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Morphine and fentanyl are among the most used opioid drugs that confer analgesia and unwanted side effects through both G protein and arrestin signaling pathways of µ-opioid receptor (µOR). Here, we report structures of the human µOR-G protein complexes bound to morphine and fentanyl, which uncover key differences in how they bind the receptor. We also report structures of µOR bound to TRV130, PZM21, and SR17018, which reveal preferential interactions of these agonists with TM3 side of the ligand-binding pocket rather than TM6/7 side. In contrast, morphine and fentanyl form dual interactions with both TM3 and TM6/7 regions. Mutations at the TM6/7 interface abolish arrestin recruitment of µOR promoted by morphine and fentanyl. Ligands designed to reduce TM6/7 interactions display preferential G protein signaling. Our results provide crucial insights into fentanyl recognition and signaling of µOR, which may facilitate rational design of next-generation analgesics.
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Fentanila , Morfina , Humanos , Analgésicos Opioides/farmacologia , Arrestina/metabolismo , Fentanila/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Morfina/farmacologia , Receptores Opioides muRESUMO
Biased agonism has been proposed as a means to separate desirable and adverse drug responses downstream of G protein-coupled receptor (GPCR) targets. Herein, we describe structural features of a series of mu-opioid-receptor (MOR)-selective agonists that preferentially activate receptors to couple to G proteins or to recruit ßarrestin proteins. By comparing relative bias for MOR-mediated signaling in each pathway, we demonstrate a strong correlation between the respiratory suppression/antinociception therapeutic window in a series of compounds spanning a wide range of signaling bias. We find that ßarrestin-biased compounds, such as fentanyl, are more likely to induce respiratory suppression at weak analgesic doses, while G protein signaling bias broadens the therapeutic window, allowing for antinociception in the absence of respiratory suppression.
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Analgésicos Opioides/administração & dosagem , Analgésicos Opioides/efeitos adversos , Receptores Opioides mu/agonistas , Animais , Fentanila/administração & dosagem , Proteínas de Ligação ao GTP/metabolismo , Camundongos , Morfina/administração & dosagem , Receptores Opioides mu/química , Sistema Respiratório/efeitos dos fármacos , Transdução de Sinais , beta-Arrestinas/metabolismoRESUMO
Opioid use disorder is a chronic, relapsing disease associated with persistent changes in brain plasticity. A common single nucleotide polymorphism (SNP) in the µ-opioid receptor gene, OPRM1 A118G, is associated with altered vulnerability to opioid addiction. Reconfiguration of neuronal connectivity may explain dependence risk in individuals with this SNP. Mice with the equivalent Oprm1 variant, A112G, demonstrate sex-specific alterations in the rewarding properties of morphine and heroin. To determine whether this SNP influences network-level changes in neuronal activity, we compared FOS expression in male and female mice that were opioid-naive or opioid-dependent. Network analyses identified significant differences between the AA and GG Oprm1 genotypes. Based on several graph theory metrics, including small-world analysis and degree centrality, we show that GG females in the opioid-dependent state exhibit distinct patterns of connectivity compared to other groups of the same genotype. Using a network control theory approach, we identified key cortical brain regions that drive the transition between opioid-naive and opioid-dependent brain states; however, these regions are less influential in GG females leading to sixfold higher average minimum energy needed to transition from the acute to the dependent state. In addition, we found that the opioid-dependent brain state is significantly less stable in GG females compared to other groups. Collectively, our findings demonstrate sex- and genotype-specific modifications in local, mesoscale, and global properties of functional brain networks following opioid exposure and provide a framework for identifying genotype differences in specific brain regions that play a role in opioid dependence.
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Analgésicos Opioides , Transtornos Relacionados ao Uso de Opioides , Masculino , Camundongos , Feminino , Animais , Receptores Opioides , Receptores Opioides mu/metabolismo , Genótipo , Transtornos Relacionados ao Uso de Opioides/genética , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Recent evidence suggests that chronic exposure to opioid analgesics such as morphine disrupts the intestinal epithelial layer and causes intestinal dysbiosis. Depleting gut bacteria can preclude the development of tolerance to opioid-induced antinociception, suggesting an important role of the gut-brain axis in mediating opioid effects. The mechanism underlying opioid-induced dysbiosis, however, remains unclear. Host-produced antimicrobial peptides (AMPs) are critical for the integrity of the intestinal epithelial barrier as they prevent the pathogenesis of the enteric microbiota. Here, we report that chronic morphine or fentanyl exposure reduces the antimicrobial activity in the ileum, resulting in changes in the composition of bacteria. Fecal samples from morphine-treated mice had increased levels of Akkermansia muciniphila with a shift in the abundance ratio of Firmicutes and Bacteroidetes. Fecal microbial transplant (FMT) from morphine-naïve mice or oral supplementation with butyrate restored (a) the antimicrobial activity, (b) the expression of the antimicrobial peptide, Reg3γ, (c) prevented the increase in intestinal permeability and (d) prevented the development of antinociceptive tolerance in morphine-dependent mice. Improved epithelial barrier function with FMT or butyrate prevented the enrichment of the mucin-degrading A. muciniphila in morphine-dependent mice. These data implicate impairment of the antimicrobial activity of the intestinal epithelium as a mechanism by which opioids disrupt the microbiota-gut-brain axis.
