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Taguchi K, Suzuki Y. Effects of microiontophoretically-applied morphine on the Purkinje cell in the cerebellum of the cat. Neuropharmacology 1989; 28:235-42. [PMID: 2725850 DOI: 10.1016/0028-3908(89)90098-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of microiontophoretically-applied and pneumatically-applied morphine on the spontaneous discharge of Purkinje cells in the cerebellum of the anesthetized cat were examined. Microiontophoretic application of morphine produced both inhibitory and excitatory responses of the Purkinje cells. Pneumatic application of morphine produced similar effects to those of microiontophoresis. Both types of application of morphine induced dose-dependent responses. Excitatory responses were antagonized by naloxone (opiate antagonist), but inhibitory responses were not affected by naloxone, propranolol (beta-receptor antagonist) or methysergide (serotonin antagonist). Bicuculline and picrotoxin, GABA antagonists, abolished completely the morphine-induced inhibitory response. These results suggest that morphine-induced excitation is connected with the opiate system and that inhibition is related to the GABAergic system, in the cerebellum of the cat.
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Affiliation(s)
- K Taguchi
- Department of Pharmacology, Showa College of Pharmaceutical Sciences, Tokyo, Japan
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Abstract
In cats anaesthetized with chloralose, the effect of morphine on arterial blood pressure and heart rate was examined by injecting the drug through different routes. When injected into the cerebral ventricles, it acted on structures in the walls of the third ventricle and produced a naloxone resistant tachycardia through a sympathetic discharge to the heart. When injected into the cisterna magna or subcutaneously, it produced a naloxone sensitive long-lasting fall in blood pressure and bradycardia resulting from inhibition of sympathetic tone to blood vessels and heart; increased vagal tone played a minor role in the development of bradycardia. When injected intracisternally or subcutaneously, morphine acted near the obex at the dorsal surface of the medulla, because it produced the same circulatory effects but in much smaller doses when applied to this region on a piece of filter paper. Conversely, small doses of naloxone similarly applied abolished or prevented the circulatory effects of subcutaneous morphine. The action of morphine may be on the commissural nucleus of the tractus solitarius. Intravenous naloxone restored the circulatory effects of intracisternal and subcutaneous morphine and sometimes produced a pronounced overshoot, but without a preceding injection of morphine, naloxone had no effect on circulation. It is suggested that inhibition of sympathetic tone to the cardiovascular system by an action on structures near the obex is the mechanism by which morphine produces in man orthostatic hypotension and its beneficial effect in left ventricular failure.
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Jensen TS, Yaksh TL. Spinal monoamine and opiate systems partly mediate the antinociceptive effects produced by glutamate at brainstem sites. Brain Res 1984; 321:287-97. [PMID: 6149792 DOI: 10.1016/0006-8993(84)90181-1] [Citation(s) in RCA: 197] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The administration of the excitatory amino acid glutamate into the periaqueductal gray (PAG) or ventromedial medulla (VM) resulted in a reliable, short lasting elevation in the tail flick and hot plate response latencies in rats. The prior intrathecal administration of methysergide (30 micrograms) or phentolamine (30 micrograms) into the lumbar space produced a significant antagonism of the elevated tail flick reflex latencies evoked by glutamate given into the PAG and VM. Intrathecal naloxone (10 micrograms) significantly antagonized the effects on tail flick produced by VM, but not PAG, injections of glutamate. No intrathecal treatment significantly antagonized the effects of intracerebral glutamate on the supraspinally organized hot plate response. These results indicate that the excitation of glutamate-receptor linked systems in the PAG and VM exert a powerful antireflexive effect on spinal processing by the activation of spinopetal monoamine pathways, but that their mechanisms do not totally overlap as the VM systems also directly or indirectly activate a naloxone sensitive link in the spinal cord. The failure to antagonize the supraspinally organized hot plate response by intrathecal antagonists indicates that aside from an effect (if any) on spinal sensory processing, these brainstem systems may also act at the supraspinal level to actively modulate the animal's response to an otherwise aversive somatic stimulus.
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Bradley PB, Brookes A. A microiontophoretic study of the actions of mu-, delta- and kappa-opiate receptor agonists in the rat brain. Br J Pharmacol 1984; 83:763-72. [PMID: 6095962 PMCID: PMC1987086 DOI: 10.1111/j.1476-5381.1984.tb16231.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The actions of mu-, delta- and kappa-opiate receptor agonists have been compared on the activity of single neurones in the brain stem, caudate nucleus and hippocampus of the rat, using the technique of microiontophoresis. In the brain stem and caudate nucleus the predominant effect of all the opiate agonists tested was depression of neuronal activity which was antagonized by naloxone. The selectivity of naloxone as an opiate receptor antagonist was indicated by its lack of effect on gamma-aminobutyric acid (GABA)-induced responses. In the hippocampus both mu- and delta-agonists mainly caused an increase in neuronal firing rates, though some neurones were depressed. In contrast, all the kappa-agonists, including the proposed endogenous ligand for the kappa-receptor, dynorphin, caused depression of neuronal activity. All of these effects were antagonized by naloxone. There was a clear distinction in the areas within the hippocampus in which the mu- and delta-agonists produced different effects. Neurones in the pyramidal cell layer were always excited by these drugs, whereas neurones in the granule cell layer of the dentate gyrus were always depressed by the same drug.
