Effect Of Cycloheximide Research Articles

The Effects of Polyphenol Oxidase and Cycloheximide on the Early Stage of Browning in Phalaenopsis Explants

Explant browning is one of the major problems in the tissue culture process, and polyphenol oxidase (PPO), is the major proteases involved in plant tissue browning. We investigated the effects of polyphenol oxidase on the early stage of browning in explants of the orchid Phalaenopsis. Our results show that PPO activity was significantly higher in explants cultured for 3 d than in the 0h control. The levels of PPO transcripts and PPO protein were significantly higher in explants cultured for 6h compared to the 0h control; these high expression levels were maintained over increasing cultivation time. Cycloheximide (CHX) treatment reduced PPO transcript levels, PPO protein levels, and PPO enzyme activity. High levels of PPO mRNA and PPO protein were detected in the cytoplasm and vascular bundles of Phalaenopsis explants cultured for 6h compared to explants cultured for 0h, 24h, and 3 d. CHX treatment did not significantly affect the distribution of PPO mRNA and PPO protein in explant tissues, but their levels were significantly lower than those of the untreated control.

Effect of anisomycin, a protein synthesis inhibitor, on the in vitro developmental potential, ploidy and embryo quality of bovine ICSI embryos.

Increasing the efficiency of intracytoplasmic sperm injection (ICSI) in domestic animals has been attempted by many researchers, however embryonic development to the blastocyst stage remains low compared with that of in vitro fertilization (IVF) embryos. One of the main problems observed in cattle is inadequate oocyte activation after ICSI. The present study compared the effect of cycloheximide (CHX), 6-dimethylaminopurine (DMAP), and anisomycin (ANY) on the fertilization rate, development, ploidy and quality of bovine embryos generated by ICSI. Although no differences were observed between treatments in terms of cleavage, higher blastocyst rates were observed for ANY (37.3%) compared with CHX (21.8%, P 0.05) treatments. No differences were observed in the quality of embryos as assessed by the total number of cells, their distribution to the different embryo compartments [inner cell mass (ICM) and trophectoderm (TE)], the proportion of ICM cells to the total cell numbers and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL)-positive cells. Similarly, no differences were observed in the normal ploidy of embryos (56, 67, and 55%) for ANY, CHX and DMAP, respectively. However, higher fertilization rates were observed for ANY (75%) and CHX (87%) treatments compared with DMAP (35%). In conclusion, ANY showed a superior developmental rate compared with CHX treatment. Although no significant differences were observed compared with an improved protocol of DMAP (2Io-DMAP), the lower fertilization rate recorded with DMAP strongly suggests that ANY could be a better alternative for oocyte activation than traditional chemical compounds used currently in ICSI.

The effect of cycloheximide and growth regulators on the senescence of cut leaves in Hosta sp. and Zantedeschia aethiopica

Abstract The leaves of Zantedeschia and Hosta are used as florist greens in different floral arrangements. The most efficient postharvest treatment for cut foliage is the use of growth regulators, which prolong their vase life by delaying degradative changes occurring in leaves, especially proteolysis. Cycloheximide (CHI) is one of the protein synthesis inhibitors, blocking the enzymes responsible for decreasing membrane integrity, a phenomenon hastening senescence. The aim of this experiment was to evaluate the effects of CHI and benzyladenine (BA) or gibberellic acid (GA3) on the longevity of cut foliage in hosta (Hosta sp.) cultivars and Ethiopian calla (Zantedeschia aethiopica) and to follow the changes in certain proteolytic processes occurring during senescence. Generally, 24 h conditioning with cycloheximide shortened the longevity of cut calla leaves while having no effect on hosta vase life. In ageing leaves of ‘Minima Glauca’ hosta and calla, the total proteolytic activity increased, including that of cysteine protease. Due to the application of BA or GA3 in hosta and calla, respectively, this activity was limited. On the contrary, the use of CHI either did not affect the activity of cysteine protease or increased it several-fold relative to the control, in hosta and calla, respectively. Leaves treated with growth regulators had many more soluble proteins and fewer free amino acids, including free proline, than leaves from other treatments. The highest free proline level was determined in calla leaves conditioned with CHI, where it increased 18-fold relative to the initial level.

