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James R Stellar - One of the best experts on this subject based on the ideXlab platform.
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comparison of Delta Opiate Receptor agonist induced reward and motor effects between the ventral pallidum and dorsal striatum
Neuropharmacology, 1994Co-Authors: Patricia I Johnson, James R StellarAbstract:Summary The role of the ventral pallidum and the dorsal striatum in mediating the rewarding effects of the Delta Receptor specific agonist [2- d -penicillamine, 5- d -penicillamine]enkephalin (DPDPE) were evaluated in the rat using the intracranial self-stimulation paradigm. Reward shifts were indicated by the change in frequency required to maintain half-maximal responding while motor/performance changes were identified by increases or decreases in the maximum responding. Each hour-long test session consisted of three identical, consecutive 20 min rate-frequency curves. In an effort to ascertain possible heterogeneity of function along the rostrocaudal axis, DPDPE (0.0 nmol = saline dose, 0.3 nmol = low dose, 1.0 nmol = medium dose, 3.0 nmol = high dose) was microinjected into either the rostral or caudal region of the two structures. Microinjections into the caudate were positioned directly above the ventral pallidum placements resulting in centromedial or caudomedial caudate placements. DPDPE microinjections into the rostral ventral pallidum resulted in a significant reward increase (28% increase or −0.14 log Hz shift) only at the high dose. In contrast, caudal ventral pallidal DPDPE microinjections showed a dose-response effect with reward increases of 19, 22 and 31% (−0.09, −0.11 and −0.16 log Hz) for the low, medium and high dose, respectively. DPDPE microinjections into the centromedial caudate resulted in a large reward increase (29% or −0.15 log Hz) at the high dose, while caudomedial caudate DPDPE microinjections had no effect on reward. Motor/ performance effects tended to follow the pattern of reward effects, with most regions showing motor increases ranging from 25 to 75% over baseline activity. The only exception was found in the caudomedial caudate, where microinjections of the high dose of DPDPE resulted in an approximate 20% suppression of motor/performance activity. These results demonstrate that the ventral pallidum and the mediocentral caudate play a role in modulating Opiate rewards, and adds to the growing body of literature regarding the regional heterogeneity within the caudate and ventral pallidum.
James L Henry - One of the best experts on this subject based on the ideXlab platform.
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mu Delta and kappa Opiate Receptors mediate antinociception in the rat tail flick test following noxious thermal stimulation of one hindpaw
Journal of Pharmacology and Experimental Therapeutics, 1995Co-Authors: Graham M Pitcher, Kiran Yashpal, Terence J Coderre, James L HenryAbstract:Experiments were performed to investigate the possible involvement of spinal mu-, Delta- and kappa-Opiate Receptors in mediating the antinociceptive effects of noxious thermal stimulation of one hindpaw on the tail flick reflex in the rat. Male Sprague-Dawley rats were implanted with chronic intrathecal catheters to the lumbar level of the spinal cord. After 5 to 7 days, they were lightly anesthetized with an i.p. injection of a mixture of Na-pentobarbital (20 mg/kg) and chloral hydrate (120 mg/kg). After baseline readings were taken in the tail flick test a conditioning noxious thermal stimulus, which consisted of immersion of one hindpaw in water at 55 degrees C for 90 sec, was applied and the effects on the latency of the tail withdrawal reflex were studied over the next 30 min. In animals pretreated with CSF intrathecally 10 min before the stimulus, an increase in tail flick reaction time was observed peaking at 30 sec after the stimulus. This response was attenuated in a dose-related manner by preadministration of the specific mu-Opiate Receptor antagonist, beta-funaltrexamine, the specific Delta-Opiate Receptor antagonist, H-Tyr-Tic psi[CH2NH]-Phe-Phe-OH or the specific kappa-Opiate Receptor antagonist, nor-binaltorphimine. The data show that the antinociceptive effect on the tail withdrawal reflex from a brief noxious thermal stimulus is provoked heterosegmentally by the noxious conditioning stimulus to the hindpaw and is mediated by the endogenous release of ligands that bind to mu-, Delta- and kappa-Opiate Receptors in the spinal cord.
Sandra L Petersen - One of the best experts on this subject based on the ideXlab platform.