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Analgésicos Opioides , Disbiose , Fentanila , Microbioma Gastrointestinal , Mucosa Intestinal , Camundongos Endogâmicos C57BL , Morfina , Animais , Morfina/farmacologia , Camundongos , Disbiose/induzido quimicamente , Disbiose/microbiologia , Microbioma Gastrointestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/microbiologia , Masculino , Fentanila/farmacologia , Analgésicos Opioides/farmacologia , Eixo Encéfalo-Intestino/efeitos dos fármacos , Transplante de Microbiota Fecal , Proteínas Associadas a Pancreatite/metabolismo , Akkermansia/efeitos dos fármacos , Peptídeos Antimicrobianos/farmacologia , Bacteroidetes/efeitos dos fármacosRESUMO
RATIONALE: Regular, low-dose, sustained-release morphine is frequently prescribed for persistent breathlessness in chronic obstructive pulmonary disease (COPD). However, effects on daytime sleepiness, perceived sleep quality and daytime function have not been rigorously investigated. OBJECTIVES: Determine the effects of regular, low-dose, sustained-release morphine on sleep parameters in COPD. METHODS: Pre-specified secondary analyses of validated sleep questionnaire data from a randomized trial of daily, low-dose, sustained -release morphine versus placebo over four weeks commencing at 8mg or 16mg/day with blinded up-titration over two weeks to a maximum of 32mg/day. Primary outcomes for these analyses were week-1 Epworth Sleepiness Scale (ESS) and Karolinska Sleepiness Scale (KSS) responses on morphine versus placebo. Secondary outcomes included Leeds Sleep Evaluation Questionnaire (LSEQ) scores (end of weeks 1 and 4), KSS and ESS beyond week-1 and associations between breathlessness, morphine, and questionnaire scores. MEASUREMENTS AND MAIN RESULTS: 156 people were randomized. Week-1 sleepiness scores were not different on morphine versus placebo (∆ESS [95%CI] versus placebo: 8mg group: -0.59 [-1.99, 0.81], p=0.41; 16mg group: -0.72 [-2.33, 0.9], p=0.38; ∆KSS versus placebo: 8mg group: 0.11 [-0.7, 0.9], p=0.78; 16mg group: -0.41 [-1.31, 0.49], p=0.37). This neutral effect persisted at later timepoints. In addition, participants who reported reduced breathlessness with morphine at 4 weeks also had improvement in LSEQ domain scores including perceived sleep quality and daytime function. CONCLUSIONS: Regular, low-dose morphine does not worsen sleepiness when used for breathlessness in COPD. Individual improvements in breathlessness with morphine may be related to improvements in sleep.
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Opioid exposure and withdrawal both cause adaptations in brain circuits that may contribute to abuse liability. These adaptations vary in magnitude and direction following different patterns of opioid exposure, but few studies have systematically manipulated the pattern of opioid administration while measuring neurobiological impact. In this study, we compared cellular and synaptic adaptations in the nucleus accumbens shell caused by morphine exposure that was either continuous or interrupted by daily bouts of naloxone-precipitated withdrawal. At the behavioral level, continuous morphine administration caused psychomotor tolerance, which was reversed when the continuity of morphine action was interrupted by naloxone-precipitated withdrawal. Using ex vivo slice electrophysiology in female and male mice, we investigated how these patterns of morphine administration altered intrinsic excitability and synaptic plasticity of medium spiny neurons (MSNs) expressing the D1 or D2 dopamine receptor. We found that morphine-evoked adaptations at excitatory synapses were predominately conserved between patterns of administration, but there were divergent effects on inhibitory synapses and the subsequent balance between excitatory and inhibitory synaptic input. Overall, our data suggest that continuous morphine administration produces adaptations that dampen the output of D1-MSNs, which are canonically thought to promote reward-related behaviors. Interruption of otherwise continuous morphine exposure does not dampen D1-MSN functional output to the same extent, which may enhance behavioral responses to subsequent opioid exposure. Our findings support the hypothesis that maintaining continuity of opioid administration could be an effective therapeutic strategy to minimize the vulnerability to opioid use disorders.SIGNIFICANCE STATEMENT Withdrawal plays a key role in the cycle of addiction to opioids like morphine. We studied how repeated cycles of naloxone-precipitated withdrawal from otherwise continuous opioid exposure can change brain function of the nucleus accumbens, which is an important brain region for reward and addiction. Different patterns of opioid exposure caused unique changes in communication between neurons in the nucleus accumbens, and the nature of these changes depended on the type of neuron being studied. The specific changes in communication between neurons caused by repeated cycles of withdrawal may increase vulnerability to opioid use disorders. This highlights the importance of reducing or preventing the experience of withdrawal during opioid treatment.
