Cr-Catalyzed Intramolecular Arylative Cross-Coupling of Unactivated C-H Bonds with C-Halide Bonds.

We report here a chromium-catalyzed intramolecular arylation of unactivated C-H bonds with C-halide bonds under mild conditions. This reaction was enabled by using a low-cost CrCl2 salt as the precatalyst in combination with allylmagnesium bromide and E/Z-mixed 1-halo-2-styrylarenes as substates, providing a strategy for the construction of functionalized phenanthrene compounds without using external ligands.

Chromium-Catalyzed Alkene Isomerization with Switchable Selectivity.

We report a single additive-responsive chromium-catalyzed system for selectively producing either of two different internal alkene isomers. The chromium catalyst, in the presence of HBpin/LiOtBu, enables the isomerization of alkenes over multiple carbon atoms to give the most thermodynamically stable isomers. The same catalyst allows for the selective isomerization of terminal alkenes over one carbon atom without an additive, exhibiting efficient and controllable alkene transposition selectivity.

First Report of the Root-Knot Nematode Meloidogyne incognita on Bletilla striata Rchb.f. (Orchidaceae) in China.

Bletilla striata Rchb.f., is a perennial herbaceous bulbous plant known as the Chinese ground or hyacinth orchid classified in the Orchidaceae. It is native to southeast Asia and mainly distributed in China, Japan and northern Myanmar (He et al. 2017). It has the functions of astringent hemostasis and analgesia, and can also be used to treat traumatic bleeding, ulcers, swelling and chapped skin. Therefore, it occupies an important position in traditional Chinese medicine (Xu et al. 2019). In June 2023, three farmers in Mengzi (103.39°N, 23.21°E), Yunnan Province, China, observed that some Bletilla striata Rchb.f. plants grew poorly with small and chlorotic leaves (Figure 1 A). We suspected that these symptoms were caused by root-knot nematode infection, but the galls on the roots were small and inconspicuous (Figure 1 A). The presence of nematode females in both the galled regions and the normal roots (Figure 1 B), revealed by fuchsin staining (Byrd et al. 1983), indicated that the symptoms were probably caused by root-knot nematode infection. To estimate the incidence rates, we randomly selected 100 B. striata Rchb.f. plants from each of five fields representing a total area of 3000 m2. In these fields, the occurrence of stained root-knot nematodes were 19.3%, 17%, 18.3%, 15%, and 13%, respectively. The gall rating of the infected plants in the B striata Rchb.f. samples collected from the five fields was 2 (rating scale of 0 to 5). Females (n=20), second-stage juveniles (J2s, n=20) and egg masses (n=20) were extracted and collected from roots and soil for morphological and molecular identification. The females had a white, pyriform body and their perineal patterns exhibited a high and square dorsal arch, lacking distinct lateral line (Figure 1. C & D). Measurements of females (n = 20) were: body length (BL) = 708.64±89.6 µm (554.36 to 844.51 µm); maximum body width (BW) = 461.73±47.44 µm (365.25 to 561.49 µm); stylet length (ST) = 15.49±3.15 µm (10.55 to 19.78 µm); and distance from dorsal esophageal gland opening to the stylet knobs (DGO) = 3.33±0.27 µm (2.77 to 3.93 µm). Measurements of J2s (n=20) were BL = 417.7±47.67 µm (342.16 to 499.68 µm); BW = 15.74±2.66 µm (11.05 to 25.63 µm); ST = 12.49±1.12 µm (10.19 to 15.02 µm); DGO = 2.64±0.59 µm (40.17 to 68.74 µm); tail length = 51.93±8.55 µm (10.43 to 27.22 µm); hyaline tail terminus = 18.23±3.99 µm (1.48 to 3.98 µm). These morphological features match the description of Meloidogyne incognita (Eisenback et al. 1981). To further confirm the species, we selected three infected plants from each field for molecular identification, the ITS region amplified using the primers 18S/26S (5'-TTGATTACGTCCCTGCCCTTT-3',5'-TTTCACTCGCCGTTACTAAGG-3') (Vrain et al. 1992) . A 729 bp PCR product of ITS region (accession nos. OR463907) was obtained from all infected plants. The amplicons from 18S/26S primer pair were sequenced and the sequences showed 95.29% homology with sequences of M. incognita (accession nos. MT209948.1). Moreover, a 835 bp DNA fragment (accession nos. OR469000) was obtained using the specific primers Mi-F/Mi-R (5'-GTGAGGATTCAGCTCCCCAG-3',5'-ACGAGGAACATACTTCTCCGTCC-3') for M. incognita (Meng et al. 2004), the sequence showed 99.28% homology with sequences of M. incognita (accession nos. ON416569). The morphological features and molecular data confirmed the identification of the root-knot nematode on B. striata Rchb.f. as M. incognita. To confirm the pathogenicity, ten healthy B. striata Rchb.f. seedlings were each inoculated with 500 freshly hatched J2s isolated from field Bletilla striata Rchb.f.. Five healthy seedlings without J2 inoculation were used as controls. At 60 days after inoculation, most of the inoculated plants exhibited similar symptoms to those initially observed by farmers in the field. On average, 1532 J2s were recovered from each inoculated plant, yielding a reproductive factor of 2.1. The gall rating for these inoculated plants was 2. Fuchsin staining revealed the presence of root-knot nematode females within the roots, with an average of 17 females detected per inoculated plant. No symptoms were observed in the control plants. This is the first report of M. incognita infecting B. striata Rchb.f. in China. M. incognita can cause severe infection and damage to some crops, resulting in serious economic losses (Eisenback, 2022). The growers need to take measures to prevent the spread of this nematode.

