Primary leiomyosarcoma of cervical spine invading the vertebra without obvious osteoclasia: Case report and literature review.

Context: Primary leiomyosarcomas are malignant tumors of smooth muscles, with few reported cases occurring in the cervical spine. The authors report a case involving a 29-year-old man with primary leiomyosarcoma in the spinal canal posterior to the C3-C5 vertebrae.Findings: No obvious osteolytic lesions could be found in neither X-ray nor computed tomography scan. Because of the confusion of nontypical imaging findings, a decompressive surgery of anterior cervical corpectomy of C4 and reconstruction with a mesh cage filled with allogenic bone grafts were performed. The patient refused a second operation and then was advised to receive the radiotherapy. No recurrence of the symptoms was evident 6 months after surgery.Conclusion: When a patient suffers from upper cervical tumor, the leiomyosarcoma should be kept in mind as possible diagnoses despite its low occurring ratio. Early detection, early diagnosis, and early treatment must be the goal of the strategy.

Fusion of CNN1 and CNN2-based magnetic resonance image diagnosis of knee meniscus injury and a comparative analysis with computed tomography.

PURPOSE: We used convolutional neural network (CNN) technology to improve the accuracy of diagnosis of knee meniscus injury and shorten the diagnosis time. METHOD: We propose a meniscus detection method based on Fusion of CNN1 and CNN2 (CNNf), which uses Magnetic Resonance Imaging (MRI) and Computer tomography (CT) to compare the diagnosis results, verifies the proposed method through 2460 images collected from 205 patients in the hospital. We used accuracy, sensitivity, specificity, receiver operating characteristics (ROC), and damage total rate to evaluate performance. RESULTS: The accuracy of our model was 93.86%, the sensitivity was 91.35%, the specificity was 94.65%, and the area under the receiver operating characteristic curve was 96.78%. The total damage rate of MRI is 91.57%, which is far greater than the total damage rate of CT diagnosis of 80.13%. CONCLUSION: CNNf-based MRI technology of knee meniscus injury has high practical value in clinical practice. It can effectively improve the accuracy of diagnosis and reduce the rate of misdiagnosis.

Retinal Vascular Changes during the Menstrual Cycle Detected with Optical Coherence Tomography Angiography.

PURPOSE: To evaluate the effects of the menstrual cycle on the retinal vascular status of healthy women by optical coherence tomography angiography (OCTA). MATERIALS AND METHODS: Healthy women with regular natural menstrual cycles of 28 to 30 days were recruited for this prospective study. The women's retinal vascular status was measured by OCTA at 3 time points: the early follicular, ovulatory, and midluteal phases of the menstrual cycle. The main outcome measures were foveal avascular zone (FAZ) parameters, perfusion density (PD) percentage in the superficial retinal capillary plexus (SCP), and PD percentage in the deep retinal capillary plexus (DCP). The mean arterial pressure (MAP), spherical equivalent (SE), best-corrected visual acuity (BCVA), intraocular pressure (IOP), and axial (AL) were also measured in a same menstrual cycle. RESULTS: In total, 62 right eyes of 62 women were included in the study. The mean age was 27.0 ± 1.73 (range, 24 to 31) years, and the mean menstrual cycle was 28.90 ± 0.84 (range, 28 to 30) days. The mean values of the DCP-PD parameters were significantly decreased in the nasal and inferior ETDRS subfields during the ovulatory phase. The mean DCP-PD in the nasal ETDRS subfield in the early follicular, ovulatory, and luteal phases was 54.11 ± 2.85, 56.39 ± 3.03, and 55.70 ± 3.27, respectively. The mean DCP-PD in the inferior ETDRS subfield in the early follicular, ovulatory, and midluteal phases was 52.90 ± 3.30, 54.86 ± 2.51, and 55.21 ± 2.64, respectively. No significant differences were found in MAP, SE, AL, IOP, FAZ area, or other quadrants of PD parameters, and no significant correlation was found between parameters by OCTA and age, MAP,SE, axial length, or IOP. CONCLUSIONS: The DCP-PD decreased in the nasal and inferior ETDRS subfields during the ovulatory phase in our study. This may indicate the need to consider the menstrual phase when interpreting DCP-PD parameters by OCTA in healthy women.

circKMT2D contributes to H2O2-attenuated osteosarcoma progression via the miR-210/autophagy pathway.

