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Wang SY, Zhang YZ, Liu XH, Guo XC, Wang XF, Han FT, Zhang Y, Wang CL. Endomorphin-2 analogs with C-terminal esterification display potent antinociceptive effects in the formalin pain test in mice. Peptides 2024; 171:171116. [PMID: 37951356 DOI: 10.1016/j.peptides.2023.171116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 10/28/2023] [Accepted: 11/08/2023] [Indexed: 11/13/2023]
Abstract
Previously, we have investigated three C-terminal esterified endomorphin-2 (EM-2) analogs EM-2-Me, EM-2-Et and EM-2-Bu with methyl, ethyl and tert-butyl ester modifications, respectively. These analogs produced significant antinociception in acute pain at the spinal and supraspinal levels, with reduced tolerance and gastrointestinal side effects. The present study was undertaken to determine the analgesic effects and opioid mechanisms of these three analogs in the formalin pain test. Our results demonstrated that intracerebroventricular (i.c.v.) administration of 0.67-20 nmol EM-2 analogs EM-2-Me, EM-2-Et and EM-2-Bu produced dose-dependent antinociceptive effects in both phase Ⅰ and phase Ⅱ of formalin pain. EM-2-Me and EM-2-Bu displayed more potent antinociception than morphine. Especially, EM-2-Bu exhibited the highest antinociception in phase Ⅱ of formalin pain, with the ED50 value being 2.1 nmol. Naloxone (80 nmol, i.c.v.) completely antagonized the antinociceptive effects of EM-2-Me, EM-2-Et and EM-2-Bu (20 nmol, i.c.v.) in both phase I and phase Ⅱ of formalin pain, suggesting a central opioid mechanism. Nevertheless, the antinociception induced by EM-2-Me might be involved in the release of dynorphin A, which subsequently acted on κ- opioid receptor. EM-2-Bu produced the antinociception probably by the direct activation of both μ- and δ-opioid receptors. EM-2-Me, EM-2-Et and EM-2-Bu also produced significant analgesic effects after peripheral administration, and the central opioid receptors were involved. Furthermore, EM-2-Bu had no influence on the locomotor activity after i.c.v. injection. The present investigation demonstrated that C-terminal esterified modifications of EM-2 will be beneficial for developing novel therapeutics in formalin pain.
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Affiliation(s)
- Si-Yu Wang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Yu-Zhe Zhang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Xiao-Han Liu
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Xue-Ci Guo
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | | | - Feng-Tong Han
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Yao Zhang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Chang-Lin Wang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China; State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, China.
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Smith MT, Kong D, Kuo A, Imam MZ, Williams CM. Analgesic Opioid Ligand Discovery Based on Nonmorphinan Scaffolds Derived from Natural Sources. J Med Chem 2022; 65:1612-1661. [PMID: 34995453 DOI: 10.1021/acs.jmedchem.0c01915] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Strong opioid analgesics, including morphine, are the mainstays for treating moderate to severe acute pain and alleviating chronic cancer pain. However, opioid-related adverse effects, including nausea or vomiting, sedation, respiratory depression, constipation, pruritus (itch), analgesic tolerance, and addiction and abuse liability, are problematic. In addition, the use of opioids to relieve chronic noncancer pain is controversial due to the "opioid crisis" characterized by opioid misuse or abuse and escalating unintentional death rates due to respiratory depression. Hence, considerable research internationally has been aimed at the "Holy Grail" of the opioid analgesic field, namely the discovery of novel and safer opioid analgesics with improved opioid-related adverse effects. In this Perspective, medicinal chemistry strategies are addressed, where structurally diverse nonmorphinan-based opioid ligands derived from natural sources were deployed as lead molecules. The current state of play, clinical or experimental status, and novel opioid ligand discovery approaches are elaborated in the context of retaining analgesia with improved safety and reduced adverse effects, especially addiction liability.
