beta-endorphin and Chronic-Pain

Chronic low back pain (CLBP) is usually quantified using the visual analog scale (VAS). However, the VAS is a subjective measure and prone to reporting bias, therefore making it difficult to differentiate patients with true pain from those seeking to obtain secondary gain. This study aimed to evaluate the feasibility of using plasma β-endorphin as an objective biomarker for CLBP.. We searched PubMed, Embase, and the Cochrane Library for randomized trials that compared treatment vs sham procedures for patients with CLBP. Changes in VAS and β-endorphin levels between baseline and final evaluations were assessed for the treatment and control groups. A meta-regression model was developed to evaluate the association between the β-endorphin level and VAS.. We included data from seven trials involving 375 patients. There was no significant difference in VAS scores and β-endorphin levels between both groups at baseline. At final evaluation, the treatment group demonstrated significantly greater improvements in VAS scores and an increased β-endorphin level compared with the control group. The change in the plasma β-endorphin level may be a surrogate marker of treatment response for patients with CLBP (explanatory power: 80%). The plasma β-endorphin level might be rarely affected by sham procedures. For patients with CLBP, the baseline β-endorphin level may reflect the intensity of CLBP (explanatory power: 66%).. A change in plasma β-endorphin level may be a surrogate marker of the treatment response for patients with CLBP. Advancements in β-endorphin measurements may help us better quantify pain intensity.

Topics: beta-Endorphin; Chronic Pain; Humans; Low Back Pain; Pain Measurement; Randomized Controlled Trials as Topic; Treatment Outcome

The purpose of this exploratory study was to examine the effects of Tai Chi on blood levels of beta endorphin (β-endorphin) and inflammatory markers in older adults with chronic pain. Forty community-dwelling older adults with chronic pain were randomized to Tai Chi or light physical exercise, and each offered twice weekly for 12 weeks. Following the 12-week intervention, neither Tai Chi nor light physical exercise changed levels of β-endorphin and inflammatory markers. However, in older adults who completed 70% or more classes, Tai Chi significantly lowered levels of β-endorphin (p < 0.05), whereas light physical exercise did not change levels of β-endorphin. The results suggest that Tai Chi may reduce levels of β-endorphin in older adults with chronic pain. Future studies are needed to better understand the role of the opioid analgesic system and immune system in regulating pain with aging and the long-term effects of Tai Chi on pain-related biomarkers.

Topics: Aged; Aged, 80 and over; beta-Endorphin; Biomarkers; Chronic Pain; Exercise; Female; Humans; Independent Living; Inflammation; Male; Tai Ji

Clinically feasible predictors of opioid analgesic responses for use in precision pain medicine protocols are needed. This study evaluated whether resting plasma β-endorphin (BE) levels predicted responses to an opioid analgesic, and whether chronic pain status or sex moderated these effects.. Participants included 73 individuals with chronic low back pain (CLBP) and 88 pain-free controls, all using no daily opioid analgesics. Participants attended 2 identical laboratory sessions during which they received either intravenous morphine (0.08 mg/kg) or saline placebo, with blood samples obtained before drug administration to assay resting plasma BE levels. Once peak drug activity was achieved in each session, participants engaged in an ischemic forearm pain task (ISC) and a heat pain task. Morphine analgesic effects were derived reflecting the difference in pain outcomes between placebo and morphine conditions.. In hierarchical regressions, significant Type (CLBP vs. control)×BE interactions (Ps<0.05) were noted for morphine effects on ISC tolerance, ISC intratask pain ratings, and thermal VAS unpleasantness ratings. These interactions derived primarily from associations between higher BE levels and smaller morphine effects restricted to the CLBP subgroup. All other BE-related effects, including sex interactions, for predicting morphine analgesia failed to reach statistical significance.. BE was a predictor of morphine analgesia for only 3 out of 9 outcomes examined, with these effects moderated by chronic pain status but not sex. On the whole, results do not suggest that resting plasma BE levels are likely to be a clinically useful predictor of opioid analgesic responses.

