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Zhao Q, He G, Zhang Z, Li Z. Efficacy and safety of acupuncture for trigeminal neuralgia: A protocol for systematic review and meta-analysis. Medicine (Baltimore) 2020; 99:e22589. [PMID: 33019477 PMCID: PMC7535756 DOI: 10.1097/md.0000000000022589] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Trigeminal neuralgia (TN) is a disease accompanied by severe facial pain, which seriously affects the daily life of patients. Acupuncture is widely used by Traditional Chinese Medicine doctors to treat various painful diseases. Acupuncture combined with the treatment of trigeminal neuralgia can increase the analgesic effect and reduce side effects. However, there is still a lack of more quality multi-center clinical controlled trials and comprehensive meta-analysis, and a lack of more comprehensive and stronger evidence-based medical evidence. METHODS The 2 reviewers used the same search strategy to search CNKI, PubMed, Web of Science, Cochrane Library, Scopus, EBSCO, and the search date is until July 19, 2020. Two people read the retrieved literatures independently, and then delete duplications. Then, use the "risk of bias" tool in Cochrane Handbook 5.2 to score. Only documents with a score greater than 5 can be included. Make a table of literature characteristics, extract baseline patient data, research methods and possible risks of bias in the literature, interventions in treatment and control groups, outcome evaluation indicators (BNI, VAS, ER and AE), and research funding support. Use Review Manager 5.3.5 for meta-analysis, use Stata 15 for regression analysis to find the source of heterogeneity, and then perform subgroup analysis to resolve the heterogeneity based on the corresponding source. RESULTS The analysis of BNI, VAS, ER and AE data can provide high-quality evidence for high-quality synthesis and/or descriptive analysis of the effectiveness and safety of acupuncture treatment of various causes of urinary retention. CONCLUSION This study can provide more comprehensive and strong evidence to prove whether acupuncture is effective and safe in the treatment of TN patients. REGISTRATION The research has been registered and approved on the PROSPERO website. The registration number is CRD42019119606.
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Affiliation(s)
- Qinyu Zhao
- College of Acupuncture and Tuina, Shandong University of Traditional Chinese Medicine, Shandong
| | | | | | - Zhanbiao Li
- Pain Department, Liaocheng People's Hospital, Liaocheng, Shandong, PR China
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2
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The differential profiles of withdrawal symptoms induced by morphine and beta-endorphin administered intracerebroventricularly in mice. Neuroscience 2012; 218:216-25. [DOI: 10.1016/j.neuroscience.2012.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 04/27/2012] [Accepted: 05/07/2012] [Indexed: 11/20/2022]
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3
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Characterization of blood glucose level regulation in mouse opioid withdrawal models. Neurosci Lett 2010; 476:119-22. [DOI: 10.1016/j.neulet.2010.03.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 03/04/2010] [Accepted: 03/04/2010] [Indexed: 11/21/2022]
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4
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Seo YJ, Kwon MS, Choi SM, Lee JK, Park SH, Jung JS, Sim YB, Suh HW. Possible involvement of the hypothalamic pro-opiomelanocortin gene and beta-endorphin expression on acute morphine withdrawal development. Brain Res Bull 2009; 80:359-70. [PMID: 19723567 DOI: 10.1016/j.brainresbull.2009.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 08/13/2009] [Accepted: 08/25/2009] [Indexed: 11/18/2022]
Abstract
We studied the effects of supraspinally administered morphine on the expression of the hypothalamic pro-opiomelanocortin (POMC) gene and beta-endorphin. Mice were administered morphine intracerebroventricularly (i.c.v.) either once or 5 times for 5 days (once/day). A single morphine administration significantly increased the hypothalamic POMC gene and beta-endorphin expression at 2h after application in dose-dependent fashion; however, repeated morphine administration had no effect on the hypothalamic POMC gene and beta-endorphin expression. In the immunoblot and immunohistochemical study, the increase of beta-endorphin was observed in the arcuate nucleus of the hypothalamus. Moreover, the expressions of c-Fos, phosphorylated calcium/calmodulin-dependent protein kinase-IIalpha (pCaMK-IIalpha), and phosphorylated cAMP response element-binding protein (pCREB) were increased by a single i.c.v. morphine injection at various time points, but the expressions of phosphorylated extracellular signal-regulated protein kinase1/2 (pERK1/2) and phosphorylated IkappaB (pIkappaB) were not. We also found that the expressions of c-Fos, pCaMKIIalpha, and pCREB were co-localized with the POMC expression. Meanwhile, naloxone as well as muscimol and baclofen significantly attenuated the increases of the POMC gene expression induced by a single morphine administration. Furthermore, the pretreatment of muscimol and baclofen 10 min before morphine injection robustly attenuated the withdrawal behavior induced by a single morphine administration. These results imply that the hypothalamic POMC gene and beta-endorphin expression may play an important role in the development of an acute physical dependency of morphine. In that, GABAergic neurotransmission appear to be involved in the regulation of the hypothalamic POMC gene expression induced by supraspinal morphine administration.
