Mitigating ammonia emission from agriculture reduces PM2.5 pollution in the Hai River Basin in China

The Hai River Basin (HRB), one of the most populated areas in China, is experiencing high NH₃ emissions, mostly from agricultural sources, and suffering from strongly enhanced PM_2.5 concentrations in all urban areas. Further population growth and urbanization projected until 2030 may exacerbate this situation. Here, the NUFER (NUtrient flows in Food chains, Environment and Resources use) and GAINS (Greenhouse gas - Air pollution Interactions and Synergies) models have been coupled for the first time to understand possible changes of agricultural NH₃ emission between 2012 and 2030 and their impacts on ambient PM_2.5 concentrations, and to explore options to improve this situation. Results show that agricultural ammonia emissions in the HRB were 1179kt NH₃ in 2012, 45% of which was from the hotspots at or near conurbation areas, including Beijing-Tianjin, Tangshan-Qinhuangdao, Shijiazhuang-Baoding, Dezhou, Handan-Liaocheng, and Xinxiang. Without intervention, agricultural ammonia emissions will further increase by 33% by 2030. The impacts of several scenarios were tested with respect to air pollution. Compared to the business-as-usual scenario, a scenario of improved technology and management combined with human diet optimization could greatly reduce emission (by 60%), and lead to 22-43% and 9-24% decrease of the secondary inorganic aerosols and PM_2.5 concentrations, respectively, in the hotspots of NH₃ emissions. Our results further confirmed that ammonia control is needed for air pollution abatement strategies (SO₂, NO_x and primary PM reduction) to be effective in terms of PM_2.5.

Tracing nitrate sources with dual isotopes and long term monitoring of nitrogen species in the Yellow River, China

A heavy load of nitrogenous compounds reflects nutrient loss and influences water quality in large rivers. Nitrogenous concentrations and dual isotopes of nitrate were measured to ascertain the spatial and temporal distributions of nitrate transformation in the Yellow River, the second-longest river in China. Assessment of the long-term record indicates that [NO₃^--N] has increased by two-fold over the past three decades. Weekly observation of ammonium over a twelve-year period revealed high concentrations and suggests impairment of water quality, particularly since 2011. The estimated total dissolved nitrogen flux was 7.2 times higher in middle reaches than that at head waters. Anthropogenic nitrogen sources become more important in lower section of the upper reaches and middle reaches because of intensive agricultural activities and urban input. Nitrate in the lower reaches was mainly derived from transportation of upstream nitrate and point sources from cities. The spatial variation of ammonium and nitrate isotopes show that nitrification is a key process governing nitrogen transformation. Riverine biological processes could potentially be responsible for the shift of nitrate isotope signature. The first step to reducing nitrogen load and improving water quality will be containment and careful management of sources from urban input, sewage waste and irrigation runoff.

[Prognostic factors of postoperative delayed gastric emptying after pancreaticoduodenectomy: a predictive model]

Objective: To study the prognostic factors of delayed gastric emptying(DGE) after pancreaticoduodenectomy(PD) and construct a prognostic predictive model for clinical application. Methods: Clinic data of 401 consecutive patients who underwent PD between January 2012 and July 2016 in the First Affiliated Hospital of Harbin Medical University were retrospectively collected and analyzed. The patients were randomly selected to modeling group(n=299) and validation group(n=102) at a ratio of 3∶1. The data of modeling group were subjected to univariate and multivariate analysis for prognostic factors and to construct a prognostic predictive model of DGE after PD. The data of validation group were applied to test the prognostic predictive model. Results: DGE after PD occurred in 35 of 299 patients(11.7%) in the modeling group. The multivariate analysis of the modeling group showed that upper abdominal operation history(χ(2)=6.533, P=0.011), diabetes mellitus(χ(2)=17.872, P=0.000), preoperative hemoglobin <90 g/L(χ(2)=14.608, P=0.000) and pylorus-preserving pancreaticoduodenectomy(PPPD)(χ(2)=8.811, P=0.003) were associated with DGE after PD independently. A prognostic predictive model of DGE after PD was constructed based on these factors and successfully tested. The area under the receiver operating characteristic(ROC) curve was 0.761(95%CI: 0.666-0.856) of the modeling group and 0.750(95% CI: 0.577-0.923) of the validation group. Conclusions: Upper abdominal operation history, diabetes mellitus, preoperative hemoglobin<90 g/L and PPPD are associated with DGE after PD independently. The preoperative assessment of a patient's prognostic for DGE after PD is feasible. The model is a valid tool to take precautions against DGE after PD.

