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  • antagonist
  • In this study, we tested basal MOR-signaling activity in brain tissue from untreated and morphine-pretreated mice, in comparison to antagonist-induced withdrawal in morphine-dependent mice. (aspetjournals.org)
  • Second, morphine pretreatment affects the antagonist properties of naloxone and naltrexone. (aspetjournals.org)
  • demonstrated that deprivation-induced feeding in rats was maximally reduced by an AS ODN probe directed against exon 2 of the KOP gene, an effect complementary to κ antagonist effects, whereas probes directed against exons 2, 3, or 4 of the MOP gene, exon 1 of the DOP gene, and exon 1 of the NOP gene resulted in modest reductions in deprivation-induced intake. (aspetjournals.org)
  • In assays measuring G-protein activation, TIPP failed to stimulate guanosine 5′- O -(3-[ 35 S]thio)triphosphate ([ 35 S]GTPγS) binding in membrane preparations, which is consistent with an antagonist profile. (aspetjournals.org)
  • intrathecal
  • THE observation that chronic intrathecal infusion of morphine sulfate leads to the appearance of organized collections of inflammatory cells in the intrathecal space adjacent to the catheter tip has been reported in case studies 1-8 and in systematic reviews. (asahq.org)
  • These two parameters, the MTD and the FAD, would permit us to assess the relative magnitude of the therapeutic ratio for that agent given by chronic intrathecal infusion. (asahq.org)
  • potency
  • Affinity and potency were determined using radioligand displacement and stimulation of guanosine 5′- O -(3-[ 35 S]thio)triphosphate binding in C6 (μ, δ) and Chinese hamster ovary (κ) cell membranes. (aspetjournals.org)
  • Compared with saline or GFP rats, the analgesic potency of morphine was increased to a similar extent in hMOR-T and hMOR rats. (uky.edu)
  • effect of chronic
  • The effect of chronic heroin self-administration to decrease μ-stimulated [ 35 S]GTPγS binding varied between regions and was highest in brainstem and lowest in the cortex and striatum. (jneurosci.org)
  • Recently, concern regarding the effect of chronic opioid exposure on neuronal degeneration has emerged. (springer.com)
  • rats
  • In brains from heroin self-administering rats, decreased μ opioid-stimulated [ 35 S]GTPγS binding was observed in periaqueductal gray, locus coeruleus, lateral parabrachial nucleus, and commissural nucleus tractus solitarius, as previously observed in chronic morphine-treated animals. (jneurosci.org)
  • Thus, to test the proposed hypothesis, rats were treated with ketamine or morphine alone or with the combination of both drugs, and then submitted to the capsaicin orofacial test. (asahq.org)
  • opiates
  • 20 Morphine, the most commonly employed opioid, and thebaine, the structure on which the vast majority of semisynthetic opiates is based, are natural alkaloids found in the poppy plant, Papaver somniferum . (pubmedcentralcanada.ca)
  • antagonism
  • However, the significant reductions in deprivation-induced feeding following antisense probes directed against either exons 2, 4, 7, 8, or 13 of the MOP gene were modest compared with μ antagonism, suggesting a role for multiple μ-mediated mechanisms. (aspetjournals.org)
  • pretreatment
  • Using guanosine 5′- O -(3-[ 35 S]thio)triphosphate ([ 35 S]GTPγS) binding and adenylyl cyclase activity assay in brain homogenates, we demonstrated that morphine pretreatment of mice enhanced basal MOR signaling in mouse brain homogenates and, moreover, caused persistent changes in the effects of naloxone and naltrexone, antagonists that elicit severe withdrawal in dependent subjects. (aspetjournals.org)
  • Moreover, naloxone and naltrexone stimulated adenylyl cyclase activity in striatum homogenates only after morphine pretreatment, by reversing the inhibitory effects of basal MOR activity. (aspetjournals.org)
  • ligand
  • TM residues within the lipophilic environment of the cell membrane are key in ligand recognition and/or signal transduction and are expected to be oriented toward a relatively hydrophilic central cavity (Surratt et al. (damasgate.com)
  • antagonists
  • Naloxone and naltrexone produce little effect per se in untreated cells, acting as neutral antagonists, whereas in morphine-pretreated cells, they exhibit inverse agonist effects that suppress basal MOR activity (Wang et al. (aspetjournals.org)
  • laboratory
  • Our laboratory has demonstrated the presence of basal MOR signaling activity in various tissues in cell culture (Wang et al. (aspetjournals.org)
  • hyperpolarization
  • 2 The activation of MORs result in reduction of 3′-5′-cyclic adenosine monophosphate, membrane hyperpolarization, and subsequent neuronal depression. (asahq.org)
  • doses
  • 2 For instance, ketamine combined with morphine might be clinically efficient at lower doses than those currently used when administered separately. (asahq.org)
  • In contrast, morphine delivered by percutaneous injections at S1-S2 had only a modest effect on thermal escape, even at higher doses. (jneurosci.org)
  • 1 Because those adverse effects occur through the use of large doses of the drug, enormous effort has been invested to find a means of enhancing its analgesic efficacy and reducing undesirable side effects of morphine. (asahq.org)
  • neuronal
  • In the same vein, chronic MOR activation-dependent direct increases in glutamatergic neurotransmission can produce neuronal excitation, which may also underlie opioid tolerance. (asahq.org)
  • Altogether, our data suggest that chronic opioid administration may cause neuronal degeneration by activation of the integrated stress response leading to induction of apoptotic signaling in neurons and also by promoting demyelination in CNS. (springer.com)
  • thus
  • While opioid chemistry has traditionally been dominated by thebaine-derived alkaloids isolated from poppy, there are a growing number of opioid natural products derived from structures other than the traditional morphinan scaffold and thus structurally not closely related to morphine. (pubmedcentralcanada.ca)
  • saline
  • 13 ). Moreover, in recent work with serial magnetic resonant imaging in dogs, substitution of saline for morphine after the development of a granuloma led to a regression of the granuloma and that formation was dependent on the concentration, not the dose, of morphine. (asahq.org)