Alterations in the spinal cord microenvironment in a neuropathic pain model in rats comprising right L-4 spinal nerve lesion were examined following 1, 2, 4 and 10 weeks using albumin and glial fibrillary acidic protein (GFAP) immunoreactivity. Rats subjected to nerve lesion showed pronounced activation of GFAP indicating astrocyte activation, and exhibited marked leakage of albumin, suggesting defects of the blood-spinal cord barrier (BSCB) function in the corresponding spinal cord segment. The intensities of these changes were most prominent in the gray matter of the lesioned side compared to the contralateral cord in both the dorsal and ventral horns. The most marked changes in albumin and GFAP immunoreaction were seen after 2 weeks and persisted with mild intensities even after 10 weeks. Distortion of nerve cells, loss of neurons and general sponginess were evident in the gray matter of the spinal cord corresponding to the lesion side. These nerve cell and glial cell changes was mainly evident in the areas showing leakage of endogenous albumin in the spinal cord. These novel observations indicate that chronic nerve lesion has the capacity to induce a selective increase in local BSCB permeability that could be instrumental in nerve cell and glial cell activation. These findings may be relevant to our current understanding on the pathophysiology of neuropathic pain.

This research suggests that activation of MC4R in PAG after peripheral nerve injury participates in pain facilitation by regulating the glial activation and inflammatory cytokines secretion.

Aims: Chronic, infrequent voiding may be a risk factor for lower urinary tract symptoms (LUTS) in women. To inform this hypothesis, we conducted a rapid literature review and meta-analysis of LUTS by occupation as an indirect measure of infrequent voiding behaviors. Methods: Two independent medical librarians searched Pubmed.gov studies (1990–2017) on adult women for occupations, industries, and workplace environment and LUTS outcomes: overactive bladder (OAB), urinary incontinence (UI), urinary tract infections (UTIs), and individual voiding and storage LUTS. Two authors reviewed full text articles meeting content criteria. Among studies with similar UI definitions, we estimated the prevalence of monthly UI using a random effects meta-analysis model. Results: Of 1078 unique citations identified, 113 underwent full article review and 33 met inclusion criteria. Twenty-six of these studies examined specific occupation groups, including nurses/midwives (n = 6 studies), healthcare workers/support staff (n = 6), military personnel (n = 3), teachers (n = 3), and other groups (n = 7), whereas eight compared findings across broad occupation groups. UI was reported in 30 studies (23% using validated measures), OAB in 6 (50% validated), and UTIs in 2 (non-validated). In pooled models, the degree of heterogeneity was too high (I2 = 96.9–99.2%) among the studies to perform valid prevalence estimates for LUTS. Conclusions: Current literature limits the ability to evaluate LUTS by occupation types. Future studies should characterize voiding frequency and toilet access in a consistent manner by occupation and explore its relation to LUTS development.

Melanocortin 4 receptor (MC4R) is implicated in the initiation and maintenance of neuropathic pain. Although the effect of MC4R on neuropathic pain is known, it remains unclear how MC4R mediates neuropathic pain. In vitro MC4R activates mitogen-activated kinase (MAPK). Accordingly, we investigate whether MC4R activates the p38MAPK cascade in vivo to trigger pain behavior of Wistar rats after chronic constriction injury (CCI). Intrathecal injection of MC4R antagonist HS014 (5 μg/day) at the moment of CCI for seven days attenuated thermal hyperalgesia and mechanical allodynia. Similarly, intrathecal injection of a p38 inhibitor (SB203580, 10 mg/day) at the moment of CCI for seven days was also effective. To assess whether the effects of HS014 were mediated via increased p38MAPK activation, ipsilateral L4 and L5 dorsal root ganglion (DRG) were analyzed for MC4R and phosphorylated p38MAPK (p-p38MAPK) after CCI alone or CCI combined with HS014 treatment or SB203580 treatment. After CCI, DRG p-p38MAPK and MC4R were elevated by three, seven, and 14 days. Treatment with SB203580 blocked p38 activation. Both MC4R and phosphorylated p38 localized in DRG neurons. These data suggest a sequential role for MC4R and p38 in the induction and maintenance of neuropathic pain. MC4R plays an important role in the establishment of neuropathic pain following CCI, seemingly dependent on p38 activation.