Comparative transcriptome analysis of self-incompatible flower stigmas and self-compatible bud stigmas following self-pollination in broccoli

DH07 is a DH line of Class I S-haplotype in broccoli (Brassica oleracea var. italica), in which stigmas of flowers show self-incompatibility (SI) and stigmas of buds show self-compatibility (SC). The molecular mechanisms that lead to stigmas at different developmental stages having different responses to self-pollination are yet unknown. In the present study, comparative transcriptome profiling of the stigmas of flowers and buds before and after self-pollination was performed by RNA-sequencing using an Illumina HiSeq^TM 2000. A total of 80,102,897 reads were generated for further analysis in four libraries. Comparisons of the transcriptome profiles before and after self-pollination revealed 579 differentially expressed genes (DEGs) in the stigmas of buds (SBs); of these, 431 DEGs showed increased and 148 DEGs showed decreased transcript abundance after self-pollination in SBs. There were a total of 686 DEGs between unpollinated stigmas of flowers (SFs) and pollinated SFs, among which, 517 DEGs were up regulated and 169 DEGs were down regulated. Following the self-pollination, 379 identified DEGs were common in both SBs and SFs. It was found that ARR7-like and oxysterol-binding family protein related DEGs could play key roles in SI or SC signal transduction. The results obtained in this study would form the foundation for further studies on investigating the molecular mechanisms of SI and SC in Brassica.

In-depth analysis of internal control genes for quantitative real-time PCR in Brassica oleracea var. botrytis

Quantitative reverse-transcription PCR (qRT-PCR) is a versatile technique for the analysis of gene expression. The selection of stable reference genes is essential for the application of this technique. Cauliflower (Brassica oleracea L. var. botrytis) is a commonly consumed vegetable that is rich in vitamin, calcium, and iron. Thus far, to our knowledge, there have been no reports on the validation of suitable reference genes for the data normalization of qRT-PCR in cauliflower. In the present study, we analyzed 12 candidate housekeeping genes in cauliflower subjected to different abiotic stresses, hormone treatment conditions, and accessions. geNorm and NormFinder algorithms were used to assess the expression stability of these genes. ACT2 and TIP41 were selected as suitable reference genes across all experimental samples in this study. When different accessions were compared, ACT2 and UNK3 were found to be the most suitable reference genes. In the hormone and abiotic stress treatments, ACT2, TIP41, and UNK2 were the most stably expressed. Our study also provided guidelines for selecting the best reference genes under various experimental conditions.

Roles of oxidative DNA damage of bone marrow hematopoietic cells in steroid-induced avascular necrosis of femoral head

An animal model of steroid-induced avascular necrosis of femoral head (SANFH) was established to investigate the role of oxidative DNA damage of bone marrow hematopoietic cells in SANFH. Forty-five-month-old Japanese white rabbits (male or female, 2.5 ± 0.5 kg) were randomly divided into groups A (methylprednisolone + Escherichia coli endotoxin), B (methylprednisolone alone), C (E. coli endotoxin alone), and D (blank control). The animals were sacrificed two and four weeks after administration of the last dose (N = 5 each group and each time). Left and right femoral heads were fixed and decalcified. Empty lacunae were counted by hematoxylin and eosin staining and oxidative DNA damage of bone marrow hematopoietic cells was detected by immunohistochemistry. At week 2, the rate of oxidative DNA damage in bone marrow hematopoietic cells was significantly higher in group A than in groups B, C, and D (P < 0.01), while there was no significant difference between groups B, C, and D. At week 4, the rate of oxidative DNA damage in bone marrow hematopoietic cells was significantly higher in group A than in groups B, C, and D (P < 0.01), while there was no significant difference among groups B, C, and D. Thus, oxidative DNA damage of bone marrow hematopoietic cells appears to play an important role in SANFH.

