[Effects of cysteinyl leukotriene receptors on phagocytosis of mouse microglial cells]

OBJECTIVE

: To determine the effects of cysteinyl leukotriene receptors (CysLT₁R and CysLT₂R) on phagocytosis of mouse BV2 microglial cells.

METHODS

: BV2 cells were stimulated with microglial activators lipopolysaccharide (LPS) or CysLT receptor agonists LTD₄. The phagocytosis of BV2 cells was observed by immunofluorescence analysis and flow cytometry. The intracellular distributions of CysLT₁R and CysLT₂R in BV2 cells were examined with immunofluorescence staining.

RESULTS

: Both LPS and LTD₄ could significantly enhance the phagocytosis of BV2 cells, and such effect could be inhibited by CysLT₁R selective antagonist Montelukast and CysLT₂R selective antagonist HAMI 3379. The activation of BV2 cells induced by LTD₄ or LPS resulted in changes in intracellular distributions of CysLT₁R and CysLT₂R. CysLT₁R and CysLT₂R was co-localization with a similar distribution.

CONCLUSIONS

: CysLT₁R and CysLT₂R regulate the phagocytosis of mouse BV2 microglial cells with a synergistic effect.

[Research progress on epithelial-mesenchymal transition in cancer recurrence and metastasis]

Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells lose their morphology and function and gradually transformed into mesenchymal-like cells. It is considered that EMT is the main cause for tumor recurrence and metastasis. Many factors are involved in the regulation of EMT, such as E-cadherin, transforming growth factor-β, Wnt signaling pathway, microRNA and EMT-related transcription factors. This article reviews the research progress on EMT and the involved mechanisms, and thus to provide a new perspective on cancer therapy in the future.

HAMI 3379, a CysLT2R antagonist, dose- and time-dependently attenuates brain injury and inhibits microglial inflammation after focal cerebral ischemia in rats

Cysteinyl leukotrienes (CysLTs) induce inflammatory responses by activating their receptors, CysLT1R and CysLT2R. We have reported that CysLT2R is involved in neuronal injury, astrocytosis, and microgliosis, and that intracerebroventricular (i.c.v.) injection of the selective CysLT2R antagonist HAMI 3379 protects against acute brain injury after focal cerebral ischemia in rats. In the present study, we clarified features of the protective effect of intraperitoneally-injected HAMI 3379 in rats. We found that HAMI 3379 attenuated the acute brain injury 24 h after middle cerebral artery occlusion (MCAO) with effective doses of 0.1-0.4 mg/kg and a therapeutic window of ∼1h. It attenuated the neurological deficits, and reduced infarct volume, brain edema, and neuronal loss and degeneration 24 and 72h after MCAO. RNA interference with i.c.v. injection of CysLT2R short hairpin RNA (shRNA) attenuated the acute injury as well. Also, HAMI 3379 inhibited release of the cytokines IL-1β, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) into the serum and cerebrospinal fluid 24h after MCAO. Moreover, HAMI 3379 ameliorated the microglial activation and neutrophil accumulation in the ischemic regions, but did not affect astrocyte proliferation 72h after MCAO. In comparison, the CysLT1R antagonist pranlukast did not affect microglial activation and IFN-γ release, but inhibited astrocyte proliferation and reduced serum IL-4. Thus, we conclude that HAMI 3379 has a protective effect on acute and subacute ischemic brain injury, and attenuates microglia-related inflammation. CysLT2R antagonist(s) alone or in combination with CysLT1R antagonists may be a novel class of therapeutic agents in the treatment of ischemic stroke.

[Zileuton, a 5-lipoxygenase inhibitor, attenuates mouse microglial cell-mediated rotenone toxicity in PC12 cells]

OBJECTIVE

To examine the effect of a selective inhibitor of 5-lipoxygenase (5-LOX) zileuton on microglia-mediated rotenone neurotoxicity.

METHODS

The supernatant from different concentrations of rotenone-stimulated mouse microglia BV2 cells was used as the conditioned media (CM) for PC12 cells. The viability of PC12 cells was determined by MTT assay and lactate dehydrogenase (LDH) release. Cell death was observed by LDH release and double fluorescence staining with Hoechst/propidiumiodide (PI). The effect of zileuton on microglia-mediated rotenone toxicity was evaluated by the above methods.

RESULTS

Rotenone at 1-10 nmol/L was nontoxic to PC12 cells directly. However, the CM from BV2 cells that were treated with rotenone (1-10 nmol/L) resulted in toxicity of PC12 cells. The BV2 CM which stimulated with rotenone (1-10 nmol/L) induced morphological changes, reduced cell viability, and increased LDH release and cell necrosis in PC12 cells. Pretreatment of BV2 cells with the 5-LOX inhibitor zileuton (0.01-1 μmol/L) protected PC12 cells from the microglia-mediated rotenone toxicity.

CONCLUSION

The 5-LOX inhibitor zileuton effectively attenuates microglia-mediated rotenone toxicity in PC12 cells. These results suggest that 5-LOX pathway may be involved in neuronal death induced by microglial inflammation.

[Effects of the water channel aquaporin 4 deficiency on bleomycin-induced lung fibrosis in mice]

OBJECTIVE

To evaluate the effect of water channel aquaporin 4 (AQP4) on bleomycin-induced lung fibrosis in mice.

METHODS

In wild type and AQP4 gene knockout (AQP4-/-) mice, lung fibrosis was induced by injection of bleomycin (3 mg/kg) into the trachea and saline injection was used as a control. At d3, 7, 14, 28 after bleomycin-treatment, mice were randomly sacrificed in batch and the lung coefficient was determined. Serum levels of TGF-β1 and TNF-α were measured by ELISA and hydroxyproline contents in lung tissue were determined by Alkaline hydrolysis method. H-E staining and Masson's staining were performed to examine the pathological changes of lung tissues after bleomycin-treatment.

RESULTS

On d14 after bleomycin-treatment, the lung coefficients in wild type mice and AQP4-/- mice were 1.9-fold (12.69 ± 6.05 vs 6.80 ± 0.82, q=4.204, P<0.05) and 2.3-fold (14.05 ± 5.82 vs 6.05± 0.58, q=5.172, P<0.01) of that in control, respectively, but no significant difference was found between wild type and AQP4-/- mice in the lung coefficient value (P>0.05). The hydroxyproline contents in the lung increased after bleomycin-treatment; on d28, the lung hydroxyproline contents in wild type and in AQP4-/- mice were 1.55-fold (0.85 ± 0.22 g/mg vs 0.55 ± 0.14 μg/mg, q=4.313, P<0.05) and 1.4-fold (0.84 ± 0.13 μg/mg vs 0.60 ± 0.14μg/mg, q=4.595，P<0.05) of that in control, respectively, but no significant difference was noticed between wild type and AQP4-/- mice in lung hydroxyproline contents. There was a tendency that serum TGF-β1 and TNF-α levels increased in bleomycin-treated mice, but no significant difference was found between wild type and AQP4-/- mice. AQP4-knockout showed no effects on pathological changes of lung tissues with H-E staining and Masson's staining in mice with bleomycin-induced lung fibrosis.

CONCLUSION

AQP4 might not be involved in bleomycin-induced lung fibrosis in mice.

[Effect of histone deacetylase inhibitor NL101 on rat neurons]

OBJECTIVE

To investigate the protective effect of histone deacetylase inhibitor NL101 on L-homocysteine (HCA)-induced toxicity in rat neurons, and the toxic effect on normal rat neurons.

METHODS

In the presence of NL101 at various concentrations, HCA (5 mmol/L)-induced changes in cell density, necrosis, and viability were determined in the mixed cultures of rat cortical cells and the primary cultures of rat neurons. The direct effect of NL101 on primary neurons was also observed in the absence of HCA. Histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) was used as the control. After the treatments, cell viability, the density, and morphology of neurons and glial cells, and cell necrosis were determined.

