Ferulic acid is a caffeic acid derivative and a common phenolic compound quite abundant in various medicinal plants that used for pain relief. The antinociceptive effect of ferulic acid has been shown; however, the action mechanisms of ferulic acid still remain unclear. The purpose of the present study was to investigate the possible mechanism of action of ferulic acid-induced antinociception i...

The functional interactions between supraspinal p, and 8 receptors were characterized in the mouse using p, receptor-selective antagonists. The effects of pretreatment with the p, opioid antagonists, /~-funaltrexamine (/'/-FNA) and naloxonazine on the modulation of morphine antinociception by the 8 agonists [D-PenZ,D-PenS]enkephalin (DPI)PE) and [D-AlaZ,MetS]enkephalinamide (DAMA) were studied....

Neurotensin has bipolar (facilitatory and inhibitory) effects on pain modulation that may physiologically exist in homeostasis. Facilitation predominates at low (picomolar) doses of neurotensin injected into the rostroventral medial medulla (RVM), whereas higher doses (nanomolar) produce antinociception. SR 48692, a neurotensin receptor antagonist, discriminates between receptors mediating thes...

Previous research from our laboratory has determined that in the absence of a gustatory response or taste hedonics, intraperitoneal (i.p.) glucose administration enhanced morphine-mediated analgesia in rats and had antinociceptive actions on its own. Two experiments examined the potential of a central mechanism for glucose's actions on morphine-mediated antinociception. Morphine (2.5 µg) was in...

We previously reported that serine/threonine protein phosphatases (PPs) play a role in the antinociception induced by the mu-opioid receptor agonist morphine. In this study we evaluated the possible involvement of PPs on the antinociception induced by agonists of others G protein-coupled receptors in the tail flick test in mice. The subcutaneous administration of clonidine (0.25-4 mg/kg), baclo...

Pruritus (itch sensation) is the most common side effect associated with spinal administration of morphine given to humans for analgesia. A variety of agents have been proposed as antipruritics with poorly understood mechanisms and they are effective with variable success. kappa-Opioid agonists possess several actions that are opposite to micro -opioid agonists. We proposed to investigate the r...

Ferulic acid is a caffeic acid derivative and a common phenolic compound quite abundant in various medicinal plants that used for pain relief. The antinociceptive effect of ferulic acid has been shown; however, the action mechanisms of ferulic acid still remain unclear. The purpose of the present study was to investigate the possible mechanism of action of ferulic acid-induced antinociception i...

Polygodial, a sesquiterpene isolated from the bark of Drymis winteri given systemically, intraplantarly, or by spinal or supraspinal sites, produced antinociception when assessed in both phases of the formalin test and against capsaicin-induced pain. Polygodial, even at high doses, had no antinociceptive or antihyperalgesic effect when assessed in hot-plate assay or in glutamate-induced hyperal...

BACKGROUND AND PURPOSE The opioid receptor family comprises four structurally homologous but functionally distinct sub-groups, the μ (MOP), δ (DOP), κ (KOP) and nociceptin (NOP) receptors. As most opioid agonists are selective but not specific, a broad spectrum of behaviours due to activation of different opioid receptors is expected. In this study, we examine whether other opioid receptor syst...

This study investigated possible sex-related differences in levels of antinociception and the rate of development of tolerance to the antinociceptive effects following prolonged (48 h) intravenous (i.v.) morphine administration in the rat. Groups of adult intact male, castrated male, female, and testosterone-pretreated female Sprague-Dawley rats received prolonged (48 h) infusions of i.v. morph...