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Morfina , Transtornos Relacionados ao Uso de Opioides , Masculino , Feminino , Camundongos , Animais , Morfina/farmacologia , Núcleo Accumbens/fisiologia , Analgésicos Opioides/farmacologia , Plasticidade Neuronal , Naloxona/farmacologiaRESUMO
The paraventricular nucleus of the thalamus (PVT) is involved in drug addiction-related behaviors, and morphine is a widely used opioid for the relief of severe pain. Morphine acts via opioid receptors, but the function of opioid receptors in the PVT has not been fully elucidated. Here, we used in vitro electrophysiology to study neuronal activity and synaptic transmission in the PVT of male and female mice. Activation of opioid receptors suppresses the firing and inhibitory synaptic transmission of PVT neurons in brain slices. On the other hand, the involvement of opioid modulation is reduced after chronic morphine exposure, probably because of desensitization and internalization of opioid receptors in the PVT. Overall, the opioid system is essential for the modulation of PVT activities.SIGNIFICANCE STATEMENT Opioid receptors modulate the activities and synaptic transmission in the PVT by suppressing the firing rate and inhibitory synaptic inputs. These modulations were largely diminished after chronic morphine exposure.
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Analgésicos Opioides , Receptores Opioides , Masculino , Feminino , Camundongos , Animais , Analgésicos Opioides/farmacologia , Núcleo Hipotalâmico Paraventricular/fisiologia , Tálamo , Transmissão Sináptica , Morfina/farmacologiaRESUMO
The complex impacts of prolonged morphine exposure continue to be a significant focus in the expanding area of addiction studies. This research investigates the effectiveness of a combined treatment using Cabergoline and Mdivi-1 to counteract the neuroadaptive changes caused by in vitro morphine treatment. The impact of Methadone, Cabergoline, and a combination of Cabergoline and Mdivi-1 on the cellular and molecular responses associated with Morphine-induced changes was studied in human Neuroblastoma (SK-N-MC) and Glioblastoma (U87-MG) cell lines that were exposed to prolong Morphine treatment. Cabergoline and Mdivi-1 combined treatment effectively influenced the molecular alterations associated with neuroadaptation in chronic morphine-exposed neural cells. This combination therapy normalized autophagy and reduced oxidative stress by enhancing total-antioxidant capacity, mitigating apoptosis, restoring BDNF expression, and balancing apoptotic elements. Our research outlines morphine's dual role in modulating mitochondrial dynamics via the dysregulation of the autophagy-apoptosis axis. This emphasizes the significant involvement of DRP1 activity in neurological adaptation processes, as well as disturbances in the dopaminergic pathway during in vitro chronic exposure to morphine in neural cells. This study proposes a novel approach by recommending the potential effectiveness of combining Cabergoline and Mdivi-1 to modulate the neuroadaptations caused by morphine. Additionally, we identified BDNF and PCNA in neural cells as potential neuroprotective markers for assessing the effectiveness of drugs against opioid toxicity, emphasizing the need for further validation. The study uncovers diverse effects observed in pretreated morphine glioblastoma cells under treatment with Cabergoline and methadone. This highlights the potential for new treatments in the DRD2 pathway and underscores the importance of investigating the interplay between autophagy and apoptosis to advance research in managing cancer-related pain. The study necessitates an in-depth investigation into the relationship between autophagy and apoptosis, with a specific emphasis on protein interactions and the dynamics of cell signaling.
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Apoptose , Autofagia , Cabergolina , Morfina , Quinazolinonas , Humanos , Autofagia/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Morfina/farmacologia , Cabergolina/farmacologia , Linhagem Celular Tumoral , Quinazolinonas/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Dinâmica Mitocondrial/efeitos dos fármacos , Glioblastoma/tratamento farmacológico , Glioblastoma/metabolismo , Glioblastoma/patologia , Fator Neurotrófico Derivado do Encéfalo/metabolismoRESUMO
Hyperalgesic priming is a preclinical model of the transition from acute to chronic pain characterized by a leftward shift in the dose-response curve for and marked prolongation of prostaglandin E2 (PGE2)-induced mechanical hyperalgesia, in vivo. In vitro, priming in nociceptors is characterized by a leftward shift in the concentration dependence for PGE2-induced nociceptor sensitization. In the present in vitro study we tested the hypothesis that a mu-opioid receptor (MOR) agonist opioid analgesic, morphine, can produce priming by its direct action on nociceptors. We report that treatment of nociceptors with morphine, in vitro, produces a leftward shift in the concentration dependence for PGE2-induced nociceptor sensitization. Our findings support the suggestion that opioids act directly on nociceptors to induce priming.