Effects of cycloheximide on photosynthetic abilities, reflectance spectra and fluorescence emission spectra in Phyllostachys edulis

CHX had remarkable inhibition on P. edulis photosynthesis, and the reflectance indexes and F 685 / F 735 had the potential value for quantifying the effects of antibiotics on trees. To reveal the effects of antibiotics on photosynthesis and provide help for remote sensing the influence of antibiotics on trees, we investigated the effects of cycloheximide (CHX) on Phyllostachys edulis. In CHX treatment, the photosynthetic pigment content in P. edulis was decreased markedly, which led to the increase in the reflectance spectra in visible region. CHX reduced the donor side and acceptor side of photosystem II (PSII), density of reaction centers, quantum production and electron transport in PSII, and raised the dissipation of absorbed light energy. Besides the dissipation, the absorbed light energy can be emitted as fluorescence with two main peaks in the red (685 nm) and far-red (735 nm) region, respectively. In 0.50 mM CHX treatment, a significant decline in the height and area of the peak at 685 nm might result from Chl loss reducing the light absorption and lower photochemical reaction in PSII. When fourth derivative analysis of fluorescence emission spectra was performed, the changes of the peaks at 718, 735 and 750 nm might result from the decline of absorbed solar radiation caused by the reduced pigment content and/or the damages to the PSI. In CHX treatment, a remarkable increase in intercellular CO2 concentrations and light compensation point and decrease in light saturation point demonstrated that the CO2 assimilation ability was decreased. Those results suggested that the photosynthesis in trees can be reduced after they were watered with wastewater containing CHX. The reflectance indexes and F 685/F 735 (H 685/H 735 and A 685/A 735) were markedly affected by CHX, demonstrating that they had the potential value for quantifying the effects of antibiotics on trees.

Cycloheximide Efficacy Varies Temporally in Improving Postharvest Performance of Cool Wet Stored Dianthus chinensis L. Cut Sprays

An experiment was designed to determine the synergistic effect of cold temperature and cycloheximide (CHI) on the postharvest performance of cut sprays of Dianthus chinensis. Sprays were harvested at 800 h with the oldest bud at paint brush stage, cut to a length of 27 cm and wet stored at 5 °C for 72 h before or after 1 h 0.1 mM CHI pulse. Another set of sprays was pulsed with 0.1 mM CHI for 1 h during storage (after 35 ½ h). A set of unpulsed sprays stored at 5 °C represented control. The treatment effects were evaluated by placing the sprays in holding solution comprising of distilled water and sucrose (SUC) (0.05 M) at room temperature (21 ± 2 °C) in the laboratory. The sprays wet stored at 5 °C and pulse treated with 0.1 mM CHI after 72 h wet storage showed an increment of vase life by 3 days; besides sustained rate of blooming, higher fresh and dry mass, floral diameter and sugar fractions, but maintained lower soluble protein content in comparison to the control. Vase life, fresh mass, dry mass and floral diameter of sprays wet stored at 5 °C and 1 h pulse treated with 0.1 mM CHI before and during storage was considerably lower than the sprays 1 h pulse treated with 0.1 mM CHI after storage, but significantly higher than that of the control. The study revealed that 1 h pulse treatment with 0.1 mM CHI after 72 h wet storage at 5 °C, followed by transfer to SUC can be used as an effective postharvest storage protocol to bring about the transportation of this beautiful cut flower within 72 h.

UV-B light contributes directly to the synthesis of chiloglottone floral volatiles.