Ellagic Acid Ameliorates Renal Ischemic-Reperfusion Injury Through NOX4/JAK/STAT Signaling Pathway.

Ellagic acid (EA), a natural polyphenolic compound, has been proved to possess multiple biological activities including alleviating ischemic-reperfusion (I/R) injury. The aim of this current study was to investigate whether EA alleviates I/R injury via regulating inflammatory signaling pathway. Rats were subjected to ischemic-reperfusion (I/R) injury and given orally with different doses of EA before surgery. H&E staining, ELISA assay, and biochemical index analysis were performed to evaluate renal injury and inflammatory factors. Oxidative stress level was detected by DCFH-DA staining and corresponding assay kits. In addition, TUNEL assay and flow cytometric assay were applied for exploring the apoptosis of tissue and cells, respectively. Western blot assay was used to assess protein expressions in tissue and cells. The results showed that EA attenuated the renal I/R injury and reserved renal cell function in vivo. The levels of TNF-a, IL-1ß, IL-6, and MCP-1, oxidative stress level, and apoptosis were suppressed in EA-treated rats. Mechanistic studies showed that EA suppressed the phosphorylation of JAK1, JAK2, and STAT1 and reduced the NOX4 level. EA reduced apoptosis, hypoxia-induced inflammatory response, and ROS levels. Moreover, overexpression of NOX4 reversed the protective function with NOX4 inhibition, indicating that the effect of EA against renal IRI or cell hypoxia/reoxygenation might mainly depend on NOX4. The results suggest that EA exerts the renoprotective effect via suppressing NOX4/JAK/STAT signaling pathway, which may be a novel potential therapy for the treatment of acute kidney injury in clinic.

Trehalose phosphate synthase 5-dependent trehalose metabolism modulates basal defense responses in Arabidopsis thaliana.

Despite the recent discovery that trehalose synthesis is important for plant development and abiotic stress tolerance, the effects of trehalose on biotic stress responses remain relatively unknown. In this study, we demonstrate that TREHALOSE PHOSPHATE SYNTHASE 5 (TPS5)-dependent trehalose metabolism regulates Arabidopsis thaliana defenses against pathogens (necrotrophic Botrytis cinerea and biotrophic Pseudomonas syringae). Pathogen infection increased trehalose levels and upregulated TPS5 expression. Application of exogenous trehalose significantly improved plant defenses against B. cinerea, but increased the susceptibility of plants to P. syringae. We demonstrate that elevated trehalose biosynthesis, in transgenic plants over-expressing TPS5, also increased the susceptibility to P. syringae, but decreased the disease symptoms caused by B. cinerea. The knockout of TPS5 prevented the accumulation of trehalose and enhanced defense responses against P. syringae. Additionally, we observed that a TPS5-interacting protein (multiprotein bridging factor 1c) was required for induced expression of TPS5 during pathogen infections. Furthermore, we show that trehalose promotes P. syringae growth and disease development, via a mechanism involving suppression of the plant defense gene, Pathogenesis-Related Protein 1. These findings provide insight into the function of TPS5-dependent trehalose metabolism in plant basal defense responses.

