Inhibition of tumor vasculogenic mimicry and prolongation of host survival in highly aggressive gallbladder cancers by norcantharidin via blocking the ephrin type a receptor 2/focal adhesion kinase/paxillin signaling pathway

Vasculogenic mimicry (VM) is a newly-defined tumor microcirculation pattern in highly aggressive malignant tumors. We recently reported tumor growth and VM formation of gallbladder cancers through the contribution of the ephrin type a receptor 2 (EphA2)/focal adhesion kinase (FAK)/Paxillin signaling pathways. In this study, we further investigated the anti-VM activity of norcantharidin (NCTD) as a VM inhibitor for gallbladder cancers and the underlying mechanisms. In vivo and in vitro experiments to determine the effects of NCTD on tumor growth, host survival, VM formation of GBC-SD nude mouse xenografts, and vasculogenic-like networks, malignant phenotypes i.e., proliferation, apoptosis, invasion and migration of GBC-SD cells. Expression of VM signaling-related markers EphA2, FAK and Paxillin in vivo and in vitro were examined by immunofluorescence, western blotting and real-time polymerase chain reaction (RT-PCR), respectively. The results showed that after treatment with NCTD, GBC-SD cells were unable to form VM structures when injecting into nude mouse, growth of the xenograft was inhibited and these observations were confirmed by facts that VM formation by three-dimensional (3-D) matrix, proliferation, apoptosis, invasion, migration of GBC-SD cells were affected; and survival time of the xenograft mice was prolonged. Furthermore, expression of EphA2, FAK and Paxillin proteins/mRNAs of the xenografts was downregulated. Thus, we concluded that NCTD has potential anti-VM activity against human gallbladder cancers; one of the underlying mechanisms may be via blocking the EphA2/FAK/Paxillin signaling pathway.

Norcantharidin inhibits tumor growth and vasculogenic mimicry of human gallbladder carcinomas by suppression of the PI3-K/MMPs/Ln-5γ2 signaling pathway

BACKGROUND

Vasculogenic mimicry (VM) is a novel tumor blood supply in some highly aggressive malignant tumors. Recently, we reported VM existed in gallbladder carcinomas (GBCs) and the formation of the special passage through the activation of the PI3K/MMPs/Ln-5γ2 signaling pathway. GBC is a highly aggressive malignant tumor with disappointing treatments and a poor prognosis. Norcantharidin (NCTD) has shown to have multiple antitumor activities against GBCs, etc; however the exact mechanism is not thoroughly elucidated. In this study, we firstly investigated the anti-VM activity of NCTD as a VM inhibitor for GBCs and its underlying mechanisms.

METHODS

In vitro and in vivo experiments to determine the effects of NCTD on proliferation, invasion, migration, VM formation, hemodynamic and tumor growth of GBC-SD cells and xenografts were respectively done by proliferation, invasion, migration assays, H&E staining and CD31-PAS double stainings, optic/electron microscopy, tumor assay, and dynamic micro-MRA. Further, immunohistochemistry, immunofluorescence, Western blotting and RT-PCR were respectively used to examine expression of VM signaling-related markers PI3-K, MMP-2, MT1-MMP and Ln-5γ2 in GBC-SD cells and xenografts in vitro and in vivo.

RESULTS

After treatment with NCTD, proliferation, invasion, migration of GBC-SD cells were inhibited; GBC-SD cells and xenografts were unable to form VM-like structures; tumor center-VM region of the xenografts exhibited a decreased signal in intensity; then cell or xenograft growth was inhibited. Whereas all of untreated GBC-SD cells and xenografts formed VM-like structures with the same conditions; the xenograft center-VM region exhibited a gradually increased signal; and facilitated cell or xenograft growth. Furthermore, expression of MMP-2 and MT1-MMP products from sections/supernates of 3-D matrices and the xenografts, and expression of PI3-K, MMP-2, MM1-MMP and Ln-5γ2 proteins/mRNAs of the xenografts were all decreased in NCTD or TIMP-2 group; (all P < 0.01, vs. control group); NCTD down-regulated expression of these VM signaling-related markers in vitro and in vivo.