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Dinoprostona , Morfina , Nociceptores , Morfina/farmacologia , Animais , Nociceptores/efeitos dos fármacos , Nociceptores/metabolismo , Dinoprostona/metabolismo , Dinoprostona/farmacologia , Receptores Opioides mu/metabolismo , Analgésicos Opioides/farmacologia , Masculino , Ratos , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/metabolismo , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Ratos Sprague-Dawley , Relação Dose-Resposta a DrogaRESUMO
While opioids remain amongst the most effective treatments for moderate-to-severe pain, their substantial side effect profile remains a major limitation to broader clinical use. One such side effect is opioid-induced hyperalgesia (OIH), which includes a transition from opioid-induced analgesia to pain enhancement. Evidence in rodents supports the suggestion that OIH may be produced by the action of opioids at Toll-like Receptor 4 (TLR4) either on immune cells that, in turn, produce pronociceptive mediators to act on nociceptors, or by a direct action at nociceptor TLR4. And, sub-analgesic doses of several opioids have been shown to induce hyperalgesia in rodents by their action as TLR4 agonists. In the present in vitro patch-clamp electrophysiology experiments, we demonstrate that low dose morphine directly sensitizes human as well as rodent dorsal root ganglion (DRG) neurons, an effect of this opioid analgesic that is antagonized by LPS-RS Ultrapure, a selective TLR4 antagonist. We found that low concentration (100 nM) of morphine reduced rheobase in human (by 36%) and rat (by 26%) putative C-type nociceptors, an effect of morphine that was markedly attenuated by preincubation with LPS-RS Ultrapure. Our findings support the suggestion that in humans, as in rodents, OIH is mediated by the direct action of opioids at TLR4 on nociceptors.
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Morfina , Nociceptores , Animais , Humanos , Ratos , Analgésicos Opioides/efeitos adversos , Hiperalgesia/tratamento farmacológico , Hiperalgesia/induzido quimicamente , Lipopolissacarídeos/farmacologia , Morfina/efeitos adversos , Dor , Ratos Sprague-Dawley , Receptor 4 Toll-LikeRESUMO
Drug dependence is characterized by a switch in motivation wherein a positively reinforcing substance can become negatively reinforcing. Put differently, drug use can transform from a form of pleasure-seeking to a form of relief-seeking. Ventral tegmental area (VTA) GABA neurons form an anatomical point of divergence between two double dissociable pathways that have been shown to be functionally implicated and necessary for these respective motivations to seek drugs. The tegmental pedunculopontine nucleus (TPP) is necessary for opiate conditioned place preferences (CPP) in previously drug-naïve rats and mice, whereas dopaminergic (DA) transmission in the nucleus accumbens (NAc) is necessary for opiate CPP in opiate-dependent and withdrawn (ODW) rats and mice. Here, we show that this switch in functional anatomy is contingent upon the gap junction-forming protein, connexin-36 (Cx36), in VTA GABA neurons. Intra-VTA infusions of the Cx36 blocker, mefloquine, in ODW rats resulted in a reversion to a drug-naïve-like state wherein the TPP was necessary for opiate CPP and where opiate withdrawal aversions were lost. Consistent with these data, conditional knockout mice lacking Cx36 in GABA neurons (GAD65-Cre;Cx36 fl(CFP)/fl(CFP)) exhibited a perpetual drug-naïve-like state wherein opiate CPP was always DA independent, and opiate withdrawal aversions were absent even in mice subjected to an opiate dependence and withdrawal induction protocol. Further, viral-mediated rescue of Cx36 in VTA GABA neurons was sufficient to restore their susceptibility to an ODW state wherein opiate CPP was DA dependent. Our findings reveal a functional role for VTA gap junctions that has eluded prevailing circuit models of addiction.