RESULTS

In the mixed cultures of cortical cells, NL101 had no effect on HCA (5 mmol/L)-induced cell number reduction at 0.001-10μmol/L; however, it significantly attenuated necrosis at 1-10 μmol/L, and increased neuronal number at 1 μmol/L. NL101 had no effect on the mixed cortical cells in the absence of HCA. In the primary neurons, NL101 reduced neuronal viability and mildly increased necrosis at 1-10 μmol/L in the absence of HCA, while it significantly attenuated HCA-induced neuronal viability reduction at 0.01-10 μmol/L and reduced neuronal necrosis at 1-10 μmol/L. The effects of NL101 were apparently similar to those of SAHA.

CONCLUSION

NL101 has protective effect on HCA-induced neuronal injury but it is neurotoxic at high concentrations, which is similar to the typical histone deacetylase inhibitor SAHA.

[Application of locomotor activity test to evaluate functional injury after global cerebral ischemia in C57BL/6 mice]

OBJECTIVE

To evaluate the application of locomotor activity test in functional injury after global cerebral ischemia (GCI) in C57BL/6 mice.

METHODS

GCI was induced by bilateral carotid arteries occlusion for 30 min in C57BL/6 mice. Mice were divided into sham group, GCI group and minocycline group. Saline or minocycline (45 mg/kg) was i.p. injected once daily for 6 d after ischemia. At Day 6 after ischemia, locomotor activity was recorded for 1 h in open field test. Total distance, central distance, central distance ratio, periphery distance, periphery distance ratio, central time and periphery time were used to evaluate the behavior characteristics of locomotor activity in C57BL/6 mice after ischemia. The survival neuron density was detected by Nissl staining in hippocampus, cortex and striatum.

RESULTS

Compared with sham group, total distance, central distance and central time increased and periphery time decreased in C57BL/6 mice after GCI (Ps<0.05). However, minocycline significantly reduced the central distance and central time and increased the periphery time (Ps<0.05). Neurons were damaged in hippocampus, cortex and striatum after GCI, which manifested by decreased neurons and the most serious damage in hippocampal CA1 region. Minocycline significantly improved the neuron appearance and increased the neuron number in hippocampus and striatum (P<0.001 or P<0.05).

CONCLUSION

Locomotor activity in open field test can objectively evaluate the behavior injury after GCI in mice. Central distance and central time can be used as indexes of quantitative assessment.

[Influence of object material and inter-trial interval on novel object recognition test in mice]

OBJECTIVE

To investigate the efficacy of novel object recognition (NOR) test in assessment of learning and memory ability in ICR mice in different experimental conditions.

METHODS

One hundred and thirty male ICR mice were randomly divided into 10 groups: 4 groups for different inter-trial intervals (ITI: 10 min, 90 min, 4 h, 24 h), 4 groups for different object materials (wood-wood, plastic-plastic, plastic-wood, wood-plastic) and 2 groups for repeated test (measured once a day or every 3 days, totally three times in each group). The locomotor tracks in the open field were recorded. The amount of time spent exploring the novel and familiar objects, the discrimination ratio (DR) and the discrimination index (DI) were analyzed.

RESULTS

Compared with familiar object, DR and DI of novel object were both increased at ITI of 10 min and 90 min (P<0.01). Exploring time, DR and DI were greatly influenced by different object materials. DR and DI remained stable by using identical object material. NOR test could be done repeatedly in the same batch of mice.

CONCLUSION

NOR test can be used to assess the learning and memory ability in mice at shorter ITI and with identical material. It can be done repeatedly.

[Antioxidative effects of cysteinyl leukotriene receptor antagonists montelukast and HAMI 3379 on ischemic injury in rat cortical neurons in vitro]

OBJECTIVE

To investigate the antioxidative effects of two cysteinyl leukotriene receptors antagonists (CysLT1R and CysLT2R) montelukast and HAMI 3379 on ischemic injury of rat cortical neurons in vitro.

METHODS

Cultured rat cortical neurons were pretreated with CysLT1R antagonist montelukast and CysLT2R antagonist HAMI 3379, and then exposed to oxygen-glucose deprivation/recovery (OGD/R）or H2O2. Reactive oxygen species (ROS) mitochondrial membrane potential (MMP) depolarization, neuronal viability and lactate dehydrogenase (LDH) release were determined. Meanwhile, RNA interference was used to inhibit the expression of CysLT1R and CysLT2R，and the effects were observed.

RESULTS

ROS production in neurons was significantly increased after 1 h OGD, which reached the peak at 30 min and lasted for 1.5 h after recovery. Montelukast and HAMI 3379 at 0.01-1μmol/L moderately decreased OGD/R-induced ROS production (P<0.05). Montelukast mildly attenuated OGD/R-induced MMP depolarization (P<0.05)，but HAMI 3379 had no effect. H2O2 reduced neuronal viability and increased LDH release, namely inducing neuronal injury. Montelukast and HAMI 3379 at 0.1-1μmol/L moderately attenuated H2O2-induced neuronal injury (P<0.05). However, both CysLT1R siRNA and CysLT2R shRNA did not significantly affect the responses mentioned above.

CONCLUSION

In ischemic neuronal injury, montelukast and HAMI 3379 exert a moderate antioxidative effect, and this effect may be receptor-independent.

[Effects of leukotriene D4 on proliferation and migration of lung epithelial A549 cells in vitro]

OBJECTIVE

To investigate the effects of cysteinyl leukotriene (CysLT) receptor agonist leukotriene D4 (LTD4) on proliferation and migration in lung epithelial A549 cells.

METHODS

The expression of CysLT1 receptor and CysLT2 receptor was determined by immunofluoresence staining in A549 cells. A549 cells were treated with LTD4 (0.01-100 nmol/L) for 24-72 h. Cell viability was detected by MTT reduction assay. Cell migration was determined by modified scratch and healing model.

RESULTS

In A549 cells, CysLT1 receptor and CysLT2 receptor were mainly expressed in the cytoplasm, membrane and few in the nuclei. The treatment of LTD4 (0.01-100 nmol/L) for 24-72 h caused no effect on cell viability (Ps>0.05); when A549 cells were treated with 100 nmol/L LTD4 for 24, 48 and 72 h the cell viability was (103.00±4.46)%，(107.00±9.45)% and (105.00±9.02)% of control, respectively (Ps>0.05). The migration rate of A549 cells after scratching during the first 24 h was markedly greater than that during the second and third 24 h in the same concentration groups; however, no significant difference in migration rate was noticed when the cells were treated with different concentrations of LTD4 (0.01-100 nmol/L)(Ps>0.05). The migration of A549 cells was 1.15-fold, 1.21-fold and 1.06-fold of that of control when the cells were treated with 100 nmol/L LTD4 for 24, 48 and 72 h, respectively (Ps>0.05).

CONCLUSION

The proliferation and migration of A549 cells are not changed when treated with 0.01-100 nmol LTD4 for up to 72h.

[Research advances on the roles of nicotinamide phosphoribosyltransferase in inflammation]

Nicotinamide phosphoribosyltransferase (Nampt) is also called visfatin or pre-B-cell colony-enhancing factor. The functions of Nampt have been reported as a cytokine, an adipokine and the rate-limiting enzyme in nicotinamide adenine dinucleotide biosynthesis. As a pleiotropic multifunctional protein, Nampt is involved in a variety of physiological and pathological conditions including innate immunity, metabolic disorders, and stress; and Nampt also participates in inflammatory disorders such as acute lung injury, atherosclerosis, myocardial infarct, obesity, type 2 diabetes, and rheumatoid arthritis. The studies indicate that Nampt might be a potential target for pharmacological intervention against inflammatory diseases. We review research advances on the roles of Nampt in inflammation.

[Leukotriene D4 activates BV2 microglia in vitro]

OBJECTIVE

To investigate the effects of CysLT receptor agonist leukotriene D4(LTD4) and antagonists on activation of microglia BV2 cells.

