Abstract 527: Natriuretic Effect Mediated by the Renal Medullary α7 Nicotinic Acetylcholine Receptor

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Weili Wang ◽  
Wei-Qing Han ◽  
Qing Zhu ◽  
Imad Damaj ◽  
Pin-Lan Li ◽  
...  
Keyword(s):  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Sodium Excretion ◽  
Urine Volume ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Renal Sodium Excretion ◽  
Α7 Nachr ◽  
Natriuretic Effect

Although there are extensive studies on the regulation of renal sodium excretion by adrenergic pathway, the role of cholinergic pathway in the renal sodium excretion is largely unknown. The present study characterized the expression of α7 nicotinic acetylcholine receptor (nAChR) in the kidneys and determined the functional role of this nAChR subtype in urinary sodium excretion in Sprague Dawley rats. RT-PCR and Western blot analyses showed that α7 nAChR was present in the kidneys. Immunohistochemistry analysis demonstrated that the strongest immunostaining of α7 nAChR was observed in the distal tubules and collecting ducts in the kidneys. Infusion of an α7 nAChR agonist PNU-282987 (2.7 μM, 10 μl/min) into the renal medulla dramatically increased the urine volume (from 15.4 ± 2.1 to 42.5 ± 3.9 μl/min/g kwt) and sodium excretion (from 1.26 ± 0.18 to 4.15 ± 0.60 μmole/min/g kwt), which was blocked by an α7 nAChR antagonist methyllycaconitine (MLA, 5 μM, 10 μl/min), in anesthetized rats. Infusion of PNU-282987 did not cause any change in renal medullary blood flow as measured by Laser Doppler flowmeter. In addition, intra-renal medullary infusion of MLA (5 μM, 10 μl/min) significantly inhibited the volume expansion-induced increase of urine volume and sodium excretion by 25%. These data suggest that activation of renal medullary α7 nAChR produces a natriuretic effect through its tubular action in rats. (Supported by NIH grant HL89563 and HL106042)

scholarly journals Activation of α7 Nicotinic Acetylcholine Receptor Upregulates HLA-DR and Macrophage Receptors: Potential Role in Adaptive Immunity and in Preventing Immunosuppression

Biomolecules ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 507 ◽  
Author(s):  
Andrei E. Siniavin ◽  
Maria A. Streltsova ◽  
Denis S. Kudryavtsev ◽  
Irina V. Shelukhina ◽  
Yuri N. Utkin ◽  
...  
Keyword(s):  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Human Leukocyte ◽  
Membrane Receptors ◽  
Receptor Expression ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Α7 Nachr ◽  
Hla Dr

Immune response during sepsis is characterized by hyper-inflammation followed by immunosuppression. The crucial role of macrophages is well-known for both septic stages, since they are involved in immune homeostasis and inflammation, their dysfunction being implicated in immunosuppression. The cholinergic anti-inflammatory pathway mediated by macrophage α7 nicotinic acetylcholine receptor (nAChR) represents possible drug target. Although α7 nAChR activation on macrophages reduces the production of proinflammatory cytokines, the role of these receptors in immunological changes at the cellular level is not fully understood. Using α7 nAChR selective agonist PNU 282,987, we investigated the influence of α7 nAChR activation on the expression of cytokines and, for the first time, of the macrophage membrane markers: cluster of differentiation 14 (CD14), human leukocyte antigen-DR (HLA-DR), CD11b, and CD54. Application of PNU 282,987 to THP-1Mϕ (THP-1 derived macrophages) cells led to inward ion currents and Ca2+ increase in cytoplasm showing the presence of functionally active α7 nAChR. Production of cytokines tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-10 was estimated in classically activated macrophages (M1) and treatment with PNU 282,987 diminished IL-10 expression. α7 nAChR activation on THP-1Mϕ, THP-1M1, and monocyte-derived macrophages (MDMs) increased the expression of HLA-DR, CD54, and CD11b molecules, but decreased CD14 receptor expression, these effects being blocked by alpha (α)-bungarotoxin. Thus, PNU 282,987 enhances the macrophage-mediated immunity via α7 nAChR by regulating expression of their membrane receptors and of cytokines, both playing an important role in preventing immunosuppressive states.

