Lavandula angustifolia essential oil inhalation reduces mechanical hyperalgesia in a model of inflammatory and neuropathic pain: The involvement of opioid and cannabinoid receptors.

Lavandula angustifolia (LaEO) essential oil has been widely used by aromatherapy in the treatment of various clinical conditions, with evidence of its analgesic and anti-inflammatory potential. Our results demonstrate that sixty-five substances were identified in LaEO. Among the compounds found, the major ones were linalool (30.61%) and linalyl acetate (20.36%). We found that LaEO inhalation reduces mechanical hyperalgesia in conditions of chronic inflammatory and neuropathic pain. Furthermore, this effect seems to be mediated by peripheral and central opioid and cannabinoid 2 receptors. The findings of the present study suggests that the LaEO inhalation is effective on the chronic pain treatment.

Aquatic exercise and Far Infrared (FIR) modulates pain and blood cytokines in fibromyalgia patients: A double-blind, randomized, placebo-controlled pilot study.

Fibromyalgia (FM) has an inflammatory component, as elevated serum levels of inflammatory biomarkers are associated with its diagnosis. Treatments decreased pain, body temperature, improved quality of life and reduced serum levels of IL-6 in both groups; however, these beneficial effects were more pronounced in aquatic exercise (AE) + Far-Infrared (FIR) group. The findings of the present study suggest that the association of AE to FIR increases the benefits of aquatic exercise in patients with FM.

The role of the endocannabinoid system in the antihyperalgesic effect of Cedrus atlantica essential oil inhalation in a mouse model of postoperative pain.

ETHNOPHARMACOLOGICAL RELEVANCE: Cedar is part of the phylum of conifers, and it's essential oil has been used for therapeutic purposes since ancient times. In our previous study, we have demonstrated that the inhalation of the Cedrus atlantica essential oil (CaEO) induces an antihyperalgesic effect in a model of postoperative pain. But the mechanism that underlies this effect is not yet fully known. AIM OF THE STUDY: This study investigates the involvement of the endocannabinoid system in the antihyperalgesic effect produced by the inhalation of CaEO in a post operative pain model. MATERIALS AND METHODS: Male Swiss mice (25-35±2g) were subjected to plantar incision. To assess the involvement of the endocannabinoid system, two different approaches were made: (1) by administering antagonists to the CB1 and CB2 receptors in different sites (intraperitoneal [i.p.], intraplantar [i.pl.] and intrathecal [i.t.]) and (2) by assessing the synergic effect of the inhalation of sub-effective doses of CaEO, Fatty acid hydrolase (FAAH) and Monoacylglycerol lipase (MAGL), and endocannabinoid degradation inhibitors (URB937 and JZL184, respectively). RESULTS: The antihyperalgesic effect of CaEO inhalation was prevented by pretreatment with AM281 or AM630 given by i.p. and i.t., but not i.pl. Additionally, in mice pretreated with FAAH or the MAGL inhibitors, the antihyperalgesic effect of CaEO inhalation was significantly longer, which demonstrates the involvement of the endocannabinoid system in the antihyperalgesic effect of CaEO inhalation in a preclinical model of postoperative pain. CONCLUSIONS: The present study shows that CaEO inhalation exerts an antihyperalgesic effect, possibly by the activation of the endocannabinoid system in a preclinical model of postoperative pain. It could be a new alternative to treat pain in a clinical environment.

Far infrared-emitting ceramics decrease Freund's adjuvant-induced inflammatory hyperalgesia in mice through cytokine modulation and activation of peripheral inhibitory neuroreceptors.