Cell autophagy and cell apoptosis are both observed in the process of hypoxia-induced ischemic cerebral infarction (ICI). Unc-51 like autophagy activating kinase 1 (Ulk1) and FUN14 Domain-containing Protein 1 (FUNDC1) are both involved in the regulation of cell autophagy. This study aimed to investigate the regulatory effects of Ulk1 and FUNDC1 on hypoxia-induced nerve cell autophagy and apoptosis. Cell viability was measured using cell counting kit-8 (CCK-8) assay. Cell apoptosis was detected using Annexin V-PE/7-ADD staining assay. qRT-PCR was used to quantify the mRNA levels of Ulk1 and FUNDC1 in PC-12 cells. Cell transfection was performed to up-regulate the expression of Ulk1. 3-Methyladenine (3-MA) was used as autophagy inhibitor and rapamycin was used as autophagy activator in our experiments. SP600125 was used as c-Jun N-terminal kinase (JNK) inhibitor. Western blotting was performed to analyze the expression levels of key factors that are related to cell autophagy, apoptosis and JNK pathway. We found that hypoxia simultaneously induced apoptosis and autophagy of PC-12 cells. The activation of Ulk1 and FUNDC1 were also found in PC-12 cells after hypoxia induction. Overexpression of Ulk1 promoted the activation of FUNDC1 and prevented PC-12 cells from hypoxia-induced apoptosis. Suppression of Ulk1 had opposite effects. Furthermore, we also found that JNK pathway participated in the effects of Ulk1 overexpression on PC-12 cell apoptosis reduction. To conclude, Ulk1/FUNDC1 played critical regulatory roles in hypoxia-induced nerve cell autophagy and apoptosis. Overexpression of Ulk1 prevented nerve cells from hypoxia-induced apoptosis by promoting cell autophagy.

Morphine creates a neuroinflammatory response and enhances release of the proinflammatory cytokines like interleukin-1β (IL-1β), which compromises morphine analgesia as well as induces morphine tolerance. In this study, we attempted to investigate the mechanisms of morphine induced IL-1β synthesis and release. Microglial cells were treated with morphine (100 μM) once daily for 3 days. Control groups underwent the same procedure but received sterile saline injection instead of morphine. Toll-like receptor 4 (TLR4) and P2X4 receptor (P2X4R) signaling were analyzed using Western blot; immunofluorescence was used to detect the signaling of CD68; real-time RT-PCR and ELISA kit was used to measure the messenger RNA and protein synthesis and release level of IL-1β. Morphine enhanced IL-1β synthesis and P2X4R protein expression. TLR4 were responsible for morphine-induced IL-1β synthesis, while morphineinduced IL-1β release was via P2X4R. Morphineinduced IL-1β release is mediated by endocytosis of TLR4. These results indicated that TLR4 and P2X4R pathways mediated IL-1β synthesis and release in microglia followed chronic morphine. TLR4 internalization is the main mechanism of morphine-induced microglia activation and IL-1β release.

