RESUMO
(-)-N-Phenethyl analogs of optically pure N-norhydromorphone were synthesized and pharmacologically evaluated in several in vitro assays (opioid receptor binding, stimulation of [35S]GTPγS binding, forskolin-induced cAMP accumulation assay, and MOR-mediated ß-arrestin recruitment assays). "Body" and "tail" interactions with opioid receptors (a subset of Portoghese's message-address theory) were used for molecular modeling and simulations, where the "address" can be considered the "body" of the hydromorphone molecule and the "message" delivered by the substituent (tail) on the aromatic ring of the N-phenethyl moiety. One compound, N-p-chloro-phenethynorhydromorphone ((7aR,12bS)-3-(4-chlorophenethyl)-9-hydroxy-2,3,4,4a,5,6-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one, 2i), was found to have nanomolar binding affinity at MOR and DOR. It was a potent partial agonist at MOR and a full potent agonist at DOR with a δ/µ potency ratio of 1.2 in the ([35S]GTPγS) assay. Bifunctional opioids that interact with MOR and DOR, the latter as agonists or antagonists, have been reported to have fewer side-effects than MOR agonists. The p-chlorophenethyl compound 2i was evaluated for its effect on respiration in both mice and squirrel monkeys. Compound 2i did not depress respiration (using normal air) in mice or squirrel monkeys. However, under conditions of hypercapnia (using air mixed with 5% CO2), respiration was depressed in squirrel monkeys.
Assuntos
Hidromorfona/análogos & derivados , Hipercapnia/tratamento farmacológico , Receptores Opioides delta/agonistas , Receptores Opioides mu/agonistas , Animais , Ligação Competitiva , Hidromorfona/química , Hidromorfona/farmacologia , Hipercapnia/patologia , Camundongos , Modelos Moleculares , Ligação Proteica , Receptores Opioides delta/antagonistas & inibidores , Receptores Opioides delta/metabolismo , Receptores Opioides mu/antagonistas & inibidores , Receptores Opioides mu/metabolismo , Respiração Artificial , Saimiri , Relação Estrutura-AtividadeRESUMO
Crossdesensitization between opioid and chemokine receptors and involvement of chemokines in pain modulation are well established. We investigated if coadministration of chemokine receptor antagonists (CRAs) with morphine would enhance the analgesic potency of morphine on incisional pain in rats. Animals underwent incisional surgery on the left hind paw and pain responses were evaluated using von Frey filaments at various time points postsurgery between 15 and 360 minutes and daily between 24 and 72 hours. Dose-response curves for morphine, maraviroc (a CCR5 antagonist), and AMD3100 (a CXCR4 antagonist) alone were established. While morphine significantly reduced pain in a time- and dose-dependent manner, maraviroc and AMD3100 had no effect by themselves. Coadministration of either maraviroc or AMD3100 with morphine significantly increased morphine's analgesic effect on incisional pain, shifting the dose-response curve to the left 2.3- and 1.8-fold, respectively. Coadministration of both CRAs with morphine significantly shifted further the morphine dose-response curve to the left 3.3-fold. The effect of treatments on mRNA levels in the draining popliteal lymph node for a panel of chemokines and cytokines showed that message for many of these mediators was upregulated by the incision, and the combination of morphine with the CRAs markedly downregulated them. The data show that combining morphine with CRAs potentiates morphine's analgesic effect on incisional pain. Thus, the same analgesic effect of morphine alone can be achieved with lower doses of morphine when combined with CRAs. Using morphine in lower doses could reduce unwanted side effects and possibly block development of tolerance and dependence.
