Nicotinic Acetylcholine Receptor Agonist Research Articles

P2.05-001 α7-nAchR Agonist GTS-21 Reduces Radiation-Induced Lung Injury by Inhibiting HMGB1/TLR-4/NF-κB Pathway: Topic: Biology

The cholinergic anti-inflammatory signaling pathway allows the autonomic nervous system to modulate immunologic stimuli and inflammatory processes α7 nicotinic acetylcholine receptor (α7-nAChR) is a major component in this pathway. GTS-21, a selective α7 nicotinic acetylcholine receptor agonist, has been demonstrated as a promising treatment for inflammation. So, the aim of this study is to determine whether treatment GTS-21 can mitigate the radiation induced lung injury. C57BL/6 mice were randomly divided into three groups: a control group, a 12 Gy thoracic irradiation group, a 12 Gy thoracic irradiation group treated with 4mg/kg GTS-21 immediately after irradiation. Each of group were sacrificed at 1, 3, 7, 14, 21d and 3m, 6m post-irradiation, and the sections were respectively stained with hematoxylin and eosin (HE) and Masson’s trichrome to assess the degree of inflammation and fibrosis. Serum concentrations of TNF-α, IL-1β and IL-6 were quantitatively measured by Cytometric Bead Array (CBA) kit. Real-time PCR and Western blot were used to detect the mRNA and protein levels of HMGB1, TLR-4, NF-κB, MyD88 and TGF-β in lung tissue from GTS-21 group and irradiation control group at different time after radiation. The result from HE and Masson staining showed that GTS-21 could dramatically reduce radiation-induced lung inflammation and following mitigate lung fibrosis. Then, we found that radiation-induced TNF-α, IL-1β and IL-6 in serum were also inhibited by GTS-21. Comparing to the control group, the mRNA levels of HMGB1,TLR-4 and NF-κB were decreased at the early time of radiation pneumonitis, and the most significant difference was observed at 21d post-irradiation(P<0.05). the mRNA levels of TGF-β was decrease in GTS-21group at 3m and 6m post -irradiation when compared to control (P<0.05). However, there did not have any different on MyD88 between GTS-21and control groups. The result from western blot showed that the protein levels of HMGB1, TLR-4 and NF-κB in GTS-21 group were also significantly decreased at 21d after radiation. After 3m and 6m from radiation, the protein level of TGF-β was decreased dramatically at GTS-21 group. GTS-21 can reduce radiation pneumonitis and fibrosis by inhibiting HMGB1/TLR-4/NF-κB pathway which subsequently decrease TGF-β expression.

Relative Toxicity of Two Aphicides to Hippodamia convergens (Coleoptera: Coccinellidae): Implications for Integrated Management of Sugarcane Aphid, Melanaphis sacchari (Hemiptera: Aphididae).

Flupyradifurone and sulfoxaflor present novel insecticide chemistries with particular efficacy against aphids, and the recent emergence of sugarcane aphid, Melanaphis sacchari (Zehntner), as a pest of sorghum in the United States has resulted in their widespread use. We examined their toxicity to Hippodamia convergens Guerin-Meneville, an important aphid biocontrol agent. We exposed beetles to topical applications of the field rate (FR) of these insecticides, fed them contaminated food (eggs of Ephestia kuehniella Zeller), and gave first-instar larvae 24-h exposures to leaf residues. More than half of fourth-instar larvae receiving topical applications of sulfoxaflor at FR survived, whereas flupyradifurone at 0.1× FR caused 90% mortality. Adults survived topical treatments better than larvae and without measurable mortality, except flupyradifurone at FR, which killed more than 80% of beetles. Survivors of all treatments had fertility similar to controls, whether treated as larvae or adults. Ingestion of contaminated food caused significant mortality in all treatments (15-40% for adults and 55-85% for larvae), with no significant differences between insecticides at FR. Leaf residues of sulfoxaflor at 1.0 and 2.0× FR caused approximately 60 and 80% mortality of first instars, respectively, whereas flupyradifurone at 0.1 and 1.0× FR caused > 90% mortality. Although sulfoxaflor was less toxic to H. convergens than flupyradifurone, the tested FR of flupyradifurone has now been reduced by half. We conclude that neither insecticide appears as toxic as other nicotinic acetylcholine receptor agonists, and that both materials are compatible with integrated pest management programs for M. sacchari.