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Conexinas , Neurônios GABAérgicos , Proteína delta-2 de Junções Comunicantes , Junções Comunicantes , Transtornos Relacionados ao Uso de Opioides , Área Tegmentar Ventral , Animais , Área Tegmentar Ventral/metabolismo , Área Tegmentar Ventral/efeitos dos fármacos , Conexinas/metabolismo , Conexinas/genética , Neurônios GABAérgicos/metabolismo , Neurônios GABAérgicos/efeitos dos fármacos , Junções Comunicantes/metabolismo , Junções Comunicantes/efeitos dos fármacos , Masculino , Ratos , Transtornos Relacionados ao Uso de Opioides/metabolismo , Transtornos Relacionados ao Uso de Opioides/fisiopatologia , Mefloquina/farmacologia , Camundongos , Ratos Sprague-Dawley , Núcleo Tegmental Pedunculopontino/metabolismo , Núcleo Tegmental Pedunculopontino/efeitos dos fármacosRESUMO
Chronic morphine withdrawal memory formation is a complex process influenced by various molecular mechanisms. In this study, we aimed to investigate the contributions of the basolateral amygdala (BLA) and complement component 1, q subcomponent-like 3 (C1QL3), a secreted and presynaptically targeted protein, to the formation of chronic morphine (repeat dosing of morphine) withdrawal memory using conditioned place aversion (CPA) and chemogenetic methods. We conducted experiments involving the inhibition of the BLA during naloxone-induced withdrawal to assess its impact on CPA scores, providing insights into the significance of the BLA in the chronic morphine memory formation process. We also examined changes in C1ql3/C1QL3 expression within the BLA following conditioning. Immunofluorescence analysis revealed the colocalization of C1QL3 and the G protein-coupled receptor, brain-specific angiogenesis inhibitor 3 (BAI3) in the BLA, supporting their involvement in synaptic development. Moreover, we downregulated C1QL3 expression in the BLA to investigate its role in chronic morphine withdrawal memory formation. Our findings revealed that BLA inhibition during naloxone-induced withdrawal led to a significant reduction in CPA scores, confirming the critical role of the BLA in this memory process. Additionally, the upregulation of C1ql3 expression within the BLA postconditioning suggested its participation in withdrawal memory formation. The colocalization of C1QL3 and BAI3 in the BLA further supported their involvement in synaptic development. Furthermore, downregulation of C1QL3 in the BLA effectively hindered chronic morphine withdrawal memory formation, emphasizing its pivotal role in this process. Notably, we identified postsynaptic density protein 95 (PSD95) as a potential downstream effector of C1QL3 during chronic morphine withdrawal memory formation. Blocking PSD95 led to a significant reduction in the CPA score, and it appeared that C1QL3 modulated the ubiquitination-mediated degradation of PSD95, resulting in decreased PSD95 protein levels. This study underscores the importance of the BLA, C1QL3 and PSD95 in chronic morphine withdrawal memory formation. It provides valuable insights into the underlying molecular mechanisms, emphasizing their significance in this intricate process.
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Complexo Nuclear Basolateral da Amígdala , Proteína 4 Homóloga a Disks-Large , Memória , Morfina , Síndrome de Abstinência a Substâncias , Animais , Morfina/farmacologia , Síndrome de Abstinência a Substâncias/metabolismo , Masculino , Camundongos , Memória/efeitos dos fármacos , Proteína 4 Homóloga a Disks-Large/metabolismo , Complexo Nuclear Basolateral da Amígdala/metabolismo , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Complemento C1q/metabolismo , Camundongos Endogâmicos C57BL , Naloxona/farmacologiaRESUMO
Patients diagnosed with obesity are prescribed opioid medications at a higher rate than the general population; however, it is not known if eating a high fat diet might impact individual sensitivity to these medications. To explore the hypothesis that eating a high fat diet increases sensitivity of rats to the effects of morphine, 24 female Sprague-Dawley rats (n=8/diet) ate either a standard laboratory chow (17% kcal from fat), a high fat/low carbohydrate (ketogenic) chow (90.5% kcal from fat), or a traditional high fat/high carbohydrate chow (60% kcal from fat). Morphine-induced antinociception was assessed using a warm water tail withdrawal procedure, during which latency (in seconds) for rats to remove their tail from warm water baths was recorded following saline or morphine (0.32-56 mg/kg, IP) injections. Morphine was administered acutely and chronically, which involved 19 days of twice daily injections (increasing in 1/4 log dose increments every 3 days: 3.2-56 mg/kg, IP) to induce dependence and assess tolerance. The adverse effects of morphine (i.e., tolerance, withdrawal, changes in body temperature) were assessed throughout the study. Morphine induced comparable antinociception in rats eating different diets, and all rats developed tolerance following chronic morphine exposure. Additional adverse effects of morphine were also comparable among rats eating different diets; however, withdrawal-induced weight loss was less severe for rats eating ketogenic chow. These results suggest that dietary manipulation might modulate the severity of withdrawal-related weight loss, in ways that could be relevant for patients. Significance Statement The present study in female rats suggests that eating a high fat/low carbohydrate (ketogenic) or a traditional high fat/high carbohydrate diet does not impact the pain-relieving or adverse effects of opioids (i.e., tolerance or withdrawal). However, eating a ketogenic diet may have beneficial effects on opioid withdrawal-related weight loss. Individuals diagnosed with obesity taking opioids for pain-related conditions might therefore consider adopting a ketogenic diet when opioid administration is discontinued to potentially mitigate withdrawal-related weight loss.
