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Martynov A, Farber B, Bomko T, Beckles DL, Kleyn I. Molecular Modeling, Synthesis, and Antihyperglycemic Activity of the New Benzimidazole Derivatives - Imidazoline Receptor Agonists. Drug Des Devel Ther 2024; 18:1035-1052. [PMID: 38585255 PMCID: PMC10999201 DOI: 10.2147/dddt.s447289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 02/28/2024] [Indexed: 04/09/2024] Open
Abstract
Introduction The paper presents the results of a study on the first synthesized benzimidazole derivatives obtained from labile nature carboxylic acids. The synthesis conditions of these substances were studied, their structure was proved, and some components were found to have sugar-reducing activity on the model of alloxan diabetes in rats. Methods The study used molecular modeling methods such as docking based on the evolutionary model (igemdock), RP_HPLC method to monitor the synthesis reaction, and 1H NMR and 13C NMR, and other methods of organic chemistry to confirm the structures of synthesized substances. Results & Discussion The docking showed that the ursodeoxycholic acid benzimidazole derivatives have high tropics to all imidazoline receptor carriers (PDB ID: 2XCG, 2bk3, 3p0c, 1QH4). The ursodeoxycholic acid benzimidazole derivative and arginine and histidine benzimidazole derivatives showed the highest sugar-lowering activity in the experiment on alloxan-diabetic rats. For these derivatives, the difference in glucose levels of treated rats was significant against untreated control. Therefore, the new derivatives of benzimidazole and labile natural organic acids can be used to create new classes of imidazoline receptor inhibitors for the treatment of diabetes mellitus and hypertension.
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Affiliation(s)
- Artur Martynov
- Laboratory and Clinical department of Molecular Immunopharmacology, SI “ I. Mechnikov Institute of Microbiology and Immunology of National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine
| | | | - Tatyana Bomko
- Laboratory and Clinical department of Molecular Immunopharmacology, SI “ I. Mechnikov Institute of Microbiology and Immunology of National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine
| | | | - Ilya Kleyn
- SUNY Downstate Medical Center / University Hospital of Brooklyn, New York, NY, USA
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Siemian JN, Woodhouse K, Liu DH, Zhang Y, Li JX. The imidazoline I 2 receptor agonist 2-BFI reduces abuse-related effects of morphine: self-administration and drug discrimination. Psychopharmacology (Berl) 2024; 241:479-487. [PMID: 38159161 DOI: 10.1007/s00213-023-06524-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
RATIONALE Increasing evidence shows that imidazoline I2 receptor agonists enhance opioid-induced analgesia, suggesting that the combination of I2 receptor agonists with opioids could be a favorable strategy for pain control. However, the effect of I2 receptor agonists on the abuse liability of opioids is unknown. This study examined the impact of the I2 receptor agonist 2-BFI on some abuse-related behavioral effects of the opioid morphine in rats. OBJECTIVES The von Frey filament test was used to determine the antinociceptive effects of 2-BFI (intravenous, i.v.) in a rat model of complete Freund's adjuvant (CFA)-induced inflammatory pain. IV self-administration was used to assess the reinforcing effects of 2-BFI alone and to assess the effects of non-contingent injections of 2-BFI (i.p.) on morphine self-administration. A two-lever drug discrimination paradigm in which rats were trained to discriminate 3.2 mg/kg morphine (i.p.) from saline was used to examine whether 2-BFI or another I2 receptor agonist 2-(4,5-dihydroimidazol-2-yl)quinoline hydrochloride (BU224) affected the discriminative stimulus effects of morphine. RESULTS 2-BFI could not maintain reliable self-administration behavior in rats with no pain or CFA-treated inflammatory pain. However, pretreatment with 2-BFI (i.p.) produced dose-dependent decreases in the dose-effect curve of morphine self-administration. Both 2-BFI and BU224 did not substitute for morphine but significantly attenuated the discriminative stimulus effects of morphine. CONCLUSIONS These results suggest that I2 receptor agonists do not enhance, but in fact appear to decrease, the abuse liability of opioids, further supporting the potential utility of I2 receptor agonist-opioid combination therapy for pain control.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Kristen Woodhouse
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | | | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
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Enhanced anxiolytic and analgesic effectiveness or a better safety profile of morphine and tramadol combination in cholestatic and addicted mice. Neuroreport 2022; 33:681-689. [DOI: 10.1097/wnr.0000000000001834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Atigari DV, Paton KF, Uprety R, Váradi A, Alder AF, Scouller B, Miller JH, Majumdar S, Kivell BM. The mixed kappa and delta opioid receptor agonist, MP1104, attenuates chemotherapy-induced neuropathic pain. Neuropharmacology 2021; 185:108445. [PMID: 33383089 PMCID: PMC8344368 DOI: 10.1016/j.neuropharm.2020.108445] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/20/2020] [Accepted: 12/20/2020] [Indexed: 01/04/2023]
Abstract
Effective treatments for chronic pain without abuse liability are urgently needed. One in 5 adults suffer chronic pain and half of these patients report inefficient treatment. Mu opioid receptor agonists (MOP), including oxycodone, tramadol and morphine, are often prescribed to treat chronic pain, however, use of drugs targeting MOP can lead to drug dependency, tolerance and overdose deaths. Kappa opioid receptor (KOP) agonists have antinociceptive effects without abuse potential; however, they have not been utilised clinically due to dysphoria and sedation. We hypothesise that mixed opioid receptor agonists targeting the KOP and delta opioid receptor (DOP) would have a wider therapeutic index, with the rewarding effects of DOP negating the negative effects of KOP. MP1104, an analogue of 3-Iodobenzoyl naltrexamine, is a novel mixed opioid receptor agonist with potent antinociceptive effects mediated via KOP and DOP in mice without rewarding or aversive effects. In this study, we show MP1104 has potent, long-acting antinociceptive effects in the warm-water tail-withdrawal assay in male and female mice and rats; and is longer acting than morphine. In the paclitaxel-induced neuropathic pain model in mice, MP1104 reduced both mechanical and cold allodynia and unlike morphine, did not produce tolerance when administered daily for 23 days. Moreover, MP1104 did not induce sedative effects in the open-field locomotor activity test, respiratory depression in mice using whole-body plethysmography, or have cross-tolerance with morphine. This data supports the therapeutic development of mixed opioid receptor agonists, particularly mixed KOP/DOP agonists, as non-addictive pain medications with reduced tolerance.
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Affiliation(s)
- Diana Vivian Atigari
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Kelly Frances Paton
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Rajendra Uprety
- Molecular Pharmacology Program and Department of Neurology, Memorial Sloan Kettering Cancer Centre, New York, USA
| | - András Váradi
- Molecular Pharmacology Program and Department of Neurology, Memorial Sloan Kettering Cancer Centre, New York, USA
| | - Amy Frances Alder
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Brittany Scouller
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - John H Miller
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Susruta Majumdar
- Center of Clinical Pharmacology, St. Louis College of Pharmacy and Washington University School of Medicine, St. Louis, MO, USA
| | - Bronwyn Maree Kivell
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand.