Assuntos
Analgésicos Opioides/farmacologia , Morfina/farmacologia , Dor/tratamento farmacológico , Receptores de Quimiocinas/antagonistas & inibidores , Animais , Regulação para Baixo/efeitos dos fármacos , Tolerância a Medicamentos/fisiologia , Masculino , Dor/metabolismo , Medição da Dor/métodos , Ratos , Ratos Sprague-Dawley , Receptores CXCR4/metabolismoAssuntos
Analgésicos Opioides/uso terapêutico , Hiperalgesia/tratamento farmacológico , Meperidina/uso terapêutico , Oxicodona/uso terapêutico , Receptores de Quimiocinas/antagonistas & inibidores , Animais , Benzilaminas , Ciclamos , Avaliação Pré-Clínica de Medicamentos/métodos , Sinergismo Farmacológico , Quimioterapia Combinada , Compostos Heterocíclicos/uso terapêutico , Masculino , Maraviroc/uso terapêutico , Ratos Sprague-DawleyRESUMO
Recently, we have shown that morphine's analgesic activity can be attenuated by chemokines, specifically CCL5 and CXCL12. Because the HIV-1 coat protein, glycoprotein 120 (gp120), binds to the same receptors as do CCL5 and CXCL12, experiments were designed to investigate the effect of gp120 in the brain on antinociception induced by morphine in the cold-water (-3°C) tail-flick (CWT) and hot-plate (+54°C) tests. In addition, mu-opioid-receptor-mediated effects in brain periaqueductal grey (PAG) slices were examined with whole-cell patch-clamp recordings. The results showed that (1) pretreatment with gp120 itself (10, 25, 50, 100 or 133 ng, PAG) had no nociceptive effect in the CWT; (2) pretreatment with gp120 (25 or 100 ng) dose-dependently reduced antinociception induced by subcutaneous (sc) injection of morphine (3 or 6 mg/kg) or PAG injection of morphine (100 ng) in the CWT; (3) a PAG injection of gp120 (133 ng), given 30 min before sc injection of morphine (6 mg/kg), similarly reduced morphine antinociception in the hot-plate test; (4) the inhibitory effect of gp120 on morphine-induced antinociception in the CWT was reversed by AMD3100, an antagonist of CXCR4; (5) pretreatment of slices with gp120 (200 pM) prevented morphine (10 µM)-induced hyperpolarization and reduction of input resistance in PAG neurons. Electrophysiology studies paralleled gp120-induced desensitization of a mu-opioid-receptor-mediated response in PAG neurons at the single-cell level. These studies are the first to demonstrate that the analgesic activity of morphine can be reduced by the presence of gp120 in the PAG and that pretreatment with AMD3100 is able to restore the analgesic effects of morphine.
Assuntos
Analgésicos Opioides/farmacologia , Proteína gp120 do Envelope de HIV/farmacologia , Morfina/farmacologia , Medição da Dor/efeitos dos fármacos , Percepção da Dor/efeitos dos fármacos , Analgesia , Animais , Comportamento Animal/efeitos dos fármacos , Benzilaminas , Temperatura Baixa , Ciclamos , Relação Dose-Resposta a Droga , Interações Medicamentosas , Compostos Heterocíclicos/farmacologia , Temperatura Alta , Masculino , Potenciais da Membrana/efeitos dos fármacos , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Substância Cinzenta Periaquedutal/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores CXCR4/antagonistas & inibidores , Receptores Opioides mu/metabolismoRESUMO
AIMS: We have shown that chemokines injected into the periaqueductal gray region of the brain blocks opioid-induced analgesia in the rat cold-water tail flick test (CWTF). The present experiments tested whether chemokine receptor antagonists (CRAs), in combination with sub-analgesic doses of morphine, would provide maximal analgesia in the CWTF test and the mouse formalin pain assay. The effect of CRAs on respiratory depression was also evaluated. MAIN METHODS: One, two or four CRAs (AMD3100/CXCR4, maraviroc/CCR5, RS504393/CCR2 orAZD8797/CX3CR1) were used in combination with sub-analgesic doses of morphine, all given systemically. Pain was assessed using the rat CWTF test or formalin injection into the paw of mice scored by licking. Respiration and oxygen saturation were measured in rats using a MouseOX® Plus - pulse oximeter. KEY FINDINGS: In the CWTF test, a sub-maximal dose of morphine in combination with maraviroc alone, maraviroc plus AMD3100, or with the four chemokine receptor antagonists, produced synergistic increases in antinociception. In the formalin test, the combination of four CRAs plus a sub-maximal dose of morphine resulted in increased antinociception in both male and female mice. AMD3100 had an additive effect with morphine in both sexes. Coadministration of CRAs with morphine did not potentiate the opioid respiratory depressive effect. SIGNIFICANCE: These results support the conclusion that combinations of CRAs can increase the potency of sub-analgesic doses of morphine analgesia without increasing respiratory depression. The results support an "opioid sparing" strategy for alleviation of pain using reduced doses of opioids in combination with CRAs to achieve maximal analgesia.