Australian sexually deceptive Chiloglottis orchids attract their specific male wasp pollinators by means of 2,5-dialkylcyclohexane-1,3-diones or 'chiloglottones', representing a newly discovered class of volatiles with unique structures. This study investigated the hypothesis that UV-B light at low intensities is directly required for chiloglottone biosynthesis in Chiloglottis trapeziformis. Chiloglottone production occurs only in specific tissue (the callus) of the labellum. Cut buds and flowers, and whole plants with buds and flowers, sourced from the field, were kept in a growth chamber and interactions between growth stage of the flowers and duration and intensity of UV-B exposure on chiloglottone production were studied. The effects of the protein synthesis inhibitor cycloheximide were also examined. Chiloglottone was not present in buds, but was detected in buds that were manually opened and then exposed to sunlight, or artificial UV-B light for ≥5 min. Spectrophotometry revealed that the sepals and petals blocked UV-B light from reaching the labellum inside the bud. Rates of chiloglottone production increased with developmental stage, increasing exposure time and increasing UV-B irradiance intensity. Cycloheximide did not inhibit the initial production of chiloglottone within 5 min of UV-B exposure. However, inhibition of chiloglottone production by cycloheximide occurred over 2 h of UV-B exposure, indicating a requirement for de novo protein synthesis to sustain chiloglottone production under UV-B. The sepals and petals of Chiloglottis orchids strongly block UV-B wavelengths of light, preventing chiloglottone production inside the bud. While initiation of chiloglottone biosynthesis requires only UV-B light, sustained chiloglottone biosynthesis requires both UV-B and de novo protein biosynthesis. The internal amounts of chiloglottone in a flower reflect the interplay between developmental stage, duration and intensity of UV-B exposure, de novo protein synthesis, and feedback loops linked to the starting amount of chiloglottone. It is concluded that UV-B light contributes directly to chiloglottone biosynthesis. These findings suggest an entirely new and unexpected biochemical reaction that might also occur in taxa other than these orchids.

非対称バーストパルスシステムによるメダカ受精卵への物質導入実験における周囲溶液の影響調査

To establish a simple method for incorporating materials into fertilized medaka eggs by applying electric pulses including nanosecond pulsed electric fields (nsPEFs), we have tested pulse parameters as pulse width, pulse intensity, number of pulses, combination of several pulses, interval of pulses, and polarities of pulses. Improvement in incorporation efficiency was achieved with a new pulse system, named asymmetric burst system, which could generate a short rectangular pulse (from ten to several hundreds nanosecond) with high intensity (several kilovolt) and asymmetric bipolar burst pulses (in a range of microsecond to millisecond) with low intensity (from several volt to several tens volt). To gain the total efficiency for incorporation, it is necessary to investigate other factors in addition to the pulse parameters. In this paper, the effects of solutions that surrounds eggs are investigated. Among the combinations of pulsing and immersed surrounding solutions, we found that the electrical and experimental deleterious effects were strongly reduced under the condition that eggs were pulsed in a 6 mS/cm NaCl solution and kept in the same solution or put into and kept in an isotonic solution for 2 hours. This might be due to an appropriate electrical conductivity and an osmotic pressure difference between the inside of an egg and the surrounding solution. Moreover the adverse effects of cycloheximide on embryogenesis appeared clearly using the same condition.

The feed contaminant deoxynivalenol affects the intestinal barrier permeability through inhibition of protein synthesis.

Deoxynivalenol (DON) has critical health effects if the contaminated grains consumed by humans or animals. DON can have negative effects on the active transport of glucose and amino acids in the small intestine of chickens. As the underlying mechanisms are not fully elucidated, the present study was performed to delineate more precisely the effects of cycloheximide (protein synthesis inhibitor, CHX) and DON on the intestinal absorption of nutrients. This was to confirm whether DON effects on nutrient absorption are due to an inhibition of protein synthesis. Changes in ion transport and barrier function were assessed by short-circuit current (Isc) and transepithelial ion conductance (Gt) in Ussing chambers. Addition of D-glucose or L-glutamine to the luminal side of the isolated mucosa of the jejunum increased (P < 0.001) the Isc compared with basal conditions in the control tissues. However, the Isc was not increased by the glucose or glutamine addition after pre-incubation of tissues with DON or CHX. Furthermore, both DON and CHX reduced Gt, indicating that the intestinal barrier is compromised and consequently induced a greater impairment of the barrier function. The remarkable similarity between the activity of CHX and DON on nutrient uptake is consistent with their common ability to inhibit protein synthesis. It can be concluded that the decreases in transport activity by CHX was evident in this study using the chicken as experimental model. Similarly, DON has negative effects on the active transport of some nutrients, and these can be explained by its influence on protein synthesis.