CONCLUSIONS

NCTD inhibited tumor growth and VM of human GBCs in vitro and in vivo by suppression of the PI3-K/MMPs/Ln-5γ2 signaling pathway. It is firstly concluded that NCTD may be a potential anti-VM agent for human GBCs.

Visceral granulomas in farmed large yellow croaker, Larimichthys crocea (Richardson), caused by a bacterial pathogen, Pseudomonas plecoglossicida

An enzootic disease characterized by granulomas in internal organs occurred in cage-farmed large yellow croaker, Larimichthys crocea (Richardson), in April and November 2010, in Ningbo, Zhejiang Province. One bacterial strain, named XSDHY-P, was isolated from the diseased fish and identified by biochemical characterization, fatty acid methyl ester (FAME) analysis and multilocus sequence analysis (MLSA). According to the results obtained from the biochemical tests, FAME analysis and phylogenetic analysis derived from 16S ribosomal RNA, gyrB, oprF, oprI, oprL and rpoD gene sequencing, the bacterial isolate, XSDHY-P, was identified as Pseudomonas plecoglossicida. Moreover, lethal dose, 50% trials were carried out to demonstrate the virulence of XSDHY-P in large yellow croaker when administered at 2.13 9 105 colony-forming units per fish. Visceral granulomas were found in the experimentally infected fish as well as in the naturally infected fish, indicating that P. plecoglossicida is another bacterial pathogen that causes granulomatosis in L. crocea.

Diurnal alterations in circadian genes and peptides in major depressive disorder before and after escitalopram treatment

BACKGROUND

Strong links exist between circadian disturbances and some of the most characteristic symptoms of clinical major depressive disorder (MDD). However, changes in the expression of clock genes or neuropeptides related to the regulation of circadian rhythm that may influence the susceptibility to recurrence after antidepressant treatment in MDD have not been investigated.

METHODS

Blood samples were collected at 4h intervals for 24h from 12 male healthy controls and 12 male MDD patients before and after treatment with escitalopram for 8 weeks. The outcome measures included the relative expression of clock gene mRNA (PERIOD1, PERIOD2, PERIOD3, CRY1, BMAL1, NPAS2, and GSK-3β), and the levels of serum melatonin, vasoactive intestinal polypeptide (VIP), cortisol, adrenocorticotropic hormone (ACTH), insulin-like growth factor-1 (IGF-1), and growth hormone (GH).

RESULTS

Compared with healthy controls, MDD patients showed disruptions in the diurnal rhythms of the expression of PERIOD1, PERIOD2, CRY1, BMAL1, NPAS2, and GSK-3β and disruptions in the diurnal rhythms of the release of melatonin, VIP, cortisol, ACTH, IGF-1, and GH. Several of these disruptions (i.e., PER1, CRY1, melatonin, VIP, cortisol, ACTH, and IGF-1) persisted 8 weeks after escitalopram treatment, similar to the increase in the 24h levels of VIP and decreases in the 24h levels of cortisol and ACTH.

CONCLUSION

These persistent neurobiological changes may play a role in MDD symptoms that are thought to contribute to the vulnerability to recurrence and long-term maintenance therapy.

CFTR suppresses tumor progression through miR-193b targeting urokinase plasminogen activator (uPA) in prostate cancer

