ar-r-17779 and Disease-Models--Animal

Inflammation plays a central role in stroke-induced brain injury. The alpha7 nicotinic acetylcholine receptor (α7nAChR) can modulate immune responses in both the periphery and the brain. The aims of the present study were to investigate α7nAChR expression in different brain regions and evaluate the potential effect of the selective α7nAChR agonist AR-R17779 on ischemia-reperfusion brain injury in mice. Droplet digital PCR (ddPCR) was used to evaluate the absolute expression of the gene encoding α7nAChR (Chrna7) in hippocampus, striatum, thalamus and cortex in adult, naïve mice. Mice subjected to transient middle cerebral artery occlusion (tMCAO) or sham surgery were treated with α7nAChR agonist AR-R17779 (12 mg/kg) or saline once daily for 5 days. Infarct size and microglial activation 7 days after tMCAO were analyzed using immunohistochemistry. Chrna7 expression was found in all analyzed brain regions in naïve mice with the highest expression in cortex and hippocampus. At sacrifice, white blood cell count was significantly decreased in AR-R17779 treated mice compared with saline controls in the sham groups, although, no effect was seen in the tMCAO groups. Brain injury and microglial activation were evident 7 days after tMCAO. However, no difference was found between mice treated with saline or AR-R17779. In conclusion, α7nAChR expression varies in different brain regions and, despite a decrease in white blood cells in sham mice receiving AR-R17779, this compound does not affect stroke-induced brain injury.

Topics: alpha7 Nicotinic Acetylcholine Receptor; Animals; Brain; Bridged-Ring Compounds; Disease Models, Animal; Infarction, Middle Cerebral Artery; Ischemic Stroke; Male; Mice, Inbred C57BL; Microglia; Nicotinic Agonists; Reperfusion Injury; Signal Transduction; Spiro Compounds

Activation of antiinflammatory cholinergic (vagal) pathways can reduce inflammation, and in vitro studies support a pivotal role of α7 nicotinic acetylcholine receptors (α7-nAChR), macrophages, and T cells in these events. The aim of this study was to assess α7-nAChR agonists as an antiinflammatory treatment for Freund's complete adjuvant (CFA)-induced monoarthritis.. Arthritis was induced by intraarticular injection of CFA unilaterally into the knee joints of mice. Animals were treated with α7-nAChR agonists (AR-R17779 or A844606), with or without antagonists (COG133 or methyllycaconitine), and joint inflammation and pain were assessed. Experiments were repeated in c-Kit(W-sh) mast cell-deficient mice, and the effects of an α7-nAChR agonist on mast cell proliferation, migration, and activation by lipopolysaccharide (LPS) were tested.. Treatment with α7-nAChR agonists significantly exacerbated CFA-induced arthritis and pain, as gauged by all indices of assessment, the specificity of which was confirmed by coadministration of an nAChR antagonist that attenuated the increase in disease severity. Toluidine blue-positive mast cells were increased in the joint capsule of CFA plus AR-R17779-treated mice, and AR-R17779 enhanced LPS-induced TNF proliferation and migration of a human mast cell line. The AR-R17779-driven increase in severity of CFA-induced arthritis was significantly reduced in mast cell-deficient mice.. Using CFA to elicit a local inflammatory response, we found that pharmacologic activation of α7-nAChR exacerbated joint inflammation and pain, in part via mast cells, which illustrates the organ- and disease-specific nature of regulatory neuroimmune mechanisms. Thus, α7-nAChR activation may not be uniformly antiinflammatory in all types of inflammatory joint disease.

Topics: Aconitine; Adjuvants, Immunologic; alpha7 Nicotinic Acetylcholine Receptor; Animals; Apolipoproteins E; Arthritis, Experimental; Bridged-Ring Compounds; Cell Movement; Cell Proliferation; Disease Models, Animal; Disease Progression; Freund's Adjuvant; Inflammation; Injections, Intra-Articular; Lipopolysaccharides; Male; Mast Cells; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Nicotinic Antagonists; Peptide Fragments; Pyrroles; Spiro Compounds; Xanthones

Activation of vagal nerve suppresses inflammatory responses through activation of α7 nicotinic acetylcholine receptor (nAchR). We sought to determine whether AR-R17779, a selective agonist of α7nAchR, affects the development of abdominal aortic aneurysm (AAA).. AAA was induced by topical application of calcium chloride (CaCl2) to abdominal aorta (AAA group). NaCl (0.9%) was substituted for CaCl2 as a sham operation (SHAM group). AR-R17779 was administered in drinking water (AAA/AR-R group). One and 6 weeks after the operation, aortic tissue was excised for histological and molecular analyses. Aortic diameter and macrophage infiltration into the aortic adventitia were increased in AAA group compared with SHAM group at 6 weeks. Treatment with AR-R17779 reduced the diameter of the aorta and macrophage infiltration compared with AAA group. Wavy morphology of the elastic lamellae was lost in AAA group while it was preserved in AAA/AR-R group. Expression of inflammatory cytokines and matrix metalloproteinase (MMP) activities were enhanced in AAA group, which was suppressed in AAA/AR-R group. AR-R17779 treatment suppressed CaCl2-induced expression of cytokines, activities of MMPs and NF-κB activation at 1 week when aortic dilatation had not developed.. Treatment with AR-R17779 prevented the enlargement of abdominal aorta induced by CaCl2 in association with reduced inflammation and extracellular matrix disruption. These findings suggest therapeutic potential of α7nAchR activation for prevention of AAA development.

