Naltrexone, an opioid antagonist, has been used in clinical trials to treat alcoholism. As the opioid peptides beta-endorphin and enkephalin increase splenic NK cell function in laboratory animals, it is anticipated that naltrexone treatment will cause immunosuppression. However, we report in this study that chronic naltrexone administration in laboratory rats increases the cytolytic activity o...

Three types of opioid receptors exist in the animals, each is encoded by a single gene, i.e., the mu opioid receptor gene, the delta opioid receptor gene, and the kappa opioid receptor gene. However, each opioid receptor gene produces multiple mRNA variants as a result of alternative promoter usages, splicing and/or polyadenylation. As such, a large reservoir of regulatory events has evolved fo...

Opioid treatment of pain is generally safe with 0.5% or less events from respiratory depression. However, fatalities are regularly reported. The only treatment currently available to reverse opioid respiratory depression is by naloxone infusion. The efficacy of naloxone depends on its own pharmacological characteristics and on those (including receptor kinetics) of the opioid that needs reversa...

In inflammation, leucocytes containing opioid peptides migrate into the tissue. Opioid peptides can be released and bind to opioid receptors on peripheral nerve terminals, which counteracts inflammatory pain. Migration of opioid peptide-containing leucocytes is controlled by chemokines and adhesion molecules. Neurokinins, such as, substance P also contribute to the recruitment of these cells. O...

Therapy (2009) 6(5), 633–635 10.2217/THY.09.44 © 2009 Future Medicine Ltd “...our awareness of the existence of large variability in opioid response, and our increasing knowledge on possible causes, will increase our ability to respond swiftly and adequately to a lack of opioid efficacy despite adequate or high opioid dose, and even more important, to increased and life-threatening opioid toxic...

The increasing number of opioid users among chronic pain patients, and opioid abusers among the general population, makes perioperative pain management challenging for health care professionals. Anesthesiologists, surgeons, and nurses should be familiar with some pharmacological phenomena which are typical of opioid users and abusers, such as tolerance, physical dependence, hyperalgesia, and ad...

Mu-opioid stimulation of cubic millimeter hedonic hotspots in either the nucleus accumbens shell (NAc) or the ventral pallidum (VP) amplifies hedonic "liking" reactions to sweetness and appetitive "wanting" for food reward. How do these two NAc-VP hotspots interact? To probe their interaction and limbic circuit properties, we assessed whether opioid activation of one hotspot recruited the other...

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...

Opioid-induced sedation is a common dose-limiting side effect of opioid therapy that can be very distressing and sometimes is more difficult to manage than pain. Opioid-induced sedation may prohibit patients from participating in certain activities of daily living, which can be a source of considerable distress for patients and their families. The issue presents a therapeutic dilemma for health...

STUDY OBJECTIVES The effect of opioid medications on sleep architecture has been demonstrated in patients with comorbid pain or opioid addiction. This study examined whether commonly used opioid medications have an adverse effect on sleep architecture in healthy adults. METHODS Forty-two healthy subjects were examined with polysomnography after a bedtime dose of placebo, sustained-release mor...