Expression Levels Of α7nAChR Research Articles

Effect of α7 nAChR-autophagy axis of deciduous tooth pulp stem cells in regulating IL-1β in the process of physiological root resorption of deciduous teeth.

Physiological root resorption of deciduous teeth is a normal phenomenon occurring during the developmental stages of children. Previous research has indicated the pivotal role of the inflammatory microenvironment in this process, although the specific mechanisms remain unclear. This study is aimed at elucidating the involvement of the alpha7 nicotinic acetylcholine receptors (α7 nAChR)-autophagy axis in the regulation of the inflammatory microenvironment during physiological root resorption in deciduous teeth. Samples were collected from deciduous teeth at various stages of physiological root resorption, and deciduous dental pulp stem cells (DDPSCs) were isolated and cultured during the mid-phase of root resorption. The findings revealed a substantial infiltration of the pulp of deciduous teeth at the mid-phase of root resorption, characterized by elevated expression levels of α7 nAChR and IL-1β. Significantly increased IL-1β and α7 nAChR expressions were observed in DDPSCs during the mid-phase of root resorption, with α7 nAChR demonstrating a regulatory effect on IL-1β. Moreover, evidence suggested that mechanical stress may act as a trigger, regulating autophagy and IL-1 expression via α7 nAChR. In conclusion, mechanical stress was identified as a regulator of autophagy in DDPSCs through α7 nAChR, influencing the expression of IL-1β and contributing to the formation of the inflammatory microenvironment. This mechanism plays a crucial role in the physiological root resorption of deciduous teeth. KEY MESSAGES: The pulp of deciduous teeth at mid-phase of root resorption was heavily infiltrated with high expression of α7nAChR and IL-1β. α7 nAChR acts as an initiating factor to regulate IL-1β through autophagy in DDPSCs. Mechanical stress can regulate autophagy of DDPSCs through α7 nAChR and thus affect IL-1β expression and inflammatory microenvironment formation in physiological root resorption in deciduous teeth.

Herbal cake-partitioned moxibustion regulates M1 and M2 macrophage polarization of colonic mucosa in rats with Crohn's disease

To observe the effect of herbal cake-partitioned moxibustion (Moxi) on the expressions of inflammatory factors and M1/M2 polarization in colonic mucosal macrophages in Crohn's disease (CD) rats, so as to explore its underlying mechanisms in the treatment of CD. Forty male SD rats were randomly divided into normal, model, Moxi and medication groups (n=10). The CD model was established by enema of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) solution (5%TNBS∶50% alcohol=2∶1, 3 mL/kg), once every 7 days, 4 times altogether. For rats of the Moxi group, cake-partitioned moxibustion was given to "Tianshu" (ST25) and "Qihai" (CV6), two moxa-cones for each acupoint every time, once daily for 10 days. For rats of the medication group, intragastric perfusion of mesalazine solution was given twice daily for 10 days. After the treatment, the colonic mucosa tissue was sampled, and the macrophages were isolated, purified and cultured. The pathological changes of colon tissues were observed by H.E. staining. The ultrastructure of colon tissue was observed by transmission electron microscopy. The expression levels of α7nAChR, NF-κB p65 and TNF-α in colon mucosal macrophages were detected by Western blot. The number of M1 and M2 macrophages in colon mucosa was detected by flow cytometry and immunofluorescence assay. Compared with the normal group, the colon tissue of rats presented huge ulceration and inflammatory manifestations, the junction of colon epithelial cells was loose, the structure of organelles was damaged; the expression level of α7nAChR in macrophages of colon mucosa was significantly decreased (P<0.01), while the expression levels of NF-κB p65 and TNF-α, and the number of M1 and M2 macrophages were increased (P<0.01, P<0.05) in the model group. In comparison with the model group, the morphology and structure of colon mucosa tissues of rats in Moxi and medication groups were improved; the expression level of α7nAChR, the number of M2 macrophage in colon mucosa were significantly increased (P<0.01, P<0.05), while the expression levels of NF-κB p65 and TNF-α, and the number of M1 macrophage were significantly decreased (P<0.01, P<0.05) in both the Moxi and medication groups. Herbal cake-partitioned moxibustion may inhibit NF-κB activation by up-regulating the expression level of α7nAChR to promote the polarization of macrophages from M1 to M2 type, and reduce the proportion of M1 macrophages, inhibit the expression of TNF-α in colonic mucosa of CD rats, so as to relieve the intestinal inflammation.

