BACKGROUND To study the influence of morphine on chemical control of breathing relative to the analgesic properties of morphine, the authors quantified morphine-induced