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Veloso C, Videira RA, Andrade PB, Cardoso C, Vitorino C. In vivo methodologies to assist preclinical development of topical fixed-dose combinations for pain management. Int J Pharm 2022; 616:121530. [PMID: 35121043 DOI: 10.1016/j.ijpharm.2022.121530] [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: 11/09/2021] [Revised: 01/18/2022] [Accepted: 01/27/2022] [Indexed: 11/24/2022]
Abstract
The combination in a fixed dose of two or more active pharmaceutical ingredients in the same pharmaceutical dosage form is an approach that has been used successfully in the treatment of several pathologies, including pain. In the preclinical development of a topical fixed-dose combination product with analgesic and anti-inflammatory activities for pain management, the main objective is to establish the nature of the interaction between the different active pharmaceutical ingredients while obtaining data on the medicinal product safety and efficacy. Despite the improvement of in vitro assays, animal models remain a fundamental strategy to characterise the interaction, efficacy and safety of active pharmaceutical ingredients at the physiological level, which cannot be reached by in vitro assays. Thus, the main goal of this review is to systematise the available animal models to evaluate the efficacy and safety of a new fixed-dose combination product for topical administration indicated for pain management. Particular emphasis is given to animal models that are accepted for regulatory purposes.
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Affiliation(s)
- Cláudia Veloso
- Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal; Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal
| | - Romeu A Videira
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, R. Jorge Viterbo Ferreira, n° 228, 4050-313 Porto, Portugal.
| | - Paula B Andrade
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, R. Jorge Viterbo Ferreira, n° 228, 4050-313 Porto, Portugal
| | - Catarina Cardoso
- Laboratórios Basi, Parque Industrial Manuel Lourenço Ferreira, lote 15, 3450-232 Mortágua, Portugal
| | - Carla Vitorino
- Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal; Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
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Bagues A, Martín MI, Higuera-Matas A, Esteban-Hernández J, Ambrosio E, Sánchez-Robles EM. Mu-Opioid Receptors in Ganglia, But Not in Muscle, Mediate Peripheral Analgesia in Rat Muscle Pain. Anesth Analg 2019; 126:1369-1376. [PMID: 29261544 DOI: 10.1213/ane.0000000000002717] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Previous studies have demonstrated the participation of peripheral μ-opioid receptors (MOR) in the antinociceptive effect of systemically administered morphine and loperamide in an orofacial muscle pain model, induced by hypertonic saline, but not in a spinally innervated one, in rats. In this study, we determine whether this peripheral antinociceptive effect is due to the activation of MOR localized in the muscle, ganglia, or both. METHODS To determine the local antinociceptive effect of morphine and loperamide, 2 models of acute muscle pain (trigeminal and spinal) were used. Also, to study the MOR expression, protein quantification was performed in the trigeminal and spinal ganglia, and in the muscles. RESULTS The behavioral results show that the intramuscular injection of morphine and loperamide did not exert an antinociceptive effect in either muscle (morphine: P = .63, loperamide: P = .9). On the other hand, MOR expression was found in the ganglia but not in the muscles. This expression was on average 44% higher (95% confidence interval, 33.3-53.9) in the trigeminal ganglia than in the spinal one. CONCLUSIONS The peripheral antinociceptive effect of systemically administered opioids may be due to the activation of MOR in ganglia. The greater expression of MOR in trigeminal ganglia could explain the higher antinociceptive effect of opioids in orofacial muscle pain than in spinal muscle pain. Therefore, peripheral opioids could represent a promising approach for the treatment of orofacial pain.