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is expressed in the epithelial cells of a wide range of organs/tissues from which most cancers are derived. Although accumulating reports have indicated the association of cancer incidence with genetic variations in CFTR gene, the exact role of CFTR in cancer development and the possible underlying mechanism have not been elucidated. Here, we report that CFTR expression is significantly decreased in both prostate cancer cell lines and human prostate cancer tissue samples. Overexpression of CFTR in prostate cancer cell lines suppresses tumor progression (cell growth, adhesion and migration), whereas knockdown of CFTR leads to enhanced malignancies both in vitro and in vivo. In addition, we demonstrate that CFTR knockdown-enhanced cell proliferation, cell invasion and migration are significantly reversed by antibodies against either urokinase plasminogen activator (uPA) or uPA receptor (uPAR), which are known to be involved in various malignant traits of cancer development. More interestingly, overexpression of CFTR suppresses uPA by upregulating the recently described tumor suppressor microRNA-193b (miR-193b), and overexpression of pre-miR-193b significantly reverses CFTR knockdown-enhanced malignant phenotype and abrogates elevated uPA activity in prostate cancer cell line. Finally, we show that CFTR gene transfer results in significant tumor repression in prostate cancer xenografts in vivo. Taken together, the present study has demonstrated a previously undefined tumor-suppressing role of CFTR and its involvement in regulation of miR-193b in prostate cancer development.

Overexpression of HIF-1α in primary gallbladder carcinoma and its relation to vasculogenic mimicry and unfavourable prognosis

As a novel mode of tumor neovascularization, vasculogenic mimicry (VM) has been reported to increase tumor-related mortality in many different solid tumors. In the present study, two established human gallbladder carcinoma (GBC) cell lines (highly aggressive GBC-SD and poorly aggressive SGC-996) cultured on a three-dimensional matrix were assessed for the ability of VM channel formation under normoxic or hypoxic conditions. In addition, the relationship between HIF-1α gene expression and VM channel formation of GBC cells in vitro was measured using the small interfering RNA (siRNA) technique, western blotting and real-time reverse transcription (RT)-PCR analysis. Furthermore, H&E and CD31/periodic acid-Schiff (PAS) staining were used to observe VM in GBC tissue samples. Additionally, all seventy-one specimens with VM and non-VM were stained for hypoxia inducible factor-1 α (HIF-1α) and its correlation with clinicopathological features and prognosis was analyzed simultaneously. We found that hypoxia could induce more VM channel formation and elevated HIF-1α expression in highly aggressive GBC-SD cells. HIF-1α siRNA efficiently knocked down HIF-1α expression and GBC VM networks under either normoxic or hypoxic conditions. VM was present in human primary GBC and overexpression of HIF-1α was significantly correlated with depth of invasion and perineural involvement in the non-VM group. Moreover, VM and HIF-1α were independent factors for the overall survival of GBC patients and correlated with decreased survival. In conclusion, VM was present in human GBC. As a critical mediator in VM formation, high expression of HIF-1α was associated with VM and tumor progression in GBC patients.

Norcantharidin: a potential antiangiogenic agent for gallbladder cancers in vitro and in vivo

Our objective was to explore the antiangiogenic activity of norcantharidin (NCTD) as an angiogenic inhibitor for gallbladder cancers. In vitro and in vivo experiments to determine the effects of NCTD on HUVECs, chicken CAM capillaries and gallbladder cancer xenograft angiogenesis in nude mice were respectively done. The MTT method was used to assay the cytotoxicity of NCTD on HUVECs. Immunofluorescence was used to evaluate HUVEC apoptosis. The scraping line method, matrigel invasion assay and tube formation assay were used to detect the migration, invasion and tube formation of HUVECs. A digital camera was used to observe chicken CAM capillaries. Experiments with NCTD in a xenograft model were used to observe the effect of NCTD on xenograft growth and survival of mice with xenografts. CD₃₄ immunohistochemistry, flow cytometry and micro-MRA were used, respectively, to determine MVD, cell apoptosis and hemodynamic analysis of the xenografts. Immunohistochemistry and RT-PCR were used, respectively, to detect the expression of VEGF, Ang-2, TSP, TIMP-2 proteins/mRNAs of the xenografts. The xenograft MVD associated with tumor volume, the PCNA/apoptosis ratio and related-protein expression was evaluated simultaneously. We found that NCTD effectively inhibited the proliferation, migration, invasion and capillary-like tube formation of HUVECs in vitro; it reduced angiogenesis and directly destroyed the formed CAM capillaries in vivo. In the experiments in mice, NCTD not only inhibited significantly xenograft proliferation and growth, prolonged survival time of mice with xenografts, decreased the xenograft MVD and vascular perfusion, but also, similarly to ES, decreased significantly the expression of VEGF or Ang-2 protein/mRNA, increased the expression of TSP or TIMP-2 protein/mRNA. Moreover, the xenograft MVD was positively related with tumor volume, PCNA/apoptosis ratio, and VEGF or Ang-2 expression, respectively (all P<0.05), but negatively correlated with TSP or TIMP-2 expression (both P<0.05). These data showed that NCTD could serve as a potential antiangiogenic agent for gallbladder cancers.