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Bousquet P, Hudson A, García-Sevilla JA, Li JX. Imidazoline Receptor System: The Past, the Present, and the Future. Pharmacol Rev 2020; 72:50-79. [PMID: 31819014 DOI: 10.1124/pr.118.016311] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Imidazoline receptors historically referred to a family of nonadrenergic binding sites that recognize compounds with an imidazoline moiety, although this has proven to be an oversimplification. For example, none of the proposed endogenous ligands for imidazoline receptors contain an imidazoline moiety but they are diverse in their chemical structure. Three receptor subtypes (I1, I2, and I3) have been proposed and the understanding of each has seen differing progress over the decades. I1 receptors partially mediate the central hypotensive effects of clonidine-like drugs. Moxonidine and rilmenidine have better therapeutic profiles (fewer side effects) than clonidine as antihypertensive drugs, thought to be due to their higher I1/α 2-adrenoceptor selectivity. Newer I1 receptor agonists such as LNP599 [3-chloro-2-methyl-phenyl)-(4-methyl-4,5-dihydro-3H-pyrrol-2-yl)-amine hydrochloride] have little to no activity on α 2-adrenoceptors and demonstrate promising therapeutic potential for hypertension and metabolic syndrome. I2 receptors associate with several distinct proteins, but the identities of these proteins remain elusive. I2 receptor agonists have demonstrated various centrally mediated effects including antinociception and neuroprotection. A new I2 receptor agonist, CR4056 [2-phenyl-6-(1H-imidazol-1yl) quinazoline], demonstrated clear analgesic activity in a recently completed phase II clinical trial and holds great promise as a novel I2 receptor-based first-in-class nonopioid analgesic. The understanding of I3 receptors is relatively limited. Existing data suggest that I3 receptors may represent a binding site at the Kir6.2-subtype ATP-sensitive potassium channels in pancreatic β-cells and may be involved in insulin secretion. Despite the elusive nature of their molecular identities, recent progress on drug discovery targeting imidazoline receptors (I1 and I2) demonstrates the exciting potential of these compounds to elicit neuroprotection and to treat various disorders such as hypertension, metabolic syndrome, and chronic pain.
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Affiliation(s)
- Pascal Bousquet
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Alan Hudson
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Jesús A García-Sevilla
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Jun-Xu Li
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
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Alsalem M, Altarifi A, Haddad M, Azab B, Kalbouneh H, Imraish A, Saleh T, El-Salem K. Analgesic Effects and Impairment in Locomotor Activity Induced by Cannabinoid/Opioid Combinations in Rat Models of Chronic Pain. Brain Sci 2020; 10:brainsci10080523. [PMID: 32781705 PMCID: PMC7547378 DOI: 10.3390/brainsci10080523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/02/2020] [Accepted: 08/03/2020] [Indexed: 11/20/2022] Open
Abstract
Both opioids and cannabinoids have well-known antinociceptive effects in different animal models of chronic pain. However, unwanted side effects limit their use. The aim of this study is to evaluate the antinociceptive effect of combining synthetic cannabinoids with subtherapeutic doses of opioids, and to evaluate the effects of these drugs/combinations on rat’s locomotor activity. Intra-plantar injection of Complete Freund’s Adjuvant (CFA) into the left hindpaw and intraperitoneal injection of streptozotocin (STZ) were used to induce inflammatory and diabetic neuropathic pain in adult male Sprague-Dawley rats, respectively. Von Frey filaments were used to assess the antinociceptive effects of opioids (morphine and tramadol) and the synthetic cannabinoids (HU210 and WIN55212) or their combinations on CFA and STZ-induced mechanical allodynia. Open field test was used to evaluate the effect of these drugs or their combinations on locomotion. HU210 and WIN55212 did not produce significant antinociceptive effect on inflammatory pain while only the maximal dose of HU210 (1 mg/kg) was effective in neuropathic pain. Only the maximal doses of morphine (3.2 mg/kg) and tramadol (10 mg/kg) had significant anti-allodynic effects in both models. Tramadol (1 mg/kg) enhanced the antinociceptive effects of WIN55212 but not HU210 in neuropathic pain with no effect on inflammatory pain. However, in open field test, the aforementioned combination did not change tramadol-induced depression of locomotion. Tramadol and WIN55212 combination produces antinociceptive effects in neuropathic but not inflammatory pain at low doses with no additional risk of locomotor impairment, which may be useful in clinical practice.
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Affiliation(s)
- Mohammad Alsalem
- Faculty of Medicine, The University of Jordan, Amman 11942, Jordan; (B.A.); (H.K.)
- Correspondence:
| | - Ahmad Altarifi
- Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan; (A.A.); (K.E.-S.)
| | - Mansour Haddad
- Faculty of Pharmacy, Philadelphia University, Amman 19392, Jordan;
| | - Belal Azab
- Faculty of Medicine, The University of Jordan, Amman 11942, Jordan; (B.A.); (H.K.)
| | - Heba Kalbouneh
- Faculty of Medicine, The University of Jordan, Amman 11942, Jordan; (B.A.); (H.K.)
| | - Amer Imraish
- Faculty of Science, The University of Jordan, Amman 11942, Jordan;
| | - Tareq Saleh
- Faculty of Medicine, The Hashemite University, Zarqa 13133, Jordan;
| | - Khalid El-Salem
- Faculty of Medicine, Jordan University of Science and Technology, Irbid 22110, Jordan; (A.A.); (K.E.-S.)
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Combining opioids and non-opioids for pain management: Current status. Neuropharmacology 2019; 158:107619. [PMID: 31029588 DOI: 10.1016/j.neuropharm.2019.04.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 04/17/2019] [Accepted: 04/24/2019] [Indexed: 12/17/2022]
Abstract
Pain remains a global health challenge. For decades, clinicians have been primarily relying on μ-opioid receptor (MOR) agonists and nonsteroidal anti-inflammatory drugs (NSAIDs) for pain management. MOR agonists remain the most efficacious analgesics available; however, adverse effects related to MOR agonists use are severe which often lead to forced drug discontinuation and inadequate pain relief. The recent opioid overdose epidemic urges the development of safer analgesics. Combination therapy is a well-established clinical pharmacotherapeutic strategy for the treatment of various clinical disorders. The combination of MOR agonists with non-MOR agonists may increase the analgesic potency of MOR agonists, reduce the development of tolerance and dependence, reduce the diversion and abuse, overdose, and reduce other clinically significant side effects associated with prolonged opioid use such as constipation. Overall, the combination therapy approach could substantially improve the therapeutic profile of MOR agonists. This review summarizes some recent developments in this field. This article is part of the Special Issue entitled 'New Vistas in Opioid Pharmacology'.
