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Brain P450 epoxygenase activity is required for the antinociceptive effects of improgan, a nonopioid analgesic.

ABSTRACT: The search for the mechanism of action of improgan (a nonopioid analgesic) led to the recent discovery of CC12, a compound that blocks improgan antinociception. Because CC12 is a cytochrome P450 inhibitor, and brain P450 mechanisms were recently shown to be required in opioid analgesic signaling, pharmacological and transgenic studies were performed in rodents to test the hypothesis that improgan antinociception requires brain P450 epoxygenase activity. Intracerebroventricular (i.c.v.) administration of the P450 inhibitors miconazole and fluconazole, and the arachidonic acid (AA) epoxygenase inhibitor N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH) potently inhibited improgan antinociception in rats at doses that were inactive alone. MW06-25, a new P450 inhibitor that combines chemical features of CC12 and miconazole, also potently blocked improgan antinociception. Although miconazole and CC12 were weakly active at opioid and histamine H(3) receptors, MW06-25 showed no activity at these sites, yet retained potent P450-inhibiting properties. The P450 hypothesis was also tested in Cpr(low) mice, a viable knock-in model with dramatically reduced brain P450 activity. Improgan (145 nmol, i.c.v.) antinociception was reduced by 37% to 59% in Cpr(low) mice, as compared with control mice. Moreover, CC12 pretreatment (200 nmol, i.c.v.) abolished improgan action (70% to 91%) in control mice, but had no significant effect in Cpr(low) mice. Thus, improgan's activation of bulbospinal nonopioid analgesic circuits requires brain P450 epoxygenase activity. A model is proposed in which (1) improgan activates an unknown receptor to trigger downstream P450 activity, and (2) brainstem epoxygenase activity is a point of convergence for opioid and nonopioid analgesic signaling.

SUBMITTER: Hough LB

PROVIDER: S-EPMC3065546 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Brain P450 epoxygenase activity is required for the antinociceptive effects of improgan, a nonopioid analgesic.

Hough Lindsay B LB Nalwalk Julia W JW Yang Jun J Conroy Jennie L JL VanAlstine Melissa A MA Yang Weizhu W Gargano Joseph J Shan Zhixing Z Zhang Shao-Zhong SZ Wentland Mark P MP Phillips James G JG Knapp Brian I BI Bidlack Jean M JM Zuiderveld Obbe P OP Leurs Rob R Ding Xinxin X

Pain 20110401 4

The search for the mechanism of action of improgan (a nonopioid analgesic) led to the recent discovery of CC12, a compound that blocks improgan antinociception. Because CC12 is a cytochrome P450 inhibitor, and brain P450 mechanisms were recently shown to be required in opioid analgesic signaling, pharmacological and transgenic studies were performed in rodents to test the hypothesis that improgan antinociception requires brain P450 epoxygenase activity. Intracerebroventricular (i.c.v.) administr ...[more]

PMID: 21316152

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Project description:This is the largest study describing the role of P450 epoxygenase metabolites in septic shock in humans and suggests a novel therapeutic target.ObjectivesOxylipins are oxidative breakdown products of cell membrane fatty acids. Animal models have demonstrated that oxylipins generated by the P450 epoxygenase pathway may be implicated in septic shock pathology. However, these mediators are relatively unexplored in humans with septic shock. We aimed to determine if there were patterns of oxylipins that were associated with 28-day septic shock mortality and organ dysfunction.DesignRetrospective analysis of samples collected during the Vasopressin versus Norepinephrine as Initial Therapy in Septic Shock trial.SettingICUs in the United Kingdom.ParticipantsAdults recruited within 6 hours of onset of septic shock.Main outcomes and measuresOxylipin profiling was performed on 404 serum samples from 152 patients using liquid chromatography-mass spectrometry.ResultsNonsurvivors were found to have higher levels of 14,15-dihydroxyeicosatrienoic acid (DHET) at baseline than survivors (p = 0.02). Patients with 14,15-DHET levels above the lower limit of quantification of the assay were more likely to die than patients with levels below this limit (hazard ratio, 2.3; 95% CI, 1.2-4.5). Patients with measurable 14,15-DHET had higher levels of organ dysfunction and fewer renal failure-free days than those in whom it was unmeasurable. Considering samples collected over the first week of intensive care stay, measurable levels of DHET species were associated with higher daily Sequential Organ Failure Assessment scores that appeared to be accounted for predominantly by the liver component. Measurable 14,15-DHET showed positive correlation with bilirubin (r s = 0.38; p < 0.001) and lactate (r s = 0.27; p = 0.001).Conclusions and relevanceThe P450 epoxygenase-derived DHET species of oxylipins were associated with organ, particularly liver, dysfunction in septic shock and 14,15-DHET was associated with septic shock mortality. These results support further investigation into the role of the P450 epoxygenase-derived oxylipins in sepsis and suggest that this pathway may offer a novel therapeutic strategy in septic shock.

Project description:We assessed pulmonary cytochrome P450 (CYP) epoxygenase expression and activity during hypoxia and explored the effects of modulating epoxygenase activity on pulmonary hypertension. The acute hypoxic vasoconstrictor response was studied in Swiss Webster mice, who express CYP2C29 in their lungs. Animals were pretreated with vehicle, the epoxygenase inhibitor (N-methylsulfonyl-6-[2-propargyloxyphenyl] hexanamide) or an inhibitor of the soluble epoxide hydrolase. Whereas the epoxygenase inhibitor attenuated hypoxic pulmonary constriction (by 52%), the soluble epoxide hydrolase inhibitor enhanced the response (by 39%), indicating that CYP epoxygenase-derived epoxyeicosatrienoic acids elicit pulmonary vasoconstriction. Aerosol gene transfer of recombinant adenovirus containing the human CYP2C9 significantly elevated mean pulmonary artery pressure and total pulmonary resistance indices, both of which were sensitive to the inhibitor sulfaphenazole. The prolonged exposure of mice to hypoxia increased CYP2C29 expression, and transcript levels increased 5-fold after exposure to normobaric hypoxia (FIO2 0.07) for 2 hours. This was followed by a 2-fold increase in protein expression and by a significant increase in epoxyeicosatrienoic acid production after 24 hours. Chronic hypoxia (7 days) elicited pulmonary hypertension and pulmonary vascular remodeling, effects that were significantly attenuated in animals continually treated with N-methylsulfonyl-6-[2-propargyloxyphenyl] hexanamide (-46% and -55%, respectively). Our results indicate that endogenously generated epoxygenase products are associated with hypoxic pulmonary hypertension in mice and that selective epoxygenase inhibition significantly reduces acute hypoxic pulmonary vasoconstriction and chronic hypoxia-induced pulmonary vascular remodeling. These observations indicate potential novel targets for the treatment of pulmonary hypertension and highlight a pivotal role for CYP epoxygenases in pulmonary responses to hypoxia.

Dataset Information

Brain P450 epoxygenase activity is required for the antinociceptive effects of improgan, a nonopioid analgesic.

Publications

Brain P450 epoxygenase activity is required for the antinociceptive effects of improgan, a nonopioid analgesic.

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