Astrocyte elevated gene-1 overexpression in human primary gallbladder carcinomas: an unfavorable and independent prognostic factor

Astrocyte elevated gene-1 (AEG-1), as an HIV-1 or TNF-α-inducible transcript, is correlated with various aspects of tumor malignancy. However, the status of AEG-1 expression and its clinical significance in human gallbladder carcinoma (GBC) remains unknown. In the present study, we investigated AEG-1 expression in two GBC cell lines (GBC-SD and SGC-996) and GBC tissues by immunohistochemical, Western blot and real-time PCR analysis. We found that AEG-1 was highly expressed in GBC samples (63.4%, 26 of 41) compared with normal gallbladder mucosa (p=0.0003) and highly invasive GBC-SD cell lines at both the protein (p=0.0043) and mRNA levels (p=0.0001), and strongly correlated with differentiation degree (p=0.006), Nevin stage (p=0.0344), Ki-67 expression (p=0.0024) and liver infiltration (p=0.0332) in these patients. Multivariate analysis indicated that AEG-1 overexpression was an independent prognostic marker for GBC patients. Moreover, patients with high AEG-1 levels had shorter survival time (p=0.008). Our results suggest that the AEG-1 protein is a valuable marker of GBC progression and could be a potential therapeutic target.

Factors affecting curve flexibility in skeletally immature and mature idiopathic scoliosis

BACKGROUND

The determination of factors affecting curve flexibility is important in idiopathic scoliosis patients with regard to the Risser sign. The objective of this retrospective study was to identify factors affecting curve flexibility in patients with skeletally immature and mature idiopathic scoliosis.

METHODS

The records of all patients with idiopathic scoliosis who received surgical treatment from July 2001 to August 2008 at our hospital were screened. The Risser sign was used to separate the patients into a skeletally mature group (Risser grade = 5) and skeletally immature group (Risser grade < 5). Data recorded and compared were flexibility (%), bending angle (°), apical vertebral rotation (°), Cobb angle (°), curve location, prior use of brace treatment, and number of vertebrae in the curve.

RESULTS

The study cohort consisted of 217 patients (34 males, 183 females) in the Risser grade < 5 group and 124 (21 males, 103 females) in the Risser grade = 5 group. Multiple linear regression analysis revealed that the Cobb angle and the curve location significantly affected curve flexibility in the Risser grade < 5 group, whereas in the Risser grade = 5 group, Cobb angle and age significantly affected flexibility.

CONCLUSIONS

Cobb angle and curve location influence main curve flexibility in skeletally immature adolescent idiopathic scoliosis, and Cobb angle and age influence curve flexibility in skeletally mature adult scoliosis. Measurement of these values may aid in the evaluation of treatment options and preoperative planning.

[Readthrough of nonsense mutation W822X in the SCN5A gene can effectively restore expression of cardiac Na+ channels W822X]

OBJECTIVE

In this study we investigated the functional restoration of nonsense mutations in the SCN5A gene.

METHODS

The readthrough-enhancing reagents were introduced to HEK293 cells to suppress one nonsense mutation W822X in the SCN5A gene. Patch-clamp was used to record the whole-cell current and dynamics. Western blot and immunofluorescence staining were used to certify the expression and the location of the sodium channel.