METHODS

The expression of CysLT1 and CysLT2 protein was determined by Western blotting and immunostaining in microglia BV2 cells. BV2 cells were pretreated with or without CysLT1 receptor selective antagonist montelukast, CysLT2 receptor selective antagonist HAMI 3379, or CysLT1/CysLT2 receptor dual antagonist BAY u9773 for 30 min, then the cells were treated with LTD4 for 24 h. Cell viability was detected by MTT reduction assay. Phagocytosis and mRNA expression of IL-6 were determined by fluorescent bead tracking and RT-PCR, respectively.

RESULTS

In BV2 cells, LTD4 did not affect proliferation but significantly enhanced phagocytosis and increased IL-6 mRNA expression in a concentration-dependent manner. LTD4 at 100 nmol/L induced a 1.4-fold increase of phagocytic index and a 2-fold up-regulation of IL-6 mRNA expression (P<0.01). HAMI 3379 and BAY u9773 (100 nmol/L) further increased LTD4-induced phagocytosis; BAY u9773 and montelukast decreased LTD4-induced IL-6 mRNA expression, while HAMI 3379 had no effect on that.

CONCLUSION

LTD4 activates BV2 cells in vitro and enhances IL-6 mRNA expression mediated by CysLT1 receptor, LTD4 induces phagocytosis which might be negatively regulated by CysLT2 receptor in BV2 cells.

[Role of G protein-coupled receptor 17 in central nervous system injury]

G-protein-coupled receptor 17 (GPR17), an originally orphan receptor, was identified as a new uracil nucleotides/cysteinyl leukotriene receptor. However, whether GPR17 is really classified as a leukotriene receptor is a matter deserving further investigation. GPR17 is involved in many physiological and pathological processes including brain injury, spinal cord injury, and oligodendrocyte differentiation. GPR17 may become a new therapeutic target in these diseases. In this article, the research progress on the pharmacology and pathophysiological roles of GPR17 is reviewed.

[Expression and distribution of cysteinyl leukotriene receptors CysLT1R and CysLT2R, and GPR17 in brain of Parkinson disease model mice]

OBJECTIVE

To examine the spatiotemporal profiles and localization of CysLT1R, CysLT2R and GPR17 in mice with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson disease (PD).

METHODS

PD model was induced by subcutaneous injection of MPTP (25 mg/kg) for 5 d in adult male C57BL/6 mice. At d10 after MPTP injection, the expression and cellular localization of CysLT1R, CysLT2R and GPR17 in the substantia nigra were detected by immunohistochemistry and immunofluorescence.

RESULTS

CysLT1R, CysLT22 and GPR17 were normally localized in TH-positive dopaminergic neurons and microglia, while CysLT2R was also expressed in astrocytes. In dopaminergic neurons, approximately 91% co-expressed GPR17, 77% co-expressed CysLT1R and 52% co-expressed CysLT2R. Compared with the control group, TH-positive cells in the substantia nigra were significantly reduced in PD mice. CysLT1R, CysLT2R and GPR17-positive cells were significantly reduced; and CysLT1R, CysLT2R, GPR17-positive dopaminergic neurons were also significantly reduced in the PD group. In the striatum, both CysLT1R and GPR17 were normally expressed in neurons; whereas CysLT2R was expressed in astrocytes. In PD striatum, CysLT1R and GPR17-positive cells were decreased, but CysLT2R expression was significantly increased which mainly expressed in the proliferating astrocytes.

CONCLUSION

CysLT1R, CysLT2R and GPR17 may be involved in the MPTP-induced PD damage in mice.

[Expression of 5-lipoxygenase in hippocampal CA1 neuronal damage following global cerebral ischemia in rats]

OBJECTIVE

To determine 5-lipoxygenase (5-LOX) expression and the effect of zileuton, a selective 5-LOX inhibitor,on hippocampal neuron injury induced by global cerebral ischemia in rats.

METHODS

Global cerebral ischemia was induced by bilateral common carotid artery occlusion combined with hypotension in rats. 5-LOX expression was detected by Western blot analyses and 5-LOX localization was visualized by immunohistochemistry and double immunofluorescence methods. The 5-LOX inhibitor zileuton (10, 30, 50 mg/kg) was orally administered for 3 d after ischemia.

RESULTS

The 5-LOX expression was increased in the ischemic hippocampus on d1-7 (peaked at d3), and 5-LOX protein was primarily localized in neurons and translocated to the nuclei in the hippocampal CA1 region after ischemia. The 5-LOX inhibitor zileuton (30, 50 mg/kg) reduced ischemia-induced hippocampal neurons death 3d after ischemia.

CONCLUSION

5-LOX is involved in global cerebral ischemic damage in rats, and the 5-LOX inhibitor zileuton has a protective effect on neuronal damage in the rat hippocampus following global cerebral ischemia.

Nuclear translocation of cysteinyl leukotriene receptor 1 is involved in oxygen-glucose deprivation-induced damage to endothelial cells

AIM

Cysteinyl leukotriene receptor 1 (CysLT(1) receptor) is located in epithelial cells, and translocates from the plasma membrane to the nucleus in a ligand-dependent manner. Here, we investigated whether CysLT(1) receptors translocated to the nucleus in endothelial cells after ischemic insult in vitro and whether it was involved in ischemic injury to endothelial cells.

METHODS

EA.hy926 cell line, derived from human umbilical vein endothelial cells, was subjected to oxygen-glucose deprivation (OGD). The expression and distribution of CysLT(1) receptors were detected by immunofluorescent staining, immunogold labeling and immunoblotting analyses. Cell viability was evaluated using MTT reduction assay. Necrosis and apoptosis were determined by double fluorescent staining with propidium iodide and Hoechst 33342.

RESULTS

CysLT(1) receptors were primarily distributed in the cytoplasm and nucleus in EA.hy926 cells, and few was found in the cell membrane. OGD induced the translocation of CysLT(1) receptors from the cytoplasm to the nucleus in a time-depen dent manner, with a peak reached at 6 h. OGD-induced nuclear translocation of CysLT(1) receptors was inhibited by pretreatment with the CysLT(1) receptor antagonist pranlukast (10 μmol/L), or by preincubation with NLS-pep, a peptide corresponding to the nuclear localization sequence of CysLT(1) receptor (10 μg/mL). However, zileuton, an inhibitor of 5-lipoxygenase that was a key enzyme in cysteinyl leukotriene generation, did not inhibit the nuclear translocation of CysLT(1) receptors. Moreover, preincubation with NLS-pep (0.4 μg/mL) significantly ameliorated OGD-induced cell viability reduction and necrosis.

CONCLUSION

CysLT(1) receptors in endothelial cells translocate to the nucleus in a ligand-independent manner after ischemic insult in vitro, and it is involved in the ischemic injury.

Application of the capture-recapture method in estimating the size of the active homosexual male population in Hangzhou city of China

The homosexual population is particularly susceptible to sexually transmitted disease because of various high-risk sexual behaviors among them. The authors explored the application of capture-recapture methods in estimating the size of the sexually active homosexual male population in Hangzhou. Homosexual men at 9 activity sites were investigated in Hangzhou, Zhejiang. The total active homosexual male population of Hangzhou estimated by the capture-recapture method and multiplier method was 2014 (95% confidence interval [CI] = 1899-2129) and 2012.5 (95% CI 1925 to 2101), respectively. This study shows that the capture-recapture method can be used to enumerate and provide accurate and reliable estimates of the active homosexual population in any area, provided that certain conditions are controlled.

[Effect of montelukast on morphological changes in neurons after ischemic injury]

OBJECTIVE

To determine the effect of montelukast, a cysteinyl leukotriene receptor 1 antagonist, on morphological changes in rat neurons after ischemic injury.