Ellagic acid promotes A549 cell apoptosis via regulating the phosphoinositide 3-kinase/protein kinase B pathway.

The present study aimed to evaluate the anti-cancer effect of ellagic acid in human non-small cell lung cancer (NSCLC) A549 cells and to reveal the potential underlying mechanism. The effects of ellagic acid on the cell proliferation of A549 cells were determined by MTT assay. Cell cycle and apoptosis were measured with flow cytometry and Annexin V-propidium iodide staining. Western blotting was used to measure the expression levels of the phosphatidylinositol 3-kinase (PI3K)/protein kinas B (Akt) signaling pathway and apoptosis-associated proteins. It was demonstrated that ellagic acid exerted an inhibitory effect in the proliferation of human NSCLC A549 cells. Flow cytometry demonstrated that G1 phase retention and apoptosis rates were significantly increased after treatment with ellagic acid. Further investigation revealed that ellagic acid treatment diminished the phosphorylation of PI3K and Akt and regulated the expression of apoptosis-associated proteins in A549 cells. In conclusion, the present results indicated that ellagic acid suppresses cell proliferation, arrests cell cycle and induces apoptosis in human NSCLC A549 cells by inhibiting the PI3K/Akt signaling pathway.

Mycoplasma-associated multidrug resistance of hepatocarcinoma cells requires the interaction of P37 and Annexin A2.

Mycoplasma infection has been reported to be associated with cancer migration, invasion, epithelial-mesenchymal transition as well as the resistance to nucleoside analogues chemotherapeutic drugs. In this study, we found that the sensitivity of hepatocarcinoma cells to Cisplatin, Gemcitabine and Mitoxantrone was increased by mycoplasma elimination. Similar to the effect of anti-mycoplasma agent, interrupting the interaction between Mycoplasma hyorhinis membrane protein P37 and Annexin A2 of host cells using the N-terminal of ANXA2 polypeptide enhanced the sensitivity of HCC97L cells to Gemcitabine and Mitoxantrone. Meanwhile, we did not observe any changes in expression or distribution of multidrug resistance associated transporters, ATP-Binding Cassette protein B1, C1 and G2, on the removal of mycoplasma. These results suggest that mycoplasma induces a resistance to multiple drugs in hepatocarcinoma cells which required the interaction of P37 and Annexin A2. The pathway downstream this interaction needs to be explored.

A Sustainable Redox-Flow Battery with an Aluminum-Based, Deep-Eutectic-Solvent Anolyte.

Nonaqueous redox-flow batteries are an emerging energy storage technology for grid storage systems, but the development of anolytes has lagged far behind that of catholytes due to the major limitations of the redox species, which exhibit relatively low solubility and inadequate redox potentials. Herein, an aluminum-based deep-eutectic-solvent is investigated as an anolyte for redox-flow batteries. The aluminum-based deep-eutectic solvent demonstrated a significantly enhanced concentration of circa 3.2 m in the anolyte and a relatively low redox potential of 2.2 V vs. Li+ /Li. The electrochemical measurements highlight that a reversible volumetric capacity of 145 Ah L-1 and an energy density of 189 Wh L-1 or 165 Wh kg-1 have been achieved when coupled with a I3- /I- catholyte. The prototype cell has also been extended to the use of a Br2 -based catholyte, exhibiting a higher cell voltage with a theoretical energy density of over 200 Wh L-1 . The synergy of highly abundant, dendrite-free, multi-electron-reaction aluminum anodes and environmentally benign deep-eutectic-solvent anolytes reveals great potential towards cost-effective, sustainable redox-flow batteries.

