Mechanisms of endogenous pain control are significant. Increasing studies have clearly produced evidence for the clinical usefulness of opioids in peripheral analgesia. The immune system uses mechanisms of cell migration not only to fight pathogens but also to control pain and inflammation within injured tissue. It has been demonstrated that peripheral inflammatory pain can be effectively contr...

the present study investigated the effects of intra-dentate gyrus microinjection of naloxone (an opioid antagonist) and thioperamide (an antagonist of histamine h3 receptors) in the formalin test in rats. subcutaneous injection of formalin (50 μl, 2.5 %) in the ventral surface of right hind paw produced a biphasic pattern (first phase: 0-5 min and second phase: 15 - 60 min) of licking/biting an...

Background and Objective: A great body of evidences suggested a marked elevation of endogenous opioid levels in plasma of animals with acute cholestasis. Endogenous opioids are implicated in the pathophysiology of cholestasis. Also, many studies have shown that endogenous opioids modulate memory processes. To clarify possible role of endogenous opioid receptors in information processing in acut...

Nicotine is the primary component of tobacco that maintains the smoking habit and develops addiction. The adaptive changes of nicotinic acetylcholine receptors produced by repeated exposure to nicotine play a crucial role in the establishment of dependence. However, other neurochemical systems also participate in the addictive effects of nicotine including glutamate, cannabinoids, GABA and opio...

Recent observations from our laboratory have led us to hypothesize that d-opioid receptors may play a role in neuronal protection against hypoxic / ischemic or glutamate excitotocity. To test our hypothesis in this work, we used two independent methods, i.e., ‘‘same field quantification’’ of morphologic criteria and a biochemical assay of lactate dehydrogenase (LDH) release (an index of cellula...

Local analgesic effects of exogenous opioid agonists are particularly prominent in painful inflammatory conditions and are mediated by opioid receptors on peripheral sensory nerves. The endogenous ligands of these receptors, opioid peptides, have been demonstrated in resident immune cells within inflamed tissue of animals and humans. Here we examine in vivo and in vitro whether interleukin 1 be...

in this study, the effects of subcutaneous (sc) injection of pilocarpine (a cholinomimetic agent) and atropine (a muscarinic receptors antagonist) were investigated on a tonic model of orofacial pain in rats. the contribution of the endogenous analgesic opioid system was assessed using naloxone (an opioid receptors antagonist). tonic orofacial pain was induced by sc injection of a diluted forma...

Heroin administered i.c.v. acts on supraspinal mu opioid receptors in ICR mice but on delta receptors in Swiss Webster mice. The purpose of this study was to determine the degree to which genotype plays a role in the opioid receptor selectivity of heroin across a range of fully inbred strains of mice. Six inbred strains were given heroin i.c.v. 10 min before the tail-flick test. Differences in ...

The relationship between analgesic activity, measured as the hot plate reaction time, and respiratory depression, measured as ventilatory frequency, was investigated in mice for a variety of mu opioid receptor agonists with differing selectivities for mu receptors compared with delta receptors. There was a weak correlation between analgesia and respiratory depression for opioids with the greate...