Compounds used to produce cloned animals are genotoxic and mutagenic in mammalian assays in vitro and in vivo

The compounds 6-dimethylaminopurine and cycloheximide promote the successful production of cloned mammals and have been used in the development of embryos produced by somatic cell nuclear transfer. This study investigated the effects of 6-dimethylaminopurine and cycloheximide in vitro, using the thiazolyl blue tetrazolium bromide colorimetric assay to assess cytotoxicity, the trypan blue exclusion assay to assess cell viability, the comet assay to assess genotoxicity, and the micronucleus test with cytokinesis block to test mutagenicity. In addition, the comet assay and the micronucleus test were also performed on peripheral blood cells of 54 male Swiss mice, 35 g each, to assess the effects of the compounds in vivo. The results indicated that both 6-dimethylaminopurine and cycloheximide, at the concentrations and doses tested, were cytotoxic in vitro and genotoxic and mutagenic in vitro and in vivo, altered the nuclear division index in vitro, but did not diminish cell viability in vitro. Considering that alterations in DNA play important roles in mutagenesis, carcinogenesis, and morphofunctional teratogenesis and reduce embryonic viability, this study indicated that 6-dimethylaminopurine and cycloheximide utilized in the process of mammalian cloning may be responsible for the low embryo viability commonly seen in nuclear transfer after implantation in utero.

Mechanism of Saccharomyces cerevisiae yeast cell death induced by heat shock. Effect of cycloheximide on thermotolerance

The mechanism of yeast cell death induced by heat shock was found to be dependent on the intensity of heat exposure. Moderate (45°C) heat shock strongly increased the generation of reactive oxygen species (ROS) and cell death. Pretreatment with cycloheximide (at 30°C) suppressed cell death, but produced no effect on ROS production. The protective effect was absent if cycloheximide was added immediately before heat exposure and the cells were incubated with the drug during the heat treatment and recovery period. The rate of ROS production and protective effect of cycloheximide on viability were significantly decreased in the case of severe (50°C) heat shock. Treatment with cycloheximide at 39°C inhibited the induction of Hsp104 synthesis and suppressed the development of induced thermotolerance to severe shock (50°C), but it had no effect on induced thermotolerance to moderate (45°C) heat shock. At the same time, Hsp104 effectively protected cells from death independently of the intensity of heat exposure. These data indicate that moderate heat shock induced programmed cell death in the yeast cells, and cycloheximide suppressed this process by inhibiting general synthesis of proteins.

Heparin-benzyl alcohol enhancement of biofilms formation and antifungal susceptibility of vaginal Candida species isolated from pregnant and nonpregnant Saudi women.