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Morphine is a widely used opioid for the treatment of pain. Differences in drug transporter expression and activity may contribute to variability in morphine pharmacokinetics and response. Using appropriate mouse models, we investigated the impact of the efflux transporters ABCB1 and ABCG2 and the OATP uptake transporters on the pharmacokinetics of morphine, morphine-3-glucuronide (M3G), and M6G. Upon subcutaneous administration of morphine, its plasma exposure in Abcb1a/1b-/-;Abcg2-/--, Abcb1a/1b-/-;Abcg2-/-;Oatp1a/1b-/-;Oatp2b1-/- (Bab12), and Oatp1a/1b-/-;Oatp2b1-/- mice was similar to that found in wild-type mice. Forty minutes after dosing, morphine brain accumulation increased by 2-fold when mouse (m)Abcb1 and mAbcg2 were ablated. Relative recovery of morphine in small intestinal content was significantly reduced in all the knockout strains. In the absence of mOatp1a/1b and mOatp2b1, plasma levels of M3G were markedly increased, suggesting a lower elimination rate. Moreover, Oatp-deficient mice displayed reduced hepatic and intestinal M3G accumulation. Mouse Oatps similarly affected plasma and tissue disposition of subcutaneously administered M6G. Human OATP1B1/1B3 transporters modestly contribute to the liver accumulation of M6G. In summary, mAbcb1, in combination with mAbcg2, limits morphine brain penetration and its net intestinal absorption. Variation in ABCB1 activity due to genetic polymorphisms/mutations and/or environmental factors might, therefore, partially affect morphine tissue exposure in patients. The ablation of mOatp1a/1b increases plasma exposure and decreases the liver and small intestinal disposition of M3G and M6G. Since the contribution of human OATP1B1/1B3 to M6G liver uptake was quite modest, the risks of undesirable drug interactions or interindividual variation related to OATP activity are likely negligible.
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Camundongos Knockout , Derivados da Morfina , Morfina , Animais , Morfina/farmacocinética , Morfina/metabolismo , Derivados da Morfina/metabolismo , Derivados da Morfina/sangue , Camundongos , Distribuição Tecidual , Masculino , Encéfalo/metabolismo , Analgésicos Opioides/farmacocinética , Analgésicos Opioides/metabolismo , Analgésicos Opioides/sangue , Camundongos Endogâmicos C57BL , Transportadores de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos/genética , Fígado/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genéticaRESUMO
BACKGROUND: Morphine relieves dyspnea in various clinical circumstances. Whether or not this applies to patients admitted to intensive care units (ICUs) for acute respiratory failure (ARF) is unknown. We evaluated the efficacy and safety of low-dose morphine on dyspnea in patients admitted to the ICU for ARF. METHODS: In this single-center, double-blind, phase 2, randomized, controlled trial, we assigned non-intubated adults admitted to the ICU for ARF with severe dyspnea, defined by a visual analog scale for dyspnea (dyspnea-VAS) from zero (no dyspnea) to 100 mm (worst imaginable dyspnea) ≥40 mm, to receive a low dose of Morphine Hydrochloride (intravenous titration followed by subcutaneous relay) or Placebo. All patients received standard therapy, including etiological treatment and non-invasive respiratory support. RESULTS: Twenty-two patients were randomized, 11 in each group. The average dyspnea (median [interquartile range]) over 24 hours did not significantly differ between the two groups (40 [25 - 43] mm in the Morphine group vs. 40 [36 - 49] mm in the Placebo group, p=0.411). Dyspnea-VAS was lower in the Morphine group than in the Placebo group at the end of intravenous titration (30 [11 - 30] vs. 35 [30 - 44], p=0.044) and four hours later (18 [10 - 29] vs. 50 [30 - 60], p=0.043). The cumulative probability of intubation was higher in the Morphine group than in the Placebo group (p=0.046) CONCLUSION: In this phase 2 pilot trial, morphine did not improve 24-hour average dyspnea in adult patients with ARF, even though it had a statistically significant immediate effect. Of concern, Morphine use was associated with a higher intubation rate. TRIAL REGISTRATION: The protocol was declared on the ClinicalTrial.gov database (no. NCT04358133) and was published in September 2022.
