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Fung T, Asiri YI, Taheri K, Wall R, Schwarz SKW, Puil E, MacLeod BA. Antinociception by intrathecal delivery of the novel non-opioid 1-amino-1-cyclobutanecarboxylic acid. Eur J Pain 2018; 23:260-271. [PMID: 30091274 DOI: 10.1002/ejp.1301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 08/02/2018] [Accepted: 08/03/2018] [Indexed: 11/11/2022]
Abstract
BACKGROUND Neuraxial opioids are widely used for intraoperative and post-operative analgesia. The risk of severe adverse effects including respiratory depression accompanies this analgesia, prompting the need for effective non-opioid alternatives. Systemic 1-amino-1-cyclobutanecarboxylic acid showed promise in preliminary studies to produce antinociception without observable toxicity. However, the effects of 1-amino-1-cyclobutanecarboxylic acid after intrathecal administration are unknown. The aim of this study was to determine whether intrathecal administration of 1-amino-1-cyclobutanecarboxylic acid produces antinociceptive effects in murine models and to elucidate its site and receptor mechanism of action. METHODS Female CD-1 mice were randomized to receive intrathecal, intraperitoneal and intraplantar injections of 1-amino-1-cyclobutanecarboxylic acid. Animals receiving intrathecal injections were anaesthetized and injected between L5 and L6. Animals then received an intraplantar injection of 10% hypertonic saline into the right hindpaw and were video-recorded for 30 min. Videos were analyzed by a blinded observer who determined the duration that animals exhibited nocifensive responses. RESULTS Intrathecal or intraperitoneal administration of 1-amino-1-cyclobutanecarboxylic acid reduced the time that animals exhibited nocifensive behaviour, whereas intraplantar administration produced no effect. The effects of intrathecal 1-amino-1-cyclobutanecarboxylic acid were restricted in dermatomal distribution, reversible and produced little or no depression of respiratory rate. An NMDA antagonist blocked antinociception, while mu-opioid or GABAB antagonists did not prevent ACBC antinociception. CONCLUSIONS Intrathecal 1-amino-1-cyclobutanecarboxylic acid in mice produces robust, brief antinociceptive effects with a dermatomal distribution corresponding to the lumbar site of administration. This amino acid merits further exploration as a non-opioid neuraxial analgesic with little or no respiratory side effects. SIGNIFICANCE The novel, non-opioid analgesic, 1-amino-1-cyclobutanecarboxylic acid, produced robust, reversible and localized antinociception in murine models of pain. This study provides evidence supporting further investigation and development of 1-amino-1-cyclobutanecarboxylic acid as a non-opioid spinal analgesic.
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Affiliation(s)
- Timothy Fung
- Hugill Anesthesia Research Centre, Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Yahya I Asiri
- Hugill Anesthesia Research Centre, Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Kamyar Taheri
- Cannevert Therapeutics Ltd, Vancouver, British Columbia, Canada
| | - Richard Wall
- Hugill Anesthesia Research Centre, Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephan K W Schwarz
- Hugill Anesthesia Research Centre, Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada.,Department of Anesthesia, Providence Health Care/St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Ernest Puil
- Hugill Anesthesia Research Centre, Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Bernard A MacLeod
- Hugill Anesthesia Research Centre, Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
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Fung T, Asiri YI, Wall R, Schwarz SKW, Puil E, MacLeod BA. Variations of isovaline structure related to activity in the formalin foot assay in mice. Amino Acids 2017; 49:1203-1213. [PMID: 28432424 DOI: 10.1007/s00726-017-2421-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 04/10/2017] [Indexed: 01/25/2023]
Abstract
Current centrally acting analgesics such as opioids are associated with adverse effects that limit their use and threaten patient safety. Isovaline is a novel prototype analgesic that produces peripheral antinociception in several pain models with little or no effect on the central nervous system. The aim of this study was to establish a preliminary structure-activity relationship for isovaline derivatives by assaying efficacy in the formalin foot assay and central adverse effect profile in mice. Selected compounds were tested using the formalin foot assay to determine efficacy in reducing formalin-induced behaviors. Of the compounds tested, R-isovaline, S-isovaline, and 1-amino-1-cyclobutanecarboxylic acid reduced nocifensive behavior in phase II of the assay. These effects occurred without affecting performance on the rotarod, indicating that the reduction in nocifensive behaviors was not due to sedation or motor incoordination. Modifications to isovaline that increased its steric size without a cyclobutane ring formation produced compounds with no activity in the formalin foot assay. These findings indicate that the conformational stability of isovaline or the ability to form a cyclobutane ring is necessary for activity in the formalin foot assay.