α-Mangostin Treats Early-Stage Adjuvant-Induced Arthritis of Rat by Regulating the CAP-SIRT1 Pathway in Macrophages.

BackgroundStudies have found that α-mangostin (MG) can relieve experimental arthritis by activating cholinergic anti-inflammatory pathway (CAP). It affects the polarization of macrophages and the balance of related immune cell subpopulations, but the specific mechanism is still unclear. It has been found that silent information regulator 1 (SIRT1) is closely related to macrophage activity. The purpose of this study is to explore the mechanism of MG intervening in macrophage polarization during treatment of early adjuvant-induced (AIA) rats through the CAP-SIRT1 pathway.MethodsWe investigated the polarization of M1 macrophages and the differentiation of Th1 in AIA rats by flow cytometry. Activity of acetylcholinesterase (AChE) and the level of nicotinic adenine dinucleotide (NAD+) in serum were also detected, and immunohistochemical was used to detect the levels of α7 nicotinic cholinergic receptor (α7nAChR) and SIRT1. Then in macrophages, the molecular mechanism of MG regulating the abnormal activation of macrophages in rats with early AIA through the CAP-SIRT1 pathway was studied.ResultsMG can significantly inhibit the polarization of M1 macrophages and the differentiation of Th1 in AIA rats in the acute phase of inflammation. MG can significantly inhibit the activity of AChE and increase the level of NAD+, thereby further up-regulated the expression levels of α7nAChR and SIRT1. Meanwhile, MG inhibited nuclear factor-κB (NF-κB)-mediated inflammation by activating the CAP-SIRT1 pathway in macrophages.ConclusionIn summary, the stimulation of MG induced CAP activation, which up-regulated SIRT1 signal, and thereby inhibited M1 polarization through the NF-κB pathway, and improved the pathological immune environment of early-stage AIA rats.

The role of α7-nicotinic acetylcholine receptor in a rat model of chronic nicotine-induced mechanical hypersensitivity

Smokers have a higher incidence of chronic pain than non-smokers, but the neural mechanism is not yet fully understood. Nicotine is the main component of tobacco and acts as an agonist for nicotinic cholinergic receptors (nAChRs) in the nervous system.This study was approved by the IACUC of UM. The effects of chronic nicotine administration on mechanical sensitivity were studied using a rat model. The changes in the expression levels of the α7 isoform of nAChR (α7-nAChR), inflammatory cytokines TNFα and COX-2, as well as the density of neuro-immune cells (astrocytes and microglia) were measured concurrently.The results indicate that long-term nicotine administration induces hypersensitivity to mechanical stimuli, as demonstrated by a significant reduction in the pain perception threshold. In response to nicotine, the expression levels of α7-nAChR increased in the periaqueductal gray matter (PAG) and decreased in the spinal cord. Acute administration of the selective α7-nAChR agonist CDP-Choline reversed this hypersensitivity. Chronic nicotine administration led to an increase of microglial cells in the dorsal horn of the spinal cord and increased expression levels of the cytokines TNFα and COX-2.This study suggests that decreased α7-nAChR expression in the spinal cord, as a result of long-term exposure to nicotine, may be causatively linked to chronic pain. Simultaneously, the increase of neuro-immune factors in the spinal cord is also a potential factor leading to chronic pain.

Expression levels of the α7 nicotinic acetylcholine receptor in the brains of patients with Alzheimer's disease and their effect on synaptic proteins in SH-SY5Y cells.