Circular RNAs (circRNAs) have been demonstrated to be involved in osteosarcoma (OS) development; however, the underlying mechanism of circKMT2D in OS progression remains unclear. The present study aimed to elucidate how circKMT2D could affect hydrogen peroxide (H2O2)-induced OS progression. H2O2 (100 µmol/l) was used to treat MG63 and U2OS cells. The cell viability, invasive ability, apoptosis and circKMT2D expression were detected using Cell Counting Kit-8 assay, Transwell assay, flow cytometry and reverse transcription-quantitative PCR, respectively. Furthermore, MG63 and U2OS cells transfected with circKMT2D short hairpin RNA and negative control were treated with H2O2, and circKMT2D expression and cell phenotype were determined. Dual-luciferase reporter assay was conducted to determine the association between circKMT2D and miR-210 expression level. Rescue experiments were conducted to examine the mechanisms through which circKMT2D and miR-210 could affect H2O2-treated MG63 cells. In addition, the effects of miR-210 on the expression of the autophagy-related proteins Beclin1 and p62 in H2O2-treated MG63 cells were detected by western blotting. An autophagy inhibitor was used to treat the MG63 cells, and whether miR-210 could affect the H2O2-treated MG63 cell phenotype through autophagy was investigated. The results demonstrated that H2O2 treatment promoted cell apoptosis and decreased cell viability, invasive ability and circKMT2D expression in MG63 and U2OS cells. Furthermore, circKMT2D knockdown decreased the cell viability and invasive ability and enhanced the apoptosis of H2O2-treated MG63 and U2OS cells. circKMT2D possessed binding sites for miR-210 and inhibited miR-210 expression. In H2O2-treated MG63 cells, miR-210 silencing partially reversed the circKMT2D knockdown-induced cell viability inhibition and apoptosis promotion. In addition, miR-210 elevated Beclin1 expression and decreased p62 expression in H2O2-treated MG63 cells. The use of the autophagy inhibitor partially reversed the miR-210 overexpression-induced promotion of apoptosis and inhibition of the viability and invasive ability of H2O2-treated MG63 cells. Taken together, these findings indicated that circKMT2D knockdown may contribute to the inhibition of H2O2-attenuated OS progression via miR-210/autophagy pathway.

Overexpression of histone deacetylase SIRT1 exerts an antiangiogenic role in diabetic retinopathy via miR-20a elevation and YAP/HIF1α/VEGFA depletion.

As a basic member of the Class III histone deacetylases, SIRT1 has been implicated in the occurrence and progression of diabetic retinopathy (DR). The current study aimed to investigate the roles of SIRT1/miR-20a/Yse-associated protein (YAP)/hypoxia-inducible factor 1 α (HIF1α)/vascular endothelial growth factor A (VEGFA) in DR. The expression of SIRT1 was initially determined through quantitative RT-PCR and Western blot analysis following the successful establishment of a DR mouse model, followed by detection of SIRT1 catalytic activity. Retinal microvascular endothelial cells (RMECs) were cultured in media supplemented with normal glucose (NG) or high glucose (HG). Thereafter, SIRT1 was either silenced or overexpressed in RMECs, after which EdU staining and Matrigel-based tube formation assay were performed to assess cell proliferation and tube formation. The binding relationship between YAP, HIF1α, and VEGFA was further illustrated using dual-luciferase reporter assay. Preretinal neovascular cell number was tallied with the IB4-positive vascular endothelial cells, as determined by immunofluorescence. SIRT1 was poorly expressed in mice with DR and HG-treated RMECs with low catalytic activity. The proliferation and tube formation capabilities of RMECs were elevated under HG conditions, which could be reversed following overexpression of SIRT1. SIRT1 was identified as positively regulating the expression of miR-20a with YAP detected as the key target gene of miR-20a. Our data suggested that YAP could upregulate VEGFA via induction of HIF1α. Moreover, SIRT1 overexpression strongly repressed RMEC proliferation and angiogenesis, which could be reversed via restoration of YAP/HIF1α/VEGFA expression. Taken together, the key findings of our study suggest that upregulation of SIRT1 inhibits the development of DR via miR-20a-induced downregulation of YAP/HIF1α/VEGFA.