Biofilm formation by Candida species is a major contribute to their pathogenic potential.The aim of this study was to determine in vitro effects of EDTA, cycloheximide, and heparin-benzyl alcohol preservative on C. albicans (126) and non-albicans (31)vaginal yeast isolates biofilm formations and their susceptibility against three antifungal Etest strips. Results of the crystal violet-assay, indicated that biofilms formation were most commonly observed [100%] for C. kefyr, C. utilis, C. famata, and Rhodotorula mucilaginosa, followed by C. glabrata [70%], C. tropicalis [50%], C. albicans [29%], Saccharomyces cerevisiae [0.0%]. EDTA (0.3mg/ml) significantly inhibited biofilm formation in both C. albicans and non-albicans isolates (P=0.0001) presumably due to chelation of necessary metal cations for the process-completion. In contrast, heparin (-benzyl alcohol preservative) stimulated biofilm formation in all tested isolates, but not at significant level (P=0.567). Conversely, cycloheximide significantly (P=0.0001) inhibited biofilm formation in all C. albicans strains(126) and its effect was even 3 fold more pronounced than EDTA inhibition, probably due to its attenuation of proteins (enzymes) and/or complex molecules necessary for biofilm formation. Results also showed that all nonalbicans yeasts isolates were susceptible to 5-flucytosine (MIC50, 0.016 µg/ml; MIC90, 0.064 µg/ml), but 14% of C. albicans isolates were resistant (MIC50, 0.064 µg/ml; MIC90 >32 µg/ml). The MIC50 value of amphotricin B for all C. albicans and non-albicans isolates was at a narrow range of 0.023 µg /ml, and the MIC90 values were 0.047 µg/ml and 0.064 µg/ml respectively, thereby confirming its efficacy as a first line empiric- treatment of Candida spp infections.

Transferrin iron uptake is stimulated by ascorbate via an intracellular reductive mechanism

Although ascorbate has long been known to stimulate dietary iron (Fe) absorption and non-transferrin Fe uptake, the role of ascorbate in transferrin Fe uptake is unknown. Transferrin is a serum Fe transport protein supplying almost all cellular Fe under physiological conditions. We sought to examine ascorbate's role in this process, particularly as cultured cells are typically ascorbate-deficient. At typical plasma concentrations, ascorbate significantly increased 59Fe uptake from transferrin by 1.5–2-fold in a range of cells. Moreover, ascorbate enhanced ferritin expression and increased 59Fe accumulation in ferritin. The lack of effect of cycloheximide or the cytosolic aconitase inhibitor, oxalomalate, on ascorbate-mediated 59Fe uptake from transferrin indicate increased ferritin synthesis or cytosolic aconitase activity was not responsible for ascorbate's activity. Experiments with membrane-permeant and -impermeant ascorbate-oxidizing reagents indicate that while extracellular ascorbate is required for stimulation of 59Fe uptake from 59Fe-citrate, only intracellular ascorbate is needed for transferrin 59Fe uptake. Additionally, experiments with l-ascorbate analogs indicate ascorbate's reducing ene-diol moiety is necessary for its stimulatory activity. Importantly, neither N-acetylcysteine nor buthionine sulfoximine, which increase or decrease intracellular glutathione, respectively, affected transferrin-dependent 59Fe uptake. Thus, ascorbate's stimulatory effect is not due to a general increase in cellular reducing capacity. Ascorbate also did not affect expression of transferrin receptor 1 or 125I-transferrin cellular flux. However, transferrin receptors, endocytosis, vacuolar-type ATPase activity and endosomal acidification were required for ascorbate's stimulatory activity. Therefore, ascorbate is a novel modulator of the classical transferrin Fe uptake pathway, acting via an intracellular reductive mechanism.

The NFKB1 Promoter Polymorphism (−94ins/delATTG) Alters Nuclear Translocation of NF-κB1 in Monocytes after Lipopolysaccharide Stimulation and Is Associated with Increased Mortality in Sepsis