[Clinical characteristics and prognosis of concurrent positive t(14; 18) and myc gene rearrangement in diffuse large B cell lymphoma]

OBJECTIVE

To study the incidence of positive t(14; 18) and myc gene rearrangement, and the clinical features and prognosis of concurrent positive t(14; 18) and myc gene rearrangement "double-hit lymphoma" (DHL) in diffuse large B cell lymphoma.

METHODS

The positive t(14; 18) and myc gene rearrangement in 106 cases of DLBCL were analyzed using interphase fluorescent in situ hybridization (FISH) technique. The expression of myc and bcl-2 proteins was determined by immunohistochemistry. The relationship of positive t(14; 18) and myc gene rearrangement with clinical features, pathogenesis and prognosis for the patients was analyzed. SPSS 16.0 software was used for statistical analysis.

RESULTS

Among the 106 cases, there were 27 (25.5%) cases with positive t(14; 18) and 13 (12.3%) cases with myc gene rearrangement, and 7 cases (6.6%) of DLBCL with concurrent t(14; 18)-positive and myc gene rearrangement. A relationship was observed between positive t(14; 18) and myc gene rearrangement (P=0.019). The follow-up data showed that the 7 DHL patients were in age of 52-84 years, the International Prognostic Index (IPI) scores were 3 in two cases, 4 in four cases and 5 in one case, and the ECOG scores were 3 in all the 7 cases. Four patients had bone marrow involvement and were combined with leukemia. The survival time ranged from 0.5 to 6 months, with a median survival of 4 months. The univariate analysis showed that B symptom, Ann Arbor stage, ECOG score, LDH level, IPI score, immunophenotype, bcl-2 protein expression, myc protein expression, and myc gene rearrangement were all associated with poor prognosis (P<0.05 for all). The multivariate analysis using a COX proportional hazard model confirmed that ECOG score, bcl-2 protein expression, myc protein expression, myc gene rearrangement, and immunophenotype were independent prognostic factors affecting survival (P<0.05 for all), among them, the myc gene rearrangement was the strongest prognostic factor (OR=4.337, P<0.001).

CONCLUSIONS

"Double-hit" DLBCL is rare and can be mainly identified only by molecular detection. Perhaps positive t(14; 18) and myc gene rearrangement play concurrent role in its "double-hit" pathogenesis. DHL are highly invasive, and most of DHL patients have poor prognosis. Further studies of larger case number are required to determine the pathologic features and the therapeutic strategy of this subgroup.

Desmoglein 4 diversity and correlation analysis with coat color in goat

Desmoglein 4 (DSG4) has an important role in the development of wool traits in domestic animals. The full-length DSG4 gene, which contains 3918 bp, a complete open-reading-frame, and encodes a 1040-amino acid protein, was amplified from Liaoning cashmere goat. The sequence was compared with that of DSG4 from other animals and the results show that the DSG4 coding region is consistent with interspecies conservation. Thirteen single-nucleotide polymorphisms (SNPs) were identified in a highly variable region of DSG4, and one SNP (M-1, G>T) was significantly correlated with white and black coat color in goat. Haplotype distribution of the highly variable region of DSG4 was assessed in 179 individuals from seven goat breeds to investigate its association with coat color and its differentiation among populations. However, the lack of a signature result indicates DGS4 haplotypes related with the color of goat coat.

Brief Note Low diversity of the major histocompatibility complex class II DRA gene in domestic goats (Capra hircus) in Southern China

DRA encodes the alpha chain of the DR heterodimer, is closely linked to DRB and is considered almost monomorphic in major histocompatibility complex region. In this study, we identified the exon 2 of DRA to evaluate the immunogenetic diversity of Chinese south indigenous goat. Two single nucleotide polymorphisms in an untranslated region and one synonymous substitution in coding region were identified. These data suggest that high immunodiversity in native Chinese population.