LINC00657 activates PD-L1 to promote osteosarcoma metastasis via miR-106a.

Osteosarcoma (OS) cells are one of the primary cancer-related causes of death around the world. Long noncoding RNAs are key for OS progression; however, the detailed molecular mechanism remains unknown. LINC00657, miR-106a, and programmed death ligand-1 (PD-L1) genes expression were detected by reverse transcription-quantitative PCR (RT-qPCR) and Western blot approaches. Invasion and lymphangiogenesis were studied using transwell invasion assay and lymphatic vessel formation assay, respectively. We used bioinformatic analyses to identify putative targets of LINC00657 and miR-106a. Luciferase activity was measured by dual-luciferase reporter assay. PD-L1 protein levels were examined by flow cytometry experiments. LINC00657 knockdown attenuates cell invasion and tumor growth of MG63 and lymphatic vessel formation. miR-106a directly binds LINC00657 and they regulate each other. Furthermore, miR-106a inhibitor strikingly enhanced lymphatic vessel formation and invasion of shLINC00657 MG63 cells. miR-106a mimic directly targeted and downregulated PD-L1. PD-L1 overexpression largely rescued miR-106a mimic-modulated OS cell metastasis. LINC00657 and PD-L1 were upregulated in clinical OS tumors compared to normal tissues. Lower expression levels of LINC00657 and PD-L1 were closely associated with higher overall survival of patients with OS. Here, we suggest a novel mechanism for LINC00657-regulated metastasis of OS cells by regulating the miR-106a/PD-L1 axis. Our conclusions facilitate the development of therapeutical approaches by targeting LINC00657.

Optical quality assessment in branch retinal vein occlusion after monthly intravitreal ranibizumab injection: a prospective, case-control study.

PURPOSE: To evaluate optical quality and intraocular scattering using the Optical Quality Analysis System (OQAS) II in branch retinal vein occlusion (BRVO) and to investigate the influences of retinal changes on optical quality. MATERIALS AND METHODS: Sixty-two patients with diagnosis of BRVO were enrolled in this prospective, case-control study. The control group consisted of the patients' fellow eyes. Initial logMAR visual acuity, central macular thickness, and optical quality parameters including modulation transfer function cutoff frequency (MTF cut off), Strehl ratio (SR), objective scatter index (OSI) and OQAS values (OVs) at 100%, 20%, and 9% contrast levels were measured. Every BRVO-affected eye was treated with monthly intravitreal ranibizumab injection. We investigated the differences between clinical parameters of the BRVO-affected eye and those of the control eye and changes in those parameters on the basis of the clinical course of BRVO over 3 months. RESULTS: All the OQAS parameters measured except objective refraction error differed statistically significantly between the two groups. As macular thickness decreased and visual acuity improved, all the optical quality parameters except for objective refraction error and OV at 100% contrast gradually recovered with time after treatment but did not return to normal compared with the control eye. Only visual acuity was found to be significantly related to central macular thickness change (p = .027). CONCLUSIONS: BRVO resulted in declined visual acuity and optical quality. It is suggested that the optical quality parameters are affected by the inner layers of the retina in BRVO.

RIPK1 suppresses apoptosis mediated by TNF and caspase-3 in intervertebral discs.

