Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Jul 2012
Rolapitant (SCH 619734): a potent, selective and orally active neurokinin NK1 receptor antagonist with centrally-mediated antiemetic effects in ferrets.
NK1 receptor antagonists have been shown to have a variety of physiological and potential therapeutic effects in animal models and in humans. The present studies demonstrate that Rolapitant (SCH 619734, (5S)-8(S)-[[1(R)-[3,5 bis(trifluoromethyl)phenyl]ethoxy]methyl]-8-phenyl-1,7-diazaspiro[4,5]decan-2-one) is a selective, bioavailable, CNS penetrant neurokinin NK1 receptor antagonist that shows behavioral effects in animals models of emesis. In vitro studies indicate that rolapitant has a high affinity for the human NK1 receptor of 0.66 nM and high selectivity over the human NK2 and NK3 subtypes of >1000-fold, as well as preferential affinity for human, guinea pig, gerbil and monkey NK1 receptors over rat, mouse and rabbit. ⋯ Rolapitant reversed NK1 agonist-induced foot tapping in gerbils following both intravenous and oral administration up to 24 hours at a minimal effective dose (MED) of 0.1 mg/kg. Rolapitant was active at 0.1 and 1 mg/kg in both acute and delayed emesis models in ferrets, respectively, consistent with clinical data for other NK1 antagonists. Clinical efficacy of anti-emetics is highly correlated with efficacy in the ferret emesis model, suggesting rolapitant is a viable clinical candidate for this indication.
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Pharmacol. Biochem. Behav. · Jul 2012
Intrathecal administration of roscovitine attenuates cancer pain and inhibits the expression of NMDA receptor 2B subunit mRNA.
Cancer pain is one of the most severe chronic pains. The mechanisms underlying cancer pain are still unclear. Because of the pain-relieving effects of Cdk5 (Cyclin-dependent kinase 5) antagonist roscovitine in inflammation pain models, we tested whether roscovitine would induce antihyperalgesia in cancer pain. ⋯ At day 14 after operation, inoculation of Osteosarcoma cells significantly enhanced mechanical allodynia and thermal hyperalgesia, which was attenuated by intrathecal administration of different doses of roscovitine. Correlated with the pain behaviors changes, RT-PCR experiments in our study revealed that there was a marked increase in the expression of NR2B mRNA in spinal cord after operation, which was attenuated by intrathecal administration of roscovitine. These results suggest that roscovitine may be a useful adjunct therapy for bone cancer pain, and NR2B in spinal cord may participate in this effect.
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Pharmacol. Biochem. Behav. · Jul 2012
Role of ATP-sensitive K+ channels in the antinociception induced by non-steroidal anti-inflammatory drugs in streptozotocin-diabetic and non-diabetic rats.
There is evidence that systemic sulfonylureas block diclofenac-induced antinociception in normal rat, suggesting that diclofenac activates ATP-sensitive K(+) channels. However, there is no evidence for the systemic interaction between different non-steroidal anti-inflammatory drugs (NSAIDs) and sulfonylureas in streptozotocin (STZ)-diabetic rats. Therefore, this work was undertaken to determine whether two sulfonylureas, glibenclamide and glipizide, have any effect on the systemic antinociception that is induced by diclofenac (30 mg/kg), lumiracoxib (56 mg/kg), meloxicam (30 mg/kg), metamizol (56 mg/kg) and indomethacin (30 mg/kg) using the non-diabetic and STZ-diabetic rat formalin test. ⋯ In contrast, pretreatment with glibenclamide or glipizide did not block lumiracoxib-, meloxicam-, metamizol-, and indomethacin-induced systemic antinociception (P>0.05) in both groups. Results showed that systemic NSAIDs are able to produce antinociception in STZ-diabetic rats. Likewise, data suggest that diclofenac, but not other NSAIDs, activated K(+) channels to induce its systemic antinociceptive effect in the non-diabetic and STZ-diabetic rat formalin test.
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Pharmacol. Biochem. Behav. · Jun 2012
Analgesic effects of lidocaine, morphine and diclofenac on movement-induced nociception, as assessed by the Knee-Bend and CatWalk tests in a rat model of osteoarthritis.
Pain is the major symptom of osteoarthritis (OA) and the main reason for patients seeking medical care, but its treatment is not optimal. Animal studies are necessary to elucidate mechanisms underlying OA-induced pain and assess analgesics' efficacy. Previously, we showed that the Knee-Bend test and dynamic weight bearing by the CatWalk test are clinically relevant methods for assessing movement-induced nociception in the mono-iodoacetate (MIA) OA model. ⋯ Diclofenac was highly effective in both tests on day 3, while on day 20 it induced a less pronounced decrease in the Knee-Bend score and was ineffective in the CatWalk test. The results showed that the Knee-Bend and CatWalk tests are reliable alternative methods for evaluating movement-induced nociception in OA animals, and measure nociception in a clinically relevant way, since an analgesic profile similar to the one described in humans was observed. Therefore, these tests might be important as good predictors of drug efficacy.
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Pharmacol. Biochem. Behav. · May 2012
The combined predictive capacity of rat models of algogen-induced and neuropathic hypersensitivity to clinically used analgesics varies with nociceptive endpoint and consideration of locomotor function.
Different neurobiological mechanism(s) might contribute to evoked and non-evoked pains and to limited translational drug discovery efforts. Other variables including the pain model and sensory testing method used, dose/route/preadministration time of compound(s), lack of adverse effect profiling and level of observer experience might also contribute. With these points in mind, we tested three mechanistically distinct analgesics in rat models of algogen-induced and neuropathic pain. ⋯ Accordingly, this comparative analysis indicates that the pharmacological sensitivity of evoked and non-evoked pain indices does not necessarily correlate within models, perhaps reflecting differing underlying mechanisms. Conversely, the pharmacological specificity of non-evoked pain indices to selected drugs was conserved across models indicative of similar underlying mechanisms enduring in the face of differing aetiology. Finally, although the predictive capacity of these models was largely unaffected by observer-related experience, it was putatively compromised when adverse event profiling of each drug was considered in parallel.