Involvement of CX3CL1/CX3CR1 signaling in spinal long term potentiation

The long-term potentiation (LTP) of spinal C-fiber-evoked field potentials is considered as a fundamental mechanism of central sensitization in the spinal cord. Accumulating evidence has showed the contribution of spinal microglia to spinal LTP and pathological pain. As a key signaling of neurons-microglia interactions, the involvement of CX3CL1/CX3CR1 signaling in pathological pain has also been investigated extensively. The present study examined whether CX3CL1/CX3CR1 signaling plays a role in spinal LTP. The results showed that 10-trains tetanic stimulation (100 Hz, 2s) of the sciatic nerve (TSS) produced a significant LTP of C-fiber-evoked field potentials lasting for over 3 h in the rat spinal dorsal horn. Blockade of CX3CL1/CX3CR1 signaling with an anti-CX3CR1 neutralizing antibody (CX3CR1 AB) markedly suppressed TSS-induced LTP. Exogenous CX3CL1 significantly potentiated 3-trains TSS-induced LTP in rats. Consistently, spinal LTP of C-fiber-evoked field potentials was also induced by TSS (100 Hz, 1s, 4 trains) in all C57BL/6 wild type (WT) mice. However, in CX3CR1^-/- mice, TSS failed to induce LTP and behavioral hypersensitivity, confirming an essential role of CX3CR1 in spinal LTP induction. Furthermore, blockade of IL-18 or IL-23, the potential downstream factors of CX3CL1/CX3CR1 signaling, with IL-18 BP or anti-IL-23 neutralizing antibody (IL-23 AB), obviously suppressed spinal LTP in rats. These results suggest that CX3CL1/CX3CR1 signaling is involved in LTP of C-fiber-evoked field potentials in the rodent spinal dorsal horn.

Dexmedetomidine inhibits Tetrodotoxin-resistant Nav1.8 sodium channel activity through Gi/o-dependent pathway in rat dorsal root ganglion neurons

Background

Systemically administered dexmedetomidine (DEX), a selective α2 adrenergic receptor (α2-AR) agonists, produces analgesia and sedation. Peripherally restricted α2-AR antagonist could block the analgesic effect of systemic DEX on neuropathic pain, with no effect on sedation, indicating peripheral analgesic effect of DEX. Tetrodotoxin-resistant (TTX-R) sodium channel Na_v1.8 play important roles in the conduction of nociceptive sensation. Both α2-AR and Nav1.8 are found in small nociceptive DRG neurons. We, therefore, investigated the effects of DEX on the Na_v1.8 currents in acutely dissociated small-diameter DRG neurons.

Results

Whole-cell patch-clamp recordings demonstrated that DEX concentration-dependently suppressed TTX-R Na_v1.8 currents in small-diameter lumbar DRG neurons. DEX also shifted the steady-state inactivation curves of Na_v1.8 in a hyperpolarizing direction and increased the threshold of action potential and decrease electrical and chemical stimuli-evoked firings in small-diameter DRG neurons. The α2-AR antagonist yohimbine or α2_A-AR antagonist BRL44408 but not α2_B-AR antagonist imiloxan blocked the inhibition of Na_v1.8 currents by DEX. Immunohistochemistry results showed that Na_v1.8 was predominantly expressed in peripherin-positive small-diameter DRG neurons, and some of them were α2_A-AR-positive ones. Our electrophysiological recordings also demonstrated that DEX-induced inhibition of Na_v1.8 currents was prevented by intracellular application of G-protein inhibitor GDPβ-s or G_i/o proteins inhibitor pertussis toxin (PTX), and bath application of adenylate cyclase (AC) activator forskolin or membrane-permeable cAMP analogue 8-Bromo-cAMP (8-Br-cAMP). PKA inhibitor Rp-cAMP could mimic DEX-induced inhibition of Na_v1.8 currents.

Conclusions

We established a functional link between α2-AR and Na_v1.8 in primary sensory neurons utilizing the G_i/o/AC/cAMP/PKA pathway, which probably mediating peripheral analgesia of DEX.