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Affiliation(s)
- Timothy Fung
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Yahya I Asiri
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Richard Wall
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Stephan K W Schwarz
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.,Department of Anesthesia, Providence Health Care/St. Paul's Hospital, Vancouver, BC, V6Z 1Y6, Canada
| | - Ernest Puil
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Bernard A MacLeod
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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Differential effects of R-isovaline and the GABA B agonist, baclofen, in the guinea pig ileum. Eur J Pharmacol 2016; 791:85-90. [PMID: 27521870 DOI: 10.1016/j.ejphar.2016.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 11/22/2022]
Abstract
R-isovaline is a non-proteinogenic amino acid which produces analgesia in a range of nociceptive assays. Mediation of this effect by metabotropic receptors for γ-aminobutyric acid (GABA) and glutamate, demonstrated by previous work, may depend on the type of tissue or receptor system. The objective of this study was to assess the activity of R-isovaline acting at GABAB and group II metabotropic glutamate receptors in guinea pig ileum, which is known to exhibit well-defined responses to GABAB agonists such as baclofen. The effects of bath-applied R-isovaline and RS-baclofen were examined on electrically evoked contractions of guinea pig ileum and during GABAB antagonism by CGP52432. In separate experiments, the group II metabotropic glutamate receptor agonist, LY354740 was applied to determine the functional presence of these receptors. R-isovaline (1-100mM) decreased the amplitude of ileal muscle contractions and increased tension. RS-baclofen reduced contraction amplitude, but decreased tension. CGP52432 did not prevent the effects of R-isovaline on contraction amplitude, but antagonized effects of RS-baclofen on contraction amplitude. The group II metabotropic glutamate receptor agonist, LY354740, produced no detectable effects on evoked contractions. R-isovaline differed significantly from RS-baclofen in its actions in the guinea pig ileum, indicated in particular by the finding that CGP52432 blocked only the effects of RS-baclofen. The ileal tissue did not respond to a group II metabotropic glutamate receptor agonist, previously shown to co-mediate R-isovaline analgesia. These findings raise the possibility of a novel therapeutic target at unknown receptors for R-isovaline-like compounds in the guinea pig ileum.
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Preclinical evaluation of 2-amino-2-[11C]methyl-butanoic acid as a potential tumor-imaging agent in a mouse model. Nucl Med Commun 2015; 36:1107-12. [PMID: 26259115 DOI: 10.1097/mnm.0000000000000364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE C-labeled 2-amino-2-methyl-butanoic acid (Iva) was previously reported to provide high tumor uptake; however, the pharmacokinetic properties of C-labeled Iva have not been characterized. In the present study, we evaluated the potential of [C]Iva as a PET probe for tumor imaging. METHODS [C]Iva was incubated in mouse serum for 60 min at 37°C and then analyzed by high-performance liquid chromatography and thin-layer chromatography. In-vitro cellular uptake of [C]Iva was determined in PBS and sodium-free buffer at 37°C using SY human small-cell lung cancer cells. The effects of inhibitors of amino acid transporters on [C]Iva uptake were also determined in PBS. In-vivo distribution and dynamic PET studies were conducted in SY tumor-bearing mice. RESULTS [C]Iva was stable in mouse serum in vitro for 60 min. The cellular uptake of [C]Iva was linearly increased for 20 min in both PBS and sodium-free buffer and almost completely inhibited by an inhibitor of system L amino acid transporters and another of LAT1, a transporter of system L. In-vivo distribution and dynamic PET studies showed that [C]Iva was highly accumulated in tumor, but not in normal tissues, except for the pancreas and kidneys. The [C]Iva uptake ratio of tumor to several normal tissues, such as the lung, muscle, and brain, was high. CONCLUSION [C]Iva was stable in mouse serum and transported through system L amino acid transporters including LAT1, which is highly expressed in several tumors. [C]Iva is a promising PET probe for noninvasive tumor imaging.
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Asseri K, Puil E, Schwarz S, MacLeod B. Group II metabotropic glutamate receptor antagonism prevents the antiallodynic effects of R-isovaline. Neuroscience 2015; 293:151-6. [DOI: 10.1016/j.neuroscience.2015.02.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/21/2015] [Accepted: 02/11/2015] [Indexed: 10/24/2022]
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Isovaline does not activate GABA(B) receptor-coupled potassium currents in GABA(B) expressing AtT-20 cells and cultured rat hippocampal neurons. PLoS One 2015; 10:e0118497. [PMID: 25706125 PMCID: PMC4337901 DOI: 10.1371/journal.pone.0118497] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/19/2015] [Indexed: 01/13/2023] Open
Abstract
Isovaline is a non-proteinogenic amino acid that has analgesic properties. R-isovaline is a proposed agonist of the γ-aminobutyric acid type B (GABAB) receptor in the thalamus and peripheral tissue. Interestingly, the responses to R-isovaline differ from those of the canonical GABAB receptor agonist R-baclofen, warranting further investigation. Using whole cell recording techniques we explored isovaline actions on GABAB receptors coupled to rectifying K+ channels in cells of recombinant and native receptor preparations. In AtT-20 cells transfected with GABAB receptor subunits, bath application of the GABAB receptor agonists, GABA (1 μM) and R-baclofen (5 μM) produced inwardly rectifying currents that reversed approximately at the calculated reversal potential for K+ R- isovaline (50 μM to 1 mM) and S-isovaline (500 μM) did not evoke a current. R-isovaline applied either extracellularly (250 μM) or intracellularly (10 μM) did not alter responses to GABA at 1 μM. Co-administration of R-isovaline (250 μM) with a low concentration (10 nM) of GABA did not result in a response. In cultured rat hippocampal neurons that natively express GABAB receptors, R-baclofen (5 μM) induced GABAB receptor-dependent inward currents. Under the same conditions R-isovaline (1 or 50 μM) did not evoke a current or significantly alter R-baclofen-induced effects. Therefore, R-isovaline does not interact with recombinant or native GABAB receptors to open K+ channels in these preparations.