BackgroundNeuropathic pain can develop after nerve injury, when deleterious changes occur in injured neurons and glia cells. Melanocortin 4 receptor (MC4R) is involved in the regulation of pain due to its high expressions in brain. Moreover, MC4R could mediate the c-Jun N-terminal kinase (JNK) signaling pathway, but whether the MC4R-regulated JNK signaling pathway participated in neuropathic pain after chronic constriction injury (CCI) is still unclear.MethodsA total of 128 Sprague-Dawley rats were allocated into four experiment groups: the SHAM group, CCI + NaCl group, CCI + HS group, and CCI + SP + HS group. For the CCI + NaCl group, the sciatic nerves were ligated. For the SHAM group, an identical manner to the CCI without ligation was performed. For CCI + HS and CCI + SP + HS groups, rats were injected with MC4R inhibitor (HS014) and HS014 plus JNK inhibitor (SP600125), respectively, from days 3 to 14 after CCI. Paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) were used to assess the nociceptive behavior. ELISA was used to detect the levels of inflammatory cytokines. qRT-PCR and Western blots (WB) were utilized to examine the mRNA and protein expressions of JNK signaling pathway-related genes. Meanwhile, the expression levels of MC4R and p-JNK were further evaluated by immunohistochemistry (IHC) and immunofluorescence (IF) experiments. Finally, in order to confirm the in vivo results, astrocytes were isolated and transfected with MC4R-overexpression plasmid. Furthermore, the protein expressions of JNK signaling pathway-related genes were tested by WB.ResultsIt was showed that the values of PWL and PWT were significantly increased in CCI + HS group and CCI + SP + HS group compared with CCI + NaCl group. The increased interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) secretion in CCI + NaCl group was lowered by HS and SP + HS. MC4R, p-JNK, ATF3, and c-Jun levels were up-regulated with CCI surgery, but down-regulated with HS and SP + HS treatments. Moreover, the IHC and IF results further revealed that MC4R and p-JNK expressions in CCI + NaCl group were remarkably higher than those in HS group and HS + SP group. In vitro data also indicated that HS, SP, and SP + HS could down-regulate the expressions of MC4R, p-JNK, ATF3, and c-Jun in M1830 astrocytes.ConclusionOur findings indicated that MC4R is involved in neuropathic pain by regulating JNK signaling pathway after CCI.

Aims: Hyperbilirubinemia is associated with postoperative acute kidney injury in patients undergoing cardiac surgeries. A high concentration of bilirubin could induce oxidative stress and cell apoptosis. The aim of this study was to investigate whether hyperbilirubinemia aggravated the renal tubule cells injury and the pro-apoptotic potential of bilirubin on renal ischemia reperfusion injury (RIRI). Methods: The human proximal tubular epithelial cell line HK-2 cells were challenged with a gradient concentration of bilirubin for 24 h. Cell injury was assessed by flow cytometry and MTT assay. Bilirubin was injected intraperitoneally into male Sprague-Dawley rats once every 12 h (100 mg/kg), 3 times in total. The same solvent volume without bilirubin powder was used as vehicle in non-bilirubin injection groups. The RIRI surgical procedure was a bilateral renal pedicles clamping (45 min) followed by 30 h reperfusion. The rats were divided into 4 groups: negative control (NC), similar surgical procedures without clamping; Bil, bilirubin injection for 36 h, then rats were sacrificed; RIRI, RIRI surgical procedures; Bil + RIRI, RIRI applied 6 h later than the first bilirubin injection, rats were sacrificed after another 30 h. Results: In vitro, bilirubin induced cell apoptosis and significantly decreased the cell viability of HK-2 cells. Bilirubin induced the active caspase 3 and phosphorylation of p38 in HK-2 cells. In vivo, serum creatinine was higher in Bil + RIRI compared with RIRI (p < 0.01). The tubular injury scores of hematoxylin and eosin and tubular necrosis scores of periodic acid-Schiff were higher in Bil + RIRI than these in RIRI (All p < 0.05). The number of Tunel-positive nuclei was higher in Bil + RIRI compared to RIRI (p < 0.001). The active caspase 3 and phosphorylation of p38 were higher and the Bcl2 was lower in Bil + RIRI compared to RIRI. Moreover, the apoptosis level was higher in Bil compared to NC. Conclusions: Our results reveal that the hyperbilirubinemia induces pro-apoptotic effects and aggravates RIRI.