Fuzhou Wang

Life is the rhythmic song needing to play with heart. Medicine is the tuner for the rhythmic life.

Opioids are still the most popular form of pain treatment, but many unavoidable side effects make opioids a big challenge in effective pain management. Opioid-induced hyperalgesia (OIH), a paradoxical phenomenon, portrays an increased sensitivity to harmful stimuli caused by opioid exposure. Changes in the neural modulation are considered a major contributor to the development of OIH. Activation of opioid receptors (ORs) and corresponding downstream molecules are the vital composition of functional performance of opioids. Increasing interests were proposed of the interaction between ORs and other neural transmitter systems such as glutamatergic, GABAergic and adrenergic ones to the genesis of OIH. G protein coupled μ-opioid receptor (MOR) was studied comprehensively on its role in the development of OIH. In addition to the relationship between MOR and other neurotransmitter receptors, a new intracellular MOR that has six transmembrane (6TM) domains was identified, and found to perform a pro-nociceptive task in contrast to the counterpart 7TM isoform. A mechanistic model of OIH in which both 6TM and 7TM MORs undergoing membrane redistribution upon opioid exposure is proposed which eventually facilitates the neurons more sensitive to nociceptive stimulation than that of the preceding opioid exposure.

Inflammation is the initial step of physiological defense against injury, and also the mainstay of the pathogenesis and development of different diseases. The balance between pro- and anti-inflammation is maintained through the involvement of various molecules. The activation of glucocorticoid receptor (GR) plays an essential role in contributing to the anti-inflammatory effect of endogenous cortical steroids and exogenous glucocorticoids (GC). During the GR activation process, receptor accessory proteins (RAPs) are important parts functioning as critical components of GR-associated signaling cascades. The binding of GR with its ligand GC and the subsequent transfer of heterologous receptor complex need the participation and regulation of various molecular chaperones. Determining the precise interaction between GR and the RAPs can help to understand the underlying molecular mechanisms of GR activation, and to insight into the potential therapeutics of GC-related treatment. We herein review the up-to-date development of RAPs, and present a new model of GR signaling activation.

To compare the analgesic efficacy and safety of the sole local anesthetic ropivacaine with the combination of both local anesthetic ropivacaine and opioidergic analgesic sufentanil given epidurally on the labor pain control.After institutional review board approval and patient consent, a total of 500 nulliparas requesting epidural labor analgesia were enrolled and 481 eventually were randomized into 2 groups: a sole local anesthetic group (ropivacaine 0.125%) and a combination of local anesthetic and opioidergic analgesic group (0.125% ropivacaine + 0.3 μg/mL sufentanil). After the test dose, a 10-mL epidural analgesic solution was given in a single bolus, followed by intermittent bolus injection of 10 to 15 mL of the solution. The primary outcome was the analgesic efficacy measured using Numerical Rating Scale (NRS) of pain. Other maternal and infant variables were evaluated as secondary outcomes.A total of 346 participants completed the study. The median NRS pain score during the 1st stage of labor was significantly lower in the combination group 2.2 (interquartile range [IQR]: 1.8-2.7) comparing to the sole local analgesic group 2.4 (IQR: 2.0-2.8) (P < 0.0001). No significant difference was observed in NRS pain score prior epidural analgesia and during the 2nd stage of labor. Patients in both groups rated same satisfaction of analgesia. Patients in the sole local analgesic group experienced fewer side effects than those in the combination group (37.7% vs 47.2%, P = 0.082). The individual analgesia-related cost in the sole local analgesic group was less ($5.7 ± 2.06) than that in the combination group ($9.76 ± 3.54) (P < 0.0001). The incidence of 1-minute Apgar ≤ 7 was lower in the sole local analgesic group 2 (1.2%) than the combination group 10 (5.5%) (P = 0.038). No difference was found between other secondary outcomes.The sole local anesthetic ropivacaine produces a comparable labor analgesic effect as the combination of both local anesthetic ropivacaine and opioidergic analgesic sufentanil at different stages of labor (ΔNRS = 0.2) but the former has less side effects, lower cost, and less incidence of lower 1-minute Apgar scoring. These results imply the necessity of a systematic reevaluation of epidural labor analgesia with sole local anesthetics against combination regimens of local anesthetics and other opioids.

Although pain is the most awful feeling for personal perception, it possesses critical benefits for preventing our human being to be injured further. Pain itself forms an overbalanced microenvironment in which people undertakes individualized changes in its neurobiological, psychological, endocrinological and genetic properties especially in the context of chronic pain or when the acute pain transmitted to chronicity. Our previous part (Part I) review the general epigenetic modification of nociceptive contributing factors in the context of chronic pain. Herein (Part II) we paid specific attention on the epigenetic regulation of pain-associated molecules including neurotransmitters and other factors. A detailed understanding of the specific modulating factors that influence individual epigenetic differences contributing to pain sensitivity and responsiveness to analgesics possesses essential implications in clinical pain management.

Our previous work found that tumor suppressor menin potentiates spinal synaptic plasticity in the context of peripheral nerve injury-induced neuropathic hypersensitivity, but the underlying molecular mechanisms are not clear. We hereby assessed the role of menin in regulating the spinal balance between glutamate and GABA and its contribution to the pathological condition of nerve injury-induced hypersensitivity. In spared nerve injury induced C57BL/6 mice, mechanical withdrawal threshold was measured with von Frey filaments after intrathecal administration of small interfering RNA (siRNA) of MEN1 or/and subcutaneous histone deacetylase (HDAC) inhibitors to control the level of glutamic acid decarboxylase 65 (GAD65). Immunoblotting and high-performance liquid chromatography were used to detect the level of protein expression and spinal glutamate and GABA, respectively. Genetic knockdown of spinal menin alleviated nerve injury evoked mechanical hypersensitivity, which was strongly associated with the alteration of the spinal level of GAD65 that resulted in an imbalance of glutamate/GABA ratio from the baseline ratio of 5.8 ± 0.9 (×10(-4)) to the peak value of 58.6 ± 11.8 (×10(-4)) at the day 14 after SNI (p < 0.001), which was reversed by MEN1 siRNA to 14.7 ± 2.1 (×10(-4)) at the day 14 after nerve injury (p < 0.01). In further, selective inhibitors of HDACs considerably reversed the ratio of spinal glutamate and GABA, and also alleviated the mechanical withdrawal threshold markedly. Our findings provide mechanistic insight into the contribution of the upregulated spinal menin to peripheral nerve injury induced neuropathic hypersensitivity by regulating glutamate-GABA balance through deactivating GAD65.

Cumulating evidence indicated that nerve injury-associated cellular and molecular changes play an essential role in contributing to the development of pathological pain, and more recent findings implicated the critical role of epigenetic mechanisms in pain-related sensitization in the DRG subsequent to nerve injury. In this part of the dyad review (Part II), we reviewed and paid special attention on the etiological contribution of DGR gene expression modulated by epigenetic mechanisms of CRPS. As essential effectors to different molecular activation, we first discussed the activation of various signaling pathways that subsequently from nerve injury, and in further illustrated the fundamental and functional underpinnings of nerve injury-induced pain, in which we argued for the potential epigenetic mechanisms in response to sensitizing stimuli or injury. Therefore, understanding the specific mediating factors that influence individual epigenetic differences contributing to pain sensitivity and responsiveness to analgesics possesses crucial clinical implications.