METHODS

The in vivo ischemia injury was induced by oxygen-glucose deprivation (OGD) for 2 h and reperfusion (R) for 24 h (OGD/R) in rat neurons primary culture and mixed cortex culture. In the presence or absence of various concentrations of montelukast, neuron number, area of neuron, number of neuritis per neuron, branch number of primary neuritis and primary neurite length were determined for evaluating morphological changes in neurons.

RESULTS

OGD/R significantly reduced neuron number, and altered neuron morphology. In cortical neuron cultures, montelukast (0.0001-1 μmol/L) attenuated OGD/R-induced reduction in neuron number, and inhibited OGD/R-induced increase in branch number of primary neuritis. In the mixed cultures, montelukast (0.0001-0.1 μmol/L) increased the primary neurite length, and reduced number of neuritis and branch number of primary neurite after OGD/R.

CONCLUSION

Montelukast has a protective effect on ischemic injury in neurons.

[Cysteinyl leukotriene receptor 1 is involved in rotenone-induced injury of PC12 cells]

OBJECTIVE

To investigate whether cysteinyl leukotriene receptor 1 (CysLT₁ receptor) is involved in rotenone-induced injury of PC12 cells.

METHODS

After 24 h treatment with rotenone or with rotenone and the CysLT₁ receptor antagonist montelukast, PC12 cell viability was determined by the colorimetric MTT reduction assay. After PC12 cells were treated with various concentrations of rotenone for 24 h or with 3 μmol/L rotenone for various durations, the expression of CysLT(1) receptor was determined by Western blotting, and its intracellular distribution was detected by immunocytochemistry.

RESULTS

Rotenone (0.3-30 μmol/L) induced PC12 cell injury; this injury was significantly attenuated by montelukast at 1 and 5 μmol/L.The expression of CysLT(1) receptor increased after rotenone treatment at 1-10 μmol/L, or at 3 μmol/L for 3 and 24 h. Rotenone caused concentration-and time-dependent translocation of CysLT₁ receptor from the nucleus to the cytosol.

CONCLUSION

Cysteinyl leukotriene receptor 1 is involved in rotenone-induced injury of PC12 cells.

The new P2Y-like receptor G protein-coupled receptor 17 mediates acute neuronal injury and late microgliosis after focal cerebral ischemia in rats

G protein-coupled receptor 17 (GPR17), the new P2Y-like receptor, is phylogenetically related to the P2Y and cysteinyl leukotriene receptors, and responds to both uracil nucleotides and cysteinyl leukotrienes. GPR17 has been proposed to be a damage sensor in ischemic stroke; however, its role in brain inflammation needs further detailed investigation. Here, we extended previous studies on the spatiotemporal profiles of GPR17 expression and localization, and their implications for brain injury after focal cerebral ischemia. We found that in the ischemic core, GPR17 mRNA and protein levels were upregulated at both 12-24 h and 7-14 days, but in the boundary zone the levels increased 7-14 days after reperfusion. The spatiotemporal pattern of GPR17 expression well matched the acute and late (subacute/chronic) responses in the ischemic brain. According to previous findings, in the acute phase, after ischemia (24 h), upregulated GPR17 was localized in injured neurons in the ischemic core and in a few microglia in the ischemic core and boundary zone. In the late phase (14 days), it was localized in microglia, especially in activated (ED1-positive) microglia in the ischemic core, but weakly in most microglia in the boundary zone. No GPR17 was detectable in astrocytes. GPR17 knockdown by a small interfering RNA attenuated the neurological dysfunction, infarction, and neuron loss at 24 h, and brain atrophy, neuron loss, and microglial activation at 14 days after reperfusion. Thus, GPR17 might mediate acute neuronal injury and late microgliosis after focal cerebral ischemia.

[Comparison of behavioral effects of psychoactive drugs between two strains of mice]

OBJECTIVE

To compare the behavioral effects of psychoactive drugs between two strains of mice.

METHODS

The Kunming (KM) and ICR mice were injected intraperitoneally with caffeine (3, 10, 30, 100 mg/kg), ephedrine (3, 10, 30, 100 mg/kg), diazepam (1, 3,1 0 mg/kg) and chloral hydrate (10, 30, 100 mg/kg), respectively. Ten min after injection, the locomotor activity in the open field was recorded for 2 h. The total distance, the distance ratio to total distance and the time in central region were analyzed for each drugs. Thirty min after injection, the latent time in the passive avoidance test was measured in a shuttle box.

RESULTS

Caffeine and diazepam prolonged the latent time, and ephedrine and chloral hydrate decreased the latent time, but there were no differences between the two strains. The two strains of mice exhibited significant differences in the total distance after injection of ephedrine 10 mg/kg, diazepam 3 mg/kg and chloral hydrate 100 mg/kg. Compared to KM mice, ICR mice exhibited an increase in the distance ratio and the time in central region after injection of ephedrine 10-100 mg/kg, but a decrease after diazepam 3-10 mg/kg.

CONCLUSION

KM and ICR mice show no differences in latent time, but significant differences in the total distance, the distance ratio and the time in central region in the locomotor activity. Therefore, selection of mouse strains is important in the study of psychoactive drugs.

[Inhibitive effect of C-21 steroidal glycosides of Cynanchum auriculatum on rat glioma cells in vitro]

OBJECTIVE

To evaluate the inhibitive effect of C-21 steroidal glycosides from the root of Cynanchum auriculatum (CGB) on rat glioma C6 cells.

METHODS

C6 cells were treated with CGB for 24, 48,72 h at concentration of 30, 60, 120 mg/L, respectively. MTT assay was used for evaluating cell viability; fluorescence-activated cell sorting analysis after Annexin V/propidium iodide staining or single propidium iodide staining was used to test cell apoptosis and cell cycle.

RESULTS

CGB at 30, 60, 120 mg/L concentration-dependently decreased C6 cell viability (P<0.001). CGB at 60 and 120 mg/L induced C6 cell apoptosis and cell cycle arrest. The fraction of G0/G1 cells was increased (P<0.05) and that of S phase cells was decreased (P<0.01).

CONCLUSION

CGB can inhibit the growth of rat glioma C6 cells, and induce apoptosis and G0/G1 cell cycle arrest.

Activation of the central histaminergic system is involved in hypoxia-induced stroke tolerance in adult mice

We hypothesized that activation of the central histaminergic system is required for neuroprotection induced by hypoxic preconditioning. Wild-type (WT) and histidine decarboxylase knockout (HDC-KO) mice were preconditioned by 3 hours of hypoxia (8% O(2)) and, 48 hours later, subjected to 30 minutes of middle cerebral artery (MCA) occlusion, followed by 24 hours of reperfusion. Hypoxic preconditioning improved neurologic function and decreased infarct volume in WT or HDC-KO mice treated with histamine, but not in HDC-KO or WT mice treated with α-fluoromethylhistidine (α-FMH, an inhibitor of HDC). Laser-Doppler flowmetry analysis showed that hypoxic preconditioning ameliorated cerebral blood flow (CBF) in the periphery of the MCA territory during ischemia in WT mice but not in HDC-KO mice. Histamine decreased in the cortex of WT mice after 2, 3, and 4 hours of hypoxia, and HDC activity increased after 3 hours of hypoxia. Vascular endothelial growth factor (VEGF) mRNA and protein expressions showed a greater increase after hypoxia than those in HDC-KO or α-FMH-treated WT mice. In addition, the VEGF receptor-2 antagonist SU1498 prevented the protective effect of hypoxic preconditioning in infarct volume and reversed increased peripheral CBF in WT mice. Therefore, endogenous histamine is an essential mediator of hypoxic preconditioning. It may function by enhancing hypoxia-induced VEGF expression.