Topics: Administration, Intravesical; Adult; Analgesics, Opioid; beta-Endorphin; Biomarkers; Chronic Pain; Cross-Over Studies; Double-Blind Method; Female; Hot Temperature; Humans; Ischemia; Low Back Pain; Male; Morphine; Pain Measurement; Pain Perception; Regression Analysis; Rest; Sex Characteristics; Treatment Outcome

Osteoarthritis of the knee is a major cause of disability among adults. Electro-acupuncture is considered a potentially useful treatment for osteoarthritis. The purpose of this study is to assess the efficacy of electro-acupuncture on pain control, pain perception, plasma cortisol and beta-endorphin levels, patient-perceived quality of life, and pain medication use in patients with chronic knee pain.. This study is a placebo-controlled, randomized, double-blind, parallel design trial. One hundred sixty out-patients who are more than 50 years old and who have osteoarthritis of the knee will be recruited from the island of Mallorca, Spain. Each participant will be randomly placed into one of two groups: (sham) electro-acupuncture non-insertion technique and real electro-acupuncture. Acupuncture treatments will be the Traditional Chinese Medicine type. The patients will be evaluated after a period of 1 month (with two weekly sessions), 3 months (with one monthly session), 6 months (with one session every 45 days), and 1 year later with follow-up sessions at the end of the study (with one session every 2 months). The primary outcomes will be based on the observed changes from the baseline of the visual analogue scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for pain measured at 12 weeks after the end of treatment. Also to be included in the study are the possible changes in the secondary efficacy variables from baseline as assessed by the Short Form 36 version 2 health survey (patient-perceived quality of life), patient plasma cortisol and beta-endorphin levels at the different treatment stages, the Goldberg Anxiety and Depression Scale, pain medication use, functional capacity and stiffness (WOMAC subscales), and a VAS. These variables will be assessed at 1 month, 3 months, 6 months, and 1 year after study commencement.. The findings from this study will help to determine whether electro-acupuncture is effective for chronic knee pain management in older people and whether electro-acupuncture can deliver results for the improvement of pain relief, stiffness, and disability. The study will therefore be a major step toward understanding the roles of the hypothalamic-pituitary-adrenal axis and the endogenous opioid system in the effectiveness of electro-acupuncture for chronic pain.. ClinicalTrials.gov identifier NCT02299713 (11 Nov. 2014).

Topics: Arthralgia; beta-Endorphin; Biomarkers; Biomechanical Phenomena; Chronic Pain; Clinical Protocols; Disability Evaluation; Double-Blind Method; Electroacupuncture; Female; Humans; Hydrocortisone; Knee Joint; Male; Middle Aged; Osteoarthritis, Knee; Pain Measurement; Quality of Life; Recovery of Function; Research Design; Spain; Surveys and Questionnaires; Time Factors; Treatment Outcome

Plasma levels of beta-endorphin (BE), an endogenous opioid analgesic, are often reported as they relate to acute and chronic pain outcomes. However, little is known about what resting plasma BE levels might reveal about functioning of the endogenous opioid antinociceptive system. This study directly examined associations between resting plasma BE and subsequent endogenous opioid analgesic responses to acute pain in 39 healthy controls and 37 individuals with chronic low back pain (LBP). Resting baseline levels of plasma BE were assessed. Next, participants received opioid blockade (8 mg naloxone i.v.) or placebo in a double-blind, randomized, crossover design. Participants then underwent two acute pain stimuli: finger pressure (FP) pain and ischaemic (ISC) forearm pain. Blockade effects (naloxone minus placebo pain ratings) were derived to index endogenous opioid analgesic function. In placebo condition analyses for both pain stimuli, higher resting BE levels were associated with subsequently greater reported pain intensity (p's < 0.05), with this effect occurring primarily in healthy controls (BE × Participant Type interactions, p's < 0.05). In blockade effect analyses across both pain tasks, higher resting plasma BE predicted less subsequent endogenous opioid analgesia (smaller blockade effects; p's < 0.05). For the ISC task, these links were significantly more prominent in LBP participants (BE × Participant Type Interactions, p's < 0.05). Results suggest that elevated resting plasma BE may be a potential biomarker for reduced endogenous opioid analgesic capacity, particularly among individuals with chronic pain. Potential clinical implications are discussed.