Alzheimer's disease (AD) is a chronic neurodegenerative, and abnormal aggregation of the neurotoxic β amyloid (Aβ) peptide is an early event in AD. The present study aimed to determine the correlation between the nicotinic acetylcholine receptor α7 subunit (α7 nAChR) and Aβ in the brains of patients with AD, and to investigate whether the increased expression levels of the α7 nAChR could alter the neurotoxicity of Aβ. The expression levels of α7 nAChR and Aβ in the brains of patients with AD and healthy brains were analyzed using immunofluorescence. Moreover, SH-SY5Y cells were used to stably overexpress or silence α7 nAChR expression levels, prior to the treatment with or without 1 µmol/l Aβ1-42 oligomer (AβO). The mRNA and protein expression levels of α7 nAChR, synaptophysin (SYP), postsynaptic density of 95 kDa (PSD-95) and synaptosomal-associated protein of 25 kDa (SNAP-25) were subsequently analyzed using reverse transcription-quantitative PCR and western blotting. In addition, the concentration of acetylcholine (ACh) and the activity of acetylcholinesterase (AChE) were analyzed using spectrophotometry, while the cell apoptotic rate was determined using flow cytometry. The expression of Aβ in the brains of patients with AD was found to be significantly increased, whereas the expression of α7 nAChR was significantly decreased compared with the healthy control group. In vitro, the expression levels of α7 nAChR were significantly increased or decreased following the overexpression or silencing of the gene, respectively. Consistent with these observations, the mRNA and protein expression levels of SYP, PSD-95 and SNAP-25 were also significantly increased following the overexpression of α7 nAChR and decreased following the genetic silencing of the receptor. In untransfected or negative control cells, the expression levels of these factors and the apoptotic rate were significantly reduced following the exposure to AβO, which was found to be attenuated by α7 nAChR overexpression, but potentiated by α7 nAChR RNA silencing. However, no significant differences were observed in either the ACh concentration or AChE activity following transfection. Collectively, these findings suggested that α7 nAChR may protect the brains of patients with AD against Aβ, as α7 nAChR overexpression increased the expression levels of SYP, SNAP-25 and PSD-95, and attenuated the inhibitory effect of Aβ on the expression of these synaptic proteins and cell apoptosis. Overall, this indicated that α7 nAChR may serve an important neuroprotective role in AD.

Electroacupuncture treatment upregulates α7nAChR and inhibits JAK2/STAT3 in dorsal root ganglion of rat with spared nerve injury.

BackgroundNeuropathic pain with complicated mechanism severely disrupts patient quality of life. The novel approaches and more effective management should be further investigated. It was reported that alpha-7 nicotinic acetylcholine receptor (α7nAChR) and janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling in dorsal root ganglion (DRG) contributed to the pathogenesis of neuropathic pain. Our previous study has shown that electroacupuncture (EA) alleviated neuropathic pain via activating α7nAChR in the spinal cord. However, whether the effect of 2 Hz EA on spared nerve injury (SNI)-induced neuropathic pain is mediated through modulation of α7nAChR and JAK2/STAT3 pathway in the DRG remains unclear.Materials and methodsThe SNI-induced neuropathic pain rat model was used in this study. After application of 2 Hz EA treatment to SNI rats on day 3, 7, 14 and 21 post-surgery, the expression levels of α7nAChR, JAK2/STAT3 and some cytokines in DRG were determined by qRT-PCR and Western blot analysis.ResultsWe found that SNI induced significant down-regulation of α7nAChR mRNA and protein expression. SNI also obviously elicited the decrease in anti-inflammatory cytokine IL-10 protein expression. The enhancement of p-JAK2, p-STAT3, pro-inflammatory cytokines IL-1β and IL-6 protein levels induced by SNI were also observed. However, 2 Hz EA treatment to SNI rats distinctly improved α7nAChR and IL-10 levels and reduced p-JAK2, p-STAT3, IL-1β and IL-6 expression in the DRG.ConclusionOur present study suggested that 2 Hz EA treatment indeed activated α7nAChR, suppressed JAK2/STAT3 signaling and re-balanced the relationship between pro-inflammatory and anti-inflammatory cytokines in DRG of SNI rat, which provided insight into our understanding of the mechanism for 2 Hz EA to attenuate neuropathic pain.

α7 Nicotinic acetylcholine receptor-mediated anti-inflammatory effect in a chronic migraine rat model via the attenuation of glial cell activation.