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Affiliation(s)
- Young-Jun Seo
- Advanced Therapy Products Research Division, National Institute of Food and Drug Safety Evaluation, Korea Food and Drug Administration, 194 Tongilro, Eunpyeong-gu, Seoul 122-704, Republic of Korea
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5
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Zarrindast MR, Ghadimi M, Ramezani-Tehrani B, Sahebgharani M. EFFECT OF GABA RECEPTOR AGONISTS OR ANTAGONISTS ON MORPHINE-INDUCED STRAUB TAIL IN MICE. Int J Neurosci 2009; 116:963-73. [PMID: 16861161 DOI: 10.1080/00207450600550428] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The effects of GABA receptor agents on Straub tail induced by morphine were investigated in mice. Subcutaneous injection of different doses of morphine (10-60 mg/kg) induced a dose-dependent Straub tail in mice. Maximum response was obtained with 40 mg/kg of the drug, 30 min after the drug administration. The morphine response was decreased by subcutaneous injection of naloxone (0.5-2 mg/kg). Intraperitoneal administration of different doses of baclofen (2-8 mg/kg) reduced Straub tail induced by morphine (40 mg/kg). The response of baclofen was decreased by Intraperitoneal injection of CGP35348 (150 mg/kg). CGP35348 by itself did not elicit any response. Different Intraperitoneally doses of muscimol (1-4 mg/kg) bicuculline (1-3 mg/kg), or picrotoxin (1-3 mg/kg) also reduced morphine effect. The effect of muscimol was not altered by bicuculline pretreatment. It is concluded that both GABAA and GABAB receptor activation reduced Straub tail induced by morphine.
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Affiliation(s)
- M R Zarrindast
- Department of Pharmacology, Medical School, Tehran University of Medical Sciences, Iran.
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6
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Anseloni VCZ, Gold MS. Inflammation-induced shift in the valence of spinal GABA-A receptor-mediated modulation of nociception in the adult rat. THE JOURNAL OF PAIN 2008; 9:732-8. [PMID: 18467182 DOI: 10.1016/j.jpain.2008.03.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 03/11/2008] [Accepted: 03/12/2008] [Indexed: 11/18/2022]
Abstract
UNLABELLED The objective of this study was to assess the impact of persistent inflammation on spinal gamma-aminobutyric acid-A (GABA-A) receptor-mediated modulation of evoked nociceptive behavior in the adult rat. Nocifensive threshold was assessed with von Frey filaments applied to the dorsal surface of the hind paw. The GABA-A receptor agonist muscimol, the antagonist gabazine, the benzodiazepine receptor agonist midazolam, and antagonists PK11195 and flumazenil were administered spinally in the presence and absence of complete Freund's adjuvant (CFA)-induced inflammation. In naive rats, muscimol increased and gabazine decreased nociceptive threshold. After CFA, the effects of these compounds were reversed: Low doses of muscimol exacerbated the inflammation-induced decrease in nociceptive threshold and gabazine increased nociceptive threshold. Midazolam increased nociceptive threshold both in the presence and absence of inflammation. Flumazenil but not PK11195 blocked the analgesic effects of midazolam. These findings indicate that inflammation-induced changes in GABA-A signaling are complex and are likely to involve several distinct mechanisms. Rectifying the changes in GABA-A signaling may provide effective relief from hypersensitivity observed in the presence of inflammation. PERSPECTIVE An inflammation-induced shift in spinal GABA-A receptor signaling from inhibition to excitation appears to underlie inflammatory pain and hypersensitivity. Use of GABA-A receptor selective general anesthetics in association with therapeutic interventions may be contraindicated. More importantly, rectifying the changes in GABA-A signaling may provide effective relief from inflammatory hypersensitivity.