Assuntos
Analgesia/métodos , Analgésicos Opioides/farmacologia , Morfina/farmacologia , Nociceptividade/efeitos dos fármacos , Dor Nociceptiva/tratamento farmacológico , Receptores de Quimiocinas/antagonistas & inibidores , Animais , Benzilaminas/administração & dosagem , Benzilaminas/farmacologia , Ciclamos/administração & dosagem , Ciclamos/farmacologia , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Feminino , Masculino , Maraviroc/administração & dosagem , Maraviroc/farmacologia , Morfina/administração & dosagem , Morfina/efeitos adversos , Dor Nociceptiva/fisiopatologia , Pirimidinas/administração & dosagem , Pirimidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Insuficiência Respiratória/induzido quimicamente , Tiazóis/administração & dosagem , Tiazóis/farmacologiaRESUMO
Known agonists of the orphan receptor GPR35 are kynurenic acid, zaprinast, 5-nitro-2-(3-phenylproplyamino) benzoic acid, and lysophosphatidic acids. Their relatively low affinities for GPR35 and prominent off-target effects at other pathways, however, diminish their utility for understanding GPR35 signaling and for identifying potential therapeutic uses of GPR35. In a screen of the Prestwick Library of drugs and drug-like compounds, we have found that pamoic acid is a potent GPR35 agonist. Pamoic acid is considered by the Food and Drug Administration as an inactive compound that enables long-acting formulations of numerous drugs, such as the antihelminthics oxantel pamoate and pyrantel pamoate; the psychoactive compounds hydroxyzine pamoate (Vistaril) and imipramine pamoate (Tofranil-PM); and the peptide hormones triptorelin pamoate (Trelstar) and octreotide pamoate (OncoLar). We have found that pamoic acid induces a G(i/o)-linked, GPR35-mediated increase in the phosphorylation of extracellular signal-regulated kinase 1/2, recruitment of ß-arrestin2 to GPR35, and internalization of GPR35. In mice, it attenuates visceral pain perception, indicating an antinociceptive effect, possibly through GPR35 receptors. We have also identified in collaboration with the Sanford-Burnham Institute Molecular Libraries Probe Production Center new classes of GPR35 antagonist compounds, including the nanomolar potency antagonist methyl-5-[(tert-butylcarbamothioylhydrazinylidene)methyl]-1-(2,4-difluorophenyl)pyrazole-4-carboxylate (CID2745687). Pamoic acid and potent antagonists such as CID2745687 present novel opportunities for expanding the chemical space of GPR35, elucidating GPR35 pharmacology, and stimulating GPR35-associated drug development. Our results indicate that the unexpected biological functions of pamoic acid may yield potential new uses for a common drug constituent.
Assuntos
Analgésicos/administração & dosagem , Arrestinas/metabolismo , Sistemas de Liberação de Medicamentos/métodos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Naftóis/administração & dosagem , Receptores Acoplados a Proteínas G/metabolismo , Animais , Arrestinas/agonistas , Linhagem Celular , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Humanos , Masculino , Camundongos , Medição da Dor/efeitos dos fármacos , Medição da Dor/métodos , Receptores Acoplados a Proteínas G/agonistas , Renilla , beta-ArrestinasRESUMO
Wasting syndrome is a common complication of HIV infection and is marked by progressive weight loss and weakness, often associated with fever. The mechanisms involved in the pathogenesis of these syndromes are not well defined, and neither are the brain areas involved. The present study tests a new hypothesis: that the preoptic anterior hypothalamus (POAH), the main brain area for thermoregulation and fever, has a role in the pathogenesis of fever induced by glycoprotein 120 (gp120), the surface envelope protein used by the HIV to gain access into immune cells, and that the CXC chemokine receptors (CXCR4) that serve as a coreceptor for HIV entry mediate the effect. A sterilized stainless steel C313G cannula guide was implanted into the POAH, and a biotelemetry system was used to monitor the body temperature (Tb) changes. The administration of gp120 into the POAH induced fever in a dose-dependent manner. To demonstrate possible links between the gp120 and CXCR4 in generating the fever, we pretreated the rats with 1,1'-[1,4-phenylenebis(methylene)]bis[1,4,8,11-tetraazacyclotetradecane] octohydrobromide dihydrate (AMD 3100), an antagonist of stromal cell-derived growth factor (SDF)-1alpha/CXCL12, acting at its receptor, CXCR4, 30 min before administration of gp120. AMD 3100 significantly reduced the gp120-induced fever. The present studies show that the presence of HIV-1 envelope glycoprotein gp120 in the POAH provokes fever via interaction CXCR4 pathway.