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dual label in situ hybridization studies provide evidence that luteinizing hormone releasing hormone neurons do not synthesize messenger ribonucleic acid for mu kappa or Delta Opiate Receptors
Endocrinology, 1997Co-Authors: M I Sannella, Sandra L PetersenAbstract:Abundant evidence suggests that Opiatergic neurons play an important intermediary role in the regulation of LHRH release by ovarian steroids; however, it is unclear whether Opiates communicate directly or indirectly with LHRH neurons. To investigate this issue, we used dual label in situ hybridization histochemistry to determine whether LHRH neurons synthesize messenger RNA (mRNA) for mu, kappa, and/or Delta Opiate Receptors. For these studies, we examined both intact (n = 3) and ovariectomized, steroid-treated rats. Ten of the ovariectomized rats were implanted 1 week later (day 0) with SILASTIC brand (Dow Corning) capsules of estradiol. On the morning of day 2, half of the estradiol-treated rats were injected with 5 mg progesterone. All animals were killed at approximately 1530 h on day 2. We found that cells expressing mu, kappa, and Delta Opiate Receptor mRNAs were in all sections that also contained LHRH neurons. In every case, LHRH neurons were seen to be surrounded by or in close proximity to cells containing mu, kappa, or Delta mRNAs. However, regardless of steroid treatment, we found no neurons containing both LHRH mRNA and mRNAs encoding any of the three Receptor subtypes. These results support the hypothesis that LHRH neurons are regulated indirectly by Opiatergic neurons.
Ernesto Callegari - One of the best experts on this subject based on the ideXlab platform.
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discovery and pharmacological characterization of a selective Delta Opiate Receptor antagonist cp 646 777
MedChemComm, 2011Co-Authors: Spiros Liras, Stanton F Mchardy, Martin Patrick Allen, Barb E Segelstein, Steven D Heck, Dianne K Bryce, Anne W Schmidt, Rebecca E Oconnor, Michelle Vanasefrawley, Ernesto CallegariAbstract:CP-646,777 (compound 2a) is identified as a potent and selective Delta opioid Receptor antagonist. The synthesis, pharmacological evaluation, disposition characteristics and pharmacokinetic properties of this compound are reported herein. An approach for reducing clearance as measured by human liver microsomes is demonstrated. The significance of p-glycoprotein efflux on CNS disposition and on the pharmacological action of CP-646,777 is also discussed.
Patricia I Johnson - One of the best experts on this subject based on the ideXlab platform.
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comparison of Delta Opiate Receptor agonist induced reward and motor effects between the ventral pallidum and dorsal striatum
Neuropharmacology, 1994Co-Authors: Patricia I Johnson, James R StellarAbstract:Summary The role of the ventral pallidum and the dorsal striatum in mediating the rewarding effects of the Delta Receptor specific agonist [2- d -penicillamine, 5- d -penicillamine]enkephalin (DPDPE) were evaluated in the rat using the intracranial self-stimulation paradigm. Reward shifts were indicated by the change in frequency required to maintain half-maximal responding while motor/performance changes were identified by increases or decreases in the maximum responding. Each hour-long test session consisted of three identical, consecutive 20 min rate-frequency curves. In an effort to ascertain possible heterogeneity of function along the rostrocaudal axis, DPDPE (0.0 nmol = saline dose, 0.3 nmol = low dose, 1.0 nmol = medium dose, 3.0 nmol = high dose) was microinjected into either the rostral or caudal region of the two structures. Microinjections into the caudate were positioned directly above the ventral pallidum placements resulting in centromedial or caudomedial caudate placements. DPDPE microinjections into the rostral ventral pallidum resulted in a significant reward increase (28% increase or −0.14 log Hz shift) only at the high dose. In contrast, caudal ventral pallidal DPDPE microinjections showed a dose-response effect with reward increases of 19, 22 and 31% (−0.09, −0.11 and −0.16 log Hz) for the low, medium and high dose, respectively. DPDPE microinjections into the centromedial caudate resulted in a large reward increase (29% or −0.15 log Hz) at the high dose, while caudomedial caudate DPDPE microinjections had no effect on reward. Motor/ performance effects tended to follow the pattern of reward effects, with most regions showing motor increases ranging from 25 to 75% over baseline activity. The only exception was found in the caudomedial caudate, where microinjections of the high dose of DPDPE resulted in an approximate 20% suppression of motor/performance activity. These results demonstrate that the ventral pallidum and the mediocentral caudate play a role in modulating Opiate rewards, and adds to the growing body of literature regarding the regional heterogeneity within the caudate and ventral pallidum.