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Affiliation(s)
- Vanessa C Z Anseloni
- Department of Biomedical Sciences, School of Dentistry, Baltimore, Maryland, USA
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Neto FL, Ferreira-Gomes J, Castro-Lopes JM. Distribution of GABA Receptors in the Thalamus and Their Involvement in Nociception. GABA 2006; 54:29-51. [PMID: 17175809 DOI: 10.1016/s1054-3589(06)54002-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Fani L Neto
- Institute of Histology and Embryology, Faculty of Medicine of Porto and IBMC, 4200-319 Porto, Portugal
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Hurley RW, Banfor P, Hammond DL. Spinal pharmacology of antinociception produced by microinjection of mu or delta opioid receptor agonists in the ventromedial medulla of the rat. Neuroscience 2003; 118:789-96. [PMID: 12710986 DOI: 10.1016/s0306-4522(03)00041-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study examined the role of spinal GABAergic, serotoninergic and alpha(2) adrenergic receptors in the antinociception produced by the microinjection of equi-antinociceptive doses of selective opioid receptor agonists in the nucleus raphe magnus (NRM) or the nucleus reticularis gigantocellularis pars alpha (NGCpalpha) of the rat. Rats were pretreated with intrathecal administration of either the GABA(A) receptor antagonist bicuculline, the GABA(B) receptor antagonist CGP35348, the serotonin(1/2) receptor antagonist methysergide, the alpha(2) adrenergic receptor antagonist yohimbine or saline. Ten minutes later, either the delta(1) opioid receptor agonist [D-Pen(2,5)]enkephalin (DPDPE), delta(2) opioid receptor agonist [D-Ala(2),Glu(4)]deltorphin (DELT) or mu opioid receptor agonist [D-Ala(2),NMePhe(4),Gly-ol(5)]enkephalin (DAMGO) was microinjected into the NRM, NGCpalpha or sites in the medulla outside these two regions. The increase in tail-flick latency produced by microinjection of DPDPE into the NRM or NGCpalpha was antagonized by intrathecal pretreatment with either methysergide or yohimbine. Intrathecal pretreatment with CGP35348 antagonized the antinociception produced by microinjection of DPDPE in the NRM, whereas bicuculline antagonized the antinociception produced by microinjection of DPDPE in the NGCpalpha. The increase in tail-flick latency produced by microinjection of DELT into the NGCpalpha, but not the NRM was antagonized by intrathecal pretreatment with yohimbine or CGP35348. Intrathecal pretreatment with methysergide or bicuculline did not antagonize the antinociception produced by microinjection of DELT into either the NRM or the NGCpalpha. The increase in tail-flick latency produced by microinjection of DAMGO in the NRM was antagonized by intrathecal pretreatment with methysergide or CGP35348, but not by bicuculline or yohimbine. Taken together, these results support the hypothesis that the antinociception produced by activation of delta(1), delta(2) or mu opioid receptors in the rostral ventromedial medulla is mediated by different neural substrates.
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MESH Headings
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Drug Interactions/physiology
- Efferent Pathways/cytology
- Efferent Pathways/drug effects
- Efferent Pathways/metabolism
- GABA Antagonists/pharmacology
- Male
- Medulla Oblongata/cytology
- Medulla Oblongata/drug effects
- Medulla Oblongata/metabolism
- Narcotics/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Nociceptors/drug effects
- Nociceptors/metabolism
- Pain/metabolism
- Pain/physiopathology
- Rats
- Rats, Sprague-Dawley
- Reaction Time/drug effects
- Reaction Time/physiology
- Receptors, GABA/drug effects
- Receptors, GABA/metabolism
- Receptors, Opioid/agonists
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
- Serotonin Antagonists/pharmacology
- Spinal Cord/cytology
- Spinal Cord/drug effects
- Spinal Cord/metabolism
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Affiliation(s)
- R W Hurley
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, IL 60637, USA
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9
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Abstract
OBJECTIVE To outline the modes of action of topiramate and to examine the theoretical reasons as to why topiramate may alleviate neuropathic pain. Results of animal and human studies in the use of topiramate for treating pain are reviewed, together with case studies describing situations where topiramate was effective when other treatments have failed. CONCLUSIONS Topiramate acts on neuronal transmission in at least five ways: by modulating voltage-gated sodium ion channels, potentiating gamma-aminobutyric acid inhibition, blocking excitatory glutamate neurotransmission, modulating voltage-gated calcium ion channels, and by inhibiting carbonic anhydrase. This review suggests that there are good theoretical reasons for a trial of topiramate in patients with neuropathic pain where conventional medical treatments have failed. Although not currently licensed for treating pain, topiramate should be considered before invasive methods of pain relief are contemplated. Most of the side effects of topiramate are dose dependent, but by starting medication with a low dose (</=25 mg/d) that is gradually titrated upward, tolerance is much more easily achieved.