Therapeutic concentrations of varenicline in the presence of nicotine increase action potential firing in human adrenal chromaffin cells.

Varenicline is a nicotinic acetylcholine receptor (nAChR) agonist used to treat nicotine addiction, but a live debate persists concerning its mechanism of action in reducing nicotine consumption. Although initially reported as α4β2 selective, varenicline was subsequently shown to activate other nAChR subtypes implicated in nicotine addiction including α3β4. However, it remains unclear whether activation of α3β4 nAChRs by therapeutically relevant concentrations of varenicline is sufficient to affect the behavior of cells that express this subtype. We used patch-clamp electrophysiology to assess the effects of varenicline on native α3β4* nAChRs (asterisk denotes the possible presence of other subunits) expressed in human adrenal chromaffin cells and compared its effects to those of nicotine. Varenicline and nicotine activated α3β4* nAChRs with EC50 values of 1.8 (1.2-2.7)μM and 19.4 (11.1-33.9)μM, respectively. Stimulation of adrenal chromaffin cells with 10ms pulses of 300μM acetylcholine (ACh) in current-clamp mode evoked sodium channel-dependent action potentials (APs). Under these conditions, perfusion of 50 or 100 nM varenicline showed very little effect on AP firing compared to control conditions (ACh stimulation alone), but at higher concentrations (250nM) varenicline increased the number of APs fired up to 436±150%. These results demonstrate that therapeutic concentrations of varenicline are unlikely to alter AP firing in chromaffin cells. In contrast, nicotine showed no effect on AP firing at any of the concentrations tested (50, 100, 250, and 500nM). However, perfusion of 50nM nicotine simultaneously with 100nM varenicline increased AP firing by 290±104% indicating that exposure to varenicline and nicotine concurrently may alter cellular behavior such as excitability and neurotransmitter release.

The effects of varenicline on methamphetamine self-administration and drug-primed reinstatement in male rats

Methamphetamine (meth) addiction is a costly burden to both the individual user and society as a whole. Establishing effective pharmacotherapies to treat meth dependence is needed to help solve this health problem. The study reported herein examined the effects of varenicline, a partial α4β2 and full α7 nicotinic acetylcholine receptor agonist, on meth self-administration and reinstatement in male Sprague-Dawley rats. Following indwelling jugular catheter surgery, rats were either trained to self-administer meth or saline on a variable ratio (VR) 3 schedule of reinforcement. Self-administration sessions (2h duration; 19 total sessions) were conducted daily. The effect of varenicline pretreatment on meth and saline self-administration was then determined using a within-study design. All rats received varenicline (0.0, 0.3, 1.0, and 3.0mg/kg) prior to 4 different test sessions. Dose order was randomly assigned and each test was separated by 2 standard self-administration sessions to assess stability of responding. Fifteen extinction sessions (no meth available) followed the last test. Extinction was followed by meth-primed (0.3mg/kg IP) reinstatement tests to examine the effect of varenicline on meth-seeking behavior. All rats again received all doses of varenicline over 4 separate reinstatement tests performed on 4 consecutive days. Varenicline did not alter self-administration of meth or saline. Additionally, the 0.3 and 1.0 doses of varenicline non-specifically increased active lever responding during the reinstatement test sessions. This latter finding suggests that varenicline may increase relapse liability and should not be utilized as pharmacotherapy to treat meth dependence.

The Effect of Thymoquinone, α7 Receptor Agonist and α7 Receptor Allosteric Modulator on the Cerebral Cortex in Experimentally Induced Alzheimer's Disease in Relation to MSCs Activation.