Because the nuclear factor-κB (NF-κB) coupled pathway is believed to amplify inflammation prevailing in sepsis, the authors tested the hypotheses that the insertion-deletion polymorphism (-94ins/delATTG) (1) alters nuclear translocation of nuclear factor-κB and activator protein-1 (NF-κB1) in monocytes after lipopolysaccharide stimulation; (2) affects lipopolysaccharide-induced NF-κB1 messenger RNA expression, tumor necrosis factor α concentrations, and tissue factor activity; and (3) may be associated with increased 30-day mortality in patients with sepsis. Nuclear translocation of NF-κB1 in monocytes after lipopolysaccharide stimulation from healthy blood donors was performed with immunofluorescence staining (n = 5 each). Lipopolysaccharide-induced NF-κB1 messenger RNA expression was measured with real-time polymerase chain reaction (PCR; n = 60), tumor necrosis factor α concentrations with a multiplexing system kit (n = 60), and tissue factor activity with thromboelastometry (n = 105). In a prospective study, multivariate proportional hazard analysis tested 30-day mortality in patients with sepsis (n = 143). The homozygous deletion genotype compared with the homozygous insertion genotype was associated with a nearly twofold increase in nuclear translocation of NF-κB1 (P = 0.001), a threefold difference in NF-κB1 messenger RNA expression (P = 0.001), and a twofold increase in tissue factor expression (P = 0.021). The deletion allele in adults with severe sepsis was tested as an independent prognostic factor for 30-day mortality (hazard ratio, 2.3; 95% CI, 1.13-4.8; P = 0.022). Mortality was 25% for homozygous insertion genotypes but 41% for combined heterozygous deletion/homozygous deletion genotypes (P = 0.034). The deletion allele of the NFκB1 insertion-deletion (-94ins/delATTG) polymorphism is associated with increased 30-day mortality in patients with severe sepsis and increased reaction of the innate immune system.

Cycloheximide stimulates suppressor of cytokine signaling-3 gene expression in 3T3-L1 adipocytes via the extracellular signal-regulated kinase pathway

Suppressor of cytokine signaling (SOCS)-3 can act as a regulator of energy metabolism and cytokine signaling in fat cells. It is regulated by hormones and toxicological factors. However, the action of cycloheximide on expression of adipocyte SOCS-3 gene is unknown. Using 3T3-L1 adipocytes, we found that cycloheximide up-regulated SOCS-3 mRNA expression in dose- and time-dependent manners. Treatment with actinomycin D prevented cycloheximide-stimulated SOCS-3 mRNA expression, suggesting that the effect of cycloheximide requires new mRNA synthesis. While cycloheximide was shown to increase activities of MEK1 and JNK, signaling was demonstrated to be inhibited by pretreatment with either MEK1 inhibitors U0126 and PD98059, or with the JNK inhibitor SP600125. U0126 and PD98059, respectively, reduced cycloheximide-stimulated SOCS-3 mRNA expression, but SP600125 did not antagonize cycloheximide effect. Moreover, cycloheximide was observed to up-regulate expression of other SOCS family members, such as SOCS-1, -2, -4, -5, -6, -7, and cytokine-inducible SH2-containing protein (CIS)-1 mRNAs. Such effects varied with the dosage and duration of cycloheximide treatment. These results imply the functional MEK1/ERK-mediated pathway is necessary for the cycloheximide stimulation of SOCS-3 gene expression.

The Cellular EJC Interactome Reveals Higher-Order mRNP Structure and an EJC-SR Protein Nexus

In addition to sculpting eukaryotic transcripts by removing introns, pre-mRNA splicing greatly impacts protein composition of the emerging mRNP. The exon junction complex (EJC), deposited upstream of exon-exon junctions after splicing, is a major constituent of spliced mRNPs. Here, we report comprehensive analysis of the endogenous human EJC protein and RNA interactomes. We confirm that the major "canonical" EJC occupancy site in vivo lies 24 nucleotides upstream of exon junctions and that the majority of exon junctions carry an EJC. Unexpectedly, we find that endogenous EJCs multimerize with one another and with numerous SR proteins to form megadalton sized complexes in which SR proteins are super-stoichiometric to EJC core factors. This tight physical association may explain known functional parallels between EJCs and SR proteins. Further, their protection of long mRNA stretches from nuclease digestion suggests that endogenous EJCs and SR proteins cooperate to promote mRNA packaging and compaction.

Effect of cycloheximide on epidermal growth factor receptor trafficking and signaling

Cycloheximide is the most common protein synthesis inhibitor, and is believed to specifically inhibit the cytoplasmic protein synthesis. Here we demonstrate that cycloheximide induces internalization and redistribution of EGF receptor to early endosomes in HeLa cells independent of receptor tyrosine phosphorylation, but dependent on p38 MAPK activity. Degradation of EGF receptor or its downstream effectors was not observed. EGF-induced activation of ERK1/2 was inhibited upon pre-treatment with cycloheximide, but did not activate JNK. The observed effects of treatment with cycloheximide alone are significant and therefore results involving the use of cycloheximide for inhibition of protein synthesis must be interpreted with caution. Structured summary of protein interactionsEEA1 and EGFRcolocalize by fluorescence microscopy (View interaction).