RESULTS

In transfected HEK293 cells, the nonsense mutation in SCN5A inhibited the expression level of full-length protein, and the sodium currents from the mutant channels were less than 3% of the wild-type level. Readthrough enhancement by decreasing translation termination efficiency with a siRNA targeting eukaryotic release factor eRF3a (a GTPase that binds eRF1), the sodium current from the mutant cDNAs was restored to as much as 30% of the wild-type. After the treatment by the readthrough-enhancing reagents, the channels from cDNA carrying W822X remained the features of wild-type phenotype, and Western blot and immunochemical staining also showed the expression of full-length channel proteins.

CONCLUSION

Readthrough-enhancing reagents could effectively suppress nonsense mutations in SCN5A and partially restore the function of sodium channel and the expression of full-length channels.

Assessment of soil contamination with Cd, Pb and Zn and source identification in the area around the Huludao Zinc Plant

The distribution characteristics of heavy metals (cadmium (Cd), lead (Pb) and zinc (Zn)) in the natural soil profiles around the Huludao Zinc Plant (HZP), an old industrial base in Northeast China, were analyzed. The pollutant source was identified using (210)Pb isotope technique to evaluate the geochemical characteristics of Pb and the historical production records of HZP. The results indicated: dust precipitation from HZP was the primary source of the pollutants. The average deposition rates of Cd, Pb and Zn were 0.33, 1.75, and 30.97 g/m(2)year, respectively at 1 km away after HZP, and 0.0048, 0.035, and 0.20 g/m(2) year, respectively at 10 km away after HZP. There is a risk of secondary pollution to the environment as well as the food chain in seriously polluted areas used for cultivation.

CCR3, CCR2A and macrophage inflammatory protein (MIP)-1a, monocyte chemotactic protein-1 (MCP-1) in the mouse hippocampus during and after pilocarpine-induced status epilepticus (PISE)

AIMS

To investigate protein and gene expressions of chemokine subtypes CCR3, CCR2A and their respective ligands macrophage inflammatory protein 1-alpha (MIP-1alpha), monocyte chemotactic protein-1 (MCP-1) in the normal mouse central nervous system (CNS) and in the hippocampus at different time points during and after pilocarpine-induced status epilepticus (PISE).

METHODS

CCR3 and MIP-1alpha protein expressions were mapped in the mouse CNS. The protein and gene expressions of CCR3 and CCR2A and their respective ligands MIP-1alpha, MCP-1 in the hippocampus were studies by immunocytochemical and quantitative real-time RT-PCR during and after PISE.

RESULTS

CCR3 and MIP-1alpha gene expression and immunopositive neurones were broadly distributed in the CNS. CCR3 and CCA2A gene and their protein expression were downregulated in the hippocampus at 1 h during PISE. The protein expression of MIP-1alpha, MCP-1 decreased but gene expression increased at 2 h during PISE. In the hilus of the dentate gyrus, significant reduction of the numbers of CCR3, CCR2A, MCP-1 immunopositive neurones occurred from 1 h during to 2 months after PISE, but the number of MIP-1alpha neurones reduced from 2 h during to 2 months after PISE. Induced expression of CCR3 at 1 week, CCR2A, MCP-1 or MIP-1alpha at 1 week and 2 months after PISE was found in reactive astrocytes. MCP-1 was also demonstrated in the blood vessels of the hippocampus at 2 months after PISE.

CONCLUSIONS

CCR3 and MIP-1alpha may play important functional roles in the mouse brain. The downregulation of CCR3, CCR2A, MIP-1alpha and MCP-1 in the hippocampal neurones at the acute stage during and after PISE may weaken the neuroprotective mechanisms. However, induced expression of MCP-1 in hippocampal blood vessel may be related to changes in permeability of the blood-brain barrier during epileptogenesis.

Expression of MMP-2, TIMP-2 protein and the ratio of MMP-2/TIMP-2 in gallbladder carcinoma and their significance

AIM: To study the correlation between expression of MMP-2, TIMP-2 protein and the ratio of MMP-2/TIMP-2 and clinical-pathological parameters of patients with gallbladder carcinoma.