BACKGROUND: Low back pain has become a serious social and economic burden and the leading cause of disability worldwide. Among a variety of pathophysiological triggers, intervertebral disc (IVD) degeneration plays a primary underlying role in causing such pain. Specifically, multiple independent endplate changes have been implicated in the initiation and progression of IVD degeneration. METHODS: In this study, we built a signaling network comprising both well-characterized IVD pathology-associated proteins as well as some potentially correlated proteins that have been associated with one or more of the currently known pathology-associated proteins. We then screened for the potential IVD degeneration-associated proteins using patients' normal and degenerative endplate specimens. Short hairpin RNAs for receptor interacting serine/threonine kinase 1 (RIPK1) were constructed to examine the effects of RIPK1 knockdown in primary chondrocyte cells and in animal models of caudal vertebra intervertebral disc degeneration in vivo. RESULTS: RIPK1 was identified as a potential IVD degeneration-associated protein based on IVD pathology-associated signaling networks and the patients' degenerated endplate specimens. Construction of the short hairpin RNAs was successful, with short-term RIPK1 knockdown triggering inflammation in the primary chondrocytes, while long-term knockdown triggered apoptosis through cleavage of the caspase 3 pathway, down-regulated NF-κB and mitogen-activating protein kinase (MAPK)s cascades, and decreased cell survival and inflammation. Animal models of caudal vertebra intervertebral disc degeneration further demonstrated that apoptosis was induced by up-regulation of tumor necrosis factor (TNF) accompanied by down-regulation of NF-κB and MAPKs cascades that are dependent on caspase and RIPK1. CONCLUSIONS: These results provide proof-of-concept for developing novel therapies to combat IVD degeneration through interfering with RIPK1-mediated apoptosis signaling pathways especially in patients with RIPK1 abnormality.

Long Noncoding RNA SNHG16 Promotes Cell Proliferation by Sponging MicroRNA-205 and Upregulating ZEB1 Expression in Osteosarcoma.

BACKGROUND/AIMS: Long noncoding RNAs (lncRNAs) have been a research hotspot, as they play important roles in tumor development. However, their expression pattern and biological function in osteosarcoma have not yet been clarified. METHODS: Differentially expressed lncRNAs in osteosarcoma and paracarcinoma tissues were identified by screening an lncRNA microarray, and candidate lncRNAs were verified by quantitative real-time PCR (qRT-PCR). A series of bioinformatics and molecular biological methods were adopted to investigate the interaction among lncRNA, microRNA (miRNA), and miRNA target genes during the development and occurrence of osteosarcoma. Cell viability was measured using a Cell Counting Kit-8 assay. RESULTS: Chip microarray screening combined with the validation of differentially expressed candidate lncRNAs showed that the lncRNA small nucleolar RNA host gene 16 (SNHG16) had the largest fold change. SNHG16 was highly expressed in osteosarcoma tissues and cell lines, and its downregulation led to the suppressed proliferation of osteosarcoma cells. Further investigations revealed that SNHG16 could upregulate zinc finger E-box-binding homeobox 1 (ZEB1) expression by acting as an endogenous sponge of miR-205. Moreover, rescue assays proved that the effects of SNHG16 on the proliferation of osteosarcoma cells were dependent on miR-205. CONCLUSION: SNHG16 can significantly enhance the proliferation of osteosarcoma cells. In addition, SNHG16, miR-205, and ZEB1 interact in a common pathway during the development and occurrence of osteosarcoma, providing novel targets for intervention in the treatment of osteosarcoma.

MicroRNA-524 promotes cell proliferation by down-regulating PTEN expression in osteosarcoma.

BACKGROUND: Increasing numbers of studies have examined the correlation between specific miRNAs and tumours to enable their diagnosis and treatment. However, there are few reports regarding the concrete role and mechanism of miRNA in osteosarcoma. METHODS: The expression of miR-524 in osteosarcoma tissues and cell lines was examined by qRT-PCR. The cell proliferation was examined using CCK-8 in vitro. A series of bioinformatics and molecular biology techniques were adopted to investigate the regulatory relationship between miR-524 and target genes in osteosarcoma. RESULTS: The results showed that the miRNA with the most significant differential expression in osteosarcoma was miR-524, which was significantly up-regulated in both osteosarcoma tissues and cell lines. MiR-524 knockdown inhibited proliferation and promoted apoptosis of osteosarcoma cells, while overexpression of miR-524 induced their proliferation. Bioinformatics analysis and luciferase assay confirmed that PTEN was a direct target gene of miR-524 and that miR-524 induced proliferation of osteosarcoma cells through activation of the PI3K/AKT pathway via inhibition of PTEN. CONCLUSIONS: MiR-524 induces the proliferation of osteosarcoma cells through activation of the PI3K/AKT pathway via inhibition of the target gene PTEN, which provides a theoretical basis for selecting a new therapeutic target for osteosarcoma.