Topics: Acute Pain; Adult; Analgesia; beta-Endorphin; Chronic Pain; Cross-Over Studies; Double-Blind Method; Female; Humans; Low Back Pain; Male; Middle Aged; Naloxone; Narcotic Antagonists; Pain Measurement; Pain Threshold; Physical Stimulation

Chronic pain conditions, especially osteoarthritis (OA), are as common in individuals with Alzheimer's disease (AD) as in the general elderly population, which results in detrimental impact on patient's quality of life. However, alteration in perception of pain in AD coupled with deteriorating ability to communicate pain sensations often result in under-diagnosis and inappropriate management of pain. Therefore, a better understanding of mechanisms in chronic pain processing in AD is needed. Here, we explored the development and progression of OA pain and the effect of analgesics in a transgenic mouse model of AD.. Unilateral OA pain was induced chemically, via an intra-articular injection of monosodium iodoacetate (MIA) in the left knee joint of AD-mice (TASTPM) and age- and gender-matched C57BL/6J (WT). Pharmacological and biochemical assessments were conducted in plasma and spinal cord tissue.. MIA resulted in hind paw mechanical hypersensitivity (allodynia), initiating on day 3, in TASTPM and WT controls. However, from 14 to 28 days, TASTPM displayed partial attenuation of allodynia and diminished spinal microglial response compared to WT controls. Naloxone, an opioid antagonist, re-established allodynia levels as observed in the WT group. Morphine, an opioid agonist, induced heightened analgesia in AD-mice whilst gabapentin was devoid of efficacy. TASTPM exhibited elevated plasma level of β-endorphin post-MIA which correlated with impaired allodynia.. These results indicate an alteration of the opioidergic system in TASTPM as possible mechanisms underlying impaired persistent pain sensitivity in AD. This work provides basis for re-evaluation of opioid analgesic use for management of pain in AD.. This study shows attenuated pain-like behaviour in a transgenic mouse model of Alzheimer's disease due to alterations in the opioidergic system and central plasticity mechanisms of persistent pain.

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Analgesics; Analgesics, Opioid; Animals; Arthralgia; Behavior, Animal; beta-Endorphin; Chronic Pain; Disease Models, Animal; Enzyme Inhibitors; Gabapentin; Humans; Hyperalgesia; Injections, Intra-Articular; Iodoacetic Acid; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Morphine; Naloxone; Narcotic Antagonists; Osteoarthritis; Pain Measurement; Pain Threshold; Quality of Life; Spinal Cord

This study is aimed at examining the long-term effects of chronic pain during early life (postnatal day 0 to 8weeks), and intervention using sucrose, on cognitive functions during adulthood in rats. Pain was induced in rat pups via needle pricks of the paws. Sucrose solution or paracetamol was administered for analgesia before the paw prick. Control groups include tactile stimulation to account for handling and touching the paws, and sucrose alone was used. All treatments were started on day one of birth and continued for 8weeks. At the end of the treatments, behavioral studies were conducted to test the spatial learning and memory using radial arm water maze (RAWM), as well as pain threshold via foot-withdrawal response to a hot plate apparatus. Additionally, the hippocampus was dissected, and blood was collected. Levels of neurotrophins (BDNF, IGF-1 and NT-3) and endorphins were assessed using ELISA. The results show that chronic noxious stimulation resulted in comparable foot-withdrawal latency between noxious and tactile groups. On the other hand, pretreatment with sucrose or paracetamol increased pain threshold significantly both in naive rats and noxiously stimulated rats (P<0.05). Chronic pain during early life impaired short-term memory, and sucrose treatment prevented such impairment (P<0.05). Sucrose significantly increased serum levels of endorphin and enkephalin. Chronic pain decreased levels of BDNF in the hippocampus and this decrease was prevented by sucrose and paracetamol treatments. Hippocampal levels of NT-3 and IGF-1 were not affected by any treatment. In conclusion, chronic pain induction during early life induced short memory impairment, and pretreatment with sucrose prevented this impairment via mechanisms that seem to involve BDNF. As evident in the results, sucrose, whether alone or in the presence of pre-noxious stimulation, increases pain threshold in such circumstances; most likely via a mechanism that involves an increase in endogenous opioids.