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Choi DH, Yun JH, Lee J. Protective effect of the imidazoline I2 receptor agonist 2-BFI on oxidative cytotoxicity in astrocytes. Biochem Biophys Res Commun 2018; 503:3011-3016. [DOI: 10.1016/j.bbrc.2018.08.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/11/2018] [Indexed: 12/29/2022]
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Tian JS, Zhai QJ, Zhao Y, Chen R, Zhao LD. 2-(2-benzofuranyl)-2-imidazoline (2-BFI) improved the impairments in AD rat models by inhibiting oxidative stress, inflammation and apoptosis. J Integr Neurosci 2018; 16:385-400. [PMID: 28891528 DOI: 10.3233/jin-170032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Alzheimer's Disease (AD) is one of the commonest neural degeneration in aging population, and has become a global health challenge. 2-(2-benzofuranyl)-2-imidazoline (2-BFI) was reported to effectively improved the damage of patients with neuropathological disorders. In the present study, we investigated the effect of 2-BFI on the improvement of antioxidative, inflammation, and apoptosis in AD rats. Sprague-Dawley rats (2 months old, n=40) were used in this study and after injection of Aβ1-42 into hippocampal CA1 (Cornu Ammonis) region, the rats were given high, moderate and low dose of 2-BFI though intraperitoneal (i.p.) injection. Then spatial memory and navigation ability were analyzed by Morrize Water Maze. For the molecular testing, chemical colorimetry, ELISA and immunoblotting were performed to measure the activities of antioxidative enzymes, the abundance of immune cytokines and expression of apoptotic proteins, respectively. Hematoxylin and Eosin staining was used to analyze the pathological changes. We observed that 2-BFI significantly ameliorated the learning and memory abilities in rat models with AD by dosage treatment, as demonstrated by the shorten learning latency and greater times of travel across the platform quadrant. Additionally, reactive oxygen species (ROS) and malondialdehyde (MDA), were decreased after treatment of 2-BFI with dosage dependency, while the activities of superoxidase dismutase (SOD) and (GPX) Glutathione peroxidase were in turn enhanced, suggesting that 2-BFI could protect the antioxidative enzymes and reduce the oxidative stress in the hippocampus. Moreover, the expression of inflammatory factors including TNF-a and IL-1β were decreased after 2-BFI treatment. Additionally, the neuronal apoptosis was also attenuated, as shown by Western blot results. Taken together, the cognitive impairment in AD rats could be significantly improved by 2-BFI in a dose-dependent manner through suppressing oxidants accumulation, inhibiting of inflammatory response, as well as enhancing the neural viability.
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Affiliation(s)
- Ji-Sha Tian
- Department of Neurology, Huai'an Second People's Hospital, Huaian, Jiangsu, 223002, PR China
| | - Qi-Jin Zhai
- Department of Neurology, Huai'an Second People's Hospital, Huaian, Jiangsu, 223002, PR China
| | - Ying Zhao
- Department of Neurology, Huai'an Second People's Hospital, Huaian, Jiangsu, 223002, PR China
| | - Rui Chen
- Department of Neurology, Huai'an Second People's Hospital, Huaian, Jiangsu, 223002, PR China
| | - Lian-Dong Zhao
- Department of Neurology, Huai'an Second People's Hospital, Huaian, Jiangsu, 223002, PR China
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Huang L, Hu J, Huang S, Wang B, Siaw-Debrah F, Nyanzu M, Zhang Y, Zhuge Q. Nanomaterial applications for neurological diseases and central nervous system injury. Prog Neurobiol 2017; 157:29-48. [PMID: 28743465 DOI: 10.1016/j.pneurobio.2017.07.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 07/18/2017] [Accepted: 07/18/2017] [Indexed: 12/20/2022]
Abstract
The effectiveness of noninvasive treatment for neurological disease is generally limited by the poor entry of therapeutic agents into the central nervous system (CNS). Most CNS drugs cannot permeate into the brain parenchyma because of the blood-brain barrier thus, overcoming this problem has become one of the most significant challenges in the development of neurological therapeutics. Nanotechnology has emerged as an innovative alternative for treating neurological diseases. In fact, rapid advances in nanotechnology have provided promising solutions to this challenge. This review highlights the applications of nanomaterials in the developing neurological field and discusses the evidence for their efficacies.
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Affiliation(s)
- Lijie Huang
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China; Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China
| | - Jiangnan Hu
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China
| | - Shengwei Huang
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China; Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China
| | - Brian Wang
- Center for Neuroscience Discovery, Institute for Healthy Aging, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Felix Siaw-Debrah
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China
| | - Mark Nyanzu
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China
| | - Yu Zhang
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China
| | - Qichuan Zhuge
- Department of Neurosurgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China; Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou City, Zhejiang Province, 325000, PR China.
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Siemian JN, Xue Z, Blough BE, Li JX. Comparison of some behavioral effects of d- and l-methamphetamine in adult male rats. Psychopharmacology (Berl) 2017; 234:2167-2176. [PMID: 28386698 PMCID: PMC5482751 DOI: 10.1007/s00213-017-4623-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 03/29/2017] [Indexed: 02/07/2023]
Abstract
RATIONALE Both l- and d-methamphetamine (l- and d-MA) are more potent to release norpepinephrine (NE) than dopamine, and the selectivity is greater for l-MA than d-MA. Little is known of the in vivo pharmacology of l-MA. OBJECTIVE This study compared the effects of l-MA and d-MA in assays of nociception, behavioral disruption, and impulsivity. METHODS Antinociceptive effects of d- and l-MA were examined in two pain assays: the warm water tail withdrawal test for acute nociception and the von Frey test in complete Freund's adjuvant (CFA)-treated rats for chronic inflammatory pain. Food-maintained operant responding and locomotion tests were used to assess generalized behavioral disruption. The 5-choice serial reaction time test (5-CSRTT) was used to assess drug-induced effects on impulse control. A delay discounting procedure was used to determine drug-induced changes in sensitivity to reinforcer delay (impulsive choice). RESULTS l-MA (3.2-10 mg/kg) produced dose-dependent antinociception in both pain assays, decreased the rate of food-maintained operant responding, and decreased locomotor activity at a higher dose (17.8 mg/kg). In contrast, d-MA (0.32-3.2 mg/kg) did not produce antinociception in either assay, produced biphasic effects on response rate, and increased locomotor activity. In the 5-CSRTT, d-MA but not l-MA produced significant increase in premature responses. In the delay discounting procedure, both drugs did not affect the delay function at doses that did not increase omissions. CONCLUSIONS These data suggest that d- and l-MA have different behavioral profiles. Consideration should be given to these differences in future studies when l-MA is proposed for potential therapies.
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Affiliation(s)
- Justin N. Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Zhaoxia Xue
- Department of Medical Psychology, College of Humanities and Social Sciences, Shanxi Medical University, Taiyuan, Shanxi, China
| | - Bruce E. Blough
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, Durham, North Carolina, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
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Abstract
Since first introduced more than two decades ago, the research in imidazoline I2 receptors has been steadily increasing. This review provides an update on the current status of I2 receptor pharmacology. Imidazoline I2 receptors or I2 binding sites refer to several (at least four) different proteins that bind to [3H]-idazoxan and [3H]-2-BFI with high affinity. The molecular identities of the proteins remain elusive. One of the proteins (45kD) seems to be consistent with the identity of brain creatine kinase. The biological functions of I2 receptors have been primarily unveiled by the studies of selective I2 receptor ligands. Accumulating evidence suggests that I2 receptor ligands are effective analgesics for persistent and chronic painful conditions such as inflammatory, neuropathic and postoperative pain. One selective I2 receptor ligand, CR4056, has been advanced to phase II clinical trial with the therapeutic indication of chronic inflammatory pain (osteoarthritis). The expansion to the treatment of other chronic pain conditions should be expected if CR4056 could eventually be approved as a new drug. I2 receptor ligands also demonstrate robust discriminative stimulus activity and induce a characteristic discriminative cue in animals. Biochemical and preclinical in vivo investigations also suggest that I2 receptor ligands have neuroprotective activity and modulate body temperature. The emerging discrepancies of a range of purported selective I2 receptor ligands suggest different pharmacological effects mediated by discrete I2 receptor components which likely attribute to the I2 receptor-related proteins. It is proposed that the I2 receptors represent an emerging drug target for the treatment of neurological disorders such as pain and stroke, and deserve more research attention to translate preclinical findings to pharmacotherapies.