Assuntos
Febre/etiologia , Proteína gp120 do Envelope de HIV/farmacologia , Área Pré-Óptica/efeitos dos fármacos , Receptores CXCR4/antagonistas & inibidores , Animais , Fármacos Anti-HIV/farmacologia , Benzilaminas , Temperatura Corporal/efeitos dos fármacos , Ciclamos , Febre/induzido quimicamente , Proteína gp120 do Envelope de HIV/administração & dosagem , Compostos Heterocíclicos/farmacologia , Masculino , Microinjeções , Ratos , Ratos Sprague-DawleyRESUMO
INTRODUCTION: Although opioids are widely prescribed for pain, in many circumstances, they have only modest efficacy. Preclinical studies have shown that chemokines, immune mediators released during tissue injury and inflammation, can desensitize opioid receptors and block opioid analgesia by a process termed "heterologous desensitization." The present studies tested the hypothesis that in evoked pain, certain chemokine receptor antagonists (CRAs), given with a submaximal dose of morphine, would result in enhanced morphine potency. METHODS: Three rodent pain assays were used: incisional pain in rats, the cold-water tail flick test in rats, and the formalin test in mice. The FDA-approved, commercially available CRAs, maraviroc and AMD3100, were used. They block the chemokine receptors and ligands, CCR5/CCL5 (RANTES) and CXCR4/CXCL4 (SDF-1α), respectively. RESULTS: In the incisional pain assay, it was found that the combination of a single CRA, or of both CRAs, with morphine significantly shifted the morphine dose-response curve to the left, as much as 3.3-fold. In the cold-water tail flick and formalin tests, significant increases of the antinociceptive effects of morphine were also observed when combined with CRAs. CONCLUSIONS: These results support the potential of a new "opioid-sparing" approach for pain treatment, which combines CRAs with reduced doses of morphine.
Assuntos
Relação Dose-Resposta a Droga , Combinação de Medicamentos , Morfina/uso terapêutico , Receptores de Quimiocinas/antagonistas & inibidores , Analgésicos Opioides/farmacologia , Analgésicos Opioides/uso terapêutico , Análise de Variância , Animais , Benzilaminas , Ciclamos , Modelos Animais de Doenças , Compostos Heterocíclicos/farmacologia , Compostos Heterocíclicos/uso terapêutico , Maraviroc/farmacologia , Maraviroc/uso terapêutico , Morfina/farmacologia , Manejo da Dor/métodos , Manejo da Dor/normas , Manejo da Dor/estatística & dados numéricos , Medição da Dor/métodos , Ratos , Ratos Sprague-Dawley , Ferida Cirúrgica/complicações , Ferida Cirúrgica/tratamento farmacológicoRESUMO
BACKGROUND AND PURPOSE: Much of the opioid epidemic arose from abuse of prescription opioid drugs. This study sought to determine if the combination of a cannabinoid with an opioid could produce additive or synergistic effects on pain, allowing reduction in the opioid dose needed for maximal analgesia. EXPERIMENTAL APPROACH: Pain was assayed using the formalin test in mice and the carrageenan assay in rats. Morphine and two synthetic cannabinoids were tested: WIN55,212-2 (WIN), which binds to both CB1 and CB2 receptors, and possibly TRPV1 channels; and GP1a, which has activity at CB2 receptors and is reported to inhibit fatty acid amide hydrolase, thus raising levels of endogenous cannabinoids. KEY RESULTS: Morphine in combination with WIN in the formalin test gave synergistic analgesia. Studies with selective antagonists showed that WIN was acting through CB1 receptors. Morphine in combination with GP1a in the formalin test was sub-additive. In the carrageenan test, WIN had no added effect when combined with morphine, but GP1a with morphine showed enhanced analgesia. Both WIN and Gp1a used alone had analgesic activity in the formalin pain test, but not in the carrageenan pain test. CONCLUSIONS AND IMPLICATIONS: The ability of a cannabinoid to produce an additive or synergistic effect on analgesia when combined with morphine varies with the pain assay and may be mediated by CB1 or CB2 receptors. These results hold the promise of using cannabinoids to reduce the dose of opioids for analgesia in certain pain conditions.