Surgical Outcomes of Single-Level Transforaminal Lumbar Interbody Fusion for Degenerative Spondylolisthesis With and Without Kyphotic Alignment.

OBJECTIVE: We sought to investigate the impact of single-level transforaminal lumbar interbody fusion (TLIF) on lumbar sagittal profile in degenerative spondylosis (DS) patients with or without kyphotic alignment, as well as compare radiologic and clinical outcomes based on preoperative sagittal alignment. BACKGROUND: DS with a kyphotic alignment at an involved segment constitutes a distinct subgroup. However, previous studies concerning surgical outcomes often lump all patients together without focusing on this distinct subgroup. METHODS: This study reviewed a consecutive series of patients who received single-level TLIF for DS between 2009 and 2016. They were assigned to Groups K and L. All patients were followed up for >2 years. Then demographics and radiographic and clinical outcomes were compared between the groups. RESULTS: There were 19 and 115 patients in Group K and Group L, respectively. Compared with Group L, Group K was characterized by loss of lumbar lordosis and anterior shifting of L1 axis S1 distance. After surgery, lumbar lordosis and L1 axis S1 distance was significantly improved in Group K, while no significant change occurred in group L. The mean reduction rate was significantly higher in Group K, which had less slippage after surgery, but the differences in slip angle, anterior disk height, and posterior disk height were not significant. The preoperative Oswestry Disability Index and visual analog scale for back pain scores were significantly higher in Group K, while no differences were found in postoperative evaluation. CONCLUSIONS: Despite effective changes radiographic parameters and clinical outcomes, our findings suggest that the 2 groups behave differently in response to single-level TLIF procedure. Reconstruction of lumbar sagittal profile can be achieved in DS with a kyphotic alignment after surgery.

Development and validation of nomogram based on miR-203 and clinicopathological characteristics predicting survival after neoadjuvant chemotherapy and surgery for patients with non-metastatic osteosarcoma.

BACKGROUND: Recently, nomograms have been used as models for risk prediction in malignant tumor because they can predict the outcome of interest for a certain individual based on many variables. This study aimed to establish an effective prognostic nomogram for osteosarcoma based on the clinicopathological factors and microRNA-203. RESULTS: The results showed that miR-203 expression was significantly lower in osteosarcoma tissues compared with the corresponding adjacent tissues (P < 0.001). Patients with low miR-203 expression had poor overall survival (OS) in osteosarcoma. The histological type, tumor size, AJCC stage and miR-203 expression were integrated in the nomogram. The nomogram showed significantly better prediction of OS than for patients with non-metastatic osteosarcoma. The ROC curve also showed higher specificity and sensitivity for predicting 3- and 5-year osteosarcoma patients' survival compared with AJCC stage. The decision curve analysis also indicated more potential of clinical application of the nomogram compared with AJCC staging system. Moreover, our findings were supported by the validation cohort. MATERIALS AND METHODS: We retrospectively investigated 301 patients with non-metastatic osteosarcoma. Data from primary cohort (n = 198) were used to develop multivariate nomograms. This nomogram was internally validated for discrimination and calibration with bootstrap samples and was externally validated with an independent patient cohort (n = 103). CONCLUSIONS: Our proposed nomogram showed more accurate prognostic prediction for patients with non-metastatic osteosarcoma.

MicroRNAs with prognostic significance in osteosarcoma: a systemic review and meta-analysis.

