morphine-3-glucuronide and Disease-Models--Animal

Topics: Animals; Central Nervous System Stimulants; Disease Models, Animal; Humans; Hyperalgesia; Hyperventilation; Morphine Derivatives; Pain

Morphine-3-glucuronide (M3G), the main metabolite of morphine, has been implicated in the development of tolerance and of opioid-induced hyperalgesia, both limiting the analgesic use of morphine. We evaluated the acute and chronic effects of M3G and morphine as well as development of antinociceptive cross-tolerance between morphine and M3G after intrathecal administration and assessed the expression of pain-associated neurotransmitter substance P in the spinal cord. Sprague-Dawley rats received intrathecal M3G or morphine twice daily for 6 days. Nociception and tactile allodynia were measured with von Frey filaments after acute and chronic treatments. Substance P levels in the dorsal horn of the spinal cord were determined by immunohistochemistry after 4-day treatments. Acute morphine caused antinociception as expected, whereas acute M3G caused tactile allodynia, as did both chronic M3G and morphine. Chronic M3G also induced antinociceptive cross-tolerance to morphine. M3G and morphine increased substance P levels similarly in the nociceptive laminae of the spinal cord. This study shows that chronic intrathecal M3G sensitises animals to mechanical stimulation and elevates substance P levels in the nociceptive laminae of the spinal cord. Chronic M3G also induces antinociceptive cross-tolerance to morphine. Thus, chronic M3G exposure might contribute to morphine-induced tolerance and opioid-induced hyperalgesia.

Topics: Animals; Central Nervous System Stimulants; Disease Models, Animal; Drug Administration Schedule; Drug Tolerance; Humans; Hyperalgesia; Injections, Spinal; Male; Morphine; Morphine Derivatives; Nociception; Pain Measurement; Rats; Spinal Cord; Substance P

Opioid analgesics are frequently prescribed in the United States and worldwide. However, serious comorbidities, such as dependence, tolerance, immunosuppression and gastrointestinal disorders limit their long-term use. In the current study, a morphine-murine model was used to investigate the role of the gut microbiome and metabolome as a potential mechanism contributing to the negative consequences associated with opioid use. Results reveal a significant shift in the gut microbiome and metabolome within one day following morphine treatment compared to that observed after placebo. Morphine-induced gut microbial dysbiosis exhibited distinct characteristic signatures, including significant increase in communities associated with pathogenic function, decrease in communities associated with stress tolerance and significant impairment in bile acids and morphine-3-glucuronide/morphine biotransformation in the gut. Moreover, expansion of Enterococcus faecalis was strongly correlated with gut dysbiosis following morphine treatment, and alterations in deoxycholic acid (DCA) and phosphatidylethanolamines (PEs) were associated with opioid-induced metabolomic changes. Collectively, these results indicate that morphine induced distinct alterations in the gut microbiome and metabolome, contributing to negative consequences associated with opioid use. Therapeutics directed at maintaining microbiome homeostasis during opioid use may reduce the comorbidities associated with opioid use for pain management.

Topics: Analgesics, Opioid; Analysis of Variance; Animals; Deoxycholic Acid; Disease Models, Animal; Drug Tolerance; Dysbiosis; Enterococcus faecalis; Female; Gastrointestinal Microbiome; Metabolome; Mice; Mice, Inbred C57BL; Morphine; Morphine Dependence; Morphine Derivatives; Naltrexone; Narcotic Antagonists; Phosphatidylethanolamines; Statistics, Nonparametric

Opiates are potent analgesics but their clinical use is limited by side effects including analgesic tolerance and opioid-induced hyperalgesia (OIH). The Opiates produce analgesia and other adverse effects through activation of the mu opioid receptor (MOR) encoded by the Oprm1 gene. However, MOR and morphine metabolism involvement in OIH have been little explored. Hence, we examined MOR contribution to OIH by comparing morphine-induced hyperalgesia in wild type (WT) and MOR knockout (KO) mice. We found that repeated morphine administration led to analgesic tolerance and hyperalgesia in WT mice but not in MOR KO mice. The absence of OIH in MOR KO mice was found in both sexes, in two KO global mutant lines, and for mechanical, heat and cold pain modalities. In addition, the morphine metabolite morphine-3beta-D-glucuronide (M3G) elicited hyperalgesia in WT but not in MOR KO animals, as well as in both MOR flox and MOR-Nav1.8 sensory neuron conditional KO mice. M3G displayed significant binding to MOR and G-protein activation when using membranes from MOR-transfected cells or WT mice but not from MOR KO mice. Collectively our results show that MOR is involved in hyperalgesia induced by chronic morphine and its metabolite M3G.