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Affiliation(s)
- Jun-Xu Li
- School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China; Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA.
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Siemian JN, Obeng S, Zhang Y, Zhang Y, Li JX. Antinociceptive Interactions between the Imidazoline I2 Receptor Agonist 2-BFI and Opioids in Rats: Role of Efficacy at the μ-Opioid Receptor. J Pharmacol Exp Ther 2016; 357:509-19. [PMID: 27056847 DOI: 10.1124/jpet.116.232421] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/07/2016] [Indexed: 12/14/2022] Open
Abstract
Although μ-opioids have been reported to interact favorably with imidazoline I2 receptor (I2R) ligands in animal models of chronic pain, the dependence on the μ-opioid receptor ligand efficacy on these interactions had not been previously investigated. This study systematically examined the interactions between the selective I2 receptor ligand 2-(2-benzofuranyl)-2-imidazoline hydrochloride (2-BFI) and three μ-opioid receptor ligands of varying efficacies: fentanyl (high efficacy), buprenorphine (medium-low efficacy), and 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-[(3'-isoquinolyl) acetamido] morphine (NAQ; very low efficacy). The von Frey test of mechanical nociception and Hargreaves test of thermal nociception were used to examine the antihyperalgesic effects of drug combinations in complete Freund's adjuvant-induced inflammatory pain in rats. Food-reinforced schedule-controlled responding was used to examine the rate-suppressing effects of each drug combination. Dose-addition and isobolographical analyses were used to characterize the nature of drug-drug interactions in each assay. 2-BFI and fentanyl fully reversed both mechanical and thermal nociception, whereas buprenorphine significantly reversed thermal but only slightly reversed mechanical nociception. NAQ was ineffective in both nociception assays. When studied in combination with fentanyl, NAQ acted as a competitive antagonist (apparent pA2 value: 6.19). 2-BFI/fentanyl mixtures produced additive to infra-additive analgesic interactions, 2-BFI/buprenorphine mixtures produced supra-additive to infra-additive interactions, and 2-BFI/NAQ mixtures produced supra-additive to additive interactions in the nociception assays. The effects of all combinations on schedule-controlled responding were generally additive. Results consistent with these were found in experiments using female rats. These findings indicate that lower-efficacy μ-opioid receptor agonists may interact more favorably with I2R ligands than high-efficacy μ-opioid receptor agonists.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.N.S., J.-X.L.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (S.O., Yan.Z.); and Research Triangle Institute, Research Triangle Park, North Carolina (Yanan.Z.)
| | - Samuel Obeng
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.N.S., J.-X.L.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (S.O., Yan.Z.); and Research Triangle Institute, Research Triangle Park, North Carolina (Yanan.Z.)
| | - Yan Zhang
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.N.S., J.-X.L.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (S.O., Yan.Z.); and Research Triangle Institute, Research Triangle Park, North Carolina (Yanan.Z.)
| | - Yanan Zhang
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.N.S., J.-X.L.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (S.O., Yan.Z.); and Research Triangle Institute, Research Triangle Park, North Carolina (Yanan.Z.)
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.N.S., J.-X.L.); Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia (S.O., Yan.Z.); and Research Triangle Institute, Research Triangle Park, North Carolina (Yanan.Z.)
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Siemian JN, Li J, Zhang Y, Li JX. Interactions between imidazoline I2 receptor ligands and acetaminophen in adult male rats: antinociception and schedule-controlled responding. Psychopharmacology (Berl) 2016; 233:873-82. [PMID: 26613734 PMCID: PMC4752914 DOI: 10.1007/s00213-015-4166-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/18/2015] [Indexed: 01/01/2023]
Abstract
RATIONALE Recent evidence suggests that imidazoline I2 receptor ligands are suitable for combination therapy with opioids. Quantitative analysis of I2 receptor ligands combined with non-opioid drugs is necessary for the justification of alternative pain therapies. OBJECTIVE This study systematically examined the antihyperalgesic and response rate-suppressing effects of selective I2 receptor ligands (2-BFI and phenyzoline) alone and in combination with acetaminophen. METHODS Von Frey and Hargreaves tests were used to examine the antihyperalgesic effects of drugs in complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. Food-reinforced schedule-controlled responding was used to assess the rate-suppressing effects of study drugs. Dose-addition and isobolographic analyses were used to assess drug-drug interactions for all assays. RESULTS 2-BFI (3.2-17.8 mg/kg, i.p.), phenyzoline (17.8-100 mg/kg, i.p.), and acetaminophen (56-178 mg/kg, i.p.) all dose-dependently produced significant antinociceptive effects. When studied as combinations, 2-BFI and acetaminophen produced infra-additive to additive interactions while phenyzoline and acetaminophen produced additive to supra-additive interactions. The same drug combinations suppressed response rate in a supra-additive manner. CONCLUSIONS Quantitative analysis of the antihyperalgesic and response rate-suppressing effects suggests that I2 receptor ligands are not well suited to combination therapy with acetaminophen.
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Affiliation(s)
- Justin N. Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Jiuzhou Li
- Department of Neurosurgery, Binzhou People’s Hospital, Binzhou, Shandong Province, China
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, North Carolina, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA.
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15
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Abstract
Opioid analgesics continue to be the mainstay of pharmacologic treatment of moderate to severe pain. Many patients, particularly those suffering from chronic pain, require chronic high-dose analgesic therapy. Achieving clinical efficacy and tolerability of such treatment regimens is hampered by the appearance of opioid-induced side effects such as tolerance, hyperalgesia and withdrawal syndrome. Among the therapeutic options to improve the opioid effectiveness, this current review focuses on strategies combining opioids to other drugs that can modulate opioid-mediated effects. We will discuss about experimental evidences reported for several potential opioid adjuvants, including N-methyl-d-aspartate receptor antagonists, 5-HT7 agonists, sigma-1 antagonists, I2-R ligands, cholecystokinin antagonists, neuropeptide FF-R antagonists and toll-like receptor 4 antagonists.