Neural circuits of disgust induced by sexual stimuli in homosexual and heterosexual men: an fMRI study

Few studies demonstrated neural circuits related to disgust were influenced by internal sexual orientation in male. Here we used fMRI to study the neural responses to disgust in homosexual and heterosexual men to investigate that issue. Thirty-two healthy male volunteers (sixteen homosexual and sixteen heterosexual) were scanned while viewing alternating blocks of three types of erotic film: heterosexual couples (F-M), male homosexual couples (M-M), and female homosexual couples (F-F) engaged in sexual activity. All the participants rated their level of disgust and sexual arousal as well. The F-F and M-M stimuli induced disgust in homosexual and heterosexual men, respectively. The common activations related to disgusting stimuli included: bilateral frontal gyrus and occipital gyrus, right middle temporal gyrus, left superior temporal gyrus, right cerebellum, and right thalamus. Homosexual men had greater neural responses in the left medial frontal gyrus than did heterosexual men to the sexual disgusting stimuli; in contrast, heterosexual men showed significantly greater activation than homosexual men in the left cuneus. ROI analysis showed that negative correlation were found between the magnitude of MRI signals in the left medial frontal gyrus and scores of disgust in homosexual subjects (p<0.05). This study indicated that there were regions in common as well as regions specific for each type of erotic stimuli during disgust of homosexual and heterosexual men.

Baicalin attenuates oxygen-glucose deprivation-induced injury by inhibiting oxidative stress-mediated 5-lipoxygenase activation in PC12 cells

AIM

To determine whether the flavonoid baicalin attenuates oxygen-glucose deprivation (OGD)-induced injury by inhibiting oxidative stress-mediated 5-lipoxygenase (5-LOX) activation in PC12 cells.

METHODS

The effects of baicalin and the 5-LOX inhibitor zileuton on the changes induced by OGD/recovery or H(2)O(2) (an exogenous reactive oxygen species [ROS]) in green fluorescent protein-5-LOX-transfected PC12 cells were compared.

RESULTS

Both baicalin and zileuton attenuated OGD/recovery- and H(2)O(2)-induced injury and inhibited OGD/recovery-induced production of 5-LOX metabolites (cysteinyl leukotrienes) in a concentration-dependent manner. However, baicalin did not reduce baseline cysteinyl leukotriene levels. Baicalin also reduced OGD/recovery-induced ROS production and inhibited 5-LOX translocation to the nuclear envelope and p38 phosphorylation induced by OGD/recovery and H(2)O(2). In contrast, zileuton did not show these effects.

CONCLUSION

Baicalin can inhibit 5-LOX activation after ischemic injury, which may partly result from inhibition of the ROS/p38 mitogen-activated protein kinase pathway.

Synthesis, biological evaluation of prenylflavonoids as vasorelaxant and neuroprotective agents

A series of prenylflavonoids with multiple hydroxyl groups were synthesized and evaluated for their vasorelaxant activities against rat aorta rings pre-contracted by phenylephrine (PE), as well as their neuroprotective effects against OGD induced PC12 cell injury. The results indicated that the prenyl group at A-ring of prenylflavonoids, as well as hydroxyl groups at B-ring was important for their activities. (+/-)Leachianone G 1b, bearing 8-prenyl and 2',4'-dihydoxyl groups, exhibited the most potent vasorelaxant and neuroprotective effects.

[5-Lipoxygenase/cysteinyl leukotriene pathway is not involved in injury of rat C6 glioma cells induced by oxygen-glucose deprivation]

OBJECTIVE

To determine whether oxygen-glucose deprivation (OGD) induces C6 cell injury, and whether 5-lipoxygenase (5-LOX)/cysteinyl leukotriene (CysLT) pathway is involved in OGD-induced injury.

METHODS

After OGD treatment and recovery for various durations, the viability of C6 cells was determined, and the effects of 5-LOX inhibitors and CysLT receptor antagonists were investigated. Intracellular distribution of 5-LOX protein was detected by immunocytochemistry, and the mRNA expressions of CysLT1 and CysLT2 receptors were detected by RT-PCR. The effect of leukotriene D(4) (LTD(4)) on C6 cells was also investigated.

RESULT

OGD for 4-8 h followed by recovery for 24-72 h significantly induced C6 cell injury. Neither 5-LOX inhibitors nor CysLT receptor antagonists inhibited OGD-induced injury. OGD did not induce 5-LOX translocation into the nuclear membrane. C6 cells highly expressed CysLT(2) receptor, but the expression of CysLT1receptor was much weaker; the expression was not affected by OGD. In addition, LTD(4) did not affect C6 cells significantly.

CONCLUSION

OGD can induce C6 cell injury, but 5-LOX/CysLT pathway might be not involved in OGD-induced injury.

Cysteinyl leukotriene receptor 1 partially mediates brain cryoinjury in mice

AIM

To determine whether the cysteinyl leukotriene receptor 1 (CysLT1 receptor) modulates brain cryoinjury and whether the CysLT1 receptor antagonist pranlukast exerts a time-dependent protective effect on cryoinjury in mice.

METHODS

Brain cryoinjury was induced by applying a liquid nitrogen-cooled metal probe to the surface of the skull for 30 s. Brain lesion, neuron density, and endogenous IgG exudation were observed 24 h after cryoinjury. Transcription and the expression of the CysLT1 receptor were detected by RT-PCR and immunoblotting, and the localization of the receptor protein by double immunofluorescence.

RESULTS

The mRNA and protein expressions of the CysLT1 receptor were upregulated in the brain 6-24 h after cryoinjury, and the CysLT1 receptor protein was primarily localized in the neurons, not in the astrocytes or microglia. Pre-injury treatments with multi-doses and a single dose of pranlukast (0.1 mg/kg) attenuated cryoinjury; postinjury single dose (0.1 mg/kg) at 30 min (not 1 h) after cryoinjury was also effective.

CONCLUSION

The CysLT1 receptor modulates cryoinjury in mice at least partly, and postinjury treatment with its antagonist pranlukast exerts the protective effect with a therapeutic window of 30 min.

Carnosine ameliorates morphine-induced conditioned place preference in rats

The histidine-containing dipeptide, carnosine (beta-alanyl-L-histidine), is present in high concentrations in mammalian brain of mammals. There are many theories about its biological functions, such as anti-inflammatory agent, free radical scavenger, and protein glycosylation inhibitor, however, the role of carnosine in morphine addiction is less understood. Therefore, the objectives of this study were to determine the effects of carnosine on the development of morphine-induced conditioned place preference (CPP) and investigate its possible mechanism of action in Sprague-Dawley rats. Intraperitioneal (i.p.) injection of carnosine (200, 500, 1000 mg/kg) significantly inhibited the development of morphine-induced CPP in a dose-dependent manner. Although carnosine had no appreciable effect on the levels of histamine in the ventral tegmental area (VTA), nucleus accumbens (NAc) and prefrontal cortex (PFC), it significantly decreased glutamate level in the VTA, dopamine levels in the NAc and PFC, and DOPAC level in the NAc of morphine-treated rats. These results indicate that carnosine inhibits morphine-induced CPP in rats, and its action may be due to modulation of dopaminergic and glutaminergic activity. The study suggests that carnosine has potential as a new anti-addictive drug.

Rutin-induced endothelium-dependent vasorelaxation in rat aortic Rings and the underlying mechanism

The aim of the present study was to determine the possible mechanism by which rutin causes vasodilatation in isolated thoracic aorta rings from the rat. The effects of rutin on rings preconstricted with phenylephrine, with or without endothelium, were determined using an organ bath technique. The mechanism was explored by measuring the effects of the nitric oxide synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME), the guanylyl cyclase inhibitor methylene blue, the cyclooxygenase inhibitor indomethacin, the ATP-sensitive K⁺channel blocker glibenclamide and the beta-adrenoceptor antagonist propranolol. Rutin at the range of 10-160 mumol/L caused dose-dependent vasorelaxation in preconstricted endothelium-intact rings, but had no effect on rings without endothelium. The maximal response calculated from the vasorelaxation curves of rutin was 44.28 plus or mines 7.48%. Pretreatment with L-NAME (0.1 mmol/L), methylene blue (10 mumol/L), glibenclamide (10 mmol/L) or indomethacin (10 mmol/L) attenuated the vasorelaxation induced by rutin in endothelium-intact rings. Glibenclamide (10 mmol/L) enhanced the vasorelaxation of rutin. Propranolol (10 mumol/L) did not block the effect of rutin. The results indicate that vasorelaxation is induced by rutin via the nitric oxide-guanylyl cyclase pathway and a prostaglandin-mediated mechanism, as well as activation of the ATP-sensitive potassium channel.