Pancreatic-derived factor impaired glucagon-like Peptide-1 production from GLUTag enterendorine L-cell line and intestines.

PURPOSE: Pancreatic-derived factor (PANDER) is a pancreatic islet-specific cytokine that co-secretes with insulin. However, its biological function remains largely unknown. We have recently shown that the intestine might be its novel target tissue. The aim of this study was to clarify whether PANDER impacts the production of glucagon-like peptide-1 (GLP-1). METHODS: We treated GLUTag cells from the mouse intestine L cell line with recombinant PANDER protein and hepatic overexpression of PANDER in an obese murine model. RESULTS: In GLUTag cells, PANDER exposure led to decreased proglucagon gene mRNA expression and GLP-1 secretion without affecting cell viability or caspase-3 activation. Overexpression of PANDER in mice induced glucose intolerance and impaired glucose-stimulated GLP-1 secretion Moreover, PANDER blocked insulin-induced GLP-1 secretion by inhibiting the insulin signalling-Wnt pathway and directly inhibited the cAMP/PKA pathway. CONCLUSIONS: Our findings indicate that intestinal L cells are responsive to PANDER, and elevated PANDER levels impair GLP-1 production in vitro and in vivo.

Olfactory Dysfunctions and Decreased Nitric Oxide Production in the Brain of Human P301L Tau Transgenic Mice.

Different patterns of olfactory dysfunction have been found in both patients and mouse models of Alzheimer's Disease. However, the underlying mechanism of the dysfunction remained unknown. Deficits of nitric oxide production in brain can cause olfactory dysfunction by preventing the formation of olfactory memory. The aim of this study was to investigate the behavioral changes in olfaction and alterations in metabolites of nitric oxide, nitrate/nitrite concentration, in the brain of human P301L tau transgenic mice. The tau mice showed impairments in olfaction and increased abnormal phosphorylation of Tau protein at AT8 in different brain areas, especially in olfactory bulb. We now report that these olfactory deficits and Tau pathological changes were accompanied by decreased nitrate/nitrite concentration in the brain, especially in the olfactory bulb, and reduced expression of nNOS in the brain of tau mice. These findings provided evidence of olfactory dysfunctions correlated with decreased nitric oxide production in the brain of tau mice.

F3MB(PANDER) decreases mice hepatic triglyceride and is associated with decreased DGAT1 expression.

OBJECTIVE: Pancreatic-derived factor (PANDER, also named as FAM3B) is secreted by pancreatic α and ß cells. Increasing evidence suggests that it may serve a hormonal function related to glycemic and lipid metabolism. In this study, we investigated the effects of PANDER overexpression on hepatic and adipose triglyceride metabolism in high-fat diet-fed male C57BL/6 mice. METHODS: PANDER overexpression was achieved by tail-vein injection of recombinant Ad-PANDER and Ad-GFP injected mice served as a control. The TG metabolism in both groups were compared. RESULTS: Adenoviral-mediated overexpression of PANDER did not affect body weight, food consumption, or liver enzymes. The triglyceride (TG) content of both liver and adipose tissue was significantly decreased in Ad-PANDER mice (liver: 6.16±1.89 mg/g vs. control 14.95±2.27 mg/g, P<0.05; adipose: 39.31±1.99 mg/100mg vs. 47.22±2.21 mg/100mg, P<0.05). The free fatty acid (FFA) content of adipose tissue in Ad-PANDER mice was also decreased (1.38±0.18 mg/g vs. 2.77±0.31 mg/g, P<0.01). The investigation of key enzymes of triglyceride hydrolysis and FFA oxidation in liver and adipose tissue showed that p-HSL/HSL was significantly increased and that DGAT1 gene and protein expression were significantly reduced in the liver of PANDER-overexpressing mice. PKA phosphorylation was also significantly increased in the livers of Ad-PANDER mice. No differences in ATGL, CPT1, ACOX1, or DGAT2 expression were observed. CONCLUSION: Overexpression of PANDER is associated with observable decreases in TG, increases in PKA phosphorylation, and decreased DGAT1 expression, suggesting a possible interrelationship. The mechanisms by which this occurs remain to be elucidated.