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16
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Thorn DA, Zhang Y, Li JX. Effects of the imidazoline I2 receptor agonist 2-BFI on the development of tolerance to and behavioural/physical dependence on morphine in rats. Br J Pharmacol 2016; 173:1363-72. [PMID: 26776953 DOI: 10.1111/bph.13435] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 01/07/2015] [Accepted: 01/12/2015] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE This study examined the effects of imidazoline I2 receptor agonists on the development of tolerance to and physical dependence on repeated morphine treatment in rats. EXPERIMENTAL APPROACH Two groups of rats (n = 9 per group) were trained to lever press for sucrose (10%) presentation under a fixed-ratio 10 schedule. The rate-suppressing effects of the opioid receptor ligands morphine and naltrexone and the I2 receptor agonist 2-BFI were examined weekly in rats treated with either daily morphine (20 mg·kg(-1) , s.c.), alone or in combination with 2-BFI (10 mg·kg(-1) ) for 3 weeks. Changes in body weight were measured following naltrexone tests in both groups of rats. In separate experiments, the antinociceptive effects of morphine were assessed using a warm-water tail-withdrawal procedure in rats before and after daily treatments (7 days) with morphine (32 mg·kg(-1) , i.p.) alone or in combination with various doses of the I2 receptor agonists 2-BFI, BU224 and CR4056. KEY RESULTS Daily treatment for 3 weeks, with morphine in combination with 2-BFI produced significantly less tolerance to the rate-suppressing effects of morphine and produced a decreased sensitivity to the rate-suppressing effects of naltrexone as well as decreased naltrexone-induced weight loss, compared with morphine-alone group. Repeated treatment for 7 days with morphine produced antinociceptive tolerance, which was attenuated by co-administration with 2-BFI, BU224 or CR4056. CONCLUSIONS AND IMPLICATIONS Imidazoline I2 receptor agonists attenuated the development of tolerance to and physical dependence on morphine, further supporting the therapeutic potential of combining I2 receptor agonists and opioids for pain treatment.
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Affiliation(s)
- David A Thorn
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, Durham, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
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Yan L, Pan M, Fu M, Wang J, Huang W, Qian H. Design, synthesis and biological evaluation of novel analgesic agents targeting both cyclooxygenase and TRPV1. Bioorg Med Chem 2016; 24:849-57. [PMID: 26795113 DOI: 10.1016/j.bmc.2016.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 01/06/2016] [Accepted: 01/06/2016] [Indexed: 01/08/2023]
Abstract
Multitarget-directed ligands might offer certain advantages over traditional single-target drugs and/or drug combinations. In the present study, a series of novel analgesic agents targeting both cyclooxygenase and TRPV1 were prepared and evaluated in an effort to optimize properties of previously described lead compounds from piperazine, ethanediamine cores. These compounds were evaluated for antagonism of hTRPV1 activation by capsaicin and the ability to inhibit Ovine COX-1 and human recombinant COX-2 in vitro. The favorable potentials of these test compounds were further characterized in preliminary analgesic and side-effects tests in vivo. On the basis of comprehensive evaluations, compound 8d which showed strong TRPV1 antagonistic activity, middle COX-2 inhibition, weak ulcerogenic action and had no hyperthermia side-effect was considered as a safe candidate for the further development of analgesic drugs.
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Affiliation(s)
- Lin Yan
- Institute of Chemistry & Biology, Henan University, Kaifeng 475004, China
| | - Miaobo Pan
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
| | - Mian Fu
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
| | - Jingjie Wang
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China; WuXiAppTec (Wuhan) Co., Ltd, Wuhan 430000, China
| | - Wenlong Huang
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China.
| | - Hai Qian
- State Key Laboratory of Natural Medicines, Center of Drug Discovery, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China.
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Anti-hyperalgesic effects of imidazoline I2 receptor ligands in a rat model of inflammatory pain: interactions with oxycodone. Psychopharmacology (Berl) 2015; 232:3309-18. [PMID: 26037946 PMCID: PMC4537836 DOI: 10.1007/s00213-015-3983-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 05/24/2015] [Indexed: 10/23/2022]
Abstract
RATIONALE Emerging preclinical evidence suggests that imidazoline I2 receptor ligands may be effective analgesics. Quantitative analysis of the combined I2 receptor ligands and opioids is needed for the justification of combination therapy. OBJECTIVE This study systematically examined the anti-hyperalgesic and response rate-suppressing effects of selective I2 receptor ligands (2-BFI and phenyzoline) alone and in combination with oxycodone in rats. METHODS Von Frey filament test was used to examine the anti-hyperalgesic effects of drugs in a rat model of complete Freund's adjuvant (CFA)-induced inflammatory pain. Schedule-controlled responding was used to assess the rate-altering effects of study drugs. Duration of actions of individual drugs (2-BFI, phenyzoline, and oxycodone) alone or in combination was studied. Dose-addition analysis was employed to assess the anti-hyperalgesic interactions between drugs. RESULTS Oxycodone (0.1-3.2 mg/kg, i.p.), 2-BFI (1-17.8 mg/kg, i.p.), and phenyzoline (17.8-56 mg/kg, i.p.) all dose-dependently produced significant antinociceptive effects. When studied as combinations, 2-BFI and oxycodone produced additive interactions while phenyzoline and oxycodone produced supra-additive interactions under all fixed ratios. The same drug combinations did not alter or significantly reduced the operant responding depending on the ratios of the drug combinations. CONCLUSIONS Quantitative analysis of the anti-hyperalgesic effects of I2 receptor ligands strongly supports the therapeutic potential of I2 receptor ligands against inflammatory pain. In addition, the data reveal that phenyzoline is superior to the prototypic I2 receptor ligand 2-BFI for the management of pain and warrants further consideration as a novel analgesic.
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Bektas N, Nemutlu D, Arslan R. The imidazoline receptors and ligands in pain modulation. Indian J Pharmacol 2015; 47:472-8. [PMID: 26600633 PMCID: PMC4621665 DOI: 10.4103/0253-7613.165196] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 04/22/2015] [Accepted: 08/09/2015] [Indexed: 11/11/2022] Open
Abstract
Pain is an unpleasant experience and effects daily routine negatively. Although there are various drugs, many of them are not entirely successful in relieving pain, since pain modulation is a complex process involving numerous mediators and receptors. Therefore, it is a rational approach to identify the factors involved in the complex process and develop new agents that act on these pain producing mechanisms. In this respect, the involvement of the imidazoline receptors in pain modulation has drawn attention in recent years. In this review, it is aimed to focus on the imidazoline receptors and their ligands which contribute to the pain modulation. It is demonstrated that imidazoline-2 (I2) receptors are steady new drug targets for analgesics. Even if the mechanism of I2 receptor is not well known in the modulation of pain, it is known that it plays a role in tonic and chronic pain but not in acute phasic pain. Moreover, the I2 receptor ligands increase the analgesic effects of opioids in both acute and chronic pain and prevent the development of opioid tolerance. So, they are valuable for the chronic pain treatment and also therapeutic coadjuvants in the management of chronic pain with opiate drugs due to the attenuation of opioid tolerance and addiction. Thus, the use of the ligands which bind to the imidazoline receptors is an effective strategy for relieving pain. This educational forum exhibits the role of imidazoline receptors and ligands in pain process by utilizing experimental studies.