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Affiliation(s)
| | | | - Alejandro Higuera-Matas
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Jesús Esteban-Hernández
- Área de Medicina Preventiva y Salud Pública, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Madrid, Spain
| | - Emilio Ambrosio
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
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3
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Kang SK, Lee YH, Park H, Ro JY, Auh QS. Effects of intramuscular morphine in men and women with temporomandibular disorder with myofascial pain. Oral Dis 2018; 24:1591-1598. [PMID: 29920852 DOI: 10.1111/odi.12919] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 05/30/2018] [Accepted: 06/08/2018] [Indexed: 11/28/2022]
Abstract
OBJECTIVES This placebo-controlled randomized double-blinded clinical study assessed the analgesic efficacy of intramuscular morphine in TMD patients with myofascial pain and sex-dependent responses of the morphine treatment. SUBJECTS AND METHODS Men and women with TMD were treated with morphine (1.5 or 5 mg), lidocaine, or saline in the masseter muscle. VAS of pain intensity, PPT, and PPtol were compared between treatment groups and gender. An additional group was treated with morphine in the trapezius muscle to evaluate the systemic effect of morphine that may reduce pain in the masseter muscle. RESULTS There was a significant difference in VAS scores between the morphine 5 mg group and the saline group favoring morphine, but not between the morphine 5 mg and lidocaine. Morphine 1.5 and 5 mg treatments led to consistently and significantly elevated PPT and PPtol measures in men, but not in women. Morphine administered in the trapezius muscle did not affect the outcome measures. CONCLUSION A single dose intramuscular morphine produced analgesic effects up to 48 hr in patients with myofascial pain. Intramuscular morphine elevated mechanical pain threshold and tolerance in the masseter only in male patients, suggesting sex differences in local morphine effects. No systemic effect of intramuscular morphine was detected.
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Affiliation(s)
- Soo-Kyung Kang
- Department of Oral Medicine, School of Dentistry, Kyung Hee University, Seoul, Korea
| | - Yeon-Hee Lee
- Department of Oral Medicine, School of Dentistry, Kyung Hee University, Seoul, Korea
| | - Hyeji Park
- Department of Dentistry, Graduate School, Kyung Hee University, Seoul, Korea
| | - Jin Y Ro
- Department of Oral Medicine, School of Dentistry, Kyung Hee University, Seoul, Korea.,Department of Neural and Pain Sciences, Program in Neuroscience, University of Maryland School of Dentistry, Baltimore, Maryland
| | - Q-Schick Auh
- Department of Oral Medicine, School of Dentistry, Kyung Hee University, Seoul, Korea
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Muley MM, Krustev E, McDougall JJ. Preclinical Assessment of Inflammatory Pain. CNS Neurosci Ther 2015; 22:88-101. [PMID: 26663896 DOI: 10.1111/cns.12486] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 12/21/2022] Open
Abstract
While acute inflammation is a natural physiological response to tissue injury or infection, chronic inflammation is maladaptive and engenders a considerable amount of adverse pain. The chemical mediators responsible for tissue inflammation act on nociceptive nerve endings to lower neuronal excitation threshold and sensitize afferent firing rate leading to the development of allodynia and hyperalgesia, respectively. Animal models have aided in our understanding of the pathophysiological mechanisms responsible for the generation of chronic inflammatory pain and allowed us to identify and validate numerous analgesic drug candidates. Here we review some of the commonly used models of skin, joint, and gut inflammatory pain along with their relative benefits and limitations. In addition, we describe and discuss several behavioral and electrophysiological approaches used to assess the inflammatory pain in these preclinical models. Despite significant advances having been made in this area, a gap still exists between fundamental research and the implementation of these findings into a clinical setting. As such we need to characterize inherent pathophysiological pathways and develop new endpoints in these animal models to improve their predictive value of human inflammatory diseases in order to design safer and more effective analgesics.
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Affiliation(s)
- Milind M Muley
- Departments of Pharmacology and Anaesthesia, Pain Management & Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
| | - Eugene Krustev
- Departments of Pharmacology and Anaesthesia, Pain Management & Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
| | - Jason J McDougall
- Departments of Pharmacology and Anaesthesia, Pain Management & Perioperative Medicine, Dalhousie University, Halifax, NS, Canada
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5
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Gregory NS, Sluka KA. Anatomical and physiological factors contributing to chronic muscle pain. Curr Top Behav Neurosci 2014; 20:327-48. [PMID: 24633937 PMCID: PMC4294469 DOI: 10.1007/7854_2014_294] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Chronic muscle pain remains a significant source of suffering and disability despite the adoption of pharmacologic and physical therapies. Muscle pain is mediated by free nerve endings distributed through the muscle along arteries. These nerves project to the superficial dorsal horn and are transmitted primarily through the spinothalamic tract to several cortical and subcortical structures, some of which are more active during the processing of muscle pain than other painful conditions. Mechanical forces, ischemia, and inflammation are the primary stimuli for muscle pain, which is reflected in the array of peripheral receptors contributing to muscle pain-ASIC, P2X, and TRP channels. Sensitization of peripheral receptors and of central pain processing structures are both critical for the development and maintenance of chronic muscle pain. Further, variations in peripheral receptors and central structures contribute to the significantly greater prevalence of chronic muscle pain in females.