Inhibition of p38 mitogen-activated protein kinase activation in the rostral anterior cingulate cortex attenuates pain-related negative emotion in rats

The emotional components of pain are far less studied than the sensory components. Previous studies have indicated that the rostral anterior cingulate cortex (rACC) is implicated in the affective response to noxious stimuli. Activation of p38 mitogen-activated protein kinase (MAPK) in the spinal cord has been documented to play an important role in diverse kinds of pathological pain states. We used formalin-induced conditioned place aversion (F-CPA) in rats, an animal model believed to reflect the emotional response to pain, to investigate the involvement of p38 MAPK in the rACC after the induction of affective pain. Intraplantar formalin injection produced a significant activation of p38 MAPK, as well as mitogen-activated kinase kinase (MKK) 3 and MKK6, its upstream activators, in the bilateral rACC. p38 MAPK was elevated in both NeuN-positive neurons and Iba1-positive microglia in the rACC, but not GFAP-positive cells. Blocking p38 MAPK activation in the bilateral rACC using its specific inhibitor SB203580 or SB239063 dose-dependently suppressed the formation of F-CPA. Inhibiting p38 MAPK activation did not affect formalin-induced two-phase spontaneous nociceptive response and low intensity electric foot-shock induced CPA. The present study demonstrated that p38 MAPK signaling pathway in the rACC contributes to pain-related negative emotion. Thus, a new pharmacological strategy targeted at the p38 MAPK cascade may be useful in treating pain-related emotional disorders.

Up-regulation of interleukin-23 induces persistent allodynia via CX3CL1 and interleukin-18 signaling in the rat spinal cord after tetanic sciatic stimulation

Tetanic stimulation of the sciatic nerve (TSS) induces sciatic nerve injury and long-lasting pain hypersensitivity in rats, and spinal glial activation and proinflammatory cytokines releases are involved. In the present study, we showed that spinal interleukin (IL)-23 and its receptor, IL-23R, are crucial for the development of mechanical allodynia after TSS. In the spinal dorsal horn, both IL-23 and IL-23R are expressed in astrocytes, and this expression is substantially increased after TSS. Inhibition of IL-23 signaling attenuated TSS-induced allodynia and decreased the induction of glial fibrillary acidic protein (GFAP, an astrocytic marker). Conversely, intrathecally delivered IL-23 induced a persistent allodynia. Similar to IL-23 signaling, an increase in IL-18 and its receptor, IL-18R, as well as CX3CL1 and its receptor, CX3CR1, was simultaneously observed in the spinal dorsal horn after TSS. Interestingly, IL-18 and CX3CR1 were exclusively expressed in microglia, while IL-18R was mainly localized in astrocytes. In contrast, CX3CL1 was predominately expressed in neurons and secondarily in astrocytes. The functional inhibition of CX3CL1 and IL-18 signaling attenuated TSS-induced allodynia and suppressed IL-23 and IL-23R upregulation. Activation of CX3CR1 and IL-18R induced similar behavioral and biochemical changes to those observed after TSS. These results indicate that the interaction among CX3CL1, IL-18 and IL-23 signaling in the spinal cord plays a critical role in the development of allodynia. Thus, interrupting this chemokine-cytokine network might provide a novel therapeutic strategy for neuropathic pain.

Spinal synaptic scaffolding protein Homer 1b/c regulates CREB phosphorylation and c-fos activation induced by inflammatory pain in rats

Previous studies have shown that spinal Homer 1b/c plays an important role in the maintenance of chronic inflammatory pain induced by complete Freund's adjuvant (CFA). This study investigated the possible mechanism underlying Homer 1b/c mediating CFA-induced inflammatory pain. Chronic inflammation was induced by CFA injection into the left hind ankle of the rat. Homer 1b/c antisense or missense oligonucleotides were administered intrathecally (10μg/10μl) from 5 to 8 days following the onset of inflammation. Immunohistochemistry was conducted to detect the expression of phosphorylated cAMP response element binding protein (pCREB) and Fos protein in the spinal dorsal horn. Intrathecal administration of Homer 1b/c antisense oligonucleotides not only markedly reduced the expression of Homer 1b/c protein, but also attenuated CFA-induced inflammation, spinal CREB phosphorylation, and Fos expression. These results demonstrate for the first time that Homer 1b/c regulates CREB phosphorylation and c-fos activation in the spinal dorsal horn during the maintenance of chronic inflammatory pain, suggesting that Homer 1b/c may be involved in the development of CFA-induced inflammation.