Effect of roscovitine and cycloheximide on ultrastructure of sheep oocytes

It is believed the temporary meiosis arrest with roscovitine or cycloheximide may improve the in vitro developmental competence of oocytes in different animal species. However, little is known about the effects of these inhibitors on ultrastructure of ovines cumulus–oocyte complexes (COCs). The aim of this study was to evaluate the progression of cytoplasmic maturation and the ultrastructural changes in sheep COCs exposed to roscovitine or cycloheximide, at acceptable concentrations. COCs were in vitro cultured for 24h in maturation medium (control group) containing 100μM roscovitine or 1μg/mL cycloheximide (treatment groups). After this time, some COCs were cultured for further 22h in inhibitor-free medium. The ultrastructure organization of COCs was evaluated by transmission electron microscopy before (immature group) and after in vitro culture for 24 and 46h. As expected, signs of immaturity and maturity were observed in immature and control groups, respectively. In treatment with roscovitine, there were cumulus cells degeneration, swelling of mitochondrias, few cortical granules and many vesicles with electron-dense material. However, in cycloheximide treatment there were not signs of degeneration or cellular senescence. Metabolic units and mitochondrial pleomorphism were found in all experimental groups. These evidences demonstrate that roscovitine promoted irreversible ultrastructural changes while cycloheximide did not affect the cytoplasmic maturation. However, the implications on embryo development are still unclear.

Mechanism of dexamethasone inhibiting U937 cell adhesion and phagocytose function

Objective To investigate the mechanism of dexamethasone (Dex) in inhibiting monocyte adhesion and phagocytose function. Methods Under the stimulation of phorbo1-12-myristate-13-acetate (PMA),U937 monocytes cultured in vitro were treated with Dex and Fasudil respectively.The adhesion rate of U937 monocles to human umbilical vein endothelial cells (HUVECs) and their phagocytic ability of India ink were studied.The protein content and activity of rho-associated coiled-coil protein kinase 1 ( ROCK1 ) as well as the effects of mifepristone and cycloheximide on Dex were determined.Results Both DEX and Fasudil could significantly inhibit the adhesion tate and phagocytosis of U937 cells stimulated by PMA and suppressed the activity of ROCK1.While mifepristone and cycloheximide could not alter these effects of DEX. Conclusion DEX interferes with the adhesion and phagocytosis function of U937 cells by inhibiting ROCKI activity. Key words: Dexamethasone; Phagocytose; Non-genomic effect

Effects of the protein synthesis inhibitor cycloheximide on anxiety-like extinction behavior in an animal model of post-traumatic stress

The effect of cycloheximide (CXM), a protein synthesis inhibitor, on memory reconsolidation and extinction was explored in rats using a model of post-traumatic stress. Forty-two animals were exposed to predator stress followed by 1, 2, or 4 extinction trials. Saline or CXM (1mg/kg) was administered following the last extinction trial and anxiety was measured in the elevated-plus maze (EPM) seventy-two hours later. Saline control animals exhibited elevated anxiety levels in comparison to a no stress control group. Cycloheximide appeared to maintain stress-induced anxiety responses, which otherwise declined with repeated extinction trials in the saline control groups. These findings suggest that cycloheximide may have induced amnesia for extinction, leaving the target memory of the predatory stress intact resulting in elevated levels of anxiety. The relationships between de novo protein synthesis and reconsolidation of anxiety-related memories following extinction trials may be more complex than originally thought.

Effect of cycloheximide on postharvest performance of cut spikes of Consolida ajacis cv. Violet Blue

Effect of cycloheximide on postharvest performance of cut spikes of Consolida ajacis cv. Violet Blue