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3
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Aguirre Siancas EE, Lam Figueroa NM, Delgado Rios JC, Ruiz Ramirez E, Portilla Flores OS, Crispín Huamaní LJ, Alarcón Velásquez L. Determination of the temperature causing a nociceptive response in the tail of albino BALB/c mice. NEUROLOGÍA (ENGLISH EDITION) 2021; 36:584-588. [PMID: 34654532 DOI: 10.1016/j.nrleng.2020.05.002] [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: 12/02/2017] [Accepted: 03/01/2018] [Indexed: 10/24/2022] Open
Abstract
INTRODUCTION Designs for determining nociceptive response in rodents are of great use in neurology and experimental neuroscience. Immersing mice's tails in warm water is one of the most widely used procedures to evaluate this response; however, a wide range of temperatures are used in different studies. Knowing the temperature that produces a powerful nociceptive response in the tail of BALB/c mice is extremely useful. METHODS Eight 2-month-old male BALB/c mice were used. A 14-cm high beaker was filled with water up to 13cm. The animals' tails were immersed in the container with a starting temperature of 36°C. The water temperature was raised in 1°C increments until we identified the temperatures that produced nociceptive responses. That response was determined by counting the time taken before the mouse shook its tail to remove it from the water. RESULTS Six of the 8 mice began shaking their tails at the temperature of 51°C. All animals removed their tails from the water at the temperatures of 54°C, 55°C, and 56°C, taking a mean time of 8.54, 7.99, and 5.33seconds, respectively. ANOVA applied to the response times for each of the 3 temperatures indicated revealed a value of F=2.8 (P=.123). CONCLUSIONS The response time was statistically similar for the temperatures of 54°C, 55°C, and 56°C; however, the data were less dispersed for the latter temperature.
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Affiliation(s)
- E E Aguirre Siancas
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Peru; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Peru; Universidad Científica del Sur, Lima, Peru.
| | - N M Lam Figueroa
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Peru; Instituto de Investigaciones Clínicas, Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - J C Delgado Rios
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Peru; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | | | - O S Portilla Flores
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Peru; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - L J Crispín Huamaní
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Peru; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - L Alarcón Velásquez
- Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Peru; Grupo de Investigación ORALRES, Universidad Nacional Mayor de San Marcos, Lima, Peru
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Zhou J, Zhao L, Wei S, Wang Y, Zhang X, Ma M, Wang K, Liu X, Wang R. Contribution of the μ opioid receptor and enkephalin to the antinociceptive actions of endomorphin-1 analogs with unnatural amino acid modifications in the spinal cord. Peptides 2021; 141:170543. [PMID: 33794284 DOI: 10.1016/j.peptides.2021.170543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/08/2021] [Accepted: 03/22/2021] [Indexed: 01/20/2023]
Abstract
Endomorphin analogs containing unnatural amino acids have demonstrated potent analgesic effects in our previous studies. In the present study, the differences in antinociception and the mechanisms thereof for analogs 1-3 administered intracerebroventricularly and intrathecally were explored. All analogs at different routes of administration produced potent analgesia compared to the parent peptide endomorphin-1. Multiple antagonists and antibodies were used to explore the mechanisms of action of these analogs, and it was inferred that analogs 1-3 stimulated the μ opioid receptor to induce antinociception. Moreover, the antibody data suggested that analog 2 may induce the release of immunoreactive [Leu5]-enkephaline and [Met5]-enkephaline to produce a secondary component of antinociception at the spinal level and analog 3 may stimulate the the release of immunoreactive [Met5]-enkephaline at the spinal level. Finally, analogs 2 and 3 produced no acute tolerance in the spinal cord. We hypothesize that the unique characteristics of the endomorphin analogs result from their capacities to stimulate the release of endogenous antinociceptive substances.
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Affiliation(s)
- Jingjing Zhou
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Long Zhao
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Shuang Wei
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Yuan Wang
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China.
| | - Xianghui Zhang
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Mengtao Ma
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Kairong Wang
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Xin Liu
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China.
| | - Rui Wang
- Department of Pharmacology, Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China.
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Zhang YZ, Yang WJ, Wang XF, Wang MM, Zhang Y, Gu N, Wang CL. The spinal anti-allodynic effects of endomorphin analogs with C-terminal hydrazide modification in neuropathic pain model. Peptides 2020; 134:170407. [PMID: 32926948 DOI: 10.1016/j.peptides.2020.170407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/09/2020] [Accepted: 09/09/2020] [Indexed: 11/18/2022]
Abstract
The present study was undertaken to further investigate the spinal anti-allodynic effects of endomorphins (EMs) and their C-terminal hydrazide modified analogs EM-1-NHNH2 and EM-2-NHNH2 in the spared nerve injury (SNI) model of neuropathic pain in mice. Our results demonstrated that intrathecal (i.t.) administration of endomorphin-1 (EM-1), endomorphin-2 (EM-2), EM-1-NHNH2 and EM-2-NHNH2 produced potent anti-allodynic effects ipsilaterally in neuropathic pain model. Judging from the area under the curve (AUC) values, these two analogs exhibited higher antinociception than their parent peptides. Moreover, they also displayed significant antinociceptive effects in the contralateral paw administered intrathecally. Interestingly, EM-1 and its analog EM-1-NHNH2 displayed their antinociception probably by μ2-opioid receptor subtype since the μ1-opioid receptor antagonist naloxonazine didn't significantly block the anti-allodynia of EM-1 and EM-1-NHNH2, which implied a same opioid mechanism. However, the anti-allodynia induced by EM-2, but not EM-2-NHNH2 was significantly reduced by both μ1-opioid antagonist, naloxonazine and κ-antagonist, nor-binaltorphamine (nor-BNI), indicating multiple opioid receptors were involved in the anti-allodynic effects of EM-2. Most importantly, EM-1-NHNH2 decreased the antinociceptive tolerance, and EM-2-NHNH2 displayed non-tolerance-forming antinociception. Therefore, C-terminal amide to hydrazide conversion changed the spinal antinociceptive profiles of EMs in neuropathic pain. The present investigation is of great value in the development of novel opioid therapeutics against neuropathic pain.