A mini review: Tau transgenic mouse models and olfactory dysfunction in Alzheimer's Disease.

Alzheimer's Disease (AD) is a chronic neurodegenerative disease that usually takes many years from preclinical phase to prodromal phase characterized by mild symptoms before the onset of dementia. Once diagnosed with AD, the brain is already severely damaged and the disease will process quickly to the most severe stages since there is no medications that reverse the neuronal injuries in the brain. Thus, simple, inexpensive, and widely available methods for detecting potential AD patients during their preclinical phases are urgently needed. In such case, olfactory testing may offer a chance for early diagnosis of AD. However, there are limitations in these olfactory tests due to the complexity of the brain areas it extends to and the frequently olfactory fatigue occurred in the behavioral olfactory tests. Great efforts have been done epidemiologically to investigate the correlation between olfactory functions and possibility of developing AD. Different patterns of olfactory dysfunction have been found in AD at early stages and even mild cognitive impairment (MIC), but the cause of the dysfunction remained unclear. Various kinds of AD animal models have been used in the field to clarify the existence of olfactory dysfunctions and thus study the underling mechanism of the dysfunction. In this review we discuss (1) the function of Tau physiologically and pathologically; (2) the genetic background and biological characteristics of the most commonly used Tau transgenic mice; (3) the structural and molecule basis of olfaction; (4) the possible relationship between Tau pathology and olfactory dysfunction. Finally, we suggest that the tau transgenic mouse models may be helpful in studying the possible mechanisms of the dysfunction.

[Change of memory function and decrease of nitric oxide level of whole brain in the transgenic mice expressing human tau 40 with P301L mutation].

OBJECTIVE: To study the mechanism of learning and memory dysfuction in the transgenic mouse expressing human tau 40 isoform with P301L mutation (F10). METHODS: The human tau protein expression and phosphor-tau protein levels were detected with Western blot method. The neurofibrillary tangles were observed with Bielshowsky silver stain. The behavior changes of learning and memory were observed by open field test and passive avoidance test. Acetyleholine level, activities of acetycholinesterase and choline acetyltransferase of whole brain was detected by colorimetry method. The nitric oxide level of whole brain was detected by nitrate enzyme reduction method. RESULTS: Exogenous human tau gene was expressed and an elevation of phosphor-tau protein level in 7 and 3-month transgenic mice's hippocampus andcerebrocortex was observed. The neurofibrillary tangles were observed in cerebrocortex of 7-month transgenic mice; the 7-month transgenic mice also presented an evident reduction of learning and memory ability and nitric oxide level of the whole brain, but not changes in acetylcholine level, acetycholinesterase activity, choline acetyltransferase activity and expression in whole brain. CONCLUSION: Tau transgenic mice (F10) can still inherit their parents' biologiccal characters, and develop learning and memory dysfunction awnodh san obvious decrease in nitric oxide level of whole brain in the 7-month old mice, suggesting a decrease of nitric oxide level of whole brain would be involved in the mechanism of learning and memory dysfunction in these transgenic mice.

[Effect of hypobaric hypoxia exposure on memory and tau phosphorylation in brain of mice].

OBJECTIVE: To investigate the effect of hypobaric hypoxia (HH)on the cognitive function of mice and the phosphorylation of tau protein in mice brain. METHODS: Forty male mice were randomly divided into 4 groups (n = 10): static control (control) group, 8 hours (8 h) group, 7 days(7 d) group and 28 days(28 d) group, which were exposed to simulated HH equivalent to 5 500 m in an animal decompression chamber for 0 hour, 8 hours, 7 days and 28 days, respectively. Cognitive performances were examined by open field and passive avoidance test, tan phosphorylation was assayed by Western blot. RESULTS: In open field test,the group exposed in hypobaric hypoxia for 28 d showed lower mean velocity (P < 0.05), time in central zone (P < 0.05) was longer than control group. In passive avoidance test 28 d group presented worse performance in both latency time and number of mistakes (P < 0.05) compared with control group. Western blot showed that phosphorylated tau was increased significantly following exposure to HH for 7 d in cortex and 28 d in hippocampus (P < 0.05). CONCLUSION: Tau hyperphosphorylation in brain of mice may play a role in chronic HH-induced cognitive function impairment.