Topics: Acetaminophen; Analgesics; Animals; Animals, Newborn; beta-Endorphin; Chronic Pain; Disease Models, Animal; Female; Hippocampus; Intercellular Signaling Peptides and Proteins; Learning; Male; Maze Learning; Memory; Pain Measurement; Pain Threshold; Physical Stimulation; Pregnancy; Rats; Sucrose

To observe the analgesic effect of electroacupuncture (EA) on collagen-induced arthritis (CIA) rats and its regulating effect on inflammation reaction and the endogenous opioid system of synovial tissues. Methods A total of 30 healthy male Wistar rats were randomly divided into a control group, a model group and an EA group, 10 rats in each one. The chronic pain model of CIA rats was made by cattle type-II collagen in the model group and EA group. Rats in the EA group were treated with EA at "Zusanli" (ST 36) and "Kunlun" (BL 60) for 30 min from 16th day after model establishment, once a day for consecutive 10 days. Rats in the control group did not receive any treatment. Rats in the model group were treated with fixation as the EA group. Threshold of pain, arthritis index, paw swelling were measured before model establishment and 16 d, 20 d, 23 d and 25 d after model establishment. The levels of beta-endorphin (β-END), met-enkephalin (met-ENK), dynorphin A (Dyn A) were measured by radioimmunoassay; the mRNA expressions of mu opioid receptor (MOR), kappa opioid receptor (KOR) and delta opioid receptor (DOR) in synovial tissues of CIA rats were detected by I quantitative polymerase chain reaction (qPCR).. Compared with the control group, threshold of pain was reduced (all P<0. 01), arthritis index was increased (all P<0. 01) and paw swelling was increased (all P<0. 01) in the model group on the 16th day, 20th day, 23rd day, 25th day after model establishment. Compared with the model group, the threshold of pain was increased in the EA group (all P<0. 01), arthritis index and paw swelling were reduced (all P<0. 01) on the 23rd day and 25th day after model establishment. Compared with the control group, the level of Dyn A in synovial tissues of CIA rats was increased in the model group (P<0. 01); the mRNA expressions of MOR, KOR and DOR were down-regulated lower than 0. 5 fold of normal level. Compared with the model group, the level of β-END in synovial tissues of the knee joint was increased in the EA group (P<0. 05), and the mRNA expressions of MOR, KOR and DOR in synovial tissues of CIA rats were up-regulated more than 2 folds of normal level.. The intervention of EA on chronic pain of CIA rats is superior, which is likely to be related with effects of EA on anti-inflammation and up-regulation of synovial tissue β-END and MOR, KOR, DOR.

Topics: Acupuncture Analgesia; Acupuncture Points; Analgesics, Opioid; Animals; Arthritis, Rheumatoid; beta-Endorphin; Cattle; Chronic Pain; Dynorphins; Electroacupuncture; Enkephalin, Methionine; Humans; Male; Rats; Rats, Wistar; Receptors, Opioid, mu; Synovial Fluid

Pain medicine still lacks mechanism-specific biomarkers to guide diagnosis and treatment, and defective top-down modulation is an important factor in the pathophysiology of chronic pain conditions. Using modern analytical tools and advanced multivariate statistical analysis, the aim of this study was to revisit two classical potential biomarkers of pro- and anti-nociception in humans (substance P and beta-endorphin), focusing particularly on the cerebrospinal fluid (CSF).. Cross-sectional, comparative, observational study.. Patients with chronic, post-traumatic and/or post-surgical, neuropathic pain refractory to conventional treatment (N = 15) and healthy controls (N = 19) were included.. Samples were taken from CSF and blood, and levels of substance P and beta-endorphin were investigated using a Luminex technology kit.. We found low levels of beta-endorphin in the CSF of neuropathic pain patients (66 ± 11 pcg/mL) compared with healthy controls (115 ± 14 pcg/mL) (P = 0.017). Substance P levels in the CSF did not differ (20 ± 2 pcg/mL, 26 ± 2, P = 0.08). However, our multivariate data analysis showed that belonging to the patient group was associated with low levels of both substances in the CSF. A higher correlation between the levels of beta-endorphin and substance P in CSF was found in healthy controls than in patients (rs  = 0.725, P < 0.001 vs. rs  = 0.574, P = 0.032).. Patients with chronic neuropathic pain due to trauma or surgery had low levels of beta-endorphin in the CSF. We speculate that this could indicate a defective top-down modulation of pain in chronic neuropathic pain. Our results also illustrate the importance of taking a system-wide, multivariate approach when searching for biomarkers.