BackgroundEvidence suggests that the activation of α7 nicotinic acetylcholine receptor (α7nAChR) can greatly decrease the neuroinflammation response. Neuroinflammation plays a pivotal role in the pathogenesis of chronic migraine (CM). Clinical observations also show that nicotine gum induces analgesic effects in migraine patients. However, whether α7nAChR is involved in CM is unclear.ObjectiveTo investigate the role of α7nAChR in CM and provide a new therapeutic target for CM.Materials and methodsThirty-six male Sprague–Dawley rats were distributed randomly into control, CM, PNU-282987, and α-bungarotoxin groups (n=9 rats in each group). The CM model was established by the recurrent daily administration of inflammatory soup on the dura over the course of 1 week. The hind paw threshold and facial allodynia were assessed by the von Frey test. The expression levels of α7nAChR, tumor necrosis factor-alpha, and interleukin-1 beta were analyzed by Western blot and real-time fluorescence quantitative polymerase chain reaction. The location of α7nAChR in the hippocampus was quantified by immunofluorescence, as well as the microglial and astrocyte alterations. Changes in the calcitonin gene-related peptide and the phosphorylated JNK protein among different groups were measured by Western blot.ResultsWe found that the expression of α7nAChR was reduced after repeated inflammatory soup administration. The increased expression of tumor necrosis factor-alpha, interleukin-1 beta, and calcitonin gene-related peptide in CM group were significantly decreased by PNU-282987 and aggravated by α-bungarotoxin. Moreover, PNU-282987 decreased the numbers of astrocytes and microglia compared with the numbers in the CM group in both hippocampal CA1 and CA3 regions. In contrast, α-bungarotoxin activated the astrocytes and microglia, but the differences with respect to the CM group were not significant. Activated c-Jun N-terminal kinase signaling was observed in CM rats and was also blocked by PNU-282987.ConclusionThe activation of α7nAChR increased the mechanical threshold and alleviated pain in the CM rat model. α7nAChR activation also decreased the upregulation of astrocytes and microglia through the p-c-Jun N-terminal kinase–mitogen-activated protein kinase signaling pathway.

α7 nicotinic acetylcholine receptor agonist reduced myocardial fibrosis possibly through inhibiting p38 mitogen activated protein kinase signaling pathway

Objective To investigate the role of α7 nicotinic acetylcholine receptor (α7nAchR) agonist in myocardial fibrosis and its possible mechanism. Methods The cardiac fibroblasts were isolated and cultured from neonatal rats. The cardiac fibroblasts were divided into the following four groups: blank control group (cardiac fibroblasts without any intervention); model group [cardiac fibroblasts treated with 10-6 mol/L angiotensin Ⅱ (Ang Ⅱ) only]; α7nAchR agonist group (cardiac fibroblasts treated with 5×10-6 mol/L PNU-282987, and 1 h later treated with 10-6 mol/L Ang Ⅱ); α7nAchR antagonist group (cardiac fibroblasts treated with 10-6 mol/L MLA, and 1 h later treated with 10-6 mol/L Ang Ⅱ). The proliferation abilities of cardiac fibroblasts in different treatment groups were measured using WST-1 method. The expression levels of α7nAchR genes in cardiac fibroblasts in different treatment groups were examined by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR). The expression levels of α7nAchR, type Ⅰ and type Ⅲ collagen, α-smooth muscle actin (α-SMA), p38 mitogen activated protein kinase (p38MAPK) and phosphorylated p38MAPK (p-p38MAPK) proteins in cardiac fibroblasts were detected by Western blotting. Results (1) The final absorbance in the α7nAchR agonist group (0.50±0.13) was significantly lower than α7nAchR antagonist group and model group (0.75±0.10, 0.63±0.11, F=10.567, P=0.000). It suggested that activation of α7nAchR could inhibit the proliferation of cardiac fibroblasts. (2) The relative expression levels of α7nAchR mRNA and protein in α7nAchR agonist group (0.87±0.15, 0.76±0.08) were significantly higher than the α7nAchR antagonist group (0.45±0.09, 0.40±0.14), model group (0.62±0.11, 0.59±0.10) and blank control group (0.32±0.13, 0.30±0.07, F=25.402, P=0.000). It suggested that α7nAchR agonists can upregulate the expression of α7nAchR gene in cardiac fibroblasts. (3) The relative expression levels of type Ⅰ and type Ⅲ collagen proteins, α-SMA protein and p-p38MAPK protein in α7nAchR agonist group (0.53±0.09, 0.50±0.12, 0.38±0.08, 0.27±0.09) were lower than the model group (0.65±0.12, 0.62±0.10, 0.57±0.11, 0.45±0.11) and α7nAchR antagonist group (0.81±0.13, 0.71±0.11, 0.70±0.10, 0.68±0.08), while were higher than the blank control group (0.41±0.08, 0.35±0.06, 0.19±0.07, 0.16±0.07, F=29.647, 32.962, 30.549, 53.665, P=0.000, 0.000, 0.000, 0.000). The relative expression of p38MAPK protein in the α7nAchR agonist group (0.71±0.12) was higher than the model group (0.52±0.10) and α7nAchR antagonist group (0.35 ± 0.09), but was lower than the blank control group (0.85 ± 0.14, F=44.347, P=0.000). Conclusion α7nAchR agonists could inhibit the proliferation of cardiac fibroblasts and reduce the synthesis of collagen between cells. The mechanism might be related to inhibition of p38MAPK signaling pathway activation. Key words: Cardiac fibroblasts; α 7 nicotinic acetylcholine receptor agonist; Fibrosis; p38 mitogen-activated protein kinase signaling pathway