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Affiliation(s)
- M S Chong
- The Medway Hospitals NHS Trust, Gillingham, United Kingdom.
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10
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Abstract
Among the opioid receptors, which have been pharmacologically classified as mu, delta, kappa and epsilon, the existence of the epsilon receptor has been controversial, and this receptor is generally not recognized as a member of the opioid peptide receptor family because it has not been precisely characterized. However, results from pharmacological, physiological and opioid receptor binding studies clearly indicate the presence of epsilon-opioid receptors, which are distinct from mu-, delta- or kappa-opioid receptors. This putative epsilon-opioid receptor is stimulated supraspinally by the endogenous opioid peptide beta-endorphin, which induces the release of Met-enkephalin, which, in turn, acts on spinal delta2-opioid receptors to produce antinociception. In this article, this beta-endorphin-sensitive epsilon-opioid receptor-mediated descending pain control system, which is distinct from that activated by the mu-opioid receptor agonist morphine, is described and the physiological role of the beta-endorphin-mediated system in pain control activated by cold-water swimming and intraplantar injection of formalin is discussed.
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Affiliation(s)
- L F Tseng
- Dept of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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11
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Suh HW, Song DK, Huh SO, Lee KC, Kim YH. Differential potentiative effects of GABA receptor agonists in the production of antinociception induced by morphine and beta-endorphin administered intrathecally in the mouse. Life Sci 2000; 66:PL61-9. [PMID: 10665991 DOI: 10.1016/s0024-3205(99)00601-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effect of muscimol or baclofen injected intrathecally (i.t.) on the inhibition of the tail-flick response induced by morphine and beta-endorphin administered i.t. was studied in ICR mice. The i.t. injection of muscimol (100 ng) or baclofen (10 ng) alone did not affect the basal inhibition of the tail-flick response. Morphine (0.2 microg) and beta-endorphin (0.1 microg) caused only slight inhibition of the tail-flick response. Baclofen, but not muscimol, injected i.t. enhanced the inhibition of the tail-flick response induced by i.t. administered morphine. Both muscimol and baclofen injected i.t. significantly enhanced i.t. injected beta-endorphin-induced inhibition of the tail-flick response. Our results suggest that the GABA(B), but not GABA(A), receptors located in the spinal cord appear to be involved in enhancing the inhibition of the tail-flick response induced by morphine administered spinally. In addition, both GABA(A) and GABA(B) receptors are involved in enhancing the inhibition of the tail-flick response induced by beta-endorphin administered i.t.
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Affiliation(s)
- H W Suh
- Department of Pharmacology, Institute of Natural Medicine, College of Medicine, Hallym University, Chunchon, Kangwon-Do, South Korea.
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12
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Ugarte SD, Homanics GE, Firestone LL, Hammond DL. Sensory thresholds and the antinociceptive effects of GABA receptor agonists in mice lacking the beta3 subunit of the GABA(A) receptor. Neuroscience 2000; 95:795-806. [PMID: 10670447 DOI: 10.1016/s0306-4522(99)00481-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A line of mice was recently created in which the gabrb3 gene, which encodes the beta3 subunit of the GABA(A) receptor, was inactivated by gene-targeting. The existence of mice with a significantly reduced population of GABA(A) receptors in the CNS enabled an investigation of the role of GABA and GABA(A) receptors in nociception. The present study examined the sensory thresholds of these mice, as well as the antinociceptive effects of subcutaneously or intrathecally administered GABA(A) and GABA(B) receptor agonists. Homozygous null (beta3-/-) mice displayed enhanced responsiveness to low-intensity thermal stimuli in the tail-flick and hot-plate test compared to C57BL/6J and 129/SvJ progenitor strain mice, and their wild-type (beta3+/+) and heterozygous (beta3+/-) littermates. The beta3-/- mice also exhibited enhanced responsiveness to innocuous tactile stimuli compared to C57BL/6J, 129/SvJ and to their beta3+/+ littermates as assessed by von Frey filaments. The presence of thermal hyperalgesia and tactile allodynia in beta3-/- mice is consistent with a loss of inhibition mediated by presynaptic and postsynaptic GABA(A) receptors in the spinal cord. As expected, subcutaneous administration of the GABA(A) receptor agonist 4,5,6,7-tetrahydroisoxazolo-(5,4-c)pyridin-3-ol did not produce antinociception in beta3-/- mice, whereas it produced a dose-dependent increase in hot-plate latency in C57BL/6J, 129/SvJ, beta3+/+ and beta3+/- mice. However, the antinociceptive effect of the GABA(B) receptor agonist baclofen in the tail-flick and hot-plate tests was also reduced in beta3-/- mice compared to the progenitor strains, beta3+/+ or beta3+/- mice after either subcutaneous or intrathecal administration. This finding was unexpected and suggests that a reduction in GABA(A) receptors can affect the production of antinociception by other analgesic drugs as well.