Background and ObjectivesAlzheimer’s disease (AD) is the most common form of dementia among older persons. Thymoquinone (TQ) has anti-inflammatory, anticonvulsant and antioxidant activity. A novel α7 nicotinic acetyl choline receptor (α7 nAChR ) agonist (PNU- 282987) have been identified to enhance the cognitive performance. An alternative treatment strategy via compounds known as nicotinic “positive allosteric modulators” (PAMs) has been reported. This study was designed to investigate the combination of PAM of α7 nAChRs with PNU- 282987 or with TQ as a possible treatment for AD in rat.Methods48 male albino rats were divided into 4 groups. Group I (Control), Group II received lipopolysaccharide, 0.8 mg/kg by intraperitoneal injection (IPI) once, Group III received TQ 10 mg/kg by IPI, Group IV received PNU-120596 1 mg/kg by IPI, in addition to PNU-282987 1 mg/kg by IPI in subgroup IVa and TQ in subgroup b. All treatment drugs were given for 5 days.ResultsAcidophilic masses, deformed neurons, Congo red +ve masses and reduced Phospho-CREB immunoexpression were seen in group II. All changes regressed by treatment. Some CD44 +ve cells were noticed in group II and few +ve cells in subgroup IVa, that became multiple in group III and subgroup IVb. The histological, histochemical and immunohistochemical changes were confirmed statistically and significant differences were recorded.ConclusionsTQ or α7 nAChR agonist combined with PAM can have an important role in treatment of AD that is superior to thymoquinone alone. Exceptionally, TQ single or combined with PAM proved activation of MSC.

Cytisine inhibits the protective activity of various classical and novel antiepileptic drugs against 6Hz-induced psychomotor seizures in mice.

Cytisine (CYT) is a partial agonist of brain α4β2 nicotinic acetylcholine receptors widely used in Central/Eastern Europe for smoking cessation. This study evaluated the effect of CYT on the ability of classical and novel antiepileptic drugs to prevent seizures evoked by the 6-Hz test, a model of psychomotor seizures in mice thought as a model of drug-resistant seizures. CYT administered intraperitoneally (i.p.) in a dose of 2mgkg-1 significantly inhibited the anticonvulsant activity of lacosamide, levetiracetam, and pregabalin, increasing their median effective doses 50 (ED50) values from 6.88 to 10.52mgkg-1 (P<0.05) for lacosamide, from 22.08 to 38.26mgkg-1 (P<0.05) for levetiracetam, and from 40.48 to 64.61mgkg-1 (P<0.01) for pregabalin, respectively. There were no significant changes in total brain concentrations of lacosamide, levetiracetam, and pregabalin following CYT i.p. administration. CYT administered in a dose of 2mgkg-1 failed to change the protective action of clobazam, clonazepam, phenobarbital, tiagabine, and valproate in the 6-Hz test. Neither CYT (2mgkg-1) alone nor its combination with the anticonvulsant drugs (at their ED50 values from the 6-Hz test) affected motor coordination; skeletal muscular strength and long-term memory, as determined in the chimney; and grip strength and passive avoidance tests, respectively. CYT-evoked alterations in the protection provided by some antiepileptic drugs against seizures can be of serious concern for epileptic smokers, who might demonstrate therapeutic failure to lacosamide, levetiracetam, and pregabalin, resulting in possible breakthrough seizure attacks.

Alpha-7 nicotinic acetylcholine receptor (nAChR) agonist inhibits the development of endometriosis by regulating inflammation.

We investigated α-7 nAchR expression in human peritoneal macrophages and examined whether activation of nAchR might be a new therapy for endometriosis. Human peritoneal fluid mononuclear cells (PFMC) were stimulated with lipopolysaccharide (LPS) in the presence of α-7 nAChR agonists. In a murine endometriosis model, α-7 nAChR modulators were administered. Human PFMC expressed α-7 nAChR at the mRNA and protein levels. Activation of α-7 nAChR with its agonists led to significant (P<.01) suppression of LPS-induced interleukin (IL) -1β expression. In a murine endometriosis model, one week after inoculation of endometrium to the peritoneal cavity, α-7 nAChR agonist significantly suppressed the expression of IL-1β mRNA (P<.01), which was negated when α-7 nAChR antagonist was administered simultaneously. α-7 nAChR agonist significantly suppressed the formation of endometriotic lesions, which was reversed with α-7 nAChR antagonist. Activation of nAChR might be a new candidate for treatment of endometriosis.

ABT-126 monotherapy in mild-to-moderate Alzheimer's dementia: randomized double-blind, placebo and active controlled adaptive trial and open-label extension.