Genetic knockout of the α7 nicotinic acetylcholine receptor gene alters hippocampal long-term potentiation in a background strain-dependent manner

Reduced α7 nicotinic acetylcholine receptor (nAChR) function is linked to impaired hippocampal-dependent sensory processing and learning and memory in schizophrenia. While knockout of the Chrna7 gene encoding the α7nAChR on a C57/Bl6 background results in changes in cognitive measures, prior studies found little impact on hippocampal synaptic plasticity in these mice. However, schizophrenia is a multi-genic disorder where complex interactions between specific genetic mutations and overall genetic background may play a prominent role in determining phenotypic penetrance. Thus, we compared the consequences of knocking out the α7nAChR on synaptic plasticity in C57/Bl6 and C3H mice, which differ in their basal α7nAChR expression levels. Homozygous α7 deletion in C3H mice, which normally express higher α7nAChR levels, resulted in impaired long-term potentiation (LTP) at hippocampal CA1 synapses, while C3H α7 heterozygous mice maintained robust LTP. In contrast, homozygous α7 deletion in C57 mice, which normally express lower α7nAChR levels, did not alter LTP, as had been previously reported for this strain. Thus, the threshold of Chrna7 expression required for LTP may be different in the two strains. Measurements of auditory gating, a hippocampal-dependent behavioral paradigm used to identify schizophrenia-associated sensory processing deficits, was abnormal in C3H α7 knockout mice confirming that auditory gating also requires α7nAChR expression. Our studies highlight the importance of genetic background on the regulation of synaptic plasticity and could be relevant for understanding genetic and cognitive heterogeneity in human studies of α7nAChR dysfunction in mental disorders.

Autonomic Dysfunction Precedes Development of Rheumatoid Arthritis: A Prospective Cohort Study

BackgroundHeart rate variability (HRV) is a validated method to establish autonomic nervous system (ANS) activity. Rheumatoid arthritis (RA) is accompanied by ANS imbalance. We hypothesized that ANS dysfunction may precede the development of RA, which would suggest that it plays a role in its etiopathogenesis. MethodsFirst, we assessed HRV parameters in supine (resting) and upright (active) position in healthy subjects (HS, n=20), individuals at risk of developing arthritis (AR subjects, n=50) and RA patients (RA, n=20). Next, we measured resting heart rate (RHR), a parasympathetic HRV parameter, in an independent prospective cohort of AR subjects (n=45). We also evaluated expression levels of the parasympathetic nicotinic acetylcholine receptor type 7 (α7nAChR) on circulating monocytes. FindingsBoth AR subjects (68 beats per minute (bpm), interquartile range (IQR) 68–73) and RA patients (68bpm, IQR 62–76) had a significantly higher RHR compared to HS (60bpm, IQR 56–63). RHR was significantly higher at baseline in individuals who subsequently developed arthritis. Expression levels of α7nAChR were lower in AR subjects with RHR ≥70bpm compared to those with RHR <70bpm, consistent with reduced activity of the parasympathetic cholinergic anti-inflammatory pathway. InterpretationThese data support the notion that autonomic dysfunction precedes the development of RA.

Brain protection against ischemic stroke using choline as a new molecular bypass treatment.