New graphene fiber coating for volatile organic compounds analysis.

In the work, a novel graphene-based solid phase microextraction-gas chromatography/mass spectrometry method was developed for the analysis of trace amount of volatile organic compounds in human exhaled breath vapor. The graphene fiber coating was prepared by a one-step hydrothermal reduction reaction. The fiber with porous and wrinkled structure exhibited excellent extraction efficiency toward eight studied volatile organic compounds (two n-alkanes, five n-aldehydes and one aromatic compound). Meanwhile, remarkable thermal and mechanical stability, long lifespan and low cost were also obtained for the fiber. Under the optimal conditions, the developed method provided low limits of detection (1.0-4.5ngL(-1)), satisfactory reproducibility (3.8-13.8%) and acceptable recoveries (93-122%). The method was applied successfully to the analysis of breath samples of lung cancer patients and healthy individuals. The unique advantage of this approach includes simple setup, non-invasive analysis, cost-efficient and sufficient sensitivity. The proposed method supply us a new possibility to monitor volatile organic compounds in human exhaled breath samples.

Secalonic acid A protects dopaminergic neurons from 1-methyl-4-phenylpyridinium (MPP⁺)-induced cell death via the mitochondrial apoptotic pathway.

Secalonic acid A (SAA) is a natural compound found in marine fungi. We have reported that SAA can attenuate the cytotoxicity of colchicine in rat cortical neurons. Whether SAA can also inhibit the neurotoxicity of 1-methyl-4-phenylpyridinium (MPP(+)) in dopaminergic neurons has not been investigated. Here, we show that pretreatment with 1 µM SAA significantly rescued tyrosine hydroxylase (TH)-positive neurons from MPP(+)-induced neurotoxicity in primary dopaminergic neuron culture. Moreover, SAA at doses of 0.15 mg/kg and 0.75 mg/kg increased the number of dopaminergic neurons and upregulated striatal dopamine in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mice experiments. We also show that SAA significantly attenuated cytotoxicity induced by 2.5 mM MPP(+) in SH-SY5Y cells. These results indicate that the activation of JNK, p38 mitogen activated protein kinase (MAPK) and caspase-3 during apoptosis triggered by MPP(+) could be suppressed by SAA; on the other hand, an MPP(+)-induced increase in the expression of Bax in SH-SY5Y cells was blocked by SAA. These results indicate that inhibition of the phosphorylation of JNK and p38 MAPK, down-regulation of Bax expression, and suppression of caspase-3 activation are involved in the protective effects of SAA against MPP(+) toxicity in SH-SY5Y cells. SAA may rescue dopaminergic neurons from MPP(+)-induced cell death through the mitochondrial apoptotic pathway.

[Generation of Tau/App/PS1 triple-transgenic mouse model and the study of its biological characteristics].

OBJECTIVE: To establish the triple-transgenic mouse model and study their biological characteristics by molecular biology, behavior and pathology. METHODS: Hybrid the Tau and amyloid precursor protein (APP)/presenilins (PS1) transgenic mouse, the genotype of offspring mice were identified by PCR. Transcribed target genes were detected by RT-PCR. The protein expression of exogenous genes was detected by Western-blot. The pathological change of neurofibrillary tangles and senile plaque were observed by Bielschowsky silver staining and ABC immunohistochemical method. The changes time of learning and memory were observed by Morris water maze. RESULTS: APP, PS1 and Tau genes were transcript in Tau/APP/PS1 mice. In 6 to 8 months old Tau/APP/PS1 mice, the neurofibrillary tangles and senile plaque could be found in cortex and hippocampus. In 6 months old Tau/APP/PS1 mice, the learning and memory abilities were worse. CONCLUSION: With the behavior change and pathological changes in Tau and beta-amyloid protein (AP), the Tau/APP/PS1 triple-transgenic mice can be used as a further study animal model of AD's pathogenesis and the target of drug treatment.