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Prado WA, Roberts MH. Antinociception from a stereospecific action of morphine microinjected into the brainstem: a local or distant site of action? Br J Pharmacol 1984; 82:877-82. [PMID: 6478116 PMCID: PMC1986928 DOI: 10.1111/j.1476-5381.1984.tb16485.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Morphine (1 microgram) was microinjected into rats in the midline medullary nucleus raphe magnus (NRM); 1 mm lateral into nucleus reticularis paragigantocellularis (NRPG); 2 mm lateral into the VIIth nerve nucleus and 3 mm lateral into the Vth nerve nucleus. The time course of changes in the sensitivity to noxious heat was followed by the tail flick test. Significant and prolonged antinociception was seen following microinjection into NRPG. At sites 1 mm from NRPG very weak effects were seen and at 2 mm from NRPG no antinociception occurred. It is concluded that 1 microgram of morphine microinjected into the brainstem is unlikely to cause antinociception by entering the circulation and having effects at remote sites. The distance diffused by morphine to cause significant antinociception after microinjection of 1 microgram is less than 1 mm. Levorphanol (1 microgram) had very similar effects to morphine but dextrorphan and saline were ineffective. It is concluded that although the concentrations achieved following microinjections may be high, they are not excessive as the effects show stereospecificity. The concentrations of endogenous substances released into the synaptic cleft may also be high.
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Watkins LR, Young EG, Kinscheck IB, Mayer DJ. The neural basis of footshock analgesia: the role of specific ventral medullary nuclei. Brain Res 1983; 276:305-15. [PMID: 6627011 DOI: 10.1016/0006-8993(83)90738-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Previous studies have demonstrated that brief front paw shock produces opiate analgesia while brief hind paw shock produces non-opiate analgesia in rats. Additionally, front paw shock and hind paw shock can produce an opiate-mediated classically conditioned analgesia; that is, when shock is delivered to an animal, environmental cues become associated with this stimulus such that these cues become capable of producing potent opiate analgesia in the absence of shock. Investigations of the neural bases of these phenomena have revealed that front paw shock and classical conditioning lead to activation of supraspinal sites which mediate analgesia via descending pathways lying solely within the dorsolateral funiculus (DLF) of the spinal cord. Hind paw footshock induced analgesia (FSIA) is also mediated by a descending DLF pathway but is unlike front paw FSIA or classically conditioned analgesia in that it involves intraspinal pathways as well. The aim of the present series of experiments was to identify the supraspinal origin of the centrifugal DLF pathway mediating front paw (opiate) FSIA, hind paw (non-opiate) FSIA, and classically conditioned (opiate) analgesia. These studies examined the effect of electrolytic lesions of the nucleus raphe magnus (NRM), nucleus reticularis paragigantocellularis (PGC), and combined lesions of these two areas (nucleus raphe alatus, NRA) on these environmentally-induced analgesias. The results of this work indicate that the NRA is the origin of the spinal cord DLF pathway mediating front paw (opiate) FSIA and classically conditioned (opiate) analgesia. Hind paw (non-opiate) FSIA is also mediated, in part, by the NRA but must involve another, yet unidentified, brainstem site(s) as well.
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Hewson G, Bradley PB. The effects of anilidopiperidine analgesics on single respiratory and non-respiratory neurones in the brain stem of the rat. Life Sci 1982; 31:2335-8. [PMID: 6131360 DOI: 10.1016/0024-3205(82)90150-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The effects of four anilidopiperidine analgesics, fentanyl, sufentanil, lofentanil and alfentanil on the activity of single neurones in the rat brain stem were examined using the technique of microiontophoresis. Neurones whose discharge rate could be related to respiration and non-respiratory neurones were studied. Alfentanil produced depression of neuronal firing which was slow in onset, shallow and prolonged, similar to the responses seen previously with etorphine. These responses were antagonised by naloxone. The depressant responses to fentanyl, sufentanil, and lofentanil were often different in character, being rapid in onset and of short duration, although slow long lasting responses also occurred and sometimes the two responses were combined. However, only the slow response was blocked by naloxone, the fast, short-duration response being naloxone-resistant. No differences in the responses of respiratory and non-respiratory neurones to these drugs were observed.