Assuntos
Analgésicos Opioides/farmacologia , Canabinoides/farmacologia , Morfina/farmacologia , Dor/tratamento farmacológico , Receptor CB1 de Canabinoide/metabolismo , Receptor CB2 de Canabinoide/metabolismo , Animais , Carragenina , Relação Dose-Resposta a Droga , Formaldeído , Masculino , Camundongos , Dor/induzido quimicamente , Dor/metabolismo , Manejo da Dor , Ratos , Ratos Sprague-Dawley , Relação Estrutura-AtividadeRESUMO
Growing evidence supports the idea that in addition to their well established role in the immune system, chemokines might play a role in both normal and pathological brain function, and the chemokine network could interact with other neuromodulators. The chemokine stromal cell-derived growth factor (SDF)-1alpha/CXCL12, a member of the CXC chemokine family, was tested for its possible effect on the analgesic responses of the cannabinoid receptor agonist aminoalkylindole 4,5-dihydro-2-methyl-4-(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo-[3,2,1ij]quinolin-6-one [(+)-WIN 55,212-2, hereafter WIN 55,212-2] at the level of the periaqueductal gray (PAG), a brain region critical to the processing of pain signals, and a primary site of action of many analgesic compounds. The administration of WIN 55,212-2 (0.1-0.4 microg/microl) into the PAG resulted in antinociception in a dose-dependent manner. The selective cannabinoid (CB)1 antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR 141716A; 1-10 microg) given into the PAG blocked the WIN 55,212-2-induced antinociception. In contrast, the selective CB2 antagonist N-[(1S)-endo-1,3,3-trimethyl bicyclo heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528; 10 microg) did not alter the WIN 55,212-2-induced antinociception. Pretreatment with SDF-1alpha/CXCL12 (100 ng) caused a reduction in antinociceptive responses of WIN 55,212-2. The inhibitory effect of SDF-1alpha/CXCL12 on WIN 55,212-2-induced antinociception was reversed by octahydrochloride [corrected] hydrate (AMD 3100) (10-50 ng), an antagonist of the SDF-1alpha/CXCL12, acting at its receptor, CXCR4. This study reports the first in vivo evidence of a functional interaction between chemokine and cannabinoid systems in the brain, showing that the activation of SDF-1alpha/CXCL12 receptors (CXCR4) in the PAG interferes with the analgesic effects of WIN 55212-2.
Assuntos
Analgésicos/uso terapêutico , Benzoxazinas/uso terapêutico , Quimiocina CXCL12/uso terapêutico , Morfolinas/uso terapêutico , Naftalenos/uso terapêutico , Dor/metabolismo , Substância Cinzenta Periaquedutal/metabolismo , Receptor CB1 de Canabinoide/agonistas , Receptores CXCR4/metabolismo , Animais , Canfanos/farmacologia , Masculino , Dor/tratamento farmacológico , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Piperidinas/farmacologia , Pirazóis/farmacologia , Ratos , Ratos Sprague-Dawley , Receptor CB1 de Canabinoide/antagonistas & inibidores , Receptor CB1 de Canabinoide/metabolismo , Receptor CB2 de Canabinoide/antagonistas & inibidores , Receptor CB2 de Canabinoide/metabolismo , RimonabantoRESUMO
We previously characterized multiple interactions between chemokine and opioid G protein-coupled receptors (GPCR), and we found both mu and delta-opioid receptors cross-desensitize CCR1, CCR2, CCR5, but not CXCR4. Here we report that the kappa-opioid receptor (KOR) is able to cross-desensitize CXCR4, and this phenomenon is bi-directional. Chemotactic responses by KOR activation are diminished with prior activation of CXCR4. Additionally, calcium mobilization assays show these cross-desensitization processes occur within seconds of receptor activation, and target receptor internalization is not responsible for desensitization between these receptors. These results have implications for several essential processes including neuronal and lymphocyte development, inflammatory responses, and pain/sensitivity.
Assuntos
HIV-1/fisiologia , Receptores CXCR4/metabolismo , Receptores Opioides kappa/metabolismo , (trans)-Isômero de 3,4-dicloro-N-metil-N-(2-(1-pirrolidinil)-ciclo-hexil)-benzenoacetamida/farmacologia , Analgésicos não Narcóticos/farmacologia , Análise de Variância , Animais , Cálcio/metabolismo , Quimiocina CXCL12/farmacologia , Quimiotaxia/efeitos dos fármacos , Quimiotaxia/fisiologia , Relação Dose-Resposta a Droga , Dinorfinas/metabolismo , Citometria de Fluxo/métodos , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Neutrófilos/efeitos dos fármacos , Neutrófilos/fisiologia , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Substância Cinzenta Periaquedutal/metabolismo , Transporte Proteico/efeitos dos fármacos , Ratos , Receptores CXCR4/genética , Receptores Opioides kappa/genética , Fatores de Tempo , Transfecção/métodosRESUMO
The widespread abuse of 3,4-methylenedioxymethamphetamine (MDMA) has intensified the need to learn more about this drug (e.g. its effects, its mechanism of action, brain areas affected). MDMA-induced hyperthermia is a severe physiological event not only because it can produce severe adverse consequences in human as well as experimental animals, but also because it plays a major role in determining the severity of the long-term MDMA-induced neurotoxicity that occurs. However, the effects of MDMA on the preoptic anterior hypothalamus, the main brain area responsible for control of body temperature, are still unknown. In vivo microdialysis-biotelemetry and pharmacological testing were used to determine whether the preoptic anterior hypothalamus is among the brain areas affected by MDMA by investigating the role of the dopamine neurotransmitter system. We examined the effect of a hyperthermic dose of MDMA on the extracellular level of dopamine in the preoptic anterior hypothalamus, and whether this effect is related to the acute hyperthermic response. The administration of a hyperthermic dose of MDMA (20 mg/kg) is accompanied by an increase in the extracellular level of dopamine in the preoptic anterior hypothalamus. Both the hyperthermia and augmented level of dopamine in the preoptic anterior hypothalamus after intraperitoneal injection of MDMA were significantly reduced by the pretreatment with D(1)-selective dopamine receptor antagonist, R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzapine (SCH 23390). These data provide the first in vivo evidence that the effects of MDMA extend to preoptic anterior hypothalamus.