BackgroundResults from a phase 2a study indicated that treatment with the novel α7 nicotinic acetylcholine receptor agonist ABT-126 25 mg once daily (QD) was associated with a trend for improvement in cognition in subjects with mild-to-moderate Alzheimer’s dementia (AD). A phase 2b program was designed to evaluate a broader dose range of ABT-126 as monotherapy in subjects with mild-to-moderate AD. The program consisted of a double-blind, placebo and active controlled study of ABT-126 (dose range 25–75 mg) and an open-label extension study (75 mg).MethodsThe randomized double-blind study enrolled 438 subjects (Mini-Mental Status Examination score of 10–24, inclusive) not currently taking acetylcholinesterase inhibitors or memantine. Subjects received 24 weeks of ABT-126 25 mg QD (n = 77), ABT-126 50 mg QD (n = 108), ABT-126 75 mg QD (n = 73), donepezil 10 mg QD (n = 76), or placebo (n = 104). The primary endpoint was the change from baseline to week 24 in the 11-item Alzheimer's Disease Assessment Scale—Cognitive subscale (ADAS-Cog) total score. Subjects completing the double-blind study could enroll in the 28-week open-label extension study. Adverse events (AEs) and other safety parameters were monitored in both studies.ResultsA total of 367 patients (83.8 %) completed the double-blind study and 349 (79.7 %) entered the open-label study. Compared with placebo, donepezil significantly improved ADAS-Cog 11-item total scores from baseline to week 24 (−2.29 ± 0.95; one-sided P = 0.008). No ABT-126 dose demonstrated a statistically significant improvement vs placebo at week 24 in the ADAS-Cog total score: ABT-126 25 mg, −0.47 ± 0.94 (P = 0.309); ABT-126 50 mg, −0.87 ± 0.85 (P = 0.153); and ABT-126 75 mg, −1.08 ± 0.94 (P = 0.127). Rates of serious AEs and discontinuations due to AEs were similar across treatment groups. The most frequently reported AEs in both studies were constipation, fall, and headache. No clinically meaningful changes were observed in other parameters.ConclusionsIn the double-blind trial, donepezil significantly improved ADAS-Cog scores but no statistically significant improvement was seen with any ABT-126 dose. ABT-126 had an acceptable safety profile in subjects with mild-to-moderate AD in both studies.Trial registrationClinicalTrials.gov NCT01527916, Registered 3 February 2012 (randomized trial). ClinicalTrials.gov NCT01676935. Registered 29 August 2012 (open-label extension study).Electronic supplementary materialThe online version of this article (doi:10.1186/s13195-016-0210-1) contains supplementary material, which is available to authorized users.

Imidacloprid inhibits IgE-mediated RBL-2H3 cell degranulation and passive cutaneous anaphylaxis.

BackgroundImidacloprid has been commonly used as a pesticide for crop protection and acts as nicotinic acetylcholine receptor agonists. Little information about the relationship between imidacloprid and allergy is available.ObjectiveThis study aims to examine the effects of imidacoprid on IgE-mediated mast cell activation.MethodsThe rat basophilic leukemia cell line RBL-2H3 (RBL-2H3 cells) were treated with 10-3 – 10-12 mol/L imidacloprid, followed by measuring the mediator production, influx of Ca2+ in IgE-activated RBL-2H3 cells, and the possible effects of imidacoprid on anti-dinitrophenyl IgE-induced passive cutaneous anaphylaxis (PCA).ResultsIt was shown that imidacoprid suppressed the production of histamine, β-hexosaminidase, leukotriene C4, interleukin-6, tumor necrosis factor-α, and Ca2+ mobilization in IgE-activated RBL-2H3 cells and decreased vascular extravasation in IgE-induced PCA.ConclusionIt is the first time to show that imidacloprid suppressed the activation of RBL-2H3 cells.

Fluorescent Agonists of the α7 Nicotinic Acetylcholine Receptor Derived from 3‐Amino‐Quinuclidine

Here, we investigated whether fluorescence labeled small molecule agonists of the α7 nicotinic acetylcholine receptor (nAChR) might be identified to enhance receptor studies. Enantiomerically pure 3‐amino‐quinuclidines appended with fluorophores at the 3‐amino group were synthesized and tested by electrophysiology on human α7 nAChR in Xenopus oocytes, uncovering (R)‐4 and (R)‐9 as the first examples of fluorescent α7 nAChR agonists. These molecules elegantly incorporate the fluorescent reporter group as part of the pharmacophore itself and provide a new class of tool compounds for the study of these ligand‐gated ion channels.

A test of the cognitive-enhancing potential of low-dose mecamylamine in healthy non-smokers.