Role of P2X7 receptor-mediated IL-18/IL-18R signaling in morphine tolerance: multiple glial-neuronal dialogues in the rat spinal cord

The glial function in morphine tolerance has been explored, but its mechanisms remain unclear. Our previous study has showed that microglia-expressed P2X7 receptors (P2X7R) contribute to the induction of tolerance to morphine analgesia in rats. This study further explored the potential downstream mechanisms of P2X7R underlying morphine tolerance. The results revealed that the blockade of P2X7 receptor by P2X7R antagonist or targeting small interfering RNA (siRNA) reduced tolerance to morphine analgesia in the pain behavioral test and spinal extracellular recordings in vivo and whole-cell recording of the spinal cord slice in vitro. Chronic morphine treatment induced an increase in the expression of interleukin (IL)-18 by microglia, IL-18 receptor (IL-18R) by astrocytes, and protein kinase Cγ (PKCγ) by neurons in the spinal dorsal horn, respectively, which was blocked by a P2X7R antagonist or targeting siRNA. Chronic morphine treatment also induced an increased release of D-serine from the spinal astrocytes. Further, both D-amino acid oxygenase (DAAO), a degrading enzyme of D-serine, and bisindolylmaleimide α (BIM), a PKC inhibitor, attenuated morphine tolerance. The present study demonstrated a spinal mechanism underlying morphine tolerance, in which chronic morphine triggered multiple dialogues between glial and neuronal cells in the spinal cord via a cascade involving a P2X7R-IL-18-D-serine-N-methyl-D-aspartate receptor (NMDAR)-PKCγ-mediated signaling pathway.

PERSPECTIVE

The present study shows that glia-neuron interaction via a cascade (P2X7R-IL-18-D-serine-NMDAR-PKCγ) in the spinal cord plays an important role in morphine tolerance. This article may represent potential new therapeutic targets for preventing morphine analgesic tolerance in clinical management of chronic pain.

Polymorphisms in the promoter of the CD14 gene and their associations with susceptibility to pulmonary tuberculosis

Although the role of CD14 in recognizing Mycobacterium tuberculosis is well-understood, the possible role of polymorphisms in susceptibility to develop tuberculosis remains unclear. This study evaluates whether there is an association of polymorphisms within the promoter of the CD14 gene with susceptibility to pulmonary tuberculosis. In a case-control study, we genotyped the eight known single nucleotide polymorphisms SNPs within the promoter of the CD14 gene of 698 Han Chinese subjects. Statistically significant differences between tuberculosis patients and healthy controls were found for G-1619A, T-1359G, A-1145G, and C-159T. The haplotype-GGGT, composed of these four SNPs, exhibited a significant association with the disease. Furthermore, expression levels of soluble CD14 were significantly higher in tuberculosis patients with the GGGT haplotype than with other haplotypes, while IgE expression levels were significantly reduced. Our results suggest that these four SNPs within the promoter of the CD14 gene are associated with susceptibility to pulmonary tuberculosis.

Effects of aquaporin 4 deficiency on the expression of spinal PKCα, PKCγ and c-Fos in naloxone-precipitated morphine withdrawal mice

The previous study indicated that aquaporin 4 (AQP4) deficiency attenuated opioid physical dependence. However, the underlying mechanism remains unknown. In the present study, the effects of AQP4 deficiency on the expression of three factors, protein kinase C (PKC) α, PKCγ and c-Fos in the spinal cord, which are known to be concerned with spinal neuronal sensitization and opiate dependence, were investigated in AQP4 knockout mice using Western blotting analysis. It was observed that AQP4 deficiency reduced the score of naloxone-precipitated abstinent jumping after repeated morphine administration compared with wild-type (P < 0.001). Meanwhile, the protein levels of PKCα and c-Fos in the spinal cord of AQP4 knockout mice were significantly higher than those in the wild-type mice; while the expression of PKCγ was decreased remarkably by AQP4 knockout during the withdrawal (P < 0.01). These data suggest that AQP4 deficiency-attenuated morphine withdrawal responses may be partially attributed to the changes in the spinal expression of PKCα, PKCγ or c-Fos.