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Affiliation(s)
- S D Ugarte
- Department of Anesthesia and Critical Care, University of Chicago, Illinois, USA
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Maione S, Oliva P, Marabese I, Palazzo E, Rossi F, Berrino L, Filippelli A. Periaqueductal gray matter metabotropic glutamate receptors modulate formalin-induced nociception. Pain 2000; 85:183-9. [PMID: 10692617 DOI: 10.1016/s0304-3959(99)00269-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The role played by periaqueductal gray (PAG) matter metabotropic glutamate receptors (mGluRs) in the modulation of persistent noxious stimulation was investigated in mice. The formalin test was used as a model of persistent pain. Intra-PAG microinjections of (S)-3, 5-DHPG (25 and 50 nmol/mouse) and L-CCG-I (30 and 60 nmol/mouse), agonists of group I and group II mGluRs, respectively, decreased the nociceptive response (-92+/-6% and -89+/-8%, respectively) during the late phase. No change of the early nociceptive phase was observed after (S)-3,5-DHPG or L-CCG-I treatments. These effects were antagonized by a pretreatment with CPCCOEt (40 nmol/mouse) and (2S)-alpha-EGlu (30 nmol/mouse). CPCCOEt is a selective antagonist of group I mGlu receptors, while (2S)-alpha-EGlu is an antagonist of group II. Intra-PAG microinjections of L-SOP (60 and 120 nmol/mouse), a selective agonist of group III mGluRs, induced an increase of the nociceptive response (+95+/-7%) during the late hyperalgesic phase. (R,S)-alpha-M-SOP (70 nmol/mouse), a selective antagonist of group III mGluRs, completely antagonized the L-SOP-induced effect. These results show that PAG mGluRs participate in modulating the late hyperalgesic behaviours induced by formalin. It seems, therefore, possible that group I and group II mGluRs positively modulate PAG antinociceptive descending pathway following a persistent noxious stimulation, while group III mGluRs modulate it negatively.
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Affiliation(s)
- S Maione
- Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery, The Second University of Naples, Via Costantinopoli 16, 80138, Naples, Italy
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Chung KM, Kim YH, Song DK, Huh SO, Suh HW. Differential modulation by baclofen on antinociception induced by morphine and beta-endorphin administered intracerebroventricularly in the formalin test. Neuropeptides 1999; 33:534-41. [PMID: 10657537 DOI: 10.1054/npep.1999.0775] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Our previous studies have demonstrated that supraspinal GABAergic receptors are differentially involved in the antinociception induced by morphine and beta-endorphin given intracerebroventricularly (i.c.v.) in the tail-flick and hot-plate tests. These two models employed a phasic, thermal nociceptive stimulus. The present study was designed to examine the possible involvement of supraspinal GABAergic receptors in opioid-induced antinociception in the formalin test. Morphine (1 microg) and beta-endorphin (1 microg) given i.c.v. displayed the almost complete inhibitory effects against the hyperalgesic response in both phases. Muscimol (75-100 ng) and baclofen (5-10 ng) injected i.c.v. produced the hypoalgesic response in the both phases. The hypoalgesic response induced by muscimol and baclofen observed during the second phase was more pronounced than that observed during the second phase. Baclofen (2.5 ng), at the dose which did not affect the hyperalgesic response, resulted in a significant reversal of the i.c.v. administered beta-endorphin-induced hypoalgesic response observed during the second, but not the first, phase. However, the hypoalgesic response induced by i.c.v. administered morphine was not changed by the same dose of muscimol or baclofen injected i.c.v. Our results indicate that, at the supraspinal level, GABA(B)receptors appear to be involved in the modulation of antinociception induced by supraspinally administered beta-endorphin, but not morphine, in the formalin test model.
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Affiliation(s)
- K M Chung
- Department of Pharmacology, Institute of Natural Medicine, College of Medicine, Hallym University, Chunchon, Kangwon Do, South Korea
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