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Analgésicos Opioides , Dispneia , Morfina , Humanos , Morfina/administração & dosagem , Método Duplo-Cego , Dispneia/tratamento farmacológico , Dispneia/diagnóstico , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Analgésicos Opioides/administração & dosagem , Analgésicos Opioides/efeitos adversos , Insuficiência Respiratória/tratamento farmacológico , Insuficiência Respiratória/diagnóstico , Resultado do Tratamento , AdultoRESUMO
Testosterone may reduce pain in cisgender women and transgender men. Rodents can provide a useful model for investigating physiological effects of hormone therapy. To this end, continuous-release testosterone or blank (placebo) capsules were implanted s.c. into young adult female rats, and three weeks later rats were either ovariectomized or sham-ovariectomized. Testosterone treatment that mimicked previously reported endogenous levels in males eliminated estrous cycling and decreased uterine weight. Testosterone also significantly increased body weight and suppressed the increases in daily wheel running observed in placebo controls over time. Subsequent ovariectomy or sham-ovariectomy decreased wheel running in all groups, but testosterone-treated rats recovered significantly more quickly than did placebo-treated rats. Neither testosterone nor ovariectomy significantly altered hindpaw mechanical threshold. Two weeks after sham/ovariectomy surgery, injection of Complete Freund Adjuvant (CFA) into one hindpaw reduced wheel running and mechanical threshold in all groups; running significantly decreased from the first to second day after CFA in testosterone- but not in placebo-treated rats. Morphine 1.0 but not 3.2 mg/kg increased CFA-suppressed wheel running similarly in all groups, whereas both doses of morphine increased CFA-suppressed mechanical threshold. These data suggest that weeks-long testosterone treatment with or without ovariectomy may provide a useful physiological model of testosterone therapy as used in human gender transition. Although testosterone administered at levels similar to those in gonadally intact males tended to hasten female rats' recovery from surgery, it did not decrease maximal pain-related behaviors after surgery or hindpaw inflammatory insult, nor did it alter opioid antinociception.
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Atividade Motora , Testosterona , Animais , Feminino , Ratos , Morfina/farmacologia , Ovariectomia , Dor/tratamento farmacológico , Testosterona/farmacologiaRESUMO
INTRODUCTION: Interoceptive stimuli elicited by drug administration acquire conditioned modulatory properties of the induction of conditioned appetitive behaviours by exteroceptive cues. This effect may be modeled using a drug discrimination task in which the drug stimulus is trained as a positive-feature (FP) occasion setter (OS) that disambiguates the relation between an exteroceptive light conditioned stimulus (CS) and a sucrose unconditioned stimulus (US). We previously reported that females are less sensitive to generalization of a FP morphine OS than males, so we investigated the role of endogenous ovarian hormones in this difference. METHODS: Male and female rats received intermixed injections of 3.2 mg/kg morphine or saline before each daily training session. Training consisted of 8 presentations of the CS, each followed by access to sucrose on morphine, but not saline sessions. Following acquisiton, rats were tested for generalization of the morphine stimulus to 0, 1.0, 3.2, and 5.4 mg/kg morphine. Female rats were monitored for estrous cyclicity using vaginal cytology throughout the study. RESULTS: Both sexes acquired stable drug discrimination. A gradient of generalization was measured across morphine doses and this behaviour did not differ by sex, nor did it differ across the estrous cycle in females. CONCLUSIONS: Morphine generalization is independent of fluctuations in levels of sex and endogenous gonadal hormones in females under these experimental conditions.
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Ciclo Estral , Morfina , Animais , Feminino , Masculino , Ciclo Estral/fisiologia , Ciclo Estral/efeitos dos fármacos , Morfina/farmacologia , Ratos , Generalização Psicológica/efeitos dos fármacos , Generalização Psicológica/fisiologia , Condicionamento Clássico/efeitos dos fármacos , Condicionamento Clássico/fisiologia , Ratos Sprague-Dawley , Interocepção/fisiologia , Interocepção/efeitos dos fármacos , Aprendizagem por Discriminação/efeitos dos fármacos , Aprendizagem por Discriminação/fisiologiaRESUMO
Morphine (MPH) is widely used for pain management; however, long-term MPH therapy results in antinociceptive tolerance and physical dependence, limiting its clinical use. Zingerone (ZIN) is a natural phenolic compound with neuroprotective effects. We investigated the effects of single and repeated doses of ZIN on MPH-induced tolerance, dependence, and underlying biochemical mechanisms. After a dose-response experiment, tolerance was developed to MPH (10 mg/kg, i.p.) for seven days. In the single-dose study, ZIN was administered on day seven. In the repeated-dose study, ZIN was administered for seven days. Naloxone (5 mg/kg, i.p., 120 min after MPH) was injected to assess withdrawal signs on day seven. The levels of thiobarbituric acid reactive substances (TBARS), nitric oxide (NO), total thiol (TT), and glutathione peroxidase (GPx) were measured in the prefrontal cortex. The protein levels of interleukin-1 beta (IL-1ß) and NLRP3-ASC-Caspase-1 axis were assessed by ELISA and Western blotting, respectively. Results showed that ZIN (100 mg/kg) had no antinociceptive activity, and subsequent experiments were performed at this dose. Repeated ZIN reversed MPH antinociceptive tolerance, whereas single ZIN did not. Single and repeated ZIN attenuated naloxone-induced jumping. In addition, repeated ZIN significantly inhibited weight loss. Repeated ZIN suppressed the MPH-induced increase in TBARS, NO, IL-1ß, NLRP3, ASC, and Caspase-1. It also inhibited MPH-induced TT and GPx reduction. In contrast, single ZIN had no effect. Findings suggest that ZIN reduces MPH-induced tolerance and dependence by suppressing oxidative stress and NLRP3 inflammasome activation. This study provides a novel therapeutic approach to reduce the side effects of MPH.
