title: Venlafaxine and oxycodone effects on human spinal and supraspinal pain processing: a randomized cross-over trial.
abstract: Severe pain is often treated with opioids. Antidepressants that inhibit serotonin and norepinephrine reuptake (SNRI) have also shown a pain relieving effect, but for both SNRI and opioids, the specific mode of action in humans remains vague. This study investigated how oxycodone and venlafaxine affect spinal and supraspinal pain processing. Twenty volunteers were included in this randomized cross-over study comparing 5-day treatment with venlafaxine, oxycodone and placebo. As a proxy of the spinal pain transmission, the nociceptive withdrawal reflex (NWR) to electrical stimulation on the sole of the foot was recorded at the tibialis anterior muscle before and after 5 days of treatment. For the supraspinal activity, 61-channel electroencephalogram evoked potentials (EPs) to the electrical stimulations were simultaneously recorded. Areas under curve (AUCs) of the EMG signals were analyzed. Latencies and AUCs were computed for the major EP peaks and brain source analysis was done. The NWR was decreased in venlafaxine arm (P = 0.02), but the EP parameters did not change. Oxycodone increased the AUC of the EP response (P = 0.04). Oxycodone also shifted the cingulate activity anteriorly in the mid-cingulate-operculum network (P < 0.01), and the cingulate activity was increased while the operculum activity was decreased (P = 0.02). Venlafaxine exerts its effects on the modulation of spinal nociceptive transmission, which may reflect changes in balance between descending inhibition and descending facilitation. Oxycodone, on the other hand, exerts its effects at the cortical level. This study sheds light on how opioids and SNRI drugs modify the human central nervous system and where their effects dominate.
authors.affiliation: Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Mølleparkvej 4, 9000, Aalborg, Denmark.
authors.forename: D
authors.initials: D
authors.lastname: Lelic
authors.affiliation: Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Mølleparkvej 4, 9000, Aalborg, Denmark.|Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: I W D
authors.initials: IW
authors.lastname: Fischer
authors.affiliation: Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Mølleparkvej 4, 9000, Aalborg, Denmark.|Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: A E
authors.initials: AE
authors.lastname: Olesen
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: C D
authors.initials: CD
authors.lastname: Mørch
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: F G
authors.initials: FG
authors.lastname: Arguissain
authors.affiliation: Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
authors.forename: J A B
authors.initials: JA
authors.lastname: Manresa
authors.affiliation: Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Dahan
authors.affiliation: Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Mølleparkvej 4, 9000, Aalborg, Denmark.|Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: A M
authors.initials: AM
authors.lastname: Drewes
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000494:pharmacology* / Q000627:therapeutic use; D016022:Case-Control Studies; D019054:Evoked Potentials, Motor; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D008297:Male; D009433:Neural Inhibition; D059225:Nociception / Q000187:drug effects*; D059226:Nociceptive Pain / Q000188:drug therapy*; D010098:Oxycodone / Q000494:pharmacology* / Q000627:therapeutic use; D017288:Pain Threshold; D011930:Reaction Time; D000068760:Serotonin and Noradrenaline Reuptake Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D013116:Spinal Cord / Q000502:physiology / Q000503:physiopathology; D000069470:Venlafaxine Hydrochloride / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000701:Analgesics, Opioid; D000068760:Serotonin and Noradrenaline Reuptake Inhibitors; D000069470:Venlafaxine Hydrochloride; D010098:Oxycodone
keywords: EEG; brain source localization; evoked potentials; nociceptive withdrawal reflexes; opioid; serotonin and norepinephrine reuptake