Involvement of estrogen in rapid pain modulation in the rat spinal cord

The pivotal role of estrogens in the pain sensitivity has been investigated in many ways. Traditionally, it is ascribed to the slow genomic changes mediated by classical nuclear estrogen receptors (ER), ERα and ERβ, depending on peripheral estrogens. Recently, it has become clear that estrogens can also signal through membrane ERs (mERs), such as G-protein-coupled ER1 (GPER1), mediating the non-genomic effects. However, the spinal specific role played by ERs and the underlying cellular mechanisms remain elusive. The present study investigated the rapid estrogenic regulation of nociception at the spinal level. Spinal administration of 17β-estradiol (E2), the most potent natural estrogen, acutely produced a remarkable mechanical allodynia and thermal hyperalgesia without significant differences among male, female and ovariectomized (Ovx) rats. E2-induced the pro-nociceptive effects were partially abrogated by ICI 182,780 (ERs antagonist), and mimicked by E2-BSA (a mER agonist). Inhibition of local E2 synthesis by 1,4,6-Androstatrien-3,17-dione (ATD, a potent irreversible aromatase inhibitor), or blockade of ERs by ICI 182,780 produced an inhibitory effect on the late phase of formalin nociceptive responses. Notably, lumbar puncture injection of G15 (a selective GPER1 antagonist) resulted in similar but more efficient inhibition of formalin nociceptive responses as compared with ICI 182,780. At the cellular level, the amplitude and decay time of spontaneous inhibitory postsynaptic currents were attenuated by short E2 or E2-BSA treatment in spinal slices. These results indicate that estrogen acutely facilitates nociceptive transmission in the spinal cord via activation of membrane-bound estrogen receptors.

Estrogen facilitates spinal cord synaptic transmission via membrane-bound estrogen receptors: implications for pain hypersensitivity

Recent evidence suggests that estrogen is synthesized in the spinal dorsal horn and plays a role in nociceptive processes. However, the cellular and molecular mechanisms underlying these effects remain unclear. Using electrophysiological, biochemical, and morphological techniques, we here demonstrate that 17β-estradiol (E2), a major form of estrogen, can directly modulate spinal cord synaptic transmission by 1) enhancing NMDA receptor-mediated synaptic transmission in dorsal horn neurons, 2) increasing glutamate release from primary afferent terminals, 3) increasing dendritic spine density in cultured spinal cord dorsal horn neurons, and 4) potentiating spinal cord long term potentiation (LTP) evoked by high frequency stimulation (HFS) of Lissauer's tract. Notably, E2-BSA, a ligand that acts only on membrane estrogen receptors, can mimic E2-induced facilitation of HFS-LTP, suggesting a nongenomic action of this neurosteroid. Consistently, cell surface biotinylation demonstrated that three types of ERs (ERα, ERβ, and GPER1) are localized on the plasma membrane of dorsal horn neurons. Furthermore, the ERα and ERβ antagonist ICI 182,780 completely abrogates the E2-induced facilitation of LTP. ERβ (but not ERα) activation can recapitulate E2-induced persistent increases in synaptic transmission (NMDA-dependent) and dendritic spine density, indicating a critical role of ERβ in spinal synaptic plasticity. E2 also increases the phosphorylation of ERK, PKA, and NR2B, and spinal HFS-LTP is prevented by blockade of PKA, ERK, or NR2B activation. Finally, HFS increases E2 release in spinal cord slices, which can be prevented by aromatase inhibitor androstatrienedione, suggesting activity-dependent local synthesis and release of endogenous E2.

Natural and anthropogenic lead in soils and vegetables around Guiyang city, southwest China: a Pb isotopic approach

Soils, vegetables and rainwaters from three vegetable production bases in the Guiyang area, southwest China, were analyzed for Pb concentrations and isotope compositions to trace its sources in the vegetables and soils. Lead isotopic compositions were not distinguishable between yellow soils and calcareous soils, but distinguishable among sampling sites. The highest (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios were found for rainwaters (0.8547-0.8593 and 2.098-2.109, respectively), and the lowest for soils (0.7173-0.8246 and 1.766-2.048, respectively). The (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios increased in vegetables in the order of roots<stems<leaves<fruits. Plots of the (207)Pb/(206)Pb ratios versus the (208)Pb/(206)Pb ratios from all samples formed a straight line and supported a binary end-member mixing model for Pb in vegetables. Using deep soils and rainwaters as geogenic and anthropogenic end members in the mixing model, it was estimated that atmospheric Pb contributed 30-77% to total Pb for vegetable roots, 43-71% for stems, 72-85% for leaves, and 90% for capsicum fruits, whereas 10-70% of Pb in all vegetable parts was derived from soils. This research supports that heavy metal contamination in vegetables can result mainly from atmospheric deposition, and Pb isotope technique is useful for tracing the sources of Pb contamination in vegetables.