INTRODUCTION: This study aimed to elucidate the prognostic value of microRNAs (miRNAs) in patients with osteosarcoma. MATERIALS AND METHODS: Studies were recruited by searching PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure, and Wanfang data-bases (final search update conducted January 2017). Eligible studies were identified and the quality was assessed using multiple search strategies. RESULTS: A total of 55 articles that investigated the correlation between miRNA expression and either patient survival or disease recurrence in osteosarcoma was initially identified. Among these, 30 studies were included in the meta-analysis. The results of our meta-analysis revealed that elevated levels of miR-21, miR-214, miR-29, miR-9 and miR-148a were associated with poor prognosis in osteosarcoma. Additionally, downregulated miR-382, miR26a, miR-126, miR-195 and miR-124 expression indicated poor prognosis in osteosarcoma. CONCLUSIONS: miRNAs may act as independent prognostic factors in patients with osteosarcoma and are useful in stratifying risk.

Activation of α7 nicotinic acetylcholine receptors prevents monosodium iodoacetate-induced osteoarthritis in rats.

BACKGROUND/AIMS: Although some evidence suggests that the prevalence of osteoarthritis (OA) is lower in smokers compared to nonsmokers, the mechanisms of nicotine-induced protection remain unclear. Stimulation of the α7 nicotinic acetylcholine receptor (α7-nAChR) appears to be a critical mechanism underlying the anti-inflammatory potential of cholinergic agonists in immune cells. The inhibition of secreted inflammatory molecules and the subsequent inflammatory processes have been proposed as a novel strategy for the treatment of OA. The objective of the present study was to determine whether nicotine-induced protection in a monosodium iodoacetate (MIA) rat model of OA occurs via α7-nAChR-mediated inhibition of chondrocytes. METHODS: Both in vivo (MIA) and in vitro (MIA; Interleukin-1ß, IL-1ß) models of OA were used to investigate the roles and the possible mechanisms whereby α7-nAChRs protect against knee joint degradation. Multiple experimental approaches, including macroscopic, histological analysis, chondrocyte cell cultures, confocal microscopy, and western blotting, were employed to elucidate the mechanisms of α7-nAChR-mediated protection. RESULTS: Systemic administration of nicotine alleviated MIA-induced joint degradation. The protective effects of nicotine were abolished by administration of the α7-nAChR-selective antagonist methyllycaconitine (MLA). In primary cultured rat chondrocytes, pretreatment with nicotine suppressed both p38, extracellular regulated kinase (Erk) 1/2 and c-Jun-N-terminal kinase (JNK) mitogen-activated protein kinases (MAPK) phosphorylation and phosphorylated nuclear factor-kappa B (NF-κB) p65 activation induced by MIA- or IL-1ß, and these effects were also reversed by MLA. CONCLUSION: Taken together, our results suggest that activation α7-nAChRs is an important mechanism underlying the protective effects of nicotine.

Activation of α7 nicotinic acetylcholine receptors protects astrocytes against oxidative stress-induced apoptosis: implications for Parkinson's disease.

Astrocytes have been implicated in the immune responses associated with Parkinson's disease (PD). Inhibition of astrocyte apoptosis is a novel strategy for the treatment of PD. Recent studies suggest that α7 nicotinic acetylcholine receptors (α7-nAChRs) expressed in glial cells are critical links between inflammation and neurodegeneration in PD. However, little is known about their contribution to astrocyte apoptosis during the development of this disorder. In the present study, we showed that nicotine exerts a protective effect on H2O2-induced astrocyte apoptosis and glial cell-derived neurotrophic factor (GDNF) downregulation, and this effect was abolished by an α7-nAChR-selective antagonist. The underlying mechanisms might involve alleviation of mitochondrial membrane potential loss, stabilization of the Bax/Bcl-2 balance, and inhibition of cleaved caspase-9 activity through α7-nAChR activation. Systemic administration of nicotine dramatically alleviated MPTP-induced symptoms, protected dopaminergic neurons against degeneration, inhibited astrocytes and microglia activation in the substantia nigra pars compacta (SNpc) and blocked the decrease of GDNF in the striatum by activating α7-nAChRs. Taken together these findings demonstrate, for the first time, that nicotine suppresses H2O2-induced astrocyte apoptosis via the mitochondrial pathway through the stimulation of α7-nAChRs. Targeting α7-nAChRs expressed in astrocytes may be a novel therapeutic strategy for the treatment of neurodegenerative disorders.