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Affiliation(s)
- Nicholas S Gregory
- Neuroscience Graduate Program, University of Iowa, 3144 Med Labs, Iowa City, IA, 52246, USA,
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Gregory NS, Harris AL, Robinson CR, Dougherty PM, Fuchs PN, Sluka KA. An overview of animal models of pain: disease models and outcome measures. THE JOURNAL OF PAIN 2013; 14:1255-69. [PMID: 24035349 PMCID: PMC3818391 DOI: 10.1016/j.jpain.2013.06.008] [Citation(s) in RCA: 258] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 06/14/2013] [Accepted: 06/24/2013] [Indexed: 01/12/2023]
Abstract
UNLABELLED Pain is ultimately a perceptual phenomenon. It is built from information gathered by specialized pain receptors in tissue, modified by spinal and supraspinal mechanisms, and integrated into a discrete sensory experience with an emotional valence in the brain. Because of this, studying intact animals allows the multidimensional nature of pain to be examined. A number of animal models have been developed, reflecting observations that pain phenotypes are mediated by distinct mechanisms. Animal models of pain are designed to mimic distinct clinical diseases to better evaluate underlying mechanisms and potential treatments. Outcome measures are designed to measure multiple parts of the pain experience, including reflexive hyperalgesia measures, sensory and affective dimensions of pain, and impact of pain on function and quality of life. In this review, we discuss the common methods used for inducing each of the pain phenotypes related to clinical pain syndromes as well as the main behavioral tests for assessing pain in each model. PERSPECTIVE Understanding animal models and outcome measures in animals will assist in translating data from basic science to the clinic.
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Affiliation(s)
- Nicholas S Gregory
- Department of Physical Therapy and Rehabilitation Science, College of Medicine, University of Iowa, Iowa City, Iowa; Neuroscience Graduate Program, College of Medicine, University of Iowa, Iowa City, Iowa
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Chen IF, Khan J, Noma N, Hadlaq E, Teich S, Benoliel R, Eliav E. Anti-nociceptive effect of IL-12p40 in a rat model of neuropathic pain. Cytokine 2013; 62:401-6. [DOI: 10.1016/j.cyto.2013.03.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 02/13/2013] [Accepted: 03/18/2013] [Indexed: 11/26/2022]
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Abstract
Musculoskeletal pain conditions, particularly those associated with temporomandibular disorders (TMD) affect a large percentage of the population. Identifying mechanisms underlying hyperalgesia could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. In this study, we provide evidence of functional interactions between two ligand-gated channels, P2X₃ and transient receptor potential V1 (TRPV1), in trigeminal sensory neurons, and propose that the interactions serve as an underlying mechanism for the development of mechanical hyperalgesia. Mechanical sensitivity of the masseter muscle was assessed in lightly anesthetized rats via an electronic anesthesiometer (Ro et al., 2009). Direct intramuscular injection of a selective P2X₃ agonist, alpha,beta-methylene adenosine triphosphate (αβmeATP), induced a dose- and time-dependent hyperalgesia. Mechanical sensitivity in the contralateral muscle was unaffected suggesting local P2X₃ mediate hyperalgesia. Anesthetizing the overlying skin had no effect on αβmeATP-induced hyperalgesia confirming the contribution of P2X₃ from the muscle. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810. P2X₃ was co-expressed with TRPV1 in the masseter muscle afferents confirming the possibility for intracellular interactions. Additionally, in a subpopulation of P2Xv/TRPV1 positive neurons, capsaicin-induced Ca(2+) transients were significantly amplified following P2X₃ activation. Finally, activation of P2X₃ induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal ganglia cultures. Significant phosphorylation was observed at 15 min, the time point at which behavioral hyperalgesia was prominent. Previously, activation of either P2X₃ or TRPV1 had been independently implicated in the development of mechanical hyperalgesia. Our data propose P2X₃ and TRPV1 interact in a facilitatory manner, which could contribute to the peripheral sensitization known to underlie masseter hyperalgesia.