Topics: alpha7 Nicotinic Acetylcholine Receptor; Animals; Aortic Aneurysm, Abdominal; Blotting, Western; Bridged-Ring Compounds; Cytokines; Disease Models, Animal; Disease Progression; Gene Expression Regulation; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Reverse Transcriptase Polymerase Chain Reaction; RNA; Spiro Compounds

Activation of the cholinergic anti-inflammatory pathway (CAP) has been shown to reduce inflammation in animal models, while abrogation of the pathway increases inflammation. We investigated whether modulation of CAP influences inflammation in the non-obese diabetic (NOD) mouse model for Sjögren's syndrome and type 1 diabetes.. The alpha-7 nicotinic acetylcholine receptor (α7nAChR) was stimulated with AR-R17779 or nicotine in NOD mice. In a second study, unilateral cervical vagotomy was performed. α7nAChR expression, focus scores, and salivary flow were evaluated in salivary glands (SG) and insulitis score in the pancreas. Cytokines were measured in serum and SG.. α7nAChR was expressed on myoepithelial cells in SG. Monocyte chemotactic protein-1 levels were reduced in SG after AR-R17779 treatment and tumor necrosis factor production was increased in the SG of the vagotomy group compared to controls. Focus score and salivary flow were unaffected. NOD mice developed diabetes more rapidly after vagotomy, but at completion of the study there were no statistically significant differences in number of mice that developed diabetes or in insulitis scores.. Intervention of the CAP in NOD mice leads to minimal changes in inflammatory cytokines, but did not affect overall inflammation and function of SG or development of diabetes.

Topics: alpha7 Nicotinic Acetylcholine Receptor; Animals; Bridged-Ring Compounds; Chemokine CCL2; Diabetes Mellitus, Type 1; Disease Models, Animal; Female; Inflammation; Islets of Langerhans; Mice; Mice, Inbred NOD; Nicotine; Pancreatitis; Saliva; Salivary Glands; Salivation; Sjogren's Syndrome; Spiro Compounds; Tumor Necrosis Factor-alpha; Vagotomy

In various models vagus nerve activation has been shown to ameliorate intestinal inflammation, via nicotinic acetylcholine receptors (nAChRs) expressed on immune cells. As the alpha7 nAChR has been put forward to mediate this effect, we studied the effect of nicotine and two selective alpha7 nAChR agonists (AR-R17779, (-)-spiro[1-azabicyclo[2.2.2] octane-3,5'-oxazolidin-2'-one and GSK1345038A) on disease severity in two mouse models of experimental colitis.. Colitis was induced by administration of 1.5% dextran sodium sulphate (DSS) in drinking water or 2 mg 2,4,6-trinitrobenzene sulphonic acid (TNBS) intrarectally. Nicotine (0.25 and 2.50 micromol.kg(-1)), AR-R17779 (0.6-30 micromol.kg(-1)) or GSK1345038A (6-120 micromol.kg(-1)) was administered daily by i.p. injection. After 7 (DSS) or 5 (TNBS) days clinical parameters and colonic inflammation were scored.. Nicotine and both alpha7 nAChR agonists reduced the activation of NF-kappaB and pro-inflammatory cytokines in whole blood and macrophage cultures. In DSS colitis, nicotine treatment reduced colonic cytokine production, but failed to reduce disease parameters. Reciprocally, treatment with AR-R17779 or GSK1345038A worsened disease and led to increased colonic pro-inflammatory cytokine levels in DSS colitis. The highest doses of GSK1345038A (120 micromol.kg(-1)) and AR-R17779 (30 micromol.kg(-1)) ameliorated clinical parameters, without affecting colonic inflammation. Neither agonist ameliorated TNBS-induced colitis.. Although nicotine reduced cytokine responses in vitro, both selective alpha7 nAChR agonists worsened the effects of DSS-induced colitis or were ineffective in those of TNBS-induced colitis. Our data indicate the need for caution in evaluating alpha7 nAChR as a drug target in colitis.

