The antinociception induced by i.t. or i.c.v. administration of endomorphins is mediated via mu-opioid receptors. However, although endomorphins do not have an appreciable affinity for kappa-opioid receptors, pretreatment with the kappa-opioid receptor antagonist norbinaltorphimine markedly reduces the antinociceptive response to i.c.v. or i.t. administered endomorphin-2 but not endomorphin-1. ...

It has been demonstrated that the exposure of rodents to the standard elevated plus-maze (sEPM: 2 open and 2 enclosed arms) elicits defensive behavioral reactions and antinociception and also activates the hypothalamo-pituitary-adrenal (HPA) axis. We have recently reported that EPM-induced antinociception is particularly observed when rats and mice are exposed to a totally open EPM (oEPM: 4 ope...

Regulator of G-protein signaling (RGS) proteins classically function as negative modulators of G-protein-coupled receptor signaling. In vitro, RGS proteins have been shown to inhibit signaling by agonists at the μ-opioid receptor, including morphine. The goal of the present study was to evaluate the contribution of endogenous RGS proteins to the antinociceptive effects of morphine and other opi...

The aim of the present study was to investigate the involvement of N-methyl-d-aspartate (NMDA) and amino-3-hydroxy-5-methyl-isoxazole-4-proprionate (AMPA)/kainate receptors of the prelimbic (PL) division of the medial prefrontal cortex (MPFC) on the panic attack-like reactions evoked by γ-aminobutyric acid-A receptor blockade in the medial hypothalamus (MH). Rats were pretreated with NaCl 0.9%,...

The antinociceptive effects of the selective noradrenaline reuptake inhibitor antidepressant reboxetine and its interaction with various opioid and noradrenaline receptor subtypes were evaluated. Reboxetine (i.p.) induced a weak dose-dependent antinociceptive effect in acute pain, using the hotplate model. The reboxetine-induced antinociception was significantly inhibited by the opioid receptor...

Two highly selective mu-opioid receptor agonists, endomorphin-1 and endomorphin-2, have been identified and postulated to be endogenous mu-opioid receptor ligands. We determined the antinociceptive effects of these two ligands at the supraspinal level in mice with the tail-flick and hot-plate responses. The i.c.v. injection of endomorphin-1 and -2 inhibited the tail-flick and hot-plate response...

AIMS Several physiological, pharmacological and behavioral lines of evidence suggest that the hippocampal formation is involved in nociception. The hippocampus is also believed to play an important role in the affective and motivational components of pain perception. Thus, our aim was to investigate the participation of cholinergic, opioidergic and GABAergic systems of the dorsal hippocampus (D...

We investigated the effects of pretreatment with low-affinity, uncompetitive NMDA receptor antagonists on morphine-induced antinociception in rats using the same intensity of thermal stimulus applied to the tail and the paws. Similar baseline responses to thermal stimuli of the same intensity were recorded from tails and hind paws. However, morphine produced equal antinociception from the tail ...

BACKGROUND Acetaminophen (APAP) by oral or intravenous (iv) routes is used for mild to moderate pain but may take time to be effective. When fast relief is required and/or oral or iv routes are not available because of the patient's condition, the transmucosal route may be an alternative. METHODOLOGY A new transmucosal/buccal (b) pharmaceutical form of APAP dissolved in 50% wt alcohol is comp...

We studied the influence of arthritis on descending modulation of nociception from the hypothalamic paraventricular nucleus (PVN) in the rat. Spinal nociception was assessed by the heat-evoked limb withdrawal in awake animals while neuronal responses were recorded in a potential brainstem relay, the rostroventromedial medulla (RVM), under pentobarbitone anesthesia. Following injection into the ...