Endothelin B receptor agonists exert antipruritic effects on itching induced via endothelin-1 (ET-1) and compound 48/80. Peripheral µ- and κ-opioid receptors (MORs and KORs, respectively) are reported to be involved in the anti-nociceptive properties triggered by ET(B) agonists. Therefore, we investigated the role of peripheral opioid receptors in the scratching response induced by ET-1. ET(A) ...

Downward phase of dose-response morphine converted U shape curve was chosen as a base for investigating the effects of different doses of naloxone (0.05-0.4 mg/Kg) on morphine reward/aversion properties using place preference method. First, male Wistar rats (200-220 g) were received morphine (1-7.5 mg/Kg) for place conditioning and marginal dose of morphine (5 mg/Kg) calculated by GraphPad soft...

Downward phase of dose-response morphine converted U shape curve was chosen as a base for investigating the effects of different doses of naloxone (0.05-0.4 mg/Kg) on morphine reward/aversion properties using place preference method. First, male Wistar rats (200-220 g) were received morphine (1-7.5 mg/Kg) for place conditioning and marginal dose of morphine (5 mg/Kg) calculated by GraphPad soft...

In the present study, the antinociceptive profiles of coumarin were examined in ICR mice. Coumarin administered orally (from 1 to 10 mg/kg) showed an antinociceptive effect in a dose-dependent manner as measured in the acetic acid-induced writhing test. Duration of antinociceptive action of coumarin maintained at least for 60 min. But, the cumulative response time of nociceptive behaviors induc...

The effect of naloxone, a non-selective opioid antagonist on some anxiolytic and analgesic drugs is reported. Noscapine is an opioid alkaloid with antitussive effect that cannot be antagonized by naloxone. The anxiolytic-like effect of noscapine has been shown in light-dark model and elevated plus maze. In this study the effect of naloxone on anxiolytic effect of noscapine in light-dark model w...

Placebo analgesia is one of the most robust and best-studied placebo effects. Recent researches suggest that placebo analgesia activated the μ-opioid receptor signalling in the human brain. However, whether other opioid receptors are involved in the placebo analgesia remains unclear. We have previously evoked placebo responses in mice (Guo et al. 2010, 2011) and these mice may serve as a model ...

We have previously reported the chemistry and antinociceptive properties of a series of glycosylated enkephalin analogs (glycopeptides) exhibiting approximately equal affinity and efficacy at δ opioid receptors (DORs) and μ opioid receptors (MORs). More detailed pharmacology of the lead glycopeptide MMP-2200 [H₂N-Tyr-D-Thr-Gly-Phe-Leu-Ser-(O-β-D-lactose)-CONH₂] is presented. MMP-2200 produced d...

Pretreatment with morphine-like agonists potentiates the behavioral effects of opioid antagonists, possibly reflecting a state of acute physical dependence. Several studies have used operant behavior to quantify these effects. However, little research has been done using unconditioned behavior. One objective of this study was to determine whether opioid agonist pretreatment (e.g., morphine, fen...

anticonvulsant activity of 7-phenyl-5h-thiazolo[5,4-e][1,2,3,4]tetrazolo[5,1-c]pyrrolo[1,2-a][1,4]diazepine (5) and 7-phenyl-5h-thiazolo[5,4-e][1,3,4]triazolo[5,1-c]pyrrolo[1,2-a][1,4]diazepines (6a-d) was measured against pentylenetetrazole (ptz)-induced seizures in mice. intraperitoneal injections of different doses (12.5, 25 and 50 mg/kg, i.p.) of test compounds decreased ptz-induced seizure...

The effect of naloxone, a non-selective opioid antagonist on some anxiolytic and analgesic drugs is reported. Noscapine is an opioid alkaloid with antitussive effect that cannot be antagonized by naloxone. The anxiolytic-like effect of noscapine has been shown in light-dark model and elevated plus maze. In this study the effect of naloxone on anxiolytic effect of noscapine in light-dark model w...