Topics: Adult; Analgesics; beta-Endorphin; Biomarkers; Chronic Pain; Clinical Trials as Topic; Cross-Sectional Studies; Female; Humans; Male; Middle Aged; Neuralgia; Pain, Intractable; Pain, Postoperative; Substance P

Authors studied changes in the levels of antibodies to endogenous bioregulators (Ab) to Β-endorphin, orphanin, serotonin, dopamine and angiotensin in 36 healthy people and 109 patients with dorsopathy with chronic pain syndrome. The association of these immunological indicators with age and sex was found. It has been concluded that the levels of Ab to endogenous bioregulators may be considered as a marker of algic system pathology that does not depend on age and is sex-related.

Topics: Adolescent; Adult; Age Factors; Aged; Angiotensins; Antibodies; beta-Endorphin; Biomarkers; Case-Control Studies; Chronic Pain; Dopamine; Female; Humans; Lumbar Vertebrae; Male; Middle Aged; Nociceptin; Opioid Peptides; Serotonin; Sex Factors; Spinal Cord Diseases

GPR40 has been reported to be activated by long-chain fatty acids, such as docosahexaenoic acid (DHA). However, reports studying functional role of GPR40 in the brain are lacking. The present study focused on the relationship between pain regulation and GPR40, investigating the functional roles of hypothalamic GPR40 during chronic pain caused using a complete Freund's adjuvant (CFA)-induced inflammatory chronic pain mouse model. GPR40 protein expression in the hypothalamus was transiently increased at day 7, but not at days 1, 3 and 14, after CFA injection. GPR40 was co-localized with NeuN, a neuron marker, but not with glial fibrillary acidic protein (GFAP), an astrocyte marker. At day 1 after CFA injection, GFAP protein expression was markedly increased in the hypothalamus. These increases were significantly inhibited by the intracerebroventricular injection of flavopiridol (15 nmol), a cyclin-dependent kinase inhibitor, depending on the decreases in both the increment of GPR40 protein expression and the induction of mechanical allodynia and thermal hyperalgesia at day 7 after CFA injection. Furthermore, the level of DHA in the hypothalamus tissue was significantly increased in a flavopiridol reversible manner at day 1, but not at day 7, after CFA injection. The intracerebroventricular injection of DHA (50 µg) and GW9508 (1.0 µg), a GPR40-selective agonist, significantly reduced mechanical allodynia and thermal hyperalgesia at day 7, but not at day 1, after CFA injection. These effects were inhibited by intracerebroventricular pretreatment with GW1100 (10 µg), a GPR40 antagonist. The protein expression of GPR40 was colocalized with that of β-endorphin and proopiomelanocortin, and a single intracerebroventricular injection of GW9508 (1.0 µg) significantly increased the number of neurons double-stained for c-Fos and proopiomelanocortin in the arcuate nucleus of the hypothalamus. Our findings suggest that hypothalamic GPR40 activated by free long chain fatty acids might have an important role in this pain control system.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Astrocytes; Benzoates; beta-Endorphin; Chronic Pain; Disease Models, Animal; DNA-Binding Proteins; Docosahexaenoic Acids; Flavonoids; Freund's Adjuvant; Gene Expression; Glial Fibrillary Acidic Protein; Hyperalgesia; Injections, Intraventricular; Male; Methylamines; Mice; Nerve Tissue Proteins; Neuroglia; Nuclear Proteins; Pain Management; Piperidines; Pro-Opiomelanocortin; Propionates; Pyrimidines; Receptors, G-Protein-Coupled; Signal Transduction; Time Factors