Assuntos
Guaiacol/análogos & derivados , Dependência de Morfina , Morfina , Camundongos , Animais , Morfina/farmacologia , Inflamassomos/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico , Naloxona/farmacologia , Naloxona/uso terapêutico , Estresse Oxidativo , Óxido Nítrico/metabolismo , Analgésicos/uso terapêutico , Caspases/metabolismo , Dependência de Morfina/metabolismoRESUMO
Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.
Assuntos
Autofagia , AVC Isquêmico , Morfina , Fármacos Neuroprotetores , Serina-Treonina Quinases TOR , Animais , Autofagia/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Masculino , AVC Isquêmico/tratamento farmacológico , AVC Isquêmico/metabolismo , AVC Isquêmico/patologia , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Morfina/farmacologia , Morfina/uso terapêutico , Camundongos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/fisiologia , Camundongos Endogâmicos C57BL , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Proteína Quinase 9 Ativada por Mitógeno/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Infarto da Artéria Cerebral Média/tratamento farmacológico , Infarto da Artéria Cerebral Média/metabolismo , Infarto da Artéria Cerebral Média/patologia , Neuroproteção/efeitos dos fármacos , Neuroproteção/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
BACKGROUND: Although cesarean delivery is the most common surgery performed in the United States, prescribing practices for analgesia vary. Strategies to manage postpartum pain have mostly focused on the immediate postpartum period when patients are still admitted to the hospital. At discharge, most providers prescribe a fixed number of opioid tablets. Most patients do not use all the opioids that they are prescribed at hospital discharge. This leads to an excess of opioids in the community, which can ultimately lead to misuse and diversion. OBJECTIVE: This study aimed to determine whether a transition from universal opioid prescribing to a personalized, patient-specific protocol decreases morphine milligram equivalents prescribed at hospital discharge after cesarean delivery while adequately controlling pain. STUDY DESIGN: This was a prospective cohort study of patients undergoing cesarean delivery before and after the implementation of a personalized opioid-prescribing practice at the time of hospital discharge. Each patient was prescribed scheduled ibuprofen and acetaminophen, with a prescription for oxycodone tablets equal to 5 times the morphine milligram equivalents used in the 24 hours before discharge, calculated via an electronic order set. The previous traditional cohorts were routinely prescribed 30 tablets of acetaminophen-codeine 300/30 mg. The primary outcome was morphine milligram equivalents prescribed at discharge. A hotline to address pain control issues after discharge was established, and calls, emergency department visits, and readmissions were examined. Statistical analyses was performed using chi-square and Wilcoxon rank-sum test, with a P value of <.05 considered statistically significant. RESULTS: Overall, 412 patients underwent cesarean delivery in the 6 weeks after initiation of the personalized prescribing protocol and were compared with 367 patients before the change. The median morphine milligram equivalents prescribed at discharge was lower with personalized prescribing (37.5 [interquartile range, 0-75] vs 135 [interquartile range, 135-135]; P<.001). Moreover, 176 patients (43%) were not prescribed opioids at discharge, which was a substantial change as all 367 patients in the traditional cohort received opioids at discharge (P<.001). Of note, 9 hotline phone calls were received; none required additional opioids after a 24-hour trial of scheduled ibuprofen, which none had taken before the call. In addition, 11 patients (2.7%) presented to the emergency department for pain evaluation, of which none required readmission or an outpatient prescription of opioids. CONCLUSION: A personalized protocol for opioid prescriptions after cesarean delivery decreased the total morphine milligram equivalents and the number of opioid tablets at discharge, without hospital readmissions or need for rescue opioid prescriptions after discharge. Opioids released into our community will be reduced by more than 90,000 tablets per year, without demonstrable adverse effect.