Topics: Animals; Disease Models, Animal; Drug Tolerance; Female; Gene Expression Regulation; Gene Knockout Techniques; Hyperalgesia; Male; Mice; Morphine; Morphine Derivatives; Receptors, Opioid, mu

Obesity causes multiorgan dysfunction, specifically metabolic abnormalities in the liver. Obese patients are opioid-sensitive and have high rates of respiratory complications after surgery. Obesity also has been shown to cause resistance to leptin, an adipose-derived hormone that is key in regulating hunger, metabolism, and respiratory stimulation. We hypothesized that obesity and leptin deficiency impair opioid pharmacokinetics (PK) independently of one another.. Morphine PK were characterized in C57BL/6J wild-type (WT), diet-induced obese (DIO), and leptin-deficient (ob/ob) mice, and in ob/ob mice given leptin-replacement (LR) therapy. WT mice received several dosing regimens of morphine. Obese mice (30 g) received one 80 mg/kg bolus of morphine. Blood was collected at fixed times after morphine injection for quantification of plasma morphine and morphine 3-glucuronide (M3G) levels. PK parameters used to evaluate morphine metabolism included area-under the curve (AUC150), maximal morphine concentration (CMAX), and M3G-to-morphine ratio, and drug elimination was determined by clearance (Cl/F), volume of distribution, and half-life (T1/2). PK parameters were compared between mouse groups by the use of 1-way analysis of variance, with P values less than .05 considered significant.. DIO compared with WT mice had significantly decreased morphine metabolism with lower M3G-to-morphine ratio (mean difference [MD]: -4.9; 95% confidence interval [CI]: -8.8 to -0.9) as well as a decreased Cl/F (MD: -4.0; 95% CI: -8.9 to -0.03) Ob/ob compared with WT mice had a large increase in morphine exposure with a greater AUC150 (MD: 980.4; 95% CI: 630.1-1330.6), CMAX (MD: 6.8; 95% CI: 2.7-10.9), and longer T1/2 (MD: 23.1; 95% CI: 10.5-35.6), as well as a decreased Cl/F (MD: -7.0; 95% CI: -11.6 to -2.7). Several PK parameters were significantly greater in ob/ob compared with DIO mice, including AUC150 (MD: 636.4; 95% CI: 207.4-1065.4), CMAX (MD: 5.3; 95% CI: 3.2-10.3), and T1/2 (MD: 18.3; 95% CI: 2.8-33.7). When leptin was replaced in ob/ob mice, PK parameters began to approach DIO and WT levels. LR compared with ob/ob mice had significant decreases in AUC150 (MD: -779.9; 95% CI: -1229.8 to -330), CMAX (MD: -6.1; 95% CI: -11.4 to -0.9), and T1/2 (MD: -19; 95% CI: -35.1 to -2.8). Metabolism increased with LR, with LR mice having a greater M3G-to-morphine ratio compared with DIO (MD: 5.3; 95% CI: 0.3-10.4).. Systemic effects associated with obesity decrease morphine metabolism and excretion. A previous study from our laboratory demonstrated that obesity and leptin deficiency decrease the sensitivity of central respiratory control centers to carbon dioxide. Obesity and leptin deficiency substantially decreased morphine metabolism and clearance, and replacing leptin attenuated the PK changes associated with leptin deficiency, suggesting leptin has a direct role in morphine metabolism.

Topics: Analgesics, Opioid; Analysis of Variance; Animals; Area Under Curve; Diet, High-Fat; Disease Models, Animal; Genetic Predisposition to Disease; Half-Life; Leptin; Male; Metabolic Clearance Rate; Mice, Inbred C57BL; Mice, Knockout; Mice, Obese; Models, Biological; Morphine; Morphine Derivatives; Obesity; Phenotype

The aim was to investigate the disposition of morphine and morphine-3-glucuronide (M3G) in a rat model of cholestasis induced by bile duct ligation (BDL).. Morphine (15 mg/kg) was administered intravenously, and morphine and M3G concentrations in the plasma and urine measured by HPLC. Changes in the mRNA expression of multidrug resistance-associated protein (MRP)2, MRP3 and UDP-glucuronosyltransferase (UGT)2B1 in the liver were estimated using RT-PCR.. Although the plasma morphine concentrations declined exponentially, the elimination was delayed 3 and 5 days after BDL. Plasma M3G concentrations on day 1 after BDL were similar to those in the untreated control group, but were increased 3 and 5 days after BDL. Expression of MRP3 and UGT2B1 mRNA increased after BDL. The urinary excretion of M3G was increased significantly after BDL.. Enhanced glucuronidation of morphine and transportation of M3G into the blood increased the plasma M3G concentration in the BDL groups. However, M3G disposition 1 day after BDL was similar to that in the untreated control group because urinary excretion of M3G increased.

Topics: Animals; ATP-Binding Cassette Transporters; Cholestasis; Disease Models, Animal; Glucuronosyltransferase; Liver; Male; Morphine; Morphine Derivatives; Multidrug Resistance-Associated Proteins; Narcotics; Rats; RNA, Messenger; Transcription, Genetic