced hyperalgesia.
  
  
  METHODS
  The studies were performed on male Wistar rats. Changes in nociceptive thresholds were determined using mechanical stimuli. Diabetes was induced by a single administration of STZ (40 mg/kg, im).
  
  
  RESULTS
  Venlafaxine was shown to modulate analgesic activity of morphine in STZ-induced hyperalgesia. However, whereas acute co-administration of venlafaxine increased the analgesic activity of morphine, chronic treatment with venlafaxine attenuated opioid efficacy.
  
  
  CONCLUSIONS
  Depending on the mode of administration (single or long-term), venlafaxine modulates analgesic activity of morphine. Further investigations are necessary to clarify the mechanisms of these interactions, which may be clinically relevant.
authors.affiliation: Department of Pharmacodynamics, Medical University of Warsaw, Krakowskie Przedmieście 26/28, PL 00-927 P.O. Box 3, Warszawa 64, Poland. kcegielska@wum.edu.pl
authors.forename: Krystyna
authors.initials: K
authors.lastname: Cegielska-Perun
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bujalska-Zadrożny
authors.forename: Helena E
authors.initials: HE
authors.lastname: Makulska-Nowak
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D003511:Cyclohexanols / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000150:complications*; D003929:Diabetic Neuropathies / Q000188:drug therapy*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013311:Streptozocin; D000069470:Venlafaxine Hydrochloride
chemical_list: D000701:Analgesics, Opioid; D003511:Cyclohexanols; D009020:Morphine; D017367:Selective Serotonin Reuptake Inhibitors; D013311:Streptozocin; D000069470:Venlafaxine Hydrochloride