Assuntos
Encéfalo/efeitos dos fármacos , Fármacos do Sistema Nervoso Central/farmacologia , N-Metil-3,4-Metilenodioxianfetamina/farmacologia , Animais , Temperatura Corporal/efeitos dos fármacos , Encéfalo/anatomia & histologia , Encéfalo/metabolismo , Dopamina/metabolismo , Espaço Extracelular/metabolismo , Masculino , Microdiálise , Área Pré-Óptica/efeitos dos fármacos , Área Pré-Óptica/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D1/antagonistas & inibidores , TelemetriaRESUMO
The present data provide the first in vivo evidence that the proinflammatory chemokine, Regulated on Activation Normal T cell Expressed and Secreted (RANTES/CCL5) microinjected directly into the periaqueductal grey in rats, a brain region critical to the processing of pain signals, and a primary site of action of many analgesic compounds, induced hyperalgesia. Pretreatment with antibodies against RANTES/CCL5 prevented the hyperalgesic response, indicating that RANTES/CCL5 is able to interfere with the control of hyperalgesia at the level of the periaqueductal grey and suggesting that chemokine blockers could have analgesic properties.
Assuntos
Quimiocina CCL5/fisiologia , Hiperalgesia/metabolismo , Substância Cinzenta Periaquedutal/metabolismo , Animais , Anticorpos Bloqueadores/farmacologia , Quimiocina CCL5/antagonistas & inibidores , Quimiocina CCL5/metabolismo , Masculino , Microinjeções , Medição da Dor , Limiar da Dor , Ratos , Ratos Sprague-DawleyRESUMO
The realization that the mu-opioid system plays a key role in the control of the process of neuroinflammation is a new concept that may lead to identification of novel therapies for this extremely widespread and intractable syndrome. Fever is the hallmark among the defense mechanisms evoked by the entry into the body of pathogens to initiate the innate immune responses. In an attempt to determine the possible involvement of mu-opioid receptors in the control of brain inflammation, we examined the effect of their deletion on the fever induced by i.c.v. injection of lipopolysaccharide (LPS). The first series of experiments examined the thermal consequence of the absence of mu-opioid receptors on circadian body temperature rhythm and basal body temperature. Mu-opioid receptor knockout mice (MOP-KO) showed a normal circadian body temperature rhythm and basal body temperature compared with the wild type (WT). The second series of experiments investigated i.c.v. administration of LPS on body temperature in WT and MOP-KO. In the WT, i.c.v. injection of 100 ng of LPS induced fever, but there was no increase in body temperature in the MOP-KO mice. Saline, given i.c.v., did not alter the body temperature, either in WT or MOP-KO. These results show that the mu-opioid system participates in the control of acute neuroinflammation, further reinforcing our earlier finding that the opioid system is involved in the pathogenesis of fever induced by bacterial LPS, and that mu-opioid receptors are the target for morphine-induced hyperthermia.
Assuntos
Encefalite/etiologia , Febre/etiologia , Receptores Opioides mu/fisiologia , Doença Aguda , Animais , Ritmo Circadiano , Modelos Animais de Doenças , Encefalite/genética , Encefalite/metabolismo , Encefalite/prevenção & controle , Febre/genética , Febre/metabolismo , Febre/prevenção & controle , Injeções Intraventriculares , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Knockout , Antagonistas de Entorpecentes/farmacologia , Antagonistas de Entorpecentes/uso terapêutico , Receptores Opioides mu/antagonistas & inibidores , Receptores Opioides mu/genéticaRESUMO
We have reported that there is heterologous interaction between the mu, delta or kappa opioid receptors and the receptors for the chemokines CCL5/RANTES or CXCL12/SDF-1 in the regulation of antinociception in rats. CX3CL1/fractalkine, a chemokine that exclusively binds to CX3CR1, has been found to affect morphine analgesia and tolerance in the spinal cord. The purpose of the present study was to see if the interaction between the chemokine CX3CL1/fractalkine receptor and mu, delta or kappa opioid receptors occurs in the periaqueductal grey (PAG) of adult male S-D rats. The cold-water tail-flick (CWT) test was used to measure antinociception. The results showed that intra-PAG injection of 100 ng CX3CL1/fractalkine 30 min before administration of 400 ng DAMGO, 100 ng DPDPE or 20 microg dynorphin significantly reduced the antinociception induced by each of these peptides. These results demonstrate that activation of the CX3CL1 receptor diminishes the effect of mu, delta and kappa opioid agonists on their receptors in the PAG of rats.