OBJECTIVE: The present study aimed to evaluate the analgesic and anti-inflammatory effects of far infrared-emitting ceramics (cFIRs) in a model of persistent inflammatory hyperalgesia and to elucidate the possible mechanisms of these effects. METHODS: Mice were injected with complete Freund's adjuvant (CFA) and treated with cFIRs via placement on a pad impregnated with cFIRs on the bottom of the housing unit for different periods of time. Mice underwent mechanical hyperalgesia and edema assessments, and tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and IL-10 levels were measured. Twenty-four hours after CFA injection and 30 min before cFIR treatment, mice were pretreated with a nonselective adenosinergic antagonist, caffeine, the selective adenosine receptor A1 antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), the selective cannabinoid receptor type 1 antagonist, AM281, the selective cannabinoid receptor type 2 antagonist, AM630, or the nonselective opioid receptor antagonist, naloxone, and mechanical hyperalgesia was assessed. RESULTS: cFIRs statistically (P < 0.05) decreased CFA-induced mechanical hyperalgesia ((82.86 ±â€¯5.21)% in control group vs (56.67 ±â€¯9.54)% in cFIR group) and edema ((1699.0 ±â€¯77.8) µm in control group vs (988.7 ±â€¯107.6) µm in cFIR group). cFIRs statistically (P < 0.05) reduced TNF-α ((0.478 ±â€¯0.072) pg/mg of protein in control group vs (0.273 ±â€¯0.055) pg/mg of protein in cFIR group) and IL-1ß ((95.81 ±â€¯3.95) pg/mg of protein in control group vs (80.61 ±â€¯4.71) pg/mg of protein in cFIR group) levels and statistically (P < 0.05) increased IL-10 ((18.32 ±â€¯0.78) pg/mg of protein in control group vs (25.89 ±â€¯1.23) pg/mg of protein in cFIR group) levels in post-CFA-injected paws. Peripheral pre-administration of inhibitory neuroreceptor antagonists (caffeine, DPCPX, AM281, AM630 and naloxone) prevented the analgesic effects of cFIRs (P < 0.05). CONCLUSION: These data provide additional support for the use of cFIRs in the treatment of painful inflammatory conditions and contribute to our understanding of the neurobiological mechanisms of the therapeutic effects of cFIRs.

Effects of Different Parameters of Continuous Training and High-Intensity Interval Training in the Chronic Phase of a Mouse Model of Complex Regional Pain Syndrome Type I.

This study evaluated the effects of continuous and interval running on a treadmill on mechanical hyperalgesia in an animal model of chronic postischemia pain and analyzed the mechanism of action of this effect. Different groups of male Swiss mice with chronic postischemia pain, induced by 3 hours of paw ischemia followed by reperfusion, ran on the treadmill in different protocols-the speed (10, 13, 16, or 19 m/min), duration (15, 30, or 60 minutes), weekly frequency (3 or 5 times), weekly increase in continuous and interval running speed-were tested. Mechanical hyperalgesia was evaluated by von Frey filament 7, 14, and 21 days after paw ischemia followed by reperfusion. On day 11 after paw ischemia followed by reperfusion and after 5 days of continuous and interval running, concentrations of cytokines, oxidative stress parameters, and extracellular signal-regulated kinase 1/2 and AKT 1/2/3 expression in the spinal cord were measured. The results showed that continuous running has an antihyperalgesic effect that depends on intensity and volume. Interval running has a longer-lasting antihyperalgesic effect than continuous running. The antihyperalgesic effect depends on intensity and volume in continuous running, and increasing speed maintains the antihyperalgesic effect in both protocols. In the spinal cord, both runs decreased tumor necrosis factor-α and interleukin-6 levels and increased interleukin-10. Both running protocols reduced oxidative damage in the spinal cord. Only interval running had lower concentrations of phosphorylated extracellular signal-regulated kinase 1/2 in the spinal cord. Interval running presented a great antihyperalgesic potential with more promising results than continuous running, which may be owing to the fact that the interval running can activate different mechanisms from those activated by continuous running. PERSPECTIVE: A minimum of .5-hour sessions of moderate to high intensity ≥3 times a week are essential parameters for continuous and interval running-induced analgesia. However, interval running was shown to be more effective than continuous running and can be an important adjuvant treatment to chronic pain.