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Jeon HJ, Han SR, Park MK, Yang KY, Bae YC, Ahn DK. A novel trigeminal neuropathic pain model: compression of the trigeminal nerve root produces prolonged nociception in rats. Prog Neuropsychopharmacol Biol Psychiatry 2012; 38:149-58. [PMID: 22449477 DOI: 10.1016/j.pnpbp.2012.03.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 03/06/2012] [Accepted: 03/06/2012] [Indexed: 12/13/2022]
Abstract
We demonstrate the establishment of a novel animal model for trigeminal neuropathic pain following compression of the trigeminal nerve root, which produces prolonged nociceptive behavior and demyelination of the trigeminal nerve root. Under anesthesia, male Sprague-Dawley rats (200-230 g) were mounted onto a stereotaxic frame and injections of a 4% agar solution (10 μl) were given to achieve compression of the trigeminal nerve root. A sham operation was performed using identical procedures but without agar injections. Nociceptive behavior was examined 3 days before and then at 3, 7, 10, 14, 17, 21, 24, 30, 40, 55, and 70 days after the surgery. Compression of the trigeminal nerve root caused mechanical allodynia, hyperalgesia, and cold hypersensitivity. Mechanical allodynia was established within 3 days and recovered to preoperative levels on postoperative day (POD) 40. Mechanical hyperalgesia and cold hypersensitivity persisted until 55 days following compression. The compression produced focal demyelination in the trigeminal nerve root. In the medullary dorsal horn, phospho-p38 (p-p38) mitogen-activated protein kinase (MAPK) was found to be exclusively expressed in the microglia on POD 14. Furthermore, intraperitoneal administration of carbamazepine (50mg/kg) significantly blocked mechanical allodynia and reduced p38 MAPK activation induced by the compression of the trigeminal nerve root. Our findings suggest that prolonged nociceptive behavior following compression of the trigeminal nerve root may mimic trigeminal neuralgia in this animal model and that the activation of p38 MAPK in the microglia contributes to pain hypersensitivity in rats that have undergone compression of the trigeminal nerve root.
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Affiliation(s)
- Hye J Jeon
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea
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Cumella J, Hernández-Folgado L, Girón R, Sánchez E, Morales P, Hurst DP, Gómez-Cañas M, Gómez-Ruiz M, Pinto DCGA, Goya P, Reggio PH, Martin MI, Fernández-Ruiz J, Silva AMS, Jagerovic N. Chromenopyrazoles: non-psychoactive and selective CB₁ cannabinoid agonists with peripheral antinociceptive properties. ChemMedChem 2012; 7:452-63. [PMID: 22302767 DOI: 10.1002/cmdc.201100568] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/18/2012] [Indexed: 01/01/2023]
Abstract
The unwanted psychoactive effects of cannabinoid receptor agonists have limited their development as medicines. These CB₁-mediated side effects are due to the fact that CB₁ receptors are largely expressed in the central nervous system (CNS). As it is known that CB₁ receptors are also located peripherally, there is growing interest in targeting cannabinoid receptors located outside the brain. A library of chromenopyrazoles designed analogously to the classical cannabinoid cannabinol were synthesized, characterized, and tested for cannabinoid activity. Radioligand binding assays were used to determine their affinities at CB₁ and CB₂ receptors. Structural features required for CB₁/CB₂ affinity and selectivity were explored by molecular modeling. Some compounds in the chromenopyrazole series were observed to be selective CB₁ ligands. These modeling studies suggest that full CB₁ selectivity over CB₂ can be explained by the presence of a pyrazole ring in the structure. The functional activities of selected chromenopyrazoles were evaluated in isolated tissues. In vivo behavioral tests were then carried out on the most effective CB₁ cannabinoid agonist, 13 a. Chromenopyrazole 13 a did not induce modifications in any of the tested parameters on the mouse cannabinoid tetrad, thus discounting CNS-mediated effects. This lack of agonistic activity in the CNS suggests that this compound does not readily cross the blood-brain barrier. Moreover, 13 a can induce antinociception in a rat peripheral model of orofacial pain. Taking into account the negative results obtained with the hot-plate test, the antinociception induced by 13 a in the orofacial test could be mediated through peripheral mechanisms.