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Gebhart GF. Opiate and opioid peptide effects on brain stem neurons: relevance to nociception and antinociceptive mechanisms. Pain 1982; 12:93-140. [PMID: 7041052 DOI: 10.1016/0304-3959(82)90189-0] [Citation(s) in RCA: 161] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- G F Gebhart
- Department of Pharmacology, University of Iowa. Iowa City, Ia. 52242 U.S.A
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Baldino F, Beckman AL. Effects of iontophoretically applied (+)- and (-)-naloxone on rat hypothalamic and septal neurons. Brain Res 1982; 232:247-52. [PMID: 7055708 DOI: 10.1016/0006-8993(82)90635-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The purpose of this study was to investigate the possible independent actions of both (+)-and (-)-naloxone on individual neurons in the preoptic/anterior hypothalamus (POAH) and septal area (SA) of the rat brain. Morphine and (-)-naloxone were applied to 31 neurons in the SA (n = 11) and the POAH (n = 20). Morphine depressed the spontaneous activity in 19 of 31 neurons. (-)-Naloxone at currents less than 10 nA did not influence these neurons. However, (-)-naloxone applied in excess of 10 nA reduced spontaneous activity in 28 of 29 neurons. This effect of (-)-naloxone was stereospecific; (+)-naloxone did not alter the spontaneous rate in 12 of 14 cells when alternately applied with (-)-naloxone at the same current intensity. Application of (+)- and (-)-naloxone at supramaximal currents produced a diminution of spike amplitude and an increase in the duration of the action potential. The results of this study indicate that naloxone reduces spontaneous activity via two mechanisms. One involves a direct stereospecific action, and a second produces a non-specific reduction in spike amplitude and a prolongation of spike duration.
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Mohrland JS, Gebhart GF. Effect of morphine administered in the periaqueductal gray and at the recording locus on nociresponsive neurons in the medullary reticular formation. Brain Res 1981; 225:401-12. [PMID: 7306796 DOI: 10.1016/0006-8993(81)90845-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Neurons in the medullary reticular formation (MRF) contained within the nuclei reticularis gigantocellularis and reticularis paragigantocellularis were evaluated for their responses to morphine administered in the periaqueductal gray (PAG) and iontophoresed at the recording site. Morphine had a predominant excitatory effect on neurons in the MRF whether microinjected in the PAG or iontophoresed at the recording locus. Although morphine generally excited neurons in the MRF when administered at either site, examination of individual neurons for their responses to both modes of administration of morphine indicated that the effect produced by morphine administered in the PAG was rarely mimicked by morphine iontophoresed at the recording locus. Moreover, morphine administered in the PAG markedly attenuated the noxious evoked excitatory response of MRF neurons, an effect not reliably produced by morphine iontophoresed in the MRF when microinjected in the PAG is not mediated by an enkephalinergic interneurons. The implications of these results on the role of the MRF in opiate-induced antinociception are discussed.
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Azami J, Wright DM, Roberts MH. Effects of morphine and naloxone on the responses to noxious stimulation of neurones in the nucleus reticularis paragigantocellularis. Neuropharmacology 1981; 20:869-76. [PMID: 7290359 DOI: 10.1016/0028-3908(81)90080-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Beleslin DB, Krstić SK, Stefanović-Denić K, Strbac M, Mićić D. Inhibition by morphine and morphine-like drugs of nicotine-induced emesis in cats. Brain Res Bull 1981; 6:451-3. [PMID: 7248811 DOI: 10.1016/s0361-9230(81)80017-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The effect of morphine, methadone and pethidine injected into the cerebral ventricle of the unanesthetized cat upon emesis produced by nicotine induced similarly was investigated. Morphine and morphine-like drugs depress or abolish the emetic effect of nicotine. The inhibitory effect of morphine, methadone and pethidine is observed after a transient emetic action of these drugs. The emetic and anti-emetic action of morphine, methadone and pethidine can perhaps be ascribed to an agonist/antagonist activity. Further, the possible site of inhibitory action of morphine and morphine-like drugs on the emesis produced by nicotine may be the area postrema of fourth ventricle.
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Haigler HJ, Spring DD. Substance P, morphine and methionine-enkephalin: effects on spontaneous and evoked neuronal firing in the nucleus reticularis gigantocellularis of the rat. Eur J Pharmacol 1980; 67:65-74. [PMID: 6158455 DOI: 10.1016/0014-2999(80)90009-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A nociceptive stimulus (e.g., foot pinch) produced a significant increase in firing in cells in the nucleus reticularis gigantocellularis (NRGC) and surrounding areas of the rat brain. Substance P (SP), a putative nociceptive neurotransmitter, infrequently produced an increase in spontaneous neuronal firing when administered micro-iontophoretically to these areas. These data indicate that the NRGC is an area involved in nociception. However, SP does not appear to be the primary nociceptive neurotransmitter or neuromodulator in the NRGC because SP did not mimic or enhance the response to the nociceptive stimulus. Morphine (MS) and methionine-enkephalin (ENK), administered microiontophoretically, rarely had any effect on spontaneous neuronal firing or rarely modified the increase in neuronal firing evoked by the nociceptive stimulus. For this reason, the NRGC is apparently not an area where MS and ENK act directly to produce analgesia.