Improved learning and memory of contextual fear conditioning and hippocampal CA1 long-term potentiation in histidine decarboxylase knock-out mice

Some studies suggest that the histaminergic system plays an important role in learning and memory. However, the results seem to be controversial in many behavioral tasks. In the present study, we used HDC knockout (HDC-KO) mice to investigate the effects of long-term histamine deficiency on learning and memory in contextual fear conditioning. We found that HDC-KO mice exhibited improved contextual fear from 1 day after training and this lasted for at least 14 days when compared with the wild-type (WT) controls. Cued fear was also improved 2 days after training in HDC-KO mice. Moreover, injection of histamine (intracerebroventricularly, 10 microg/mouse) immediately after training reversed the improvement in contextual fear conditioning when tested 1 day after training. Electrophysiological data showed that hippocampal CA1 long-term potentiation (LTP) in HDC-KO mice was much greater than that in WT mice, and paired-pulse facilitation decreased 2 h after LTP induction in HDC-KO mice. In contrast, HDC-KO mice showed smaller LTP than did WT mice 1 day after training. Hippocampal glutamate levels significantly increased in HDC-KO mice 1 and 4 days after training. The results indicated that histamine deficiency may improve consolidation of contextual fear conditioning. This improvement may be due to the increased hippocampal CA1 LTP, and presynaptic glutamate release. The relationship between behavior and synaptic plasticity provides support for the involvement of activity-dependent LTP in learning and memory.

Cysteinyl leukotriene receptors CysLT1 and CysLT2 are upregulated in acute neuronal injury after focal cerebral ischemia in mice

AIM

To determine whether cysteinyl leukotriene receptors (CysLT1 and CysLT2) are upregulated in acute neuronal injury after focal cerebral ischemia in mice, and to confirm CysLT1 receptor localization.

METHODS

After permanent focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO), neurological deficits and neuron loss were determined at various time points within 48 h. The mRNA expressions of CysLT1 and CysLT2 receptors in the brain were analyzed by RT-PCR. CysLT1 receptor localization was detected by double immunofluorescence.

RESULTS

Neurological deficits and neuron loss were found 6, 24 and 48 h after MCAO. The mRNA expressions of both CysLT1 and CysLT2 receptors were upregulated in the ischemic hemisphere 1, 24, and 48 h after MCAO with peaks at 24 h. The CysLT1 receptor was selectively localized in neurons 24 h after MCAO.

CONCLUSION

CysLT1 and CysLT2 receptors are upregulated in acute neuronal injury after focal cerebral ischemia, and the CysLT1 receptor is localized in neurons after ischemia.

Cysteinyl leukotriene receptor 1 is involved in N-methyl-D-aspartate-mediated neuronal injury in mice

AIM

To determine whether cysteinyl leukotriene receptor 1 (CysLT1 receptor) is involved in N-methyl-D-aspartate (NMDA)-induced excitotoxic injury in the mouse brain.

METHODS

Brain injury was induced by NMDA microinjection (50-150 nmol in 0.5 microL) into the cerebral cortex. The changes in CysLT1 receptor expression 24 h after NMDA injection and the effects of a CysLT1 receptor antagonist, pranlukast (0.01 and 0.1 mg/kg), an NMDA receptor antagonist, ketamine (30 mg/kg), and an antioxidant, edaravone (9 mg/kg) were observed.

RESULTS

In the NMDA-injured brain, the CysLT1 receptor mRNA, and protein expression were upregulated, and the receptor was mainly localized in the neurons and not in the astrocytes. Pranlukast, ketamine and edaravone decreased NMDA-induced injury; pranlukast (0.1 mg/kg) and ketamine inhibited the upregulated expression of the CysLT1 receptor.

CONCLUSION

CysLT1 receptor expression in neurons is upregulated after NMDA injection, and NMDA-induced responses are inhibited by CysLT1 receptor antagonists, indicating that the increased CysLT1 receptor is involved in NMDA excitotoxicity.

Edaravone protects PC12 cells from ischemic-like injury via attenuating the damage to mitochondria

BACKGROUND

Edaravone had been validated to effectively protect against ischemic injuries. In this study, we investigated the protective effect of edaravone by observing the effects on anti-apoptosis, regulation of Bcl-2/Bax protein expression and recovering from damage to mitochondria after OGD (oxygen-glucose deprivation)-reperfusion.

METHODS

Viability of PC12 cells which were injured at different time of OGD injury, was quantified by measuring MTT (2-(4,5-dimethylthia-zol-2-yl)-2,5-diphenyltetrazolium bromide) staining. In addition, PC12 cells' viability was also quantified after their preincubation in different concentration of edaravone for 30 min followed by (OGD). Furthermore, apoptotic population of PC12 cells that reinsulted from OGD-reperfusion with or without preincubation with edaravone was determined by flow cytometer analysis, electron microscope and Hoechst/PI staining. Finally, change of Bcl-2/Bax protein expression was detected by Western blot.

RESULTS

(1) The viability of PC12 cells decreased with time (1 - 12 h) after OGD. We regarded the model of OGD 2 h, then replacing DMEM (Dulbecco's Modified Eagle's Medium) for another 24 h as an OGD-reperfusion in this research. Furthermore, most PC12 cells were in the state of apoptosis after OGD-reperfusion. (2) The viability of PC12 cells preincubated with edaravone at high concentrations (1, 0.1, 0.01 micromol/L) increased significantly with edaravone protecting PC12 cells from apoptosis after OGD-reperfusion injury. (3) Furthermore, edaravone attenuates the damage of OGD-reperfusion on mitochondria and regulated Bcl-2/Bax protein imbalance expression after OGD-reperfusion.

CONCLUSION

Neuroprotective effects of edaravone on ischemic or other brain injuries may be partly mediated through inhibition of Bcl-2/Bax apoptotic pathways by recovering from the damage of mitochondria.

Caffeic acid ameliorates early and delayed brain injuries after focal cerebral ischemia in rats

AIM

To investigate the effects of caffeic acid on early and delayed injuries after focal cerebral ischemia in rats, and the possible relation to 5-lipoxygenase inhibition.

METHODS

Transient focal cerebral ischemia was induced by middle cerebral artery occlusion in Sprague-Dawley rats. Caffeic acid (10 and 50 mg/kg) was ip injected for 5 d after ischemia. The brain injuries were observed, and the levels of cysteinyl leukotrienes and leukotriene B4 in the brain tissue were measured.

RESULTS

Caffeic acid (50 mg/kg) ameliorated neurological dysfunction and neuron loss, and decreased infarct volume 24 h after ischemia; it attenuated brain atrophy, infarct volume, and particularly astrocyte proliferation 14 d after ischemia. In addition, it reduced the production of leukotrienes (5-lipoxygenase metabolites) in the ischemic hemispheres 3 h and 7 d after ischemia.

CONCLUSION

Caffeic acid has protective effect on both early and delayed injuries after focal cerebral ischemia in rats; and this effect may partly relate to 5-lipoxygenase inhibition.

[Incomplete protective effects of minocycline on traumatic brain injury in rats and mice]

OBJECTIVE

To evaluate protective effect of minocycline,a semisynthetic tetracycline derivative on different traumatic brain injuries in rats and mice.

METHODS

The opened brain trauma was induced in rats and the closed head injury and cold brain injury were induced in mice. In 3 brain trauma models, minocycline (45 mg/kg, ip) was administered twice daily for 2 d before the operation, at 30 min before and 1 h after the operation, and once daily for 2 d following the operation (totally 8 doses in 5 d). After the operation, the behavioral alteration was observed daily, lesion area and survival neuron density were measured at the end of the experiments (14 d after the injuries).