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Affiliation(s)
- Yu-Zhe Zhang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin, 150001, China
| | - Wen-Jiao Yang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin, 150001, China
| | - Xiao-Fang Wang
- Jiangxi University of Traditional Chinese Medicine, Nanchang, China
| | - Meng-Meng Wang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin, 150001, China
| | - Yao Zhang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin, 150001, China
| | - Ning Gu
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin, 150001, China.
| | - Chang-Lin Wang
- School of Life Science and Technology, Harbin Institute of Technology, 92 West Dazhi Street, Harbin, 150001, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, 210009, China; State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
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6
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Aguirre Siancas EE, Lam Figueroa NM, Delgado Rios JC, Ruiz Ramirez E, Portilla Flores OS, Crispín Huamaní LJ, Alarcón Velásquez L. Determination of the temperature causing a nociceptive response in the tail of albino BALB/c mice. Neurologia 2018; 36:S0213-4853(18)30147-6. [PMID: 29891340 DOI: 10.1016/j.nrl.2018.03.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 03/01/2018] [Indexed: 11/15/2022] Open
Abstract
INTRODUCTION Designs for determining nociceptive response in rodents are of great use in neurology and experimental neuroscience. Immersing mice's tails in warm water is one of the most widely used procedures to evaluate this response; however, a wide range of temperatures are used in different studies. Knowing the temperature that produces a powerful nociceptive response in the tail of BALB/c mice is extremely useful. METHODS Eight 2-month-old male BALB/c mice were used. A 14-cm high beaker was filled with water up to 13 cm. The animals' tails were immersed in the container with a starting temperature of 36°C. The water temperature was raised in 1°C increments until we identified the temperatures that produced nociceptive responses. That response was determined by counting the time taken before the mouse shook its tail to remove it from the water. RESULTS Six of the 8 mice began shaking their tails at the temperature of 51°C. All animals removed their tails from the water at the temperatures of 54°C, 55°C, and 56°C, taking a mean time of 8.54, 7.99, and 5.33seconds, respectively. ANOVA applied to the response times for each of the 3 temperatures indicated revealed a value of F=2.8 (P=.123). CONCLUSIONS The response time was statistically similar for the temperatures of 54°C, 55°C, and 56°C; however, the data were less dispersed for the latter temperature.
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Affiliation(s)
- E E Aguirre Siancas
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Perú; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú; Universidad Científica del Sur, Lima, Perú.