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Fry JP, Zieglgänsberger W, Herz A. Specific versus non-specific actions of opioids on hippocampal neurones in the rat brain. Brain Res 1979; 163:295-305. [PMID: 218682 DOI: 10.1016/0006-8993(79)90357-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An investigation has been made into the pharmacological specificity of the actions of microelectrophoretically applied opioids on neurones in the rat hippocampus, a structure containing a low concentration of specific receptors for these substances. The majority of hippocampal neurones remained unaffected by morphine or enkephalin. Some neurones, however, displayed either inhibitory or excitatory responses to the opioids. Of the inhibitory effects, a few appeared to be specific, in that they could be antagonized by naloxone, but most of the other inhibitory responses were found to be potentiated by this drug. Similarly, naloxone not only failed to antagonize, but frequently potentiated the excitatory responses to the opioids. Further evidence for the predominantly non-specific nature of the responses of hippocampal neurones to opioids was provided by experiments with the stereoisomers levorphanol and dextrorphan. Neurones could be found which were either inhibited or excited by both enantiomers. Stereospecific responses, when observed, were inhibitory. Although non-specific, the excitatory effects of enkephalin and morphine on hippocampal neurones were greatly reduced in morphine tolerant/dependent rats. Indeed, in the hippocampus of these animals, the opioids had predominantly inhibitory effects which were potentiated, not antagonized, by naloxone. It is concluded that the low concentration of opiate receptors in the rat hippocampus renders neurones within this structure sensitive to a variety of nonspecific opioid actions.
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Chan SH. Participation of the nucleus reticularis gigantocellularis in the morphine suppression of jaw-opening reflex in cats. Brain Res 1979; 160:377-8. [PMID: 761072 DOI: 10.1016/0006-8993(79)90436-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Bramwell GJ, Bradley PB. Effects of morphine on brainstem neurones in naive and chronic morphine-treated rats, and effects of PCPA. Neuropharmacology 1978; 17:975-8. [PMID: 152873 DOI: 10.1016/0028-3908(78)90141-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Davies J, Dray A. Pharmacological and electrophysiological studies of morphine and enkephalin on rat supraspinal neurones and cat spinal neurones. Br J Pharmacol 1978; 63:87-96. [PMID: 206309 PMCID: PMC1668299 DOI: 10.1111/j.1476-5381.1978.tb07778.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
1 The actions of morphine, methionine and leucine enkephalin, administered electrophoretically, were studied on supraspinal neurones in the cortex and brainstem of the rat anaesthetized with urethane and on spinal Renshaw cells and dorsal horn interneurones in the cat anaesthetized with pentobarbitone.2 The majority of Renshaw cells and cortical and brainstem neurones were excited by all three compounds although some supraspinal neurones were depressed.3 Naloxone reversibly antagonized both excitatory and depressant actions of morphine and enkephalin. Acetylcholine-induced excitation but not amino acid-induced excitation was also antagonized by naloxone.4 Neither morphine nor the enkephalins had any naloxone-reversible action on dorsal horn neurones when ejected from conventional multibarrelled electrodes. However, morphine but not enkephalin, administered into the substantia gelatinosa region of the spinal cord selectively reduced responses to noxious stimuli of neurones in deeper laminae. Naloxone administered into the same region antagonized this action of morphine.5 Intravenous morphine also antagonized responses of dorsal horn neurones to noxious stimuli and subsequent intravenous naloxone reversed this effect.6 It was concluded that the excitatory and inhibitory effects of morphine and enkephalin on central neurones may be mediated by actions on different opiate receptors and that depression of noxious responses of dorsal horn neurones may be relevant to the analgesic action of morphine.
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Morphine and naloxone effects on spontaneous unit activity in the caudate, central grey, and amygdala. ACTA ACUST UNITED AC 1978. [DOI: 10.1016/0364-7722(78)90002-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Greaves MW, Hensby CN, Plummer NA, Warin AP. The effect of short wavelength ultraviolet (C (254 nm), irradiation on arachidonic acid and prostaglandins E2 and F2alpha concentrations in human skin [proceedings]. Br J Pharmacol 1977; 61:445P-446P. [PMID: 588810 PMCID: PMC1667841 DOI: 10.1111/j.1476-5381.1977.tb08439.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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