RESULT

For rat opened traumatic injury, minocycline promoted the recovery of hindlimb motor activity (inclined board angle), but did not alter other indexes. For mouse closed head traumatic injury, minocycline reduced the neuron loss, but did not improve behavioral dysfunction. For mouse cold injury-induced trauma, minocycline reduced death rate and lesion area, but did not remarkably improve behavior and neuron loss.

CONCLUSION

Minocycline only has an incomplete neuroprotective effect on different brain traumatic injuries in rats and mice.

Increased expression of cysteinyl leukotriene receptor-1 in the brain mediates neuronal damage and astrogliosis after focal cerebral ischemia in rats

Cysteinyl leukotrienes are potent pro-inflammatory mediators. Cysteinyl leukotriene receptor 1 is one of the two cysteinyl leukotriene receptors cloned. We recently reported that cysteinyl leukotriene receptor 1 antagonists protected against cerebral ischemic injury, and an inducible expression of cysteinyl leukotriene receptor 1 was found in neuron- and glial-appearing cells after traumatic injury in human brain. To determine the role of cysteinyl leukotriene receptor 1 in ischemic brain injury, we investigated the temporal and spatial profile of cysteinyl leukotriene receptor 1 expression in rat brain from 3 h to 14 days after 30 min of middle cerebral artery occlusion, and observed the effect of pranlukast, a cysteinyl leukotriene receptor 1 antagonist, on the ischemic injury. We found that cysteinyl leukotriene receptor 1 mRNA expression was up-regulated in the ischemic core both 3-12 h and 7-14 days, and in the boundary zone 7-14 days after reperfusion. In the ischemic core, cysteinyl leukotriene receptor 1 was primarily localized in neurons 24 h, and in macrophage/microglia 14 days after reperfusion; while in the boundary zone it was localized in proliferated astrocytes 14 days after reperfusion. Pranlukast attenuated neurological deficits, reduced infarct volume and ameliorated neuron loss in the ischemic core 24 h after reperfusion; it reduced infarct volume, ameliorated neuron loss and inhibited astrocyte proliferation in the boundary zone 14 days after reperfusion. Thus, we conclude that cysteinyl leukotriene receptor 1 mediates acute neuronal damage and subacute/chronic astrogliosis after focal cerebral ischemia.

Effect of endogenous histamine in the ventral hippocampus on fear memory deficits induced by scopolamine as evaluated by step-through avoidance response in rats

In the present study, the effects of endogenous histamine in the ventral hippocampus on fear memory deficits induced by scopolamine were investigated as evaluated by step-through avoidance response in adult male rats. Bilateral ventral hippocampal injection of scopolamine (i.h., 2, 5 microg/site) significantly produced depressant effects on the active avoidance response in a dose-dependent manner. Histamine H(3)-antagonist clobenpropit (5, 10 microg/site) significantly ameliorated the fear memory deficits induced by scopolamine in a dose-dependent manner. Its procognitive effect was completely antagonized by immepip (10 microg/site), a selective histamine H(3)-agonist. Both histamine H(1)-antagonist pyrilamine and H(2)-antagonist cimetidine, also inhibited the procognitive effects of clobenpropit. Additionally, the procognitive effects of clobenpropit on the fear memory deficits induced by scopolamine were significantly potentiated by intraperitoneal (i.p.) injection of histidine, a precursor of histamine, but markedly reversed by i.h. injection of alpha-fluoromethylhistidine (FMH, 10 microg/site), a selective and potent histidine decarboxylase inhibitor. It is concluded that the increased endogenous histamine release in the ventral hippocampus ameliorates the scopolamine-induced fear memory deficits, and its action is mainly mediated by histamine presynaptic H(3)-receptors and postsynaptic H(1)- and H(2)-receptors.

[H2 receptor mediates the protective effect of histamine against the cellular edema and viability reduction induced by oxygen-glucose deprivation in rat hippocampal slices]

AIM

To determine the effect of histamine on ischemia-induced cellular edema and viability reduction in rat hippocampal slices, and the involved subtypes of histamine receptor in this effect.

METHODS

In vitro ischemic injury of hippocampal slices was induced by oxygen-glucose deprivation (OGD). The slice injury was determined by real-timely measuring the changes of light transmittance (LT) for the cellular edema in CA1 region of the hippocampal slice, and by detecting the product of 2, 3, 5-triphenyltetrazolium chloride (TTC), formazan, for the slice viability. The effect of histamine at various concentrations on the slice injury was observed, and the blockage by antagonists of histamine receptors was also investigated.

RESULTS

Histamine (0.01-10 micromol x L(-1)) inhibited the peak value of LT during OGD in hippocampal slices and improved the reduced viability after OGD. Diphenhydramine (0.1-10 micromol x L(-1)), an H1 receptor antagonist, did not affect the effect of histamine, while cimetidine (0.1-10 micromol x L(-1)), an H2 receptor antagonist, partly abolished the protective effect of histamine.

CONCLUSION

Histamine protects hippocampal slices against ischemia-induced cellular edema and viability reduction; this effect might be mediated via, at least partly, H2 receptor.

[Homeostatic conditions affect the protective effect of edaravone on ischemic injury in neurons]

OBJECTIVE

To determine whether homeostatic conditions (pH, glycine or ion concentration) affect the protective effects of edaravone on ischemic injury in rat cortical neurons.

METHODS

In cultured rat cortical neurons, the compositions in the experimental solutions were changed to mimic the disturbance of homeostasis after cerebral ischemia. In vitro ischemic injury was induced by oxygen-glucose deprivation (OGD) for 3 h and reperfusion for 12 h, and the neuron injury was evaluated by 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) reduction assay and lactate dehydrogenase (LDH) release. Effect of edaravone on OGD injury was observed in different experimental solutions.

RESULT

In weak alkalified solution (pH 7.8) or the solution containing glycine (10 micromol/L), OGD injury became more serious; but in weak acidic (pH 6.5) or higher Mg(2+) (1.8 mmol/L) solutions, OGD injury was attenuated. Edaravone (1 micromol/L) reversed the injury in the solutions with pH 6.1,7.4 and 7.8 or the solution containing glycine, but did not show protective effect in the solution with pH 6.5 and the higher Mg(2+) or lower Ca(2+) solution.

CONCLUSION

The changes of homeostatic conditions affect the severity of ischemic injury of neurons and the protective effect of edaravone.

Pranlukast reduces neutrophil but not macrophage/microglial accumulation in brain after focal cerebral ischemia in mice

AIM

To determine whether pranlukast, a cysteinyl leukotriene receptor-1 antagonist, exerts an anti-inflammatory effect on focal cerebral ischemia in mice.

METHODS

Focal cerebral ischemia in mice was induced by permanent middle cerebral artery occlusion (MCAO). In addition to neurological deficits, infarct volume, degenerated neurons and endogenous IgG exudation, we detected accumulation of neutrophils and macrophage/microglia in the ischemic brain tissue 72 h after MCAO. Pranlukast was ip injected 30 min before and after MCAO.

RESULTS

Pranlukast significantly attenuated neurological deficits, infarct volume, neuron degeneration and IgG exudation. Importantly, pranlukast (0.01 and 0.1 mg/kg) inhibited myeloperoxidase-positive neutrophil, but not CD11b-positive macrophage/microglial accumulation in the ischemic cortical tissue.

CONCLUSION

Pranlukast exerts an anti-inflammatory effect on focal cerebral ischemia in the subacute phase that is limited to neutrophil recruitment through the disrupted blood-brain barrier.

[Photomacrography of brain surface for evaluating blood-brain barrier disruption within 24 h after focal cerebral ischemia in mice]

OBJECTIVE

To establish a new photomacrographic analysis of morphological changes on brain surface to evaluate blood-brain barrier (BBB) disruption.