The beneficial effects of nicotinic acetylcholine receptor (nAChR) agonists on cognitive performance have been widely shown. Paradoxically, recent preclinical studies employing extremely low doses of nAChR antagonists have also found cognitive enhancement, perhaps pointing to a novel treatment mechanism for cognitive deficits. The aim was to test whether low doses of the nAChR antagonist mecamylamine would benefit performance in human volunteers. The study employed a double-blind within-subject design. Over four separate days, healthy adult non-smokers (n=23) were tested with placebo and three trace doses of mecamylamine (0.25-1mg, p.o.), adjusted for body weight. Participants performed three computerized tasks: a task of spatial selective attention and stimulus detection, the rapid visual information processing task (RVIPT) taxing sustained attention and working memory, and a change detection short-term memory task. Subjective state and vital signs were assessed repeatedly. Mecamylamine did not improve performance in any of the tasks. Any trends that were observed instead pointed toward performance impairment. Mecamylamine also had no effects on subjective state or vital signs. The present results do not support the hypothesized cognitive-enhancing potential of low doses of mecamylamine. Contrary to preclinical reports, these findings speak against low-dose nAChR antagonism as a novel avenue for treating cognitive deficits.

Effect of α7nAChR agonists on brain injury induced by cardiopulmonary bypass in rats

Objective To evaluate the effect of α7 nicotinic acetylcholine receptor (α7nAChR) agonists on brain injury induced by cardiopulmonary bypass (CPB) in rats. Methods Seventy-two pathogen-free adult male Sprague-Dawley rats, weighing 350-450 g, were randomly divided into 3 groups (n=24 each) using a random number table: sham operation group (group S), CPB group, and α7nAChR agonist PHA568487 group (group PHA). The rats underwent no CPB and were mechanically ventilated for 60 min in group S. CPB was performed for 60 min in CPB and PHA groups.At 30 min before CPB, PHA568487 0.8 mg/kg was injected intraperitoneally in group PHA, and the equal volume of normal saline was given in group CPB.Before CPB (T0), immediately after termination of CPB (T1), and at 2 and 6 h after operation (T2, 3), 6 rats were sacrificed, and blood samples were collected from the internal jugular vein for determination of serum S100β protein, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) concentrations by enzyme-linked immunosorbent assay.Hippocampal tissues were obtained and stained with haematoxylin and eosin for microscopic examination of the pathologic changes and for detection of apoptosis in hippocampal neurons (by TUNEL) and caspase-3 expression (by immunohistochemistry). Results Compared with group S, the concentrations of serum S100β protein, TNF-α and IL-6 were significantly increased, the number of apoptotic neurons was significantly increased, and the expression of caspase-3 was significantly up-regulated at T1-T3 (P<0.05), and the pathologic changes of hippocampal tissues were obvious in CPB and PHA groups.Compared with group CPB, the concentrations of serum S100β protein, TNF-α and IL-6 were significantly decreased, the number of apoptotic neurons was significantly reduced, and the expression of caspase-3 was significantly down-regulated at T1-T3 (P<0.05), and the pathologic changes of hippocampal tissues were significantly attenuated in group PHA. Conclusion α7nAChR agonists can reduce the brain injury induced by CPB in rats, and the mechanism may be related to inhibition of systemic inflammatory responses and apoptosis in hippocampal neurons. Key words: Cholinergic agonists; Cardiopulmonary bypass; Brain injuries

The Novel, Nicotinic Alpha7 Receptor Partial Agonist, BMS-933043, Improves Cognition and Sensory Processing in Preclinical Models of Schizophrenia.