METHODS: Carcinomas (n = 45) and polypoid lesions (n = 15) of the gallbladder were studied for the expression of MMP-2 and TIMP-2 protein by immunohistochemical avidin-biotin-complex method and image analysis. Clinical-pathological data of patients with gallbladder carcinoma such as histological type, grade of differentiation, level of infiltration, liver invasion and lymph node involvement, etc, were recorded.

RESULTS: There was significant difference between the average level (1.123 ± 0.108 vs 1.030 ± 0.054, P = 0.002) of MMP-2, the ratio (1.050 ± 0.013 vs 0.937 ± 0.078, P = 0.003) of MMP-2/TIMP-2 in gallbladder carcinomas and in polypoid lesions of the gallbladder. Significant difference was found between the expression of MMP-2 in early stage and advanced tumors, but there was no correlation between MMP - 2 protein expression and histological type, differentiation degree, infiltration level, lymph node involvement or liver invasion. Although no difference was observed between TIMP-2 expression and histological type or differentiation degree, significant difference was found between TIMP-2 expression and different Nevin stage, infiltration level, local lymph node involvement or liver invasion (1.168 ± 0.067 vs 1.048 ± 0.075, 1.170 ± 0.062 vs 1.039 ± 0.069, 1.039 ± 0.076 vs 1.147 ± 0.083, 1.048 ± 0.074 vs 1.103 ± 0.095, P < 0.05). MMP-2/TIMP-2 ratio did not correlate with histological type, grade of differentiation and liver invasion, but significant differences were found between MMP-2/TIMP-2 ratio and different Nevin stage, infiltration level and lymph node involvement in patients with carcinoma of gallbladder.

CONCLUSION: TIMP-2 and MMP-2/TIMP-2 ratio could reflect more accurately biological characteristic of gallbladder carcinoma and MMP-2/TIMP-2 ratio might be a new significant marker in early diagnosis, in the judgment of invasion or metastasis and the estimate of prognosis in patients with gallbladder carcinomas.

New drugs derived from medicinal plants

In China, increasing emphasis has been laid in recent years on research on natural products. About 140 new drugs have been developed from Chinese medicinal plants. For example, anisodamine possesses good effects in the treatment of septic shock and morphine addiction; 3-n-butylphthalide isolated from seeds of celery was shown to be a new cerebral anti-ischemic agent; indirubin was identified as an anti-leukemic drug with no inhibition of bone marrow; huperzine is a potent and reversible inhibitor of acetylcholinesterase (AChE) and its selective action is superior to that of donepezil; clausenamide was shown to be a potassium channel blocker, its nootropic effect was 50-100 times more potent than that of piracetam; bicyclol was synthesized from schizandrin C isolated from Fructus schizandrae. It has remarkable hepatoprotective and certain anti-hepatitis virus actions; salvianolic acid B is a very strong antioxidant agent with potential anti-dementia effects; yingzhaosu A and artemisinin are anti-malaria drugs containing a peroxide ring which is very rarely seen in natural substances.

NO mediates ginsenoside Rg1-induced long-term potentiation in anesthetized rats

AIM

To investigate the effect of ginsenoside Rg1 on synaptic transmission in anesthetized rats and the effect of NOS inhibitor, 7-nitroindazole (7-NI), on long-term potentiation (LTP) induced by Rg1.

METHODS

Extracellular recording technique was used to record the population spike (PS) in the dentate gyrus (DG) of anesthetized rats. Drug or vehicle injections were delivered via a cannula in the lateral cerebral ventricle.

RESULTS

Rg1 (10 and 100 nmol/L) enhanced the basic synaptic transmission and the magnitude of LTP induced by high frequency stimulation (HFS). Selective nNOS inhibitor 7-NI (5 nmol) icv could inhibit the induction of perforant path-dentate gyrus LTP elicited by Rg1 (P<0.05), and L-arginine 250 g/L ip prevented the action of 7-nitroindazole (P<0.05).

CONCLUSION

Rg1-accelerated synaptic transmission and nitric oxide produced by nNOS played a role in the induction of PP-DG LTP in anesthetized rats.