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Affiliation(s)
- Nurcan Bektas
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Turkey
| | - Dilara Nemutlu
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Turkey
| | - Rana Arslan
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Turkey
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Qiu Y, Zhang Y, Li JX. Discriminative stimulus effects of the imidazoline I2 receptor ligands BU224 and phenyzoline in rats. Eur J Pharmacol 2015; 749:133-41. [PMID: 25617792 DOI: 10.1016/j.ejphar.2015.01.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 01/09/2015] [Accepted: 01/14/2015] [Indexed: 01/25/2023]
Abstract
Although imidazoline I2 receptor ligands have been used as discriminative stimuli, the role of efficacy of I2 receptor ligands as a critical determinant in drug discrimination has not been explored. This study characterized the discriminative stimulus effects of selective imidazoline I2 receptor ligands BU224 (a low-efficacy I2 receptor ligand) and phenyzoline (a higher efficacy I2 receptor ligand) in rats. Two groups of male Sprague-Dawley rats were trained to discriminate 5.6mg/kg BU224 or 32mg/kg phenyzoline (i.p.) from their vehicle in a two-lever food-reinforced drug discrimination procedure, respectively. All rats acquired the discriminations after an average of 18 (BU224) and 56 (phenyzoline) training sessions, respectively. BU224 and phenyzoline completely substituted for one another symmetrically. Several I2 receptor ligands (tracizoline, CR4056, RS45041, and idazoxan) all occasioned>80% drug-associated lever responding in both discriminations. The I2 receptor ligand 2-BFI and a monoamine oxidase inhibitor harmane occasioned>80% drug-associated lever responding in rats discriminating BU224. Other drugs that occasioned partial or less substitution to BU224 cue included clonidine, methamphetamine, ketamine, morphine, methadone and agmatine. Clonidine, methamphetamine and morphine also only produced partial substitution to phenyzoline cue. Naltrexone, dopamine D2 receptor antagonist haloperidol and serotonin (5-HT)2A receptor antagonist MDL100907 failed to alter the discriminative stimulus effects of BU224 or phenyzoline. Combined, these results are the first to demonstrate that BU224 and phenyzoline can serve as discriminative stimuli and that the low-efficacy I2 receptor ligand BU224 shares similar discriminative stimulus effects with higher-efficacy I2 receptor ligands such as phenyzoline and 2-BFI.
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Affiliation(s)
- Yanyan Qiu
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
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Li JX, Thorn DA, Qiu Y, Peng BW, Zhang Y. Antihyperalgesic effects of imidazoline I(2) receptor ligands in rat models of inflammatory and neuropathic pain. Br J Pharmacol 2014; 171:1580-90. [PMID: 24329196 DOI: 10.1111/bph.12555] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE A new imidazoline I2 receptor ligand, CR4056, is effective for chronic inflammatory pain and diabetic neuropathy. However, it is unclear whether other I2 receptor ligands have similar effects and whether antinociceptive tolerance develops with repeated treatment. EXPERIMENTAL APPROACH The Von Frey filament test was used to measure mechanical hyperalgesia and the plantar test to measure thermal hyperalgesia in rats injected with complete Freund's adjuvant (CFA) treatment or had undergone surgery to induce chronic constriction injury (CCI), models of inflammatory pain and peripheral neuropathic pain respectively. The effects of morphine and I2 receptor ligands, 2-BFI, BU224, tracizoline and CR4056, 3.2-32 mg·kg(-1) , i.p., on hyperalgesia or affective pain (as measured by a place escape/avoidance paradigm) were studied in separate experiments. KEY RESULTS Morphine and the I2 receptor ligands (2-BFI, BU224 and tracizoline) all dose-dependently attenuated mechanical and thermal hyperalgesia in CFA-treated rats. The anti-hyperalgesic effects of 2-BFI in CFA-treated and CCI rats were attenuated by the I2 receptor antagonist idazoxan. The combination of 2-BFI and morphine produced additive effects against mechanical hyperalgesia in CFA-treated rats. Repeated treatment (daily for 7-9 days) with 2-BFI or CR4056 did not produce antinociceptive tolerance in CFA-treated or CCI rats. Morphine and the I2 receptor ligands (2-BFI, BU224 and CR4056) were all effective at attenuating place escape/avoidance behaviour in CFA-treated rats. CONCLUSIONS AND IMPLICATIONS Imidazoline I2 receptor ligands have antihyperalgesic effects in rat models of inflammatory and neuropathic pain and may represent a new class of pharmacotherapeutics for the management of chronic pain.
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
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Qiu Y, He XH, Zhang Y, Li JX. Discriminative stimulus effects of the novel imidazoline I₂ receptor ligand CR4056 in rats. Sci Rep 2014; 4:6605. [PMID: 25308382 PMCID: PMC4194429 DOI: 10.1038/srep06605] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 09/22/2014] [Indexed: 01/27/2023] Open
Abstract
This study examined whether a novel imidazoline I2 receptor ligand CR4056 could serve as a discriminative stimulus and whether it shares similar discriminative stimulus effects with other reported I2 receptor ligands. Eight male Sprague-Dawley rats were trained to discriminate 10.0 mg/kg CR4056 (i.p.) from vehicle in a two-lever food-reinforced drug discrimination procedure. Once rats acquired the discrimination, substitution and combination studies were conducted to elucidate the underlying receptor mechanisms. All rats acquired CR4056 discrimination after an average of 26 training sessions. Several I2 receptor ligands (phenyzoline, tracizoline, RS45041, and idazoxan, 3.2–75 mg/kg, i.p.) all occasioned > 80% CR4056-associated lever responding. Other drugs that occasioned partial or no CR4056-associated lever responding included methamphetamine, ketamine, the endogenous imidazoline ligand agmatine, the monoamine oxidase (MAO) inhibitor harmane, the α2-adrenoceptor agonist clonidine, the μ-opioid receptor agonists morphine and methadone, and the selective I2 receptor ligands BU224 and 2-BFI. The α1 adrenoceptor antagonist WB4101, α2 adrenoceptor antagonist yohimbine and μ-opioid receptor antagonist naltrexone failed to alter the stimulus effects of CR4056. Together, these results show that CR4056 can serve as a discriminative stimulus in rats, which demonstrates high pharmacological specificity and appears to be mediated by imidazoline I2 receptors.
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Affiliation(s)
- Yanyan Qiu
- 1] Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA [2] Department of Physiology, School of Basic Medical Sciences, Wuhan University, Hubei, China
| | - Xiao-Hua He
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Hubei, China
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
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Ding Y, Qiu Y, Jing L, Thorn DA, Zhang Y, Li JX. Behavioral effects of the cannabinoid CB1 receptor allosteric modulator ORG27569 in rats. Pharmacol Res Perspect 2014; 2:e00069. [PMID: 25431655 PMCID: PMC4186448 DOI: 10.1002/prp2.69] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 07/15/2014] [Indexed: 01/03/2023] Open
Abstract
The cannabinoid CB1 receptor system is involved in feeding behaviors and the CB1 receptor antagonist SR141716A is an effective antiobesity drug. However, SR141716A also has serious side effects, which prompted the exploration of alternative strategies to modulate this important drug target. Recently a CB1 receptor allosteric modulating site has been discovered and the allosteric modulating activity of several modulators including ORG27569 has been characterized in vitro. Yet, little is known of the in vivo pharmacological effects of ORG27569. This study examined the behavioral pharmacology of ORG27569 in rats. ORG27569 (3.2–10 mg/kg, i.p.) selectively attenuated the hypothermic effects of CB1 receptor agonists CP55940 (0.1–1 mg/kg) and anandamide (3.2–32 mg/kg). In contrast, SR141716A only attenuated the hypothermic effects of CP55940 but not anandamide. SR141716A but not ORG27569 blocked CP55940-induced catalepsy and antinociception. In addition, ORG27569 did not modify SR141716A-elicited grooming and scratching behaviors. In feeding studies, ORG27569 decreased palatable and plain food intake which was partially blocked by CP55940. The hypophagic effect of ORG27569 developed tolerance after 4 days of daily 5.6 mg/kg treatment; however, the effect on body weight gain outlasted the drug treatment for 10 days. These data suggest that ORG27569 may not function as a CB1 receptor allosteric modulator in vivo, although its hypophagic activity still has potential therapeutic utility.