The development of alpha7 nicotinic acetylcholine receptor agonists is considered a promising approach for the treatment of cognitive symptoms in schizophrenia patients. In the present studies we characterized the novel agent, (2R)-N-(6-(1H-imidazol-1-yl)-4-pyrimidinyl)-4'H-spiro[4-azabicyclo[2.2.2]octane-2,5'-[1,3]oxazol]-2'-amine (BMS-933043), in vitro and in rodent models of schizophrenia-like deficits in cognition and sensory processing. BMS-933043 showed potent binding affinity to native rat (Ki = 3.3 nM) and recombinant human alpha7 nicotinic acetylcholine receptors (Ki = 8.1 nM) and agonist activity in a calcium fluorescence assay (EC50 = 23.4 nM) and whole cell voltage clamp electrophysiology (EC50 = 0.14 micromolar (rat) and 0.29 micromolar (human)). BMS-933043 exhibited a partial agonist profile relative to acetylcholine; the relative efficacy for net charge crossing the cell membrane was 67% and 78% at rat and human alpha7 nicotinic acetylcholine receptors respectively. BMS-933043 showed no agonist or antagonist activity at other nicotinic acetylcholine receptor subtypes and was at least 300 fold weaker at binding to and antagonizing human 5-HT3A receptors (Ki = 2,451 nM; IC50 = 8,066 nM). BMS-933043 treatment i) improved 24 hour novel object recognition memory in mice (0.1–10 mg/kg, sc), ii) reversed MK-801-induced deficits in Y maze performance in mice (1–10 mg/kg, sc) and set shift performance in rats (1–10 mg/kg, po) and iii) reduced the number of trials required to complete the extradimensional shift discrimination in neonatal PCP treated rats performing the intra-dimensional/extradimensional set shifting task (0.1–3 mg/kg, po). BMS-933043 also improved auditory gating (0.56–3 mg/kg, sc) and mismatch negativity (0.03–3 mg/kg, sc) in rats treated with S(+)ketamine or neonatal phencyclidine respectively. Given this favorable preclinical profile BMS-933043 was selected for further development to support clinical evaluation in humans.

Alpha7 nicotinic acetylcholine receptor agonists and PAMs as adjunctive treatment in schizophrenia. An experimental study

Nicotine has been found to improve cognition and reduce negative symptoms in schizophrenia and a genetic and pathophysiological link between the α7 nicotinic acetylcholine receptors (nAChRs) and schizophrenia has been demonstrated. Therefore, there has been a large interest in developing drugs affecting the α7 nAChRs for schizophrenia. In the present study we investigated, in rats, the effects of a selective α7 agonist (PNU282987) and a α7 positive allosteric modulator (PAM; NS1738) alone and in combination with the atypical antipsychotic drug risperidone for their utility as adjunct treatment in schizophrenia. Moreover we also investigated their utility as adjunct treatment in depression in combination with the SSRI citalopram. We found that NS1738 and to some extent also PNU282987, potentiated a subeffective dose of risperidone in the conditioned avoidance response test. Both drugs also potentiated the effect of a sub-effective concentration of risperidone on NMDA-induced currents in pyramidal cells of the medial prefrontal cortex. Moreover, NS1738 and PNU282987 enhanced recognition memory in the novel object recognition test, when given separately. Both drugs also potentiated accumbal but not prefrontal risperidone-induced dopamine release. Finally, PNU282987 reduced immobility in the forced swim test, indicating an antidepressant-like effect. Taken together, our data support the utility of drugs targeting the α7 nAChRs, perhaps especially α7 PAMs, to potentiate the effect of atypical antipsychotic drugs. Moreover, our data suggest that α7 agonists and PAMs can be used to ameliorate cognitive symptoms in schizophrenia and depression.

Abstract 3574: Nicotine prevents chemotherapy-induced peripheral neuropathy in vivo, and fails to stimulate the growth of lung cancer cells or interfere with the effectiveness of chemotherapy in vitro

