oxytocin and Low-Back-Pain

The neuropeptide oxytocin (OT) has been shown to play a modulatory role in nociception. However, analgesic effects of OT in chronic pain conditions remain elusive and the neural underpinnings have not yet been investigated in humans. Here, we conducted an exploratory, randomized, placebo-controlled, cross-over study to examine effects of intranasal OT in male patients suffering from chronic low back pain (CBP) versus healthy controls (HC). N = 22 participants with CBP and 22 HCs were scanned using functional magnetic resonance imaging (fMRI) while they continuously rated either spontaneously occurring back pain or acute thermal pain stimuli applied to the lower back. During heat pain processing we found that OT versus PL attenuated pain intensity ratings and increased BOLD responses in the caudate nucleus of the striatum in CBP versus HCs. Spontaneously experienced pain in contrast to heat pain was associated with activation changes in the medial frontal cortex (MFC) and the anterior cingulate cortex (ACC) as reported in previous studies. However, we did not observe OT effects on spontaneously experienced pain in CBP patients. Overall, our preliminary data may suggest that the striatum is a key structure underlying the pain-modulating effects of OT in patients with chronic pain and adds to the growing evidence linking the neuropeptide to pain modulation in humans. Further studies on neuronal OT effects in larger samples of chronic back pain patients are needed to understand probable mechanisms of OT effects in chronic pain. This article is part of the special issue on Neuropeptides.

Topics: Administration, Intranasal; Adult; Aged; Brain Mapping; Caudate Nucleus; Cross-Over Studies; Female; Humans; Hyperthermia; Low Back Pain; Magnetic Resonance Imaging; Male; Middle Aged; Oxytocin; Pain Measurement; Treatment Outcome

The effect of oxytocin on low back pain in patients and its mechanism in rats were investigated.. Intrathecal injection, radioimmunoassay, and potassium iontophoresis tail-flick test were used to investigate the effect of oxytocin.. In humans, acute and chronic low back pain causes a marked change of oxytocin content within cerebral spinal fluid and plasma; oxytocin relieves low back pain (ED50 0.172 in chronic and 0.121 micrograms/kg in acute). In rats, oxytocin had a dose-related analgesic effect (ED50 0.067 micrograms/kg). At high levels, oxytocin induced locomotor ataxia (ED50 17.915 micrograms/kg) and death (LD50 27.224 micrograms/kg). Oxytocin antagonist [d(CH2)5, Tyr(Me)2, Orn8]-vasotocin and opiate receptor-blocker naloxone could reverse oxytocin-induced analgesia. Oxytocin also increased beta-endorphin, L-encephalin, and dynorphin A1-13 contents in the spinal cord, whereas oxytocin antagonist caused a decrease.. These results suggest that oxytocin induces analgesia in low back pain involving the endogenous opiate peptide system and may be effective and safe in acute and chronic low back pain.

Topics: Adult; Analgesia; Animals; Double-Blind Method; Endorphins; Female; Humans; Injections, Spinal; Low Back Pain; Male; Middle Aged; Oxytocin; Rats; Rats, Sprague-Dawley; Spinal Cord

Modulation of pain perception by oxytocin (OXT) has attracted increased scientific and clinical interest. Neural mechanisms underlying these effects are poorly understood. In this study, we aimed to investigate the effects of intranasally applied OXT on intrinsic neural activity in patients with chronic low back pain (cLBP).. Twenty-four male patients with cLBP and 23 healthy males were examined using resting-state functional magnetic resonance imaging. Participants were scanned twice and received either intranasally applied OXT (24 international units) or placebo 40 min before scanning. The fractional amplitude of low-frequency fluctuations (fALFF) was computed to investigate regionally specific effects of OXT on intrinsic neural activity. In addition a multivariate statistical data analysis strategy was employed to explore OXT-effects on functional network strength.. Differential effects of OXT were observed in cLBP and healthy controls. FALFF decreased in left nucleus accumbens and right thalamus in cLBP and increased in right thalamus in healthy controls after OXT application compared to placebo. OXT also induced activity changes in bilateral thalamus, left caudate nucleus and right amygdala in cLBP. OXT was associated with increased medial frontal, parietal and occipital functional network strength, though this effect was not group-specific. Regression analyses revealed significant associations between left nucleus accumbens, left caudate nucleus and right amygdala with pain-specific psychometric scores in cLBP.. These data suggest OXT-related modulation of regional activity and neural network strength in patients with cLBP and healthy controls. In patients, distinct regions of the pain matrix may be responsive to modulation by OXT.. Our data suggest significant oxytocin-related modulation of intrinsic regional activity and neural network strength in patients with chronic low back pain and healthy controls. In patients, distinct regions of the pain matrix may be responsive to modulation by oxytocin. Therapeutic effects of oxytocin for improved pain treatment need to be further investigated.

Topics: Amygdala; Chronic Pain; Humans; Low Back Pain; Magnetic Resonance Imaging; Male; Oxytocin