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Affiliation(s)
- Jose Cumella
- Instituto de Química Médica, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
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Ahn DK, Lim EJ, Kim BC, Yang GY, Lee MK, Ju JS, Han SR, Bae YC. Compression of the trigeminal ganglion produces prolonged nociceptive behavior in rats. Eur J Pain 2012; 13:568-75. [DOI: 10.1016/j.ejpain.2008.07.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 07/14/2008] [Accepted: 07/27/2008] [Indexed: 10/21/2022]
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12
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Jeon HJ, Han SR, Lim KH, Won KA, Bae YC, Ahn DK. Intracisternal administration of NR2 subunit antagonists attenuates the nociceptive behavior and p-p38 MAPK expression produced by compression of the trigeminal nerve root. Mol Pain 2011; 7:46. [PMID: 21651766 PMCID: PMC3123587 DOI: 10.1186/1744-8069-7-46] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 06/08/2011] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND We investigated the role of the central NMDA receptor NR2 subunits in the modulation of nociceptive behavior and p-p38 MAPK expression in a rat model with compression of the trigeminal nerve root. To address this possibility, changes in air-puff thresholds and pin-prick scores were determined following an intracisternal administration of NR2 subunit antagonists. We also examined effects of NR2 subunit antagonists on the p-p38 MAPK expression. RESULTS Experiments were carried out using male Sprague-Dawley rats weighing (200-230 g). Compression of the trigeminal nerve root was performed under pentobarbital sodium (40 mg/kg) anesthesia. Compression of the trigeminal nerve root produced distinct nociceptive behavior such as mechanical allodynia and hyperalgesia. Intracisternal administration of 10 or 20 μg of D-AP5 significantly increased the air-puff threshold and decreased the pin-prick scores in a dose-dependent manner. The intracisternal administration of PPPA (1, 10 μg), or PPDA (5, 10 μg) increased the air-puff threshold and decreased the pin-prick scores ipsilateral as well as contralateral to the compression of the trigeminal root. Compression of the trigeminal nerve root upregulated the expression of p-p38 MAPK in the ipsilateral medullary dorsal horn which was diminished by D-AP5, PPPA, PPDA, but not Ro25-6981. CONCLUSIONS Our findings suggest that central NMDA receptor NR2 subunits play an important role in the central processing of trigeminal neuralgia-like nociception in rats with compression of the trigeminal nerve root. Our data further indicate that the targeted blockade of NR2 subunits is a potentially important new treatments strategy for trigeminal neuralgia-like nociception.
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Affiliation(s)
- Hye J Jeon
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea.
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Saloman JL, Niu KY, Ro JY. Activation of peripheral delta-opioid receptors leads to anti-hyperalgesic responses in the masseter muscle of male and female rats. Neuroscience 2011; 190:379-85. [PMID: 21664434 DOI: 10.1016/j.neuroscience.2011.05.062] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 05/23/2011] [Accepted: 05/25/2011] [Indexed: 11/18/2022]
Abstract
In this project, we examined peripheral δ-opioid receptor (DOR)-mediated anti-hyperalgesic responses in the context of an acute orofacial muscle pain condition in both male and female rats. We also investigated whether the ATP-sensitive K+ channel (KATP), a downstream target of OR signaling, contributes to DOR-mediated anti-hyperalgesic responses. Local pretreatment of the masseter with a DOR agonist, [D-Pen², D-Pen⁶]-enkephalin (DPDPE), dose-dependently attenuated capsaicin-induced mechanical hypersensitivity in both male and female rats. However, there were sex differences in the potency of local DPDPE in that a 10-fold higher dose of DPDPE was required in female rats to produce the level of anti-hyperalgesia achieved in male rats. The sex differences in the DPDPE effect may not be fully explained by DOR expression level since there was no significant sex difference in DOR mRNA levels in trigeminal ganglia (TG). Finally, pretreatment of the masseter with the KATP antagonist, glibenclamide, significantly blocked the effects of DPDPE in male rats suggesting that the peripheral DOR effect is mediated by the KATP. These studies revealed novel information about sex differences with regards to peripherally localized DOR-mediated anti-hyperalgesia under an orofacial muscle pain condition.
