ABSTRACT
Increasing evidence supported that oxidative stress induced by herniated lumbar disc played important role in the formation of lumbar disc herniation sciatica (LDHS), however, the neural mechanisms underlying LDHS need further clarification. Endomorphin-2 (EM2) is the endogenous ligand for mu-opioid receptor (MOR), and there is increasing evidence implicating the involvement of spinal EM2 in neuropathic pain. In this study, using an nucleus pulposus implantation induced LDHS rat model that displayed obvious mechanical allodynia, it was found that the expression of EM2 in dorsal root ganglion (DRG) and spinal cord was significantly decreased. It was further found that oxidative stress in DRG and spinal cord was significantly increased in LDHS rats, and the reduction of EM2 in DRG and spinal cord was determined by oxidative stress dominated increment of dipeptidylpeptidase IV activity. A systemic treatment with antioxidant could prevent the forming of mechanical allodynia in LDHS rats. In addition, MOR expression in DRG and spinal cord remained unchanged in LDHS rats. Intrathecal injection of MOR antagonist promoted pain behavior in LDHS rats, and the analgesic effect of intrathecal injection of EM2 was stronger than that of endomorphin-1 and morphine. Taken together, our findings suggest that oxidative stress mediated decrement of EM2 in DRG and spinal cord causes the loss of endogenous analgesic effects and enhances the pain sensation of LDHS.
Subject(s)
Intervertebral Disc Displacement , Oligopeptides , Oxidative Stress , Rats, Sprague-Dawley , Sciatica , Animals , Oxidative Stress/physiology , Oxidative Stress/drug effects , Intervertebral Disc Displacement/metabolism , Rats , Oligopeptides/pharmacology , Sciatica/metabolism , Sciatica/drug therapy , Male , Spinal Cord/metabolism , Spinal Cord/drug effects , Lumbar Vertebrae , Ganglia, Spinal/metabolism , Ganglia, Spinal/drug effects , Receptors, Opioid, mu/metabolismABSTRACT
Patients with colorectal cancer (CRC) are at high risk of frailty, leading to reduced quality of life and survival. Diet is associated with frailty in the elderly through regulating inflammation. Thus, we hypothesized that dietary inflammatory potential (as assessed by dietary inflammatory index [DII]) might be associated with frailty in patients with CRC through regulating inflammatory biomarkers. A total of 231 patients with CRC were included in this cross-sectional study. Dietary intake was evaluated by 3-day, 24-hour dietary recalls, and frailty status was assessed in accordance with the Fried frailty criteria. Plasma inflammatory cytokines were determined in 126 blood samples. A total of 67 patients (29.0%) were frail, with significantly higher DII scores than nonfrail patients, accompanied with significantly increased interleukin-6 (IL-6) and decreased interleukin-10 (IL-10) concentrations. Each 1-point increase of DII was related to a 25.0% increased risk of frailty. IL-6 was positively correlated with frailty and DII, whereas IL-10 was negatively correlated. After adjusting for age, sex, body mass index, education level, smoking status, and energy, mediation analysis revealed that the association between DII and frailty was significantly mediated by IL-6 (average causal mediation effect [ACME], 0.052; 95% confidence interval, 0.020-0.087; P = .002) and IL-10 (ACME, 0.025; 95% confidence interval, 0.004-0.063; P = .016). The ρ values for the sensitivity measure at which estimated ACMEs were zero were 0.3 and -0.2 for IL-6 and IL-10, respectively. Therefore, a pro-inflammatory diet was associated with frailty in patients with CRC possibly in part by affecting circulating IL-6 and IL-10 concentrations.