Chemokine CCL2 and its receptor CCR2 in the medullary dorsal horn are involved in trigeminal neuropathic pain

Background

Neuropathic pain in the trigeminal system is frequently observed in clinic, but the mechanisms involved are largely unknown. In addition, the function of immune cells and related chemicals in the mechanism of pain has been recognized, whereas few studies have addressed the potential role of chemokines in the trigeminal system in chronic pain. The present study was undertaken to test the hypothesis that chemokine C-C motif ligand 2 (CCL2)-chemokine C-C motif receptor 2 (CCR2) signaling in the trigeminal nucleus is involved in the maintenance of trigeminal neuropathic pain.

Methods

The inferior alveolar nerve and mental nerve transection (IAMNT) was used to induce trigeminal neuropathic pain. The expression of ATF3, CCL2, glial fibrillary acidic protein (GFAP), and CCR2 were detected by immunofluorescence histochemical staining and western blot. The cellular localization of CCL2 and CCR2 were examined by immunofluorescence double staining. The effect of a selective CCR2 antagonist, RS504393 on pain hypersensitivity was checked by behavioral testing.

Results

IAMNT induced persistent (>21 days) heat hyperalgesia of the orofacial region and ATF3 expression in the mandibular division of the trigeminal ganglion. Meanwhile, CCL2 expression was increased in the medullary dorsal horn (MDH) from 3 days to 21 days after IAMNT. The induced CCL2 was colocalized with astroglial marker GFAP, but not with neuronal marker NeuN or microglial marker OX-42. Astrocytes activation was also found in the MDH and it started at 3 days, peaked at 10 days and maintained at 21 days after IAMNT. In addition, CCR2 was upregulated by IAMNT in the ipsilateral medulla and lasted for more than 21 days. CCR2 was mainly colocalized with NeuN and few cells were colocalized with GFAP. Finally, intracisternal injection of CCR2 antagonist, RS504393 (1, 10 μg) significantly attenuated IAMNT-induced heat hyperalgesia.

Conclusion

The data suggest that CCL2-CCR2 signaling may be involved in the maintenance of orofacial neuropathic pain via astroglial–neuronal interaction. Targeting CCL2-CCR2 signaling may be a potentially important new treatment strategy for trigeminal neuralgia.

Involvement of microglia and interleukin-18 in the induction of long-term potentiation of spinal nociceptive responses induced by tetanic sciatic stimulation

OBJECTIVE

The present study aimed to investigate the potential roles of spinal microglia and downstream molecules in the induction of spinal long-term potentiation (LTP) and mechanical allodynia by tetanic stimulation of the sciatic nerve (TSS).

METHODS

Spinal LTP was induced in adult male Sprague-Dawley rats by tetanic stimulation of the sciatic nerve (0.5 ms, 100 Hz, 40 V, 10 trains of 2-s duration at 10-s intervals). Mechanical allodynia was determined using von Frey hairs. Immunohistochemical staining and Western blot were used to detect changes in glial expression of interleukin-18 (IL-18) and IL-18 receptor (IL-18R).

RESULTS

TSS induced LTP of C-fiber-evoked field potentials in the spinal cord. Intrathecal administration of the microglial inhibitor minocycline (200 μg/20 μL) 1 h before TSS completely blocked the induction of spinal LTP. Furthermore, after intrathecal injection of minocycline (200 μg/20 μL) by lumbar puncture 1 h before TSS, administration of minocycline for 7 consecutive days (once per day) partly inhibited bilateral allodynia. Immunohistochemistry showed that minocycline inhibited the sequential activation of microglia and astrocytes, and IL-18 was predominantly colocalized with the microglial marker Iba-1 in the spinal superficial dorsal horn. Western blot revealed that repeated intrathecal injection of minocycline significantly inhibited the increased expression of IL-18 and IL-18Rs in microglia induced by TSS.

CONCLUSION

The IL-18 signaling pathway in microglia is involved in TSS-induced spinal LTP and mechanical allodynia.