| | - N M Lam Figueroa
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Perú; Instituto de Investigaciones Clínicas, Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - J C Delgado Rios
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Perú; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | | | - O S Portilla Flores
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Perú; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - L J Crispín Huamaní
- Grupo de Investigación NEURON, Universidad Nacional Mayor de San Marcos, Lima, Perú; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú
| | - L Alarcón Velásquez
- Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú; Grupo de Investigación ORALRES, Universidad Nacional Mayor de San Marcos, Lima, Perú
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Wang CL, Yang DJ, Yuan BY, Wang Y. C-terminal hydrazide modification changes the spinal antinociceptive profiles of endomorphins in mice. Peptides 2018; 99:128-133. [PMID: 28888771 DOI: 10.1016/j.peptides.2017.08.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/24/2017] [Accepted: 08/28/2017] [Indexed: 01/11/2023]
Abstract
Previously, we have demonstrated that endomorphins (EMs) analogs with C-terminal hydrazide modification retained the μ-opioid receptor affinity and selectivity, and exhibited potent antinociception after intracerebroventricular (i.c.v.) administration. In the present study, we extended our studies to evaluate the antinociceptive profiles of EMs and their analogs EM-1-NHNH2, EM-2-NHNH2 given spinally in the radiant heat paw withdrawal test. Following intrathecal (i.t.) administration, EM-1, EM-2, EM-1-NHNH2 and EM-2-NHNH2 dose-dependently increased the latency for paw withdrawal response. EM-1-NHNH2 displayed the highest antinociceptive effects, with the ED50 values being 1.63 nmol, more potent than the parent EM-1 (1.96 nmol), but with no significant difference. By contrast, the analgesic activities of EM-2 and its analog EM-2-NHNH2 were almost equivalent (P>0.05). Naloxone and β-funaltrexamine (β-FNA) almost completely attenuated the antinociceptive effects of EMs and their analogs EM-1-NHNH2, EM-2-NHNH2 (10 nmol, i.t.), indicating the involvement of μ-opioid receptors. Notably, the antinociception of EM-1 was not significantly antagonized by naloxonazine, a selective μ1-opioid receptor antagonist, but partially reversed the effects of EM-2, suggesting that EM-1 and EM-2 may produce antinociception through distinct μ1- and μ2-opioid receptor subtypes. Moreover, naloxonazine didn't significantly block the antinociceptive effects of EM-1-NHNH2 and EM-2-NHNH2, and nor-BNI, the κ-opioid receptor antagonist, attenuated the analgesic effects of EM-2, but not EM-1, EM-1-NHNH2 or EM-2-NHNH2. These results indicated that C-terminal amide to hydrazide conversion changed the antinociceptive opioid mechanisms of EM-2 but not EM-1 at the spinal level. Herein, the acute antinociceptive tolerance were further determined and compared. EM-1-NHNH2 and EM-2-NHNH2 shifted the dose-response curve rightward by only 2.8 and 1.5-fold as determined by tolerance ratio, whereas EM-1 and EM-2 by 3.4 and 4.6-fold, respectively, indicating substantially reduced antinociceptive tolerance. The present study demonstrated that C-terminal hydrazide modification changes the spinal antinociceptive profiles of EMs.
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Affiliation(s)
- Chang-Lin Wang
- School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China; State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China.
| | - Dai-Jun Yang
- School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Bi-Yu Yuan
- School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
| | - Yu Wang
- School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China
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Wang CL, Yang DJ, Yuan BY, Qiu TT. Antiallodynic Effects of Endomorphin-1 and Endomorphin-2 in the Spared Nerve Injury Model of Neuropathic Pain in Mice. Anesth Analg 2017; 125:2123-2133. [PMID: 28787346 DOI: 10.1213/ane.0000000000002318] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND The spared nerve injury (SNI) model is a new animal model that can mimic several characteristics of clinical neuropathic pain. Opioids are recommended as treatment of neuropathic pain. Therefore, the present study was conducted to investigate the antinociceptive effects of endomorphin-1 (EM-1) and endomorphin-2 (EM-2) given centrally and peripherally in the SNI model of neuropathic pain in mice. METHODS The SNI model was made in mice by sparing the sural nerve intact, when the other 2 of 3 terminal branches of the sciatic nerve (common peroneal and tibial nerves) were tightly ligated and cut. Von Frey monofilaments were used to measure the SNI-induced mechanical allodynia-like behavior. The antiallodynic effects of EM-1 and EM-2 were determined after central and peripheral administration in the SNI model of neuropathic pain. Also, the specific opioid receptor antagonists were used to determine the opioid mechanisms of EMs involved in neuropathic pain. Values were expressed as the mean ± standard deviation. RESULTS Our results showed that the SNI mice developed prolonged mechanical allodynia-like behavior in ipsilateral paw after surgery, with the withdrawal threshold value being 0.061 ± 0.02 g after 14 days. EM-1 and EM-2 produced significant antiallodynic effects in ipsilateral paw after intracerebroventricular (i.c.v.) administration, more effective than that of morphine. The peak withdrawal thresholds of 10 nmol EM-1 and EM-2 determined at 5 minutes after injection were 0.92 ± 0.36 and 0.87 ± 0.33 g, respectively, higher than that of morphine (0.46 ± 0.20 g). Moreover, both EMs (10 nmol, i.c.v.) exerted significant antiallodynic effects in the contralateral paw, whereas no significant antinociceptive activity was seen after i.c.v. administration of morphine with equimolar dose. It was noteworthy that EM-1 and EM-2 produced antinociception through distinct μ1- and μ2-opioid receptor subtypes, and the EM-2-induced antiallodynia contained an additional component that was mediated by the release of endogenous dynorphin A, acting on κ-opioid receptor. In addition, the antiallodynic activities of peripheral administration of EM-1, EM-2, and morphine were also investigated. Intraplantar, but not subcutaneous administration of EM-1 and EM-2 also exhibited potent antinociception, establishing the peripheral and local effects. Both μ1- and μ2-opioid receptor subtypes, but not the δ- or κ-opioid receptors were involved in the peripheral antiallodynia of EMs. CONCLUSIONS The present investigation demonstrated that both EM-1 and EM-2 given centrally and peripherally produced potent antiallodynic activities in SNI mice, and differential opioid mechanisms were involved.