To determine whether administration of choline could attenuate brain injury in a rat model of ischemic stroke and the underlying mechanisms. A rat model of ischemic stroke was established through permanent middle cerebral artery occlusion (pMCAO). After the surgery, the rats were treated with choline or choline plus the specific α7 nAChR antagonist methyllycaconitine (MLA), or with the control drug nimodipine for 10 days. The neurological deficits, brain-infarct volume, pial vessel density and the number of microvessels in the cortex were assessed. Rat brain microvascular endothelial cells (rBMECs) cultured under hypoxic conditions were used in in vitro experiments. Oral administration of choline (100 or 200 mg·kg(-1)·d(-1)) or nimodipine (20 mg·kg(-1)·d(-1)) significantly improved neurological deficits, and reduced infarct volume and nerve cell loss in the ischemic cerebral cortices in pMCAO rats. Furthermore, oral administration of choline, but not nimodipine, promoted the pial arteriogenesis and cerebral-cortical capillary angiogenesis in the ischemic regions. Moreover, oral administration of choline significantly augmented pMCAO-induced increases in the expression levels of α7 nAChR, HIF-1α and VEGF in the ischemic cerebral cortices as well as in the serum levels of VEGF. Choline-induced protective effects were prevented by co-treatment with MLA (1 mg·kg(-1)·d(-1), ip). Treatment of rBMECs cultured under hypoxic conditions in vitro with choline (1, 10 and 100 μmol/L) dose-dependently promoted the endothelial-cell proliferation, migration and tube formation, as well as VEGF secretion, which were prevented by co-treatment with MLA (1 μmol/L) or by transfection with HIF-1α siRNA. Choline effectively attenuates brain ischemic injury in pMCAO rats, possibly by facilitating pial arteriogenesis and cerebral-cortical capillary angiogenesis via upregulating α7 nAChR levels and inducing the expression of HIF-1α and VEGF.

Increased expression of α7nAChR in chronic rhinosinusitis: The intranasal cholinergic anti-inflammatory hypothesis.

Chronic rhinosinusitis results from a dysfunctional host-environment interaction at the site of interface, in the nose and paranasal sinuses. A parasympathetic-mediated anti-inflammatory reflex is known to have a pivotal role in the control of damage induced by immune response to injury and infection; acetylcholine released by peripheral nerves interacts with nicotinic acetylcholine receptor subunit α7 - α7nAChR - of innate immune cells, inhibiting pro-inflammatory signalling. This work aims to investigate whether cholinergic function is implicated in chronic rhinosinusitis. α7nAChR mRNA and protein levels were measured in nasal biopsy specimens of 14 patients with CRSwNP, 8 with CRSsNP and 10 control subjects, undergoing surgery. Gene expression levels of α7nAChR did not differ between groups; protein expression was significantly higher in CRSwNP than in CRSsNP (p=0.041), and both of these patient groups showed significant higher levels than controls (CRSwNP vs Controls - p=0.001; CRSsNP vs Controls - p=0.041). Elevated α7nAChR protein levels suggest that the cholinergic system is involved in the inflammatory response of chronic rhinosinusitis. This can shed light on both, the disease pathophysiology and the development of future treatment options.

Neuroprotective effect of cellular prion protein (PrPC) is related with activation of alpha7 nicotinic acetylcholine receptor (α7nAchR)-mediated autophagy flux.

Activation of the alpha7 nicotinic acetylcholine receptor (α7nAchR) is regulated by prion protein (PrPC) expression and has a neuroprotective effect by modulating autophagic flux. In this study, we hypothesized that PrPC may regulate α7nAchR activation and that may prevent prion-related neurodegenerative diseases by regulating autophagic flux. PrP(106-126) treatment decreased α7nAchR expression and activation of autophagic flux. In addition, the α7nAchR activator PNU-282987 enhanced autophagic flux and protected neuron cells against PrP(106-126)-induced apoptosis. However, activation of autophagy and the protective effects of PNU-282987 were inhibited in PrPC knockout hippocampal neuron cells. In addition, PrPC knockout hippocampal neuron cells showed decreased α7nAchR expression levels. Adenoviral overexpression of PrPC in PrPC knockout hippocampal neuron cells resulted in activation of autophagic flux and inhibition of prion peptide-mediated cell death via α7nAchR activation. This is the first report demonstrating that activation of α7nAchR-mediated autophagic flux is regulated by PrPC, and that activation of α7nAchR regulated by PrPC expression may play a pivotal role in protection of neuron cells against prion peptide-induced neuron cell death by autophagy. These results suggest that α7nAchR-mediated autophagic flux may be involved in the pathogenesis of prion-related diseases and may be a therapeutic target for prion-related neurodegenerative diseases.