[Advancement in mechanisms of long-term potentiation]

Synaptic plasticity in mammalian brain is one of the most widely studied topics in neuroscience over the last decade. Long-term potentiation (LTP), mainly involving post-synaptic mechanisms, is a reflection of neural plasticity. Study on the mechanisms of LTP was formerly focused on the properties of NMDA receptor and the intracellular cascade of reaction after activation of the receptor. However, the definition of "silent synapses" with only NMDA receptors without AMPA receptors was frequently referred in LTP study, showing the importance of AMPA receptor in post-synaptic mechanism of LTP.

[Effect and mechanism of securinine on synaptic transmission in the dentate gyrus of anesthetized rats]

AIM

To study the effects of (+) and (-) securinine on the basic synaptic transmission and long-term potentiation (LTP) induced by high-frequency stimulation in the dentate gyrus of anesthetized rats and its possible mechanism.

METHODS

The population spike (PS) was recorded by electrophysiological techniques.

RESULTS

The results showed that at the concentration of 2 x 10(-9) mol.L-1, (+), (-) securinine showed no effect on either the basal PS or LTP. At high cocentrations (2 x 10(-8), 2 x 10(-7) mol.L-1), (+), (-) securinine not only potentiated the basal PS but also enhanced the magnitude of LTP. (+), (-) Securinine showed similar effects; and the effects were completely inhibited by the inhibitory amino acid GABA.

CONCLUSION

These results suggest that the effects of (+), (-) securinine on induction and maintenance of LTP may be related to its blockade of GABA receptor.

Effects of ginsenoside Rg1 on synaptic plasticity of freely moving rats and its mechanism of action

AIM

To investigate the effect and mechanism of ginsenoside Rg1 on synaptic plasticity of freely moving rats.

METHODS

SD rats were chronically implanted with a stimulation electrode in the perforant path (PP) of hippocampus and a recording electrode in the granule cell of dentate gyrus. After administration of ginsenoside Rg(1) (10, 30 mg/kg, ip) for 12 d, extracellular recording technique was used to record the population spike (PS). Mossy fiber (MF) sprouting was measured using Timm's staining, and an immunohistochemical technique was used to detect the expression of presynaptic growth-associated protein 43 (GAP-43).

RESULTS

Rg1 could significantly increase the sensitivity of evoking PS, the amplitude of PS and induce PP-DG long-term potentiation (LTP) in the dentate gyrus (DG) of freely moving rats. In the meantime, Rg1 accelerated MF sprouting in CA3 cell field of hippocampus. The expression level of GAP-43 was elevated in granule cell layer and hilus of DG of Rg1-treated rats.

CONCLUSION

The increased synaptic plasticity may attribute to the increased expression of GAP-43 in granule cell layer of DG and the onset of the sprouting of granule cell axon-MF. The MF sprouting accelerated the synaptic transmission in positive-feedback. Their interaction and the synergism is part of the mechanisms underlying the nootropic effect of Rg1.

Two subcellular localizations of eIF3 p170 and its interaction with membrane-bound microfilaments: implications for alternative functions of p170

We previously identified a 170-kDa protein (p170) highly expressed in lung cancers as the major subunit of the eukaryotic translation initiation factor 3 (eIF3). p170 was recently cloned and little is known concerning its characteristics and subcellular localization. In this paper, we report our surprising findings that about 20% of p170 is associated with membranes while the remaining portion is located in the cytoplasm presumably in the eIF3 complex. We also find that p170 interacts with both endoplasmic reticulum and plasma membranes. The binding of p170 to membranes is through actin filaments, consistent with the fact that p170 contains a spectrin repeat motif that may be involved in actin binding. Furthermore, the cytoplasmic p170 is phosphorylated at serine and threonine residues and the phosphorylation is stimulated by serum. However, the membrane-actin-bound p170 is not phosphorylated. The results obtained in this study suggest that p170 may have other functions in addition to participating in translation initiation. Phosphorylation may play an important regulatory role in the function of p170 in translation initiation and other alternative functions.