Abstract W P98: Activation of α7 Nicotinic Acetylcholine Receptor Reduces Pro-Inflammatory Macrophage and Improves Ischemic Stroke Recovery

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Zhenying Han ◽  
Fanxia Shen ◽  
Yue He ◽  
Vincent Degos ◽  
Marine Camus ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Stroke Recovery ◽  
Behavioral Tests ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Α7 Nachr ◽  
Adhesive Removal ◽  
Inflammatory Macrophages

Background and Purpose: Inflammation influences stroke recovery. Activation of α7 nicotinic acetylcholine receptor (α7 nAchR) attenuates inflammation. We hypothesize that α7 nAchR agonist treatment reduces pro-inflammatory macrophages (M1) and improves ischemic stroke recovery. Methods: C57BL/6 mice underwent permanent distal middle cerebral artery occlusion (pMCAO). They were randomly assigned to 7 groups: injected intraperitoneally with 0.4 or 0.8 mg/Kg PHA568487 (PHA, α7 nAchR agonist), 4 or 6 mg/Kg methyllycaconitine (MLA, α7 nAchR antagonist), or saline immediately after pMCAO, or with 0.8 mg/Kg PHA or 6 mg/kg MLA immediately and 24 hours after pMCAO. Behavior was assessed by corner and adhesive removal tests at 3, 7, and 14 days after pMCAO (n=12). Atrophic volume (n=7) and the percentage of total (CD68 + ) and M1 (CD11b + /Iba1 + ) macrophages (n=6) among total cells in the peri-infarct region were quantified 14 days after pMCAO. The expression of M1 (CD11b and iNOS) and M2 marker (CD206) were quantified using real-time RT-PCR (n=4). Results: Compared to the saline-treated mice, those treated with two doses of 0.8 mg/kg PHA performed better in both behavioral tests at 3 (adhesive: p=0.01, corner: p=0.02) and 7 (adhesive: p=0.005, corner: p=0.03) days, and in the adhesive removal test at 14 days (p=0.004) after pMCAO. They had smaller atrophic volume (16±7 mm 3 vs 26±5 mm 3 , p=0.008), and fewer total (9±2.5% vs 15.8±1.7%, p<0.001) and M1 (14±2.3% vs 20.6±4.2%, p=0.005) macrophages. Mice treated with two doses of 6 mg/kg MLA performed worse in the behavioral tests at all times (p<0.05), had larger atrophic volume (48±20 mm 3 , p=0.03), and more total (25±4.2%, p=0.0003) and M1 macrophages (28±4.5%, p=0.01). The expression of CD11b and iNOS decreased (p<0.05) in the PHA group, and increased (p=0.01) in the MLA group. CD206 expression increased (p=0.04) in the PHA group and did not change in the MLA group. One-dose treatment had no effect. Conclusions: Activation of α7 nAchR reduces pro-inflammatory macrophages in the peri-infarct region, which is associated with reduction of atrophic volume and improvement of behavioral recovery.

scholarly journals Correction: The Role of α7 Nicotinic Acetylcholine Receptor in Modulation of Heart Rate Dynamics in Endotoxemic Rats

PLoS ONE ◽  
2015 ◽  
Vol 10 (5) ◽  
pp. e0127826 ◽  
Author(s):  
Roham Mazloom ◽  
Golnar Eftekhari ◽  
Maryam Rahimi-Balaei ◽  
Vahid Khori ◽  
Sohrab Hajizadeh ◽  
...  
Keyword(s):  
Heart Rate ◽  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Heart Rate Dynamics

scholarly journals Molecular blueprint of allosteric binding sites in a homologue of the agonist-binding domain of the α7 nicotinic acetylcholine receptor

2015 ◽  
Vol 112 (19) ◽  
pp. E2543-E2552 ◽  
Author(s):  
Radovan Spurny ◽  
Sarah Debaveye ◽  
Ana Farinha ◽  
Ken Veys ◽  
Ann M. Vos ◽  
...  
Keyword(s):  
Binding Site ◽  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Binding Sites ◽  
Agonist Binding ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Α7 Nachr ◽  
Allosteric Binding Sites ◽  
Α Helix