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A practical chemoenzymatic synthesis of (R)-isovaline based on the asymmetric hydrolysis of 2-ethyl-2-methyl-malonamide. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.tetasy.2014.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Pitman KA, Puil E, Borgland SL. GABA(B) modulation of dopamine release in the nucleus accumbens core. Eur J Neurosci 2014; 40:3472-80. [PMID: 25229321 DOI: 10.1111/ejn.12733] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 08/20/2014] [Indexed: 11/27/2022]
Abstract
Modulation of the concentration of dopamine (DA) released from dopaminergic terminals in the nucleus accumbens (NAc) influences behaviours such as the motivation to obtain drugs of abuse. γ-Aminobutyric acid type B (GABAB ) receptors are expressed throughout the mesolimbic circuit, including in the NAc, and baclofen, an agonist of GABAB receptors, can decrease drug-seeking behaviours. However, the mechanism by which GABAB receptors modulate terminal DA release has not been well studied. We explored how baclofen modulates the concentration of DA released from terminals in the NAc core using fast-scan cyclic voltammetry in brain slices from adult male C57BL/6J mice. We found that baclofen concentration-dependently decreased single pulse-evoked DA release. This effect was blocked by the GABAB antagonist, CGP 52432, but not by a nicotinic acetylcholine receptor antagonist. Suppression of DA release by a saturating concentration of baclofen was sustained for up to 1 h. The effect of baclofen was reduced with electrical stimulations mimicking burst firing of DA neurons. Similar to the D2 receptor agonist, quinpirole, baclofen reduced the probability of DA release, supporting a mechanistic overlap with D2 receptors. Baclofen-mediated suppression of DA release persisted after a locomotor-sensitizing cocaine treatment, indicating that GABAB receptors on DA terminals were not altered by cocaine exposure. These data suggest that baclofen-mediated suppression of terminal DA release is due to GABAB activation on DA terminals to reduce the probability of DA release. This effect does not readily desensitize, and persists regardless of chronic cocaine treatment.
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Affiliation(s)
- Kimberley A Pitman
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, BC, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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Yu W, Smith AB, Pilitsis J, Shin DS. Isovaline attenuates epileptiform activity and seizure behavior in 4-aminopyridine treated rats. Epilepsy Res 2014; 108:331-5. [DOI: 10.1016/j.eplepsyres.2013.11.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 11/01/2013] [Accepted: 11/21/2013] [Indexed: 01/16/2023]
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Behavioral effects of alpha-alkylated amino acid analogs in the C57BL/6J mouse. Behav Brain Res 2013; 252:432-8. [PMID: 23756141 DOI: 10.1016/j.bbr.2013.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Revised: 05/31/2013] [Accepted: 06/03/2013] [Indexed: 11/24/2022]
Abstract
Although a series of amino acid analogs have been shown to modulate brain function, information on the pharmacology of alpha-alkylated amino acids (AAAA) is limited. In particular there is no information on the effect of these amino acid analogs (AAA) on the elevated plus maze, the tail suspension test and the forced swim test. It was therefore the aim of the study to test a series of AAAA in these paradigms in order to explore behavioral activities of this compound class. 10 male mice per group aged between 10 and 14 weeks were used. Vehicle-treated controls were used in addition to intraperitoneal injections of 1, 10 and 100mg/kg body weight of each, alpha-amino-isobutyic acid (AIB), isovaline (IVA), alpha-propyl-alanine (APA), alpha-butyl-alanine (ABA), alpha-pentyl-alanine (APnA), alpha-ethylphenylglycine (AEPG) and alpha-methyl-valine (AMV). The elevated plus maze (EPM), the tail suspension test (TST) and forced swim test (FST) were used for behavioral testing. There were dose-dependent results: all compounds increased time and pathlength in the open arm of the EPM at least at one dose administered. In the TST and in the FST only the 100mg dose was showing an effect. The results show pharmacological activity modifying the EPM in low doses suggesting the use in treatment of behavioral traits and symptoms represented by or linked to the EPM including anxiety-related behavior including depression. Compounds acting at higher doses may be used to induce behavioral changes and thus serve as neurobiological-neuropharmacological tools.
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Whitehead R, Puil E, Ries C, Schwarz S, Wall R, Cooke J, Putrenko I, Sallam N, MacLeod B. GABAB receptor-mediated selective peripheral analgesia by the non-proteinogenic amino acid, isovaline. Neuroscience 2012; 213:154-60. [DOI: 10.1016/j.neuroscience.2012.04.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 04/10/2012] [Accepted: 04/12/2012] [Indexed: 12/20/2022]
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