METHODS

Permanent focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in mice. Brains were removed 10 min, 0.5, 1, 3, 6, 12 and 24 h after MCAO. The whole brains and brain slices were photographed by a digital camera. BBB disruption was evaluated by hemorrhage and traced Evans blue (EB) on the brain surface. Fluoremetric quantitation of EB and water content in the brains were also performed at various time points.

RESULT

Photomacrographic morphological analysis showed that hemorrhage and traced EB on the surface of the brains significantly increased from 3 h after focal cerebral ischemia,which were correlated to the results in the brain slices. EB content in the ischemic hemispheres was significantly increased from 0.5 h after MCAO, and water content was increased from 1 h after MCAO.

CONCLUSION

Photomacrographic measurement is a simple and useful method for evaluating BBB disruption semi-quantitatively, and can detect BBB disruption earlier after focal cerebral ischemia in mice.

Effect of oxygen-glucose deprivation on degranulation and histamine release of mast cells

The purpose of this study was to investigate the effect of oxygen-glucose deprivation (OGD) on degranulation and histamine release of mast cells. Cultured mast cells were exposed to OGD for 1, 2, 4, 8, or 16 h. At 2 h of OGD exposure, the degranulation percentage of mast cells had increased and subsequently showed a progressive further increase, associated with a similar change in lactate dehydrogenase release. Histamine release increased significantly from 1 h of OGD exposure. These results indicate that OGD induces mast cells to degranulate, possibly via a cytotoxic response. This in vitro ischemic model of mast cells might clarify their roles in the pathological processes induced by cerebral ischemia.

GM1 stabilizes expression of NMDA receptor subunit 1 in the ischemic hemisphere of MCAo/reperfusion rat

OBJECTIVE

To determine the protective effect of monosialoganglionside (GM1) and evaluate the influence of GM1 on expression of N-methyl-D-aspartate receptor subunit 1 (NMDAR1) in Sprague-Dawley (SD) rats with focal cerebral ischemia-reperfusion (I/R).

METHODS

Left middle cerebral artery (MCA) was occluded by an intraluminal suture for 1 h and the brain was reperfused for 72 h in SD rats when infarct volume was measured, GM1 (10 mg/kg) was given ip (intraperitoneally) at 5 min (group A), 1 h (group B) and 2 h (group C) after MCA occlusion (MCAo). Expression of NMDAR1 was detected by Western blot at various time after reperfusion (4 h, 6 h, 24 h, 48 h and 72 h) in ischemic hemispheres of the rats with or without GM1 administered.

RESULTS

(1) Adjusted relative infarct volumes of groups A and B were significantly smaller than that of group C and the control group (P<0.01 and P<0.05, respectively). (2) Expression level of NMDAR1 was temporally high at 6 h after reperfusion, and dipped below the normal level at 72 h after reperfusion. GM1 at 5 min after MCAo significantly suppressed the expression of NMDAR1 at 6 h after reperfusion (P<0.05 vs the control). At 72 h after reperfusion, the NMDAR1 expression level of rats treated with GM1 administered (at 5 min or 2 h after MCAo) was significantly higher than that of the control (P<0.05).

CONCLUSION

GM1 can time-dependently reduce infarct volume in rats with focal cerebral I/R partly through stabilizing the expression of NMDAR1.

Distribution of cysteinyl leukotriene receptor 2 in human traumatic brain injury and brain tumors

AIM

To determine the distribution of cysteinyl leukotriene receptor 2 (CysLT2), one of the cysteinyl leukotriene receptors, in human brains with traumatic injury and tumors.

METHODS

Brain specimens were obtained from patients who underwent brain surgery. CysLT2 in brain tissues was examined using immunohistochemical analysis.

RESULTS

CysLT2 was expressed in the smooth muscle cells (not in the endothelial cells) of arteries and veins. CysLT2 was also expressed in the granulocytes in both vessels and in the brain parenchyma. In addition, CysLT2 was detected in neuron- and glial-appearing cells in either the late stages of traumatic injury or in the area surrounding the tumors. Microvessels regenerated 8 d after trauma and CysLT2 expression was recorded in their endothelial cells.

CONCLUSION

CysLT2 is distributed in vascular smooth muscle cells and granulocytes, and brain trauma and tumor can induce its expression in vascular endothelial cells and in a number of other cells.

ONO-1078 reduces NMDA-induced brain injury and vascular cell adhesion molecule-1 expression in rats

AIM

To determine whether ONO-1078 (pranlukast), a potent cysteinyl leukotriene receptor 1 (CysLT1) antagonist, has an effect on N-methyl-D-aspartate (NMDA)-induced brain injury and vascular cell adhesion molecule-1 (VCAM-1) expression in rats.

METHODS

Brain injury was induced by direct microinjection of NMDA (0.3 mumol in 1 muL of sterile 0.1 mol/L PBS, pH 7.4) into the cerebral cortex. The lesion volume (area), brain edema and neuron density were assessed by an image analyzer and the expression of VCAM-1 in the cortex was detected by Western blot 24 h after NMDA injection. ONO-1078 (0.03, 0.1, or 0.3 mg/kg) and edaravone (MCI-186, 10 mg/kg), a neuroprotective agent, were ip injected 30 min before and after NMDA injection.

RESULTS

NMDA microinjection produced well-defined focal lesions dose- and time-dependently. ONO-1078 (0.1, 0.3 mg/kg) and edaravone (10 mg/kg) decreased the total lesion volume, lesion area and brain edema induced by NMDA. Furthermore, ONO-1078 (0.1, 0.3 mg/kg) significantly inhibited the enhanced expression of VCAM-1 in the injured cortices, but edaravone did not have this effect.

CONCLUSION

CysLT1 receptor antagonist ONO-1078 attenuates NMDA-induced brain damage in rats, and this might relate to the attenuation of NMDA receptor-dependent neurotoxicity and the inhibition of the upregulation of VCAM-1 expression.

Increased expression of aquaporin-4 in human traumatic brain injury and brain tumors

OBJECTIVE

To characterize the expression of aquaporin-4 (AQP4), one of the aquaporins (AQPs), in human brain specimens from patients with traumatic brain injury or brain tumors.

METHODS

Nineteen human brain specimens were obtained from the patients with traumatic brain injury, brain tumors, benign meningioma or early stage hemorrhagic stroke. MRI or CT imaging was used to assess brain edema. Hematoxylin and eosin staining were used to evaluate cell damage. Immunohistochemistry was used to detect the AQP4 expression.

RESULTS

AQP4 expression was increased from 15 h to at least 8 d after injury. AQP4 immunoreactivity was strong around astrocytomas, ganglioglioma and metastatic adenocarcinoma. However, AQP4 immunoreactivity was only found in the centers of astrocytomas and ganglioglioma, but not in metastatic adenocarcinoma derived from lung.

CONCLUSION

AQP4 expression increases in human brains after traumatic brain injury, within brain-derived tumors, and around brain tumors.

[A novel method for continuously assessing the spatio-temporal properties of locomotor activity in mice]

OBJECTIVE

To develop a novel method for continuously assessing the spatio-temporal properties of locomotor activity of mice in an open field using a video-tracking system.

METHODS

The locomotor tracks in the open field were recorded by video camera within 22 h, and analyzed by AnalyPower1.1 system that we developed recently. Total distance, distances traveled in different zones and their ratios to total distance; total time,times spent in different zones and their ratios to total time were used as indicators to assess the properties of locomotor activity.

RESULTS

In free and wakeful state, the locomotor activity of mice presented obvious regional and temporal properties. Mice preferred to stay in home base (food and water zones), and frequently visited the peripheral zones but seldom the center zones within 22 h. On the other hand, mice were most active within the first 1 h, and then their activity obviously decreased. After their activity became stable, the mice showed the obvious circadian variation of the activity as they were more active in the night.

CONCLUSION

The novel method we developed in this study can continuously assess the spatio-temporal properties of locomotor activity quantitatively and objectively.