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Affiliation(s)
- J L Saloman
- Program in Neuroscience, Department of Neural and Pain Sciences, University of Maryland Baltimore School of Dentistry, 650 W. Baltimore Street, Baltimore, MD 21201, USA
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Niu K, Saloman JL, Zhang Y, Ro JY. Sex differences in the contribution of ATP-sensitive K+ channels in trigeminal ganglia under an acute muscle pain condition. Neuroscience 2011; 180:344-52. [PMID: 21296645 DOI: 10.1016/j.neuroscience.2011.01.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 01/20/2011] [Accepted: 01/20/2011] [Indexed: 11/25/2022]
Abstract
In this study, we examined whether functional subunits of the ATP-dependent K+ channel (KATP) are expressed in trigeminal ganglia (TG), which contains sensory neurons that innervate oral and facial structures. We also investigated whether direct activation of the KATP effectively attenuates mechanical hypersensitivity in the context of an acute orofacial muscle pain condition. The KATP expression in TG and behavioral studies were conducted in age matched male and female Sprague-Dawley rats. RT-PCR experiments showed that the mRNAs for the inwardly rectifying pore-forming subunits, Kir6.1 and Kir6.2, as well as the regulatory sulfonylurea subunits, SUR1 and SUR2, were reliably detected in TG. Subsequent western blot analysis confirmed that proteins for all four subunits are expressed in TG, and showed that Kir6.2 is expressed at a significantly higher level in male TG compared to that of female rats. This observation was confirmed by the immunohistochemical demonstration of higher percentages of Kir6 positive masseter afferents in female rats. Masseteric injection of capsaicin evokes a time dependent increase in masseter sensitivity to noxious mechanical stimulation. A specific KATP agonist, pinacidil, dose-dependently attenuated the capsaicin-induced mechanical hypersensitivity in male rats. The dose of pinacidil (20 μg) that completely blocked the capsaicin responses in male rats was ineffective in female rats regardless of their estrus phases. Only at the highest dose (300 μg) we used, pinacidil was partially effective in female rats. Similarly, another KATP agonist, diazoxide which targets different KATP subunits also showed sex specific responses in attenuating capsaicin-induced masseter hypersensitivity. These data suggested that sex differences in functional KATP expression in TG may underlie sex specific responses to KATP agonists. The present study provided novel information on sex differences in KATP expression in TG and its contribution under an orofacial muscle pain condition.
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Affiliation(s)
- K Niu
- Program in Neuroscience, Department of Neural and Pain Sciences, University of Maryland Baltimore School of Dentistry, 650 West Baltimore Street, Baltimore, MD 21201, USA
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15
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Sánchez EM, Bagües A, Martín MI. Contributions of peripheral and central opioid receptors to antinociception in rat muscle pain models. Pharmacol Biochem Behav 2010; 96:488-95. [PMID: 20637793 DOI: 10.1016/j.pbb.2010.07.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 06/17/2010] [Accepted: 07/09/2010] [Indexed: 11/18/2022]
Abstract
Administration of hypertonic saline (HS) is an accepted model to study muscular pain. HS-induced nociceptive responses were tested in masseter, already described, and in two new pain models of spinally innervated muscles (gastrocnemius and triceps) developed in rats at our laboratory. HS administration in the masseter induced vigorous hindpaw shaking and in the gastrocnemius or triceps, paw withdrawal or flexing. Participation of the central and peripheral opioid receptors in HS-induced pain is compared in these muscles: masseter, innervated by trigeminal nerve, and gastrocnemius and triceps by spinal nerves. Morphine and loperamide were used to reveal peripheral and central components of opioid analgesia. Both agonists reduced HS-induced nociceptive behaviours in the masseter and were antagonised by the opioid antagonist naloxone and by naloxone methiodide, an opioid receptor antagonist that poorly penetrates the blood-brain barrier. Unexpectedly, in the gastrocnemius and triceps, morphine, but not loperamide, decreased the nociceptive behaviour and this effect was only reversed by naloxone. So, peripheral opioid receptors seem to participate in HS-induced masseter pain, whereas only central opioid receptors reduced the nociception in gastrocnemius and triceps. Our results suggest that the use of peripheral opioids can be more advantageous than central opioids for treatment of orofacial muscular pain.