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Affiliation(s)
- Chang-Lin Wang
- From the School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, China
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Wang Y, Zhou J, Liu X, Zhao L, Wang Z, Zhang X, Wang K, Wang L, Wang R. Structure-constrained endomorphin analogs display differential antinociceptive mechanisms in mice after spinal administration. Peptides 2017; 91:40-48. [PMID: 28363796 DOI: 10.1016/j.peptides.2017.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 12/12/2022]
Abstract
We previously reported a series of novel endomorphin analogs with unnatural amino acid modifications. These analogs display good binding affinity and functional activity toward the μ opioid receptor (MOP). In the present study, we further investigated the spinal antinociceptive activity of these compounds. The analogs were potent in several nociceptive models. Opioid antagonists and antibodies against several endogenous opioid peptides were used to determine the mechanisms of action of these peptides. Intrathecal pretreatment with naloxone and β-funaltrexamine (β-FNA) effectively inhibited analog-induced analgesia, demonstrating that activity of the analogs is regulated primarily through MOP. Antinociception induced by analog 2 through 4 was not reversed by δ opioid receptor (DOP) or κ opioid receptor (KOP) antagonist; antibodies against dynorphin-A (1-17), dynorphin-B (1-13), and Leu5/Met5-enkephalin had no impact on the antinociceptive effects of these analogs. In contrast, antinociceptive effects induced by a spinal injection of the fluorine substituted analog 1 were significantly reversed by KOP antagonism. Furthermore, intrathecal pretreatment with antibodies against dynorphin-B (1-13) attenuated the antinociceptive effect of analog 1. These results indicate that the antinociceptive activity exerted by intrathecally-administered analog 1 is mediated, in part, through KOP with increased release of dynorphin-B (1-13). The chemical modifications used in the present study may serve as a useful tool to gain insight into the mechanisms of endomorphins activity.
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MESH Headings
- Analgesia
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/antagonists & inhibitors
- Analgesics, Opioid/chemistry
- Analgesics, Opioid/pharmacology
- Analysis of Variance
- Animals
- Antibodies/immunology
- Dynorphins/administration & dosage
- Dynorphins/antagonists & inhibitors
- Dynorphins/chemistry
- Dynorphins/pharmacology
- Enkephalin, Leucine/administration & dosage
- Enkephalin, Leucine/antagonists & inhibitors
- Enkephalin, Leucine/chemistry
- Enkephalin, Leucine/pharmacology
- Enkephalin, Methionine/administration & dosage
- Enkephalin, Methionine/antagonists & inhibitors
- Enkephalin, Methionine/chemistry
- Enkephalin, Methionine/pharmacology
- Fluorine/chemistry
- Injections, Spinal
- Male
- Mice
- Naloxone/administration & dosage
- Naloxone/pharmacology
- Naltrexone/administration & dosage
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Oligopeptides/administration & dosage
- Oligopeptides/antagonists & inhibitors
- Oligopeptides/chemistry
- Oligopeptides/pharmacology
- Opioid Peptides/administration & dosage
- Opioid Peptides/antagonists & inhibitors
- Opioid Peptides/chemistry
- Opioid Peptides/pharmacology
- Pain/drug therapy
- Pain/metabolism
- Pain Measurement
- Receptors, Opioid, kappa/antagonists & inhibitors
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, sigma/antagonists & inhibitors
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Affiliation(s)
- Yuan Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Jingjing Zhou
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Xin Liu
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Long Zhao
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Zhaojuan Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Xianghui Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Kezhou Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Linqing Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China
| | - Rui Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Pharmacology, Institute of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, PR China.
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Endomorphin-2 analogs with C-terminal esterification produce potent systemic antinociception with reduced tolerance and gastrointestinal side effects. Neuropharmacology 2017; 116:98-109. [DOI: 10.1016/j.neuropharm.2016.12.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/19/2016] [Accepted: 12/29/2016] [Indexed: 01/28/2023]
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Abstract
This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 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 (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 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 (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).
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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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