Abstract Chemotherapy has played a significant and unparalleled role in the treatment and survival of cancer patients. However, this pharmacological approach can lead to long-term symptoms of drug toxicity, including chemotherapy-induced peripheral neuropathy (CIPN), a result of peripheral nerve fiber dysfunction or degeneration. CIPN is characterized by sensory symptoms such as numbness, tingling, cold sensitivity, or allodynia, and an overall decrease in quality of life. Paclitaxel (Taxol), a taxane that is commonly used to treat breast, lung, and ovarian cancers, has been found to cause CIPN in 59 to 78% of patients. There is currently no effective preventative or therapeutic treatment for this side effect, which can present either during or after chemotherapy administration. Without the development of an efficacious treatment, CIPN can be a dose-limiting factor for chemotherapy or delay treatment, thereby influencing survival and quality of life. Our studies have revealed that the prototypical nicotinic acetylcholine receptor agonist, nicotine, is capable of reversing and preventing the development of paclitaxel-induced CIPN in vivo, and does not interfere with the cytotoxic properties of paclitaxel in vitro. Male C57BL/6J mice were infused with 24 mg/kg of nicotine via subcutaneous 7-day osmotic minipumps starting 48 hours prior to paclitaxel treatment, which consisted of 8 mg/kg intraperitoneal injections every other day for a total of four injections. The use of von Frey filament testing revealed that nicotine dose-dependently reverses and prevents paclitaxel-induced mechanical allodynia. In regards to the in vitro studies, MTT and MTS colorimetric assays showed that concentrations of nicotine ranging from 0.1 to 10 μM fail to significantly increase or decrease the viability of A549, H460, Lewis lung carcinoma, or human explant lung cancer cells. Similar results were obtained in ovarian cancer cell lines, where no significant difference in cell growth was observed following nicotine treatment of SKOV-3/DDP and OVCAR-3 cells. Most importantly, the paclitaxel-induced decreases in both H460 cell viability and growth were not significantly attenuated by nicotine. Moreover, 1 μM nicotine did not interfere with paclitaxel-induced sub-G1 DNA content or apoptosis of A549 cells. These findings suggest that nicotinic acetylcholine receptors may be promising drug targets for the prevention and treatment of CIPN. Citation Format: Sarah L. Kyte, Wisam Toma, M I. Damaj, Xianjun Fang, David A. Gewirtz. Nicotine prevents chemotherapy-induced peripheral neuropathy in vivo, and fails to stimulate the growth of lung cancer cells or interfere with the effectiveness of chemotherapy in vitro. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3574.

An in silico guided identification of nAChR agonists from Withania somnifera

ABSTRACTIn Indian traditional practice of medicines, numerous plants have been used against various neurodegenerative disorders like Alzheimer's disease (AD). Withania somnifera (Ashwagandha in Sanskrit) is one of the medicinal plants exhibiting broad spectrum activity against various diseases. Due to its ability to improve cognitive functions, aswagandha extracts are used in various memory supplements. In the present study, the pharmacological activity of various bioactive compounds of aswagandha has been studied with respect to AD. The blood brain barrier penetrability and central nervous system (CNS) activity of these bioactive compounds were predicted using in silico tools. The predicted pharmacological properties and structure activity relationship focuses that the compounds such as anaferine, anahygrine, cuscohygrine and isopelletierine can be CNS active and neuronal nicotinic acetylcholine receptor (nAChR) agonists. In order to investigate the structure activity relationship results, molecular modeling studies has been carried out with promising ligands against nAChR. It is a known fact that the agonists of nAChRs are capable to improve communication between neurons and hence these compounds may be useful as lead compounds for the development of drugs against neurodegenerative disorders. This study also indirectly focuses how ayurvedic formulations (those containing aswagandha) are effective against neurodegenerative disorders.

A nicotinic acetylcholine receptor agonist affects honey bee sucrose responsiveness and decreases waggle dancing.

A nicotinic acetylcholine receptor agonist, imidacloprid, impairs memory formation in honey bees and has general effects on foraging. However, little is known about how this agonist affects two specific aspects of foraging: sucrose responsiveness (SR) and waggle dancing (which recruits nestmates). Using lab and field experiments, we tested the effect of sublethal doses of imidacloprid on (1) bee SR with the proboscis extension response assay, and (2) free-flying foragers visiting and dancing for a sucrose feeder. Bees that ingested imidacloprid (0.21 or 2.16 ng bee(-1)) had higher sucrose response thresholds 1 h after treatment. Foragers that ingested imidacloprid also produced significantly fewer waggle dance circuits (10.5- and 4.5-fold fewer for 50% and 30% sucrose solutions, respectively) 24 h after treatment as compared with controls. However, there was no significant effect of imidacloprid on the sucrose concentrations that foragers collected at a feeder 24 h after treatment. Thus, imidacloprid temporarily increased the minimum sucrose concentration that foragers would accept (short time scale, 1 h after treatment) and reduced waggle dancing (longer time scale, 24 h after treatment). The effect of time suggests different neurological effects of imidacloprid resulting from the parent compound and its metabolites. Waggle dancing can significantly increase colony food intake, and thus a sublethal dose (0.21 ng bee(-1), 24 p.p.b.) of this commonly used pesticide may impair colony fitness.