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Affiliation(s)
- Eva Ma Sánchez
- Departamento de Farmacología y Nutrición, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Madrid, Spain.
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Morphine peripheral analgesia depends on activation of the PI3Kgamma/AKT/nNOS/NO/KATP signaling pathway. Proc Natl Acad Sci U S A 2010; 107:4442-7. [PMID: 20147620 DOI: 10.1073/pnas.0914733107] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Morphine is one of the most prescribed and effective drugs used for the treatment of acute and chronic pain conditions. In addition to its central effects, morphine can also produce peripheral analgesia. However, the mechanisms underlying this peripheral action of morphine have not yet been fully elucidated. Here, we show that the peripheral antinociceptive effect of morphine is lost in neuronal nitric-oxide synthase null mice and that morphine induces the production of nitric oxide in primary nociceptive neurons. The activation of the nitric-oxide pathway by morphine was dependent on an initial stimulation of PI3Kgamma/AKT protein kinase B (AKT) and culminated in increased activation of K(ATP) channels. In the latter, this intracellular signaling pathway might cause a hyperpolarization of nociceptive neurons, and it is fundamental for the direct blockade of inflammatory pain by morphine. This understanding offers new targets for analgesic drug development.
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Abstract
This paper is the 31st consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2008 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 and thermoregulation (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, 65-30 Kissena Blvd, Flushing, NY 11367, United States.
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Jeong Y, Holden JE. Lateral Hypothalamic-Induced Alpha-Adrenoceptor Modulation Occurs in a Model of Inflammatory Pain in Rats. Biol Res Nurs 2009; 10:331-9. [DOI: 10.1177/1099800408325053] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Previous work from our lab showed that stimulation of the lateral hypothalamus (LH) produces analgesia (antinociception) in a model of thermal nociceptive pain. This antinociceptive effect is mediated by α2-adrenoceptors in the spinal cord dorsal horn. However, a concomitant, opposing hyperalgesic (pro-nociceptive) response also occurs, which is mediated by α1-adrenoceptors in the dorsal horn. Antinociception predominates but is attenuated by the pronociceptive response. To determine whether such an effect occurs in a model of inflammatory pain, we applied mustard oil (allyl isothiocyanate; 20 μl) to the left ankle of female Sprague-Dawley rats. We then stimulated the LH using carbamylcholine chloride (carbachol; 125 nmol). The foot withdrawal latencies were measured. Some rats received intrathecal α-adrenoceptor antagonists to determine whether the opposing α-adrenoceptor response was present. Mustard oil application produced hyperalgesia in the affected paw, while the LH stimulation increased the foot withdrawal latencies for the mustard oil paw as compared to the control group. Following carbachol microinjection in the LH, WB4101, an α1-adrenoceptor antagonist, produced significantly longer foot withdrawal latencies compared to saline controls, while yohimbine, an α2-antagonist, decreased the foot withdrawal latencies from 10 min postinjection ( p < .05). These findings support the hypothesis that the LH-induced nociceptive modulation is mediated through an α-adrenoceptor opposing response in a model of inflammatory pain.
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Affiliation(s)
- Younhee Jeong
- College of Nursing Science, Kyunghee University, Seoul,
Korea
| | - Janean E. Holden
- University of Illinois at Chicago, and Department of
Medical-Surgical Nursing, College of Nursing, Chicago, Illinois,
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