[Breeding of transgenic mice expressing human tau isoform with P301L mutation and identification of homozygous transgenic mice].

OBJECTIVE: To establish homozygous transgenic mouse strain expressing human tau isoform with P301L mutation. METHODS: Five transgenic mice expressing human tau isoform with P301L mutation were obtained by microinjection into male nuclei. Homozygote and hemizygote were identified by PCR and real-time fluorescent quantitative PCR. RESULTS: Ninety five homozygous transgenic mice were selected, and the results indicated that homozygous transgenic mice were superior to hemizygote in simulating the changes of biological characteristics. CONCLUSION: Exogenous gene tau is able to stably transmit to next generation and the combination of SYBR Green real-time fluorescent quantitative PCR with the traditional mating is a fast, reliable and economical way to screen homozygous and hemizygous transgenic mice.

Neuroprotection by nicotine against colchicine-induced apoptosis is mediated by PI3-kinase--Akt pathways.

Although nicotine is known to protect against ß-amyloid (Aß)-induced neurotoxicity, the effect of nicotine on colchicine-induced neurotoxicity remains unknown. Colchicine is a microtubule-interfering agent and is able to induce neural apoptosis. Here we investigated whether nicotine exhibits similar neuroprotective effects and the mechanism against colchicine-induced neurotoxicity of the primarily cultured cortical neurons. In this study, we investigated the effect of nicotine on the protection of neurons against colchicine damage and evaluated the associated intracellular signaling pathways. Nicotine-induced protection was blocked by an α7 nicotinic acetylcholine receptors (nAChRs) antagonist and a phosphatidylinositol 3-kinase (PI3K) inhibitor. These results suggest that the neuroprotective effects of nicotine are mediated by the α7 nAChRs and PI3K-Akt signaling pathway. In addition, we reveal that blockade of p38 and JNK (c-Jun N-terminal kinase) signaling increased Akt signaling, thus enhancing the survival of cell treatment with colchicine. On the other hand, inhibition of constitutively active Akt enhanced p38 or JNK signaling phosphorylation. These data suggested that crosstalk between PI3K Akt and p38 or JNK signaling pathways contributed to nicotine against colchicine-induced cytotoxicity.

Similar potency of catechin and its enantiomers in alleviating 1-methyl-4-phenylpyridinium ion cytotoxicity in SH-SY5Y cells.

OBJECTIVES: Previously, the flavonoid (±)-catechin was shown to exert potent neuroprotective action in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease model. The purpose of this study was to investigate whether the different enantiomers of catechin ((+)-catechin, (-)-catechin and (±)-catechin, a 50:50 mixture of (+)-catechin and (-)-catechin) could protect SH-SY5Y cells against 1-methyl-4-phenylpyridinium ion (MPP(+) ) toxicity by decreasing the generation of oxygen free radicals. The inhibitive effect of (±)-catechin on JNK/c-Jun activation was investigated. METHODS: The effects of (+)-catechin, (-)-catechin or (±)-catechin in protecting against MPP(+) toxicity were evaluated and compared in SH-SY5Y cells by testing the release of lactate dehydrogenase. The generation of reactive oxygen species (ROS) was measured by immunochemistry and the phosphorylation level of JNK/c-Jun was determined by Western blotting. KEY FINDINGS: In SH-SY5Y cells, (+)-catechin, (-)-catechin or (±)-catechin reduced apoptosis induced by MPP(+) and decreased ROS generation caused by MPP(+) . Different enantiomers of catechin showed protective effects at similar potency. Moreover (±)-catechin decreased JNK/c-Jun phosphorylation which was increased by MPP(+). CONCLUSIONS: Catechin and its two enantiomers could protect SH-SY5Y cells against MPP(+) cytotoxicity at a similar potency. Antioxidative stress and inhibition of the JNK/c-Jun signalling pathway might have been involved in the neuroprotective mechanisms of catechin against MPP(+) cytotoxicity in SH-SY5Y cells.