Assuntos
Analgésicos Opioides/farmacologia , Quimiocina CX3CL1/farmacologia , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Receptores Opioides/agonistas , Análise de Variância , Animais , Interações Medicamentosas , Dinorfinas/farmacologia , Ala(2)-MePhe(4)-Gly(5)-Encefalina/farmacologia , D-Penicilina (2,5)-Encefalina/farmacologia , Masculino , Medição da Dor/métodos , Ratos , Ratos Sprague-DawleyRESUMO
Nociceptin/orphanin FQ (N/OFQ), a 17-amino-acid peptide, is an endogenous agonist whose receptor is similar in sequence to mu, delta and kappa opioid receptors. It has been reported that N/OFQ can block antinociceptive effects induced by opioid receptor agonists in the radiant heat tail-flick test and warm water tail-withdrawal test. The present study was designed to see the effect of N/OFQ on antinociception induced by opioid receptor agonists in the cold water tail-flick (CWT) test, which measures a different type of pain. In adult male Sprague-Dawley (S-D) rats given subcutaneous (s.c.) injections of saline or morphine (8 mg/kg), intracerebroventricular (i.c.v.) injection of N/OFQ (18 microg) 15 min later produced a significant reversal of morphine antinociception (P<0.01, ANOVA followed by Duncan's test), compared to the corresponding saline control group. Saline (t=+15 min, i.c.v.) had no effect on s.c. morphine antinociception (P>0.01), compared to the corresponding saline control group. When the kappa opioid receptor agonist spiradoline (80 mg/kg, s.c.) was used instead of morphine, similar results were observed. In another series of experiments, it was found that i.c.v. injection of N/OFQ (18 microg) reversed the antinociception induced by i.c.v. injection of the selective mu opioid agonist PL017 (2 microg), delta opioid agonist DPDPE (50 ng) and kappa opioid agonist dynorphin (21.5 microg), respectively. These results indicate that N/OFQ may be an endogenous anti-opioid peptide in the brain of rats in the CWT test.
Assuntos
Peptídeos Opioides/farmacologia , Medição da Dor/efeitos dos fármacos , Receptores Opioides delta/antagonistas & inibidores , Receptores Opioides kappa/antagonistas & inibidores , Receptores Opioides mu/antagonistas & inibidores , Analgésicos Opioides/farmacologia , Animais , Temperatura Baixa , Dinorfinas/farmacologia , Endorfinas/farmacologia , D-Penicilina (2,5)-Encefalina/farmacologia , Masculino , Morfina/farmacologia , Dor/tratamento farmacológico , Pirrolidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Opioides delta/agonistas , Receptores Opioides kappa/agonistas , Receptores Opioides mu/agonistas , Cauda , Água , NociceptinaRESUMO
Previous studies have shown pretreatment with chemokines CCL5/RANTES (100 ng) or CXCL12/SDF-1alpha (100 ng) injected into the periaqueductal grey (PAG) region of the brain, 30 min before the mu opioid agonist DAMGO (400 ng), blocked the antinociception induced by DAMGO in the in vivo cold water tail-flick (CWT) antinociceptive test in rats. In the present experiments, we tested whether the action of other agonists at mu and delta opioid receptors is blocked when CCL5/RANTES or CXCL12/SDF-1alpha is administered into the PAG 30 min before, or co-administered with, opioid agonists in the CWT assay. The results showed that: (1) CXCL12/SDF-1alpha (100 ng, PAG) or CCL5/RANTES (100 ng, PAG), given 30 min before the opioid agonist morphine, or selective delta opioid receptor agonist DPDPE, blocked the antinociceptive effect of these drugs; (2) CXCL12/SDF-1alpha (100 ng, PAG) or CCL5/RANTES (100 ng, PAG), injected at the same time as DAMGO or DPDPE, significantly reduced the antinociceptive effect induced by these drugs. These results demonstrate that the heterologous desensitization is rapid between the mu or delta opioid receptors and either CCL5/RANTES receptor CCR5 or CXCL12/SDF-1alpha receptor CXCR4 in vivo, but the effect is greater if the chemokine is administered before the opioid.