Topics: alpha7 Nicotinic Acetylcholine Receptor; Animals; Bridged-Ring Compounds; Cells, Cultured; Colitis; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Injections, Intraperitoneal; Macrophages; Mice; Mice, Inbred C57BL; NF-kappa B; Nicotine; Nicotinic Agonists; Receptors, Nicotinic; Severity of Illness Index; Spiro Compounds

The parasympathetic nervous system, through the vagus nerve, can down-regulate inflammation in vivo by decreasing the release of cytokines, including tumor necrosis factor alpha (TNFalpha), by activated macrophages. The vagus nerve may exert antiinflammatory actions via a specific effect of its principal neurotransmitter, acetylcholine, on the alpha7 subunit of nicotinic acetylcholine receptors (alpha7nAChR) on macrophages. The present study was undertaken to obtain insight into the role of the cholinergic antiinflammatory pathway in arthritis.. To inhibit the cholinergic antiinflammatory pathway, mice were subjected to unilateral cervical vagotomy or sham surgery, after which arthritis was induced with type II collagen. In a separate study, nicotine was added to the drinking water of mice with collagen-induced arthritis (CIA). In addition, we investigated the effects of intraperitoneally (IP)-injected nicotine and the specific alpha7nAChR agonist AR-R17779.. Clinical arthritis was exacerbated by vagotomy and ameliorated by oral nicotine administration. Moreover, oral nicotine inhibited bone degradation and reduced TNFalpha expression in synovial tissue. Both IP-injected nicotine and AR-R17779 ameliorated clinical arthritis and reduced synovial inflammation. This was accompanied by a reduction of TNFalpha levels in both plasma and synovial tissue. The effect of AR-R17779 was more potent compared with that of nicotine and was associated with delayed onset of the disease as well as with protection against joint destruction.. These data provide the first evidence of a role of the cholinergic antiinflammatory pathway in the murine CIA model of rheumatoid arthritis.

Topics: Administration, Oral; alpha7 Nicotinic Acetylcholine Receptor; Animals; Arthritis, Experimental; Arthritis, Rheumatoid; Bridged-Ring Compounds; Cartilage; Disease Models, Animal; Injections, Intraperitoneal; Macrophages; Male; Mice; Mice, Inbred DBA; Nicotine; Nicotinic Agonists; Parasympathetic Nervous System; Receptors, Nicotinic; Spiro Compounds; Synovial Membrane; Synovitis; Tumor Necrosis Factor-alpha; Vagus Nerve

We previously showed that intestinal inflammation is reduced by electrical stimulation of the efferent vagus nerve, which prevents postoperative ileus in mice. We propose that this cholinergic anti-inflammatory pathway is mediated via alpha7 nicotinic acetylcholine receptors expressed on macrophages. The aim of this study was to evaluate pharmacologic activation of the cholinergic anti-inflammatory pathway in a mouse model for postoperative ileus using the alpha7 nicotinic acetylcholine receptor-agonist AR-R17779.. Mice were pretreated with vehicle, nicotine, or AR-R17779 20 minutes before a laparotomy (L) or intestinal manipulation (IM). Twenty-four hours thereafter gastric emptying was determined using scintigraphy and intestinal muscle inflammation was quantified. Nuclear factor-kappaB transcriptional activity and cytokine production was assayed in peritoneal macrophages.. Twenty-four hours after surgery IM led to a delayed gastric emptying compared with L (gastric retention: L(saline) 14% +/- 4% vs IM(saline) 38% +/- 10%, P = .04). Pretreatment with AR-R17779 prevented delayed gastric emptying (IM(AR-R17779) 15% +/- 4%, P = .03). IM elicited inflammatory cell recruitment (L(saline) 50 +/- 8 vs IM(saline) 434 +/- 71 cells/mm(2), P = .001) which was reduced by AR-R17779 pretreatment (IM(AR-R17779) 231 +/- 32 cells/mm(2), P = .04). An equimolar dose of nicotine was not tolerated. Subdiaphragmal vagotomy did not affect the anti-inflammatory properties of AR-R17779. In peritoneal macrophages, both nicotinic agonists reduced nuclear factor kappaB transcriptional activity and proinflammatory cytokine production, with nicotine being more effective than AR-R17779.. AR-R17779 treatment potently prevents postoperative ileus, whereas toxicity limits nicotine administration to ineffective doses. Our data further imply that nicotinic inhibition of macrophage activation may involve other receptors in addition to alpha7 nicotinic acetylcholine receptor.

Topics: alpha7 Nicotinic Acetylcholine Receptor; Animals; Anti-Inflammatory Agents; Bridged-Ring Compounds; Cells, Cultured; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Electric Stimulation Therapy; Female; Gastric Emptying; Gastroenteritis; Ileus; Intestines; Macrophages, Peritoneal; Mice; Mice, Inbred BALB C; NF-kappa B; Nicotine; Nicotinic Agonists; Postoperative Complications; Receptors, Nicotinic; Spiro Compounds; Transcription, Genetic; Vagotomy; Vagus Nerve

Topics: alpha7 Nicotinic Acetylcholine Receptor; Animals; Anti-Inflammatory Agents; Bridged-Ring Compounds; Central Nervous System; Cytokines; Disease Models, Animal; Electric Stimulation Therapy; Gastric Emptying; Gastroenteritis; Humans; Ileus; Intestines; Macrophages, Peritoneal; NF-kappa B; Nicotine; Nicotinic Agonists; Postoperative Complications; Receptors, Nicotinic; Reflex; Spiro Compounds; Transcription, Genetic; Vagotomy; Vagus Nerve