54 A7 Nicotinic Acetylcholine Receptor Agonist Nicotine attenuates neuronal cell death through Akt activation in a mouse model of eclampsia

Introduction Brain injury especially neuronal cell death plays an important role in the pathological process of seizure. Eclampsia is defined as the development of grand mal seizures in patients with gestational hypertension or preeclampsia. Objectives In this study we will evaluate neuronal apoptosis and the effects of α7 Nicotinic Acetylcholine Receptor Agonist Nicotine on seizure and cell death following eclampsia; then we will investigate whether α7nAChR stimulation could inhibit caspase activity via PI3K-Akt signaling. Methods C57 pregnant mice was subjected to intraperitoneal injection of pentylenetetrazole (PTZ) from gestation day (GD) 16 to GD 18 in the basis of lipopolysaccharide (LPS) administration on GD 14. Eclampsia animals received either vehicle administration, or 1 mg/kg of α7nAChR agonist nicotine, or 1 μg/kg of α7nAChR antagonist α-bungarotoxin (α-BGT) combined with nicotine. Clinical symptoms of eclampsia were evaluated; behavioral assessment of seizure severity was recorded; neuronal cell death was quantified with nissl staining and TUNEL staining. Electron microscopy was used for observing the morphological changes of neuronal apoptosis; immunofluorescence staining and Western blotting were used for the quantification and localization of activated Akt (p-Akt), and cleaved caspase-3 (CC3). Results Nicotine effectively decreased systolic blood pressure and eclampsia-like seizure severity. Electron microscopy showed that typical cell apoptotic morphology was seen in the cortex following eclampsia, nicotine significantly reduced neuronal apoptosis in the cortex. Nicotine significantly decreased CC3 levels and increased p-Akt levels in the cortex. α-Bungarotoxin reversed effects of nicotine treatment. Conclusions α7 Nicotinic Acetylcholine Receptor Agonist Nicotine improved neurological outcomes and decreased neuronal cell death in a mouse model of eclampsia. Nicotine reduced the expression of cleaved caspase-3 via the PI3K-Akt signaling pathway.

Hippocampal network dynamics in response to α7 nACh receptors activation in amyloid-β overproducing transgenic mice

Amyloid-β (Aβ) peptide overproduction is one of the pathomechanisms contributing to Alzheimer's disease (AD). Agonists of α7 nicotinic acetylcholine receptors (α7 nAChRs) are under development as symptomatic treatments for AD, and clinical findings suggest that α7 nAChR agonists may improve cognitive functions in AD patients. However, interactions between Aβ and α7 nAChRs have been observed, implying that high levels of Aβ may modify the effects of α7 nAChR agonists. Therefore, we tested the α7 nAChR agonist FRM-17874, an analogue of encenicline, in 8-month-old Aβ overproducing 5xFAD mice in an in vivo neurophysiological assay with a high construct and predictive validity for testing procognitive drugs. By recording changes in brainstem-stimulation–elicited hippocampal oscillations, we identified previously undescribed neurophysiological impairments in 5xFAD mice, including significantly decreased power of theta and gamma oscillations and theta-phase–gamma-amplitude coupling. Compared with their saline controls, systemically administered FRM-17874 significantly increased stimulation-induced theta power by 30% in both 5xFAD and wild-type mice. However, FRM-17874 did not impact gamma oscillation or theta-phase–gamma-amplitude coupling in either wild type or 5xFAD mice, and it did not eliminate the significant differences in these parameters between the 2 groups.

Conformational analysis of 2-substituted piperazines

The unusual activity differences of carbon linked versus oxygen linked 2-substituted piperazines as α7 nicotinic acetylcholine receptor agonists led to a conformational study of several examples. The conformational preferences of which are absent from the literature. We report the first study and explanation of the conformational preference of 2-substiturted piperazines and show an example of how this preference controls binding in a pharmaceutically relevant case. In all cases the axial conformation for these 1-acyl and 1 aryl 2-substituted piperazines was found to be preferred. For the ether linked compounds, the axial conformation was found to be further stabilized by an intramolecular hydrogen bond. The axial orientation also places the basic and pyridyl nitrogens into a special orientation that closely mimics nicotine. Molecular modeling studies confirm that the R enantiomers of the compounds can bind to the α7 nicotinic acetylcholine receptor with the basic and pyridyl nitrogens colocalized with their counterparts in Epibatidine.