α7 nicotinic acetylcholine receptor-mediated neuroprotection against dopaminergic neuron loss in an MPTP mouse model via inhibition of astrocyte activation.

BACKGROUND: Although evidence suggests that the prevalence of Parkinson's disease (PD) is lower in smokers than in non-smokers, the mechanisms of nicotine-induced neuroprotection remain unclear. Stimulation of the α7 nicotinic acetylcholine receptor (α7-nAChR) seems to be a crucial mechanism underlying the anti-inflammatory potential of cholinergic agonists in immune cells, including astrocytes, and inhibition of astrocyte activation has been proposed as a novel strategy for the treatment of neurodegenerative disorders such as PD. The objective of the present study was to determine whether nicotine-induced neuroprotection in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model occurs via α7-nAChR-mediated inhibition of astrocytes. METHODS: Both in vivo (MPTP) and in vitro (1-methyl-4-phenylpyridinium ion (MPP+) and lipopolysaccharide (LPS)) models of PD were used to investigate the role(s) of and possible mechanism(s) by which α7-nAChRs protect against dopaminergic neuron loss. Multiple experimental approaches, including behavioral tests, immunochemistry, and stereology experiments, astrocyte cell cultures, reverse transcriptase PCR, laser scanning confocal microscopy, tumor necrosis factor (TNF)-α assays, and western blotting, were used to elucidate the mechanisms of the α7-nAChR-mediated neuroprotection. RESULTS: Systemic administration of nicotine alleviated MPTP-induced behavioral symptoms, improved motor coordination, and protected against dopaminergic neuron loss and the activation of astrocytes and microglia in the substantia nigra. The protective effects of nicotine were abolished by administration of the α7-nAChR-selective antagonist methyllycaconitine (MLA). In primary cultured mouse astrocytes, pretreatment with nicotine suppressed MPP(+)-induced or LPS-induced astrocyte activation, as evidenced by both decreased production of TNF-α and inhibition of extracellular regulated kinase1/2 (Erk1/2) and p38 activation in astrocytes, and these effects were also reversed by MLA. CONCLUSION: Taken together, our results suggest that α7-nAChR-mediated inhibition of astrocyte activation is an important mechanism underlying the protective effects of nicotine.

Dynamic alterations of gene expression of nicotinic acetylcholine receptor α7, α4 and ß2 subunits in an acute MPTP-lesioned mouse model.

Epidemiologic studies show that the prevalence of Parkinson's disease (PD) is lower in smokers than in nonsmokers. Nicotine, a potent agonist of nicotinic acetylcholine receptors (nAChRs), excites midbrain dopaminergic neurons and this may contribute to the anti-parkinsonian effects. However, the alterations in gene expression of nAChR subunits using an acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse PD model remain unclear. In the present study, we profile the time course of nAChR α7, α4 and ß2 subunit expression levels using a comparative RT-PCR approach after acute MPTP injection. The results fall into four categories. (1) MPTP treatment transiently increased nAChR α7 (after last injection of MPTP 3 and 24 h), α4 and ß2 (24 h) mRNA expression in the substantia nigra (SN) and striatum. (2) Compared to cortical and hippocampal tissues, this transient increase of nAChR subunit expression specifically occurred in the SN and striatum. (3) In the acute MPTP model, time-courses of altered expression for nAChR α7, α4 and ß2 subunits closely mirrored the deficits observed in animal motor activity. (4) Stereological data showed that after administration of MPTP for 24h, there was a robust astrogliosis in the SN associated with significant dopaminergic neurodegeneration. These changes followed or paralleled MPTP-induced elevation in the levels of α7, α4 and ß2 mRNAs. Collectively, our results demonstrate that nAChRs are important targets in the MPTP neurotoxic process. These data suggest that therapeutic strategies targeted toward nAChR α7, α4 and ß2 subunits may have potential for developing new treatments for PD.