Assuntos
D-Penicilina (2,5)-Encefalina/farmacologia , Medição da Dor/efeitos dos fármacos , Dor/tratamento farmacológico , Receptores de Quimiocinas/efeitos dos fármacos , Receptores Opioides delta/efeitos dos fármacos , Receptores Opioides mu/efeitos dos fármacos , Analgésicos Opioides/farmacologia , Animais , Quimiocina CCL5 , Masculino , Morfina/farmacologia , Ratos , Ratos Sprague-DawleyRESUMO
Recently, we demonstrated that lipopolysaccharide (LPS)-induced fever could be suppressed by a selective mu-opioid receptor antagonist, indicating that the mu-opioid system is involved in the LPS fever. In the present study, to confirm the role of the mu-opioid system in the pathogenesis of LPS fever, we used mice lacking the mu-opioid receptor. In the wild type (WT), following intraperitoneal (i.p.) injection of 100 microg kg(-1) of LPS, body temperature (T(b)) increased approximately 1 degrees C and remained elevated during the 360-min recording period. In the mu-opioid receptor knockout (MOR-KO) mice, the administration of 100 microg kg(-1) i.p. of LPS did not induce fever during the recording period. Saline by itself, given i.p., did not alter the T(b), either in WT or MOR-KO. These results confirm that the mu-opioid system is involved in LPS-induced fever.
Assuntos
Tolerância a Medicamentos/genética , Febre/genética , Febre/metabolismo , Lipopolissacarídeos/toxicidade , Receptores Opioides mu/deficiência , Receptores Opioides mu/genética , Animais , Temperatura Corporal/efeitos dos fármacos , Temperatura Corporal/genética , Febre/induzido quimicamente , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Opioides mu/fisiologiaRESUMO
Previous studies demonstrated that intracerebroventricular (icv) injection of a kappa opioid receptor agonist decreased, and a mu agonist increased, body temperature (Tb) in rats. A dose-response study with the selective kappa antagonist nor-binaltorphimine (nor-BNI) showed that a low dose (1.25 nmol, icv) alone had no effect, although a high dose (25 nmol, icv) increased Tb. It was hypothesized that the hyperthermia induced by nor-BNI was the result of the antagonist blocking the kappa opioid receptor and releasing its inhibition of mu opioid receptor activity. To determine whether the Tb increase caused by nor-BNI was a mu receptor-mediated effect, we administered the selective mu antagonist CTAP (1.25 nmol, icv) 15 min after nor-BNI (25 nmol, icv) and measured rectal Tb in unrestrained rats. CTAP significantly antagonized the Tb increase induced by icv injection of nor-BNI. Injection of 5 or 10 nmol of CTAP alone significantly decreased the Tb, and 1.25 nmol of nor-BNI blocked that effect, indicating that the CTAP-induced hypothermia was kappa-mediated. The findings strongly suggest that mu antagonists, in blocking the basal hyperthermia mediated by mu receptors, can unmask the endogenous kappa receptor-mediated hypothermia, and that there is a tonic balance between mu and kappa opioid receptors that serves as a homeostatic mechanism for maintaining Tb.
Assuntos
Regulação da Temperatura Corporal/fisiologia , Naltrexona/análogos & derivados , Receptores Opioides kappa/metabolismo , Receptores Opioides mu/metabolismo , Animais , Relação Dose-Resposta a Droga , Antagonismo de Drogas , Dinorfinas/farmacologia , Injeções Intraventriculares , Masculino , Naltrexona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Neurotransmissores/farmacologia , Fragmentos de Peptídeos , Peptídeos/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Opioides kappa/antagonistas & inibidores , Receptores Opioides mu/antagonistas & inibidores , SomatostatinaRESUMO
Although opioids have been extensively studied for their impact on the immune system, limited information is available about the specific actions of opioids on intracellular antiviral innate immunity against HIV infection. Thus, we investigated whether heroin, one of the most abused drugs, inhibits the expression of intracellular HIV restriction microRNA (miRNA) and facilitates HIV replication in macrophages. Heroin treatment of macrophages enhanced HIV replication, which was associated with the downregulation of several HIV restriction miRNAs. These heroin-mediated actions on the miRNAs and HIV could be antagonized by naltrexone, an opioid receptor antagonist. Furthermore, the in vitro negative impact of heroin on HIV-associated miRNAs was confirmed by the in vivo observation that heroin addicts had significantly lower levels of macrophage-derived HIV restriction miRNAs than those in the control subjects. These in vitro and in vivo findings indicate that heroin use compromises intracellular anti-HIV innate immunity, providing a favorable microenvironment for HIV survival in the target cells.