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Affiliation(s)
- Yuanyuan Ding
- Department of Pharmacology and Toxicology, University at Buffalo Buffalo, New York
| | - Yanyan Qiu
- Department of Pharmacology and Toxicology, University at Buffalo Buffalo, New York
| | - Li Jing
- Department of Pharmacology and Toxicology, University at Buffalo Buffalo, New York ; Department of Physiology and Pathophysiology, Tianjin Medical University Tianjin, China
| | - David A Thorn
- Department of Pharmacology and Toxicology, University at Buffalo Buffalo, New York
| | - Yanan Zhang
- Research Triangle Institute Research Triangle Park, North Carolina
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo Buffalo, New York
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Andurkar SV, Reniguntala MSJ, Gulati A, DeRuiter J. Synthesis and antinociceptive properties of N-phenyl-N-(1-(2-(thiophen-2-yl)ethyl)azepane-4-yl)propionamide in the mouse tail-flick and hot-plate tests. Bioorg Med Chem Lett 2014; 24:644-8. [DOI: 10.1016/j.bmcl.2013.11.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 11/19/2013] [Accepted: 11/25/2013] [Indexed: 10/25/2022]
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Li JX, Shah AP, Patel SK, Rice KC, France CP. Modification of the behavioral effects of morphine in rats by serotonin 5-HT₁A and 5-HT₂A receptor agonists: antinociception, drug discrimination, and locomotor activity. Psychopharmacology (Berl) 2013; 225:791-801. [PMID: 22993050 PMCID: PMC3549012 DOI: 10.1007/s00213-012-2870-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 08/28/2012] [Indexed: 11/29/2022]
Abstract
RATIONALE Indirect-acting serotonin (5-HT) receptor agonists can enhance the antinociceptive effects of morphine; however, the specific 5-HT receptor subtype(s) mediating this enhancement is not established. OBJECTIVE This study examined interactions between morphine and both 5-HT(1A) and 5-HT(2A) receptor agonists in rats using measures of antinociception (radiant heat tail flick and warm water tail withdrawal), drug discrimination (3.2 mg/kg morphine versus saline), and locomotion. METHODS Male Sprague-Dawley rats (n = 7-8 per group) were used to examine the effects of morphine alone and in combination with DOM (5-HT(2A) agonist) and 8-OH-DPAT (5-HT(1A) agonist). RESULTS DOM did not modify antinociceptive or discriminative stimulus effects while modestly attenuating locomotor-stimulating effects of morphine; the effect of DOM (0.32 mg/kg) on morphine-induced locomotion was prevented by the 5-HT(2A) receptor-selective antagonist MDL 100907. In contrast, 8-OH-DPAT (0.032-0.32 mg/kg) fully attenuated the antinociceptive effects (both procedures), did not modify the discriminative stimulus effects, and enhanced (0.32 mg/kg) the locomotor-stimulating effects of morphine. These effects of 8-OH-DPAT were prevented by the 5-HT(1A) receptor-selective antagonist WAY100635. CONCLUSION Agonists acting at 5-HT(1A) or 5-HT(2A) receptors do not modify all effects of mu opioid receptor agonists in a similar manner. Moreover, interactions between 5-HT and opioid receptor agonists vary significantly between rats and nonhuman primates, underscoring the value of comparing drug interactions across a broad range of conditions and in multiple species.
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Affiliation(s)
- Jun-Xu Li
- Corresponding author: Charles P France, Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900,
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Garau C, Miralles A, García-Sevilla JA. Chronic treatment with selective I2-imidazoline receptor ligands decreases the content of pro-apoptotic markers in rat brain. J Psychopharmacol 2013; 27:123-34. [PMID: 22719017 DOI: 10.1177/0269881112450785] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Selective I(2)-imidazoline receptor ligands induce neuroprotection through various molecular mechanisms including blockade of N-methyl-D-aspartate (NMDA) receptors. To investigate new neuroprotective mechanisms associated with I(2)-imidazoline receptors, the effects of selective (2-styryl-2-imidazoline (LSL 61122), 2-(2-benzofuranyl)-2-imidazoline (2-BFI), 2-(4,5-dihydroimidazol-2-yl) quinoline hydrochloride (BU-224)) and non-selective (idazoxan) I(2)-drugs on canonical apoptotic pathways were assessed in rat brain cortex. The acute treatment with LSL 61122 (10 mg/kg) reduced the content of mitochondrial (pro-apoptotic) Bax (-33%) and cytochrome c (-31%), which was prevented by idazoxan, an I(2)-receptor antagonist. The sustained stimulation of I(2)-imidazoline receptors with selective drugs (10 mg/kg, every 12 h for seven days) was associated with down-regulation of key components of the extrinsic (Fas receptor: -20%; Fas associated protein with death domain (FADD) adaptor: -47-54%) and/or intrinsic (Bax: -20-23%; cytochrome c: -22-28%) apoptotic signalling and/or up-regulation of survival anti-apoptotic factors (p-Ser194 FADD/FADD ratio: +1.6-2.5-fold; and/or Bcl-2/Bax ratio: +1.5-fold), which in the long-term could dampen cell death in the brain. Similar chronic treatments with LSL 60101 (the imidazole analogue of 2-BFI) and idazoxan (a mixed I(2)/α(2)-ligand) did not induce significant alterations of pro- or anti-apoptotic proteins. The disclosed anti-apoptotic mechanisms of selective I(2)-imidazoline drugs may work in concert with other molecular mechanisms of neuroprotection (e.g. blockade of NMDA receptors) that are engaged by I(2)-ligands.
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Affiliation(s)
- Celia Garau
- Laboratori de Neurofarmacologia, Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Universitat de les Illes Balears, Palma de Mallorca, Spain
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Potentiation of oxycodone antinociception in mice by agmatine and BMS182874 via an imidazoline I2 receptor-mediated mechanism. Pharmacol Biochem Behav 2013; 103:550-60. [DOI: 10.1016/j.pbb.2012.10.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/11/2012] [Accepted: 10/15/2012] [Indexed: 11/18/2022]
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Abstract
This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States.