The nicotinic acetylcholine receptor α7 in subcutaneous mature adipocytes: downregulation in human obesity and modulation by diet-induced weight loss

It is known that cholinergic anti-inflammatory reflex regulates inflammation in peripheral tissues. Nicotinic acetylcholine receptors (nAChRs) are mediators of this anti-inflammatory pathway and also non-neuronal cells express functional nAChrs. A role for α7-subtype acetylcholine cholinergic receptor (α7nAChR) in insulin sensitivity improvement has already been shown in rodents both in vivo and in vitro. However, no data are available on α7nAChR expression in human adipocytes. To investigate the expression and protein content of α7nAChR in human subcutaneous adipose tissue (SAT) and in isolated mature adipocytes. A total of 39 SAT biopsy specimens obtained from obese and normal-weight subjects were used to assess α7nAChR messenger RNA levels and to stimulate α7nAChR with a specific agonist and antagonist in vitro. Additional SATs from eight non-diabetic obese subjects were also studied, before and after a 3-month lifestyle intervention. α7nAChR expression was significantly lower in the SAT of obese subjects compared with that of normal-weight subjects. In mature adipocytes isolated from morbidly obese subjects (body mass index > 40 kg m(-2)), α7nAChR expression was 75% lower compared with adipocytes from normal-weight subjects. In adipocytes of obese subjects, α7nAChR was downregulated also at protein level. In eight non-diabetic obese subjects, a lifestyle intervention (3 months of diet and physical activity) induced a significant weight loss and an increase in α7nAChR SAT expression. In vitro stimulation of adipocytes with the specific α7nAChR agonist PNU282987 induced a significant anti-inflammatory effect. Furthermore, a similar downregulation of the inflammatory profile, associated with a significant increase in α7nAChR protein level, was observed after genistein stimulation. These results provide evidence that α7nAChR expression levels are significantly decreased in obese subjects, and that this receptor modulates inflammatory gene expression in human adipocytes. The upregulation of α7nAChR by genistein stimulation opens new insights for the management of low-grade inflammation linked to human obesity.

Expression and regulation of nicotine receptor and osteopontin isoforms in human pancreatic ductal adenocarcinoma.

Osteopontin (OPN) is a secreted phospho-protein that confers on cancer cells a migratory phenotype. We have recently shown that nicotine, a risk factor in pancreatic ductal adenocarcinoma (PDA), induces an alpha7-nicotine acetylcholine receptor (α7-nAChR)-mediated increase of OPN in PDA cells. In this study, we tested nicotine's effect on the expression of OPN splice variants (OPNa, b, c) in PDA cells. We also analyzed the correlation between patients' smoking history with OPN and α7-nAChR levels. RT-PCR and UV-light-illumination of ethidium-bromide staining were used to examine the mRNA expression in tissue and PDA cells treated with or without nicotine (3-300 nM). Localization of total OPN, OPNc and α7-nAChR was analyzed by immunohistochemistry, and their mRNA tissue expression levels were correlated with the patients' smoking history. PDA cells expressed varying levels of OPNa, OPNb, and α7-nAChR. Nicotine treatment selectively induced denovo expression of OPNc and increased α7-nAChR expression levels. In PDA tissue, OPNc was found in 87% of lesions, of which 73% were smokers. OPNc and total OPN levels were correlated in the tissue from patients with invasive PDA. Nicotine receptor was expressed in the invasive and premalignant lesions without clear correlation with smoking history. We show here for the first time that α7-nAChR is expressed in PDA cells and tissues and is regulated by nicotine in PDA cells. This, together with our previous findings that α7-nAChR mediates the metastatic effects of nicotine in PDA, suggest that combined targeting of α7-nAChR and OPNc could be a valid novel therapeutic strategy for invasive PDA, especially in the smoking population.