The α7 nicotinic acetylcholine receptor (nAChR) belongs to the family of pentameric ligand-gated ion channels and is involved in fast synaptic signaling. In this study, we take advantage of a recently identified chimera of the extracellular domain of the native α7 nicotinic acetylcholine receptor and acetylcholine binding protein, termed α7-AChBP. This chimeric receptor was used to conduct an innovative fragment-library screening in combination with X-ray crystallography to identify allosteric binding sites. One allosteric site is surface-exposed and is located near the N-terminal α-helix of the extracellular domain. Ligand binding at this site causes a conformational change of the α-helix as the fragment wedges between the α-helix and a loop homologous to the main immunogenic region of the muscle α1 subunit. A second site is located in the vestibule of the receptor, in a preexisting intrasubunit pocket opposite the agonist binding site and corresponds to a previously identified site involved in positive allosteric modulation of the bacterial homolog ELIC. A third site is located at a pocket right below the agonist binding site. Using electrophysiological recordings on the human α7 nAChR we demonstrate that the identified fragments, which bind at these sites, can modulate receptor activation. This work presents a structural framework for different allosteric binding sites in the α7 nAChR and paves the way for future development of novel allosteric modulators with therapeutic potential.

scholarly journals Cynandione A alleviates neuropathic pain through spinal microglial interleukin-10/β-endorphin expression following α7 nicotinic acetylcholine receptor activation

2020 ◽  
Author(s):  
Qiao-Qiao Han ◽  
Min Yin ◽  
Zi-Ying Wang ◽  
Hao Liu ◽  
Jun-Ping Ao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Spinal Cord ◽  
Neuropathic Pain ◽  
Acetylcholine Receptor ◽  
Nicotinic Acetylcholine Receptor ◽  
Receptor Activation ◽  
Primary Microglia ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Nicotinic Acetylcholine ◽  
Α7 Nachr

Abstract Background Cynandione A, an acetophenone isolated from Cynanchum Wilfordii Radix, exhibits antihypersensitivity effects in neuropathic pain. This study sought to explore the target molecule and mechanisms underlying cynandione A mechanical antiallodynia, particularly related to the spinal glial expression of IL-10/β-endorphin, cAMP/PKA/p38/CREB signaling and α7 nicotinic acetylcholine receptor (α7 nAChR) activation. Methods IL-10 and β-endorphin in the spinal cord of spinal nerve ligation-induced neuropathic pain rats and cultured primary microglia were assessed by qRT-PCR and ELISA assays. Double immunofluorescence staining of IL-10, β-endorphin with glial and neuronal cellular biomarkers was also conducted in the spinal cord and cultured primary microglia. Microglial phosphorylation of PKA, p38, CREB and STAT3 were detected using western blot. Results Cynandione A significantly attenuated mechanical allodynia in neuropathic rats and substantially increased IL-10 and β-endorphin (but not dynorphin A) expression in the spinal cords and cultured primary microglia. The IL-10 antibody attenuated cynandione A-induced spinal or microglial gene expression of β-endorphin and mechanical antiallodynia, whereas the β-endorphin antiserum blocked cynandione A-induced mechanical antiallodynia but not spinal or microglial IL-10 gene expression. The α7 nAChR antagonist methyllycaconitine significantly declined cynandione A-induced mechanical antiallodynia and spinal or microglial expression of IL-10 and β-endorphin. Cynandione A stimulated microglial phosphorylation of PKA, p38 and CREB, which was inhibited by methyllycaconitine. Treatment with the adenylyl cyclase inhibitor DDA, PKA inhibitor H-89, p38 inhibitor SB203580 and CREB inhibitor KG501 attenuated cynandione A-induced mechanical antiallodynia and spinal or microglial expression of IL-10 and β-endorphin. Cynandione A stimulated spinal phosphorylation of the transcription factor STAT3, which was inhibited by methyllycaconitine, H-89 and the IL-10 antibody. The STAT3 inhibitor NSC74859 weakened cynandione A-induced mechanical antiallodynia and spinal expression of β-endorphin. Conclusion Our results illustrate that cynandione A produces mechanical antiallodynia through spinal microglial expression of IL-10 via the cAMP/PKA/p38/CREB signaling and subsequent β-endorphin expression via the IL-10/STAT3 signaling, following α7 nAChR activation.

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