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Thorn DA, An XF, Zhang Y, Pigini M, Li JX. Characterization of the hypothermic effects of imidazoline I₂ receptor agonists in rats. Br J Pharmacol 2012; 166:1936-45. [PMID: 22324428 DOI: 10.1111/j.1476-5381.2012.01894.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Imidazoline I(2) receptors have been implicated in several CNS disorders. Although several I(2) receptor agonists have been described, no simple and sensitive in vivo bioassay is available for studying I(2) receptor ligands. This study examined I(2) receptor agonist-induced hypothermia as a functional in vivo assay of I(2) receptor agonism. EXPERIMENTAL APPROACH Different groups of rats were used to examine the effects of I(2) receptor agonists on the rectal temperature and locomotion. The pharmacological mechanisms were investigated by combining I(2) receptor ligands and different antagonists. KEY RESULTS All the selective I(2) receptor agonists examined (2-BFI, diphenyzoline, phenyzoline, CR4056, tracizoline, BU224 and S22687, 3.2-56 mg·kg(-1) , i.p.) dose-dependently and markedly decreased the rectal temperature (hypothermia) in rats, with varied duration of action. Pharmacological mechanism of the observed hypothermia was studied by combining the I(2) receptor agonists (2-BFI, BU224, tracizoline and diphenyzoline) with imidazoline I(2 ) receptor/ α(2) adrenoceptor antagonist idazoxan, selective I(1) receptor antagonist efaroxan, α(2) adrenoceptor antagonist/5-HT(1A) receptor agonist yohimbine. Idazoxan but not yohimbine or efaroxan attenuated the hypothermic effects of 2-BFI, BU224, tracizoline and diphenyzoline, supporting the I(2) receptor mechanism. In contrast, both idazoxan and yohimbine attenuated hypothermia induced by the α(2) adrenoceptor agonist clonidine. Among all the I(2) receptor agonists studied, only S22687 markedly increased the locomotor activity in rats. CONCLUSIONS AND IMPLICATIONS Imidazoline I(2) receptor agonists can produce hypothermic effects, which are primarily mediated by I(2) receptors. These data suggest that I(2) receptor agonist-induced hypothermia is a simple and sensitive in vivo assay for studying I(2) receptor ligands.
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Affiliation(s)
- David A Thorn
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, the State University of New York, Buffalo, NY, USA
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Tramadol antinociception is potentiated by clonidine through α2-adrenergic and I2-imidazoline but not by endothelin ETA receptors in mice. Eur J Pharmacol 2012; 683:109-15. [DOI: 10.1016/j.ejphar.2012.03.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 02/29/2012] [Accepted: 03/07/2012] [Indexed: 11/17/2022]
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Liu Q, Zhang M, Qin WJ, Wang YT, Li YL, Jing L, Li JX, Lawrence AJ, Liang JH. Septal nuclei critically mediate the development of behavioral sensitization to a single morphine injection in rats. Brain Res 2012; 1454:90-9. [DOI: 10.1016/j.brainres.2012.03.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 03/09/2012] [Accepted: 03/11/2012] [Indexed: 10/28/2022]
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An XF, Zhang Y, Winter JC, Li JX. Effects of imidazoline I2 receptor agonists and morphine on schedule-controlled responding in rats. Pharmacol Biochem Behav 2012; 101:354-9. [DOI: 10.1016/j.pbb.2012.01.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/24/2012] [Accepted: 01/31/2012] [Indexed: 11/24/2022]
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Tesfai J, Crane L, Baziard-Mouysset G, Edwards LP. Novel I 1-Imidazoline Agonist S43126 Augment Insulin Secretion in Min6 Cells. ACTA ACUST UNITED AC 2012; 3. [PMID: 27429837 PMCID: PMC4944854 DOI: 10.4172/2155-6156.1000183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The I1-imidazoline receptor is a novel drug target for hypertension and insulin resistance which are major disorders associated with Type II diabetes. In the present study, we examined the effects of a novel imidazoline agonist S43126 on calcium fluxes and insulin secretion from Min6 β-cells. We also examined the effects of S43126 on the induction of IRAS, and phosphorylation of components in the I1-imidazoline signaling pathways, namely ERK and PKB. Min6 β-cells were treated with varying doses of S43126 [10−8M to 10−5M] for various time (5–60mins). S43126 at higher dose [10−5M] stimulated insulin secretion under elevated glucose concentration compared to basal. In addition, insulin secretion and Ca2+ influx mediated by S43126 [10−5M] were decreased following co-treatment with efaroxan (I1-antagonist) and nifedipine (L-type voltage-gated Ca2+-channel blocker) at various times (5–60mins). Furthermore, S43126 at [10−5M] increased Ca2+ oscillation, [Ca2+] and 45Ca2+ uptake in a time and dose-dependent manner. Moreover, Western blot analysis of treated samples showed that S43126 caused an increased protein expression of IRAS as well as phosphorylation of both ERK1/2 and PKB in a concentration-dependent manner. We conclude that S43126 exerts its insulinotropic effect in a glucose dependent manner by a mechanism involving L-type calcium channels and imidazoline I1-receptors.
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Affiliation(s)
- Jerusalem Tesfai
- Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Louis Crane
- Laboratoire de Chimie Pharmaceutique, Universite Paul Sabatier, Faculté de Pharmacie, USA
| | | | - Lincoln P Edwards
- Center for Dental Research, School of Dentistry and School of Medicine, Loma Linda University, Loma Linda, CA, USA
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Li JX, Zhang Y. Emerging drug targets for pain treatment. Eur J Pharmacol 2012; 681:1-5. [DOI: 10.1016/j.ejphar.2012.01.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 12/25/2011] [Accepted: 01/18/2012] [Indexed: 11/30/2022]
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Thorn DA, Winter JC, Li JX. Agmatine attenuates methamphetamine-induced conditioned place preference in rats. Eur J Pharmacol 2012; 680:69-72. [PMID: 22329899 DOI: 10.1016/j.ejphar.2012.01.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 01/24/2012] [Accepted: 01/28/2012] [Indexed: 12/15/2022]
Abstract
The polyamine agmatine modulates a variety of behavioral effects including the abuse-related effects of opioids and has been proposed as a potential medication candidate for the treatment of opioid abuse. However, little is known of the effects of agmatine on the abuse-related effects of other drugs of abuse. This study examined the effects of agmatine on the rewarding effects of methamphetamine in rats using a conditioned place preference paradigm. Methamphetamine (0.1-1.0mg/kg) dose-dependently increased the time spent in methamphetamine-paired side (place preference). Agmatine, at doses that did not produce place preference or aversion (10-32mg/kg), significantly decreased the development of methamphetamine-induced place preference when agmatine was administered in combination with methamphetamine during place conditioning. Agmatine also significantly decreased the expression of methamphetamine-induced place preference when an acute injection of agmatine was given immediately before test session. These doses of agmatine do not alter the motor activity in rats, suggesting that the observed attenuation of methamphetamine-induced place preference was not due to general behavioral disruption. Together, these data suggests that agmatine attenuates the rewarding effects of methamphetamine and may be able to modulate the abuse liability of methamphetamine.
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Affiliation(s)
- David A Thorn
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, the State University of New York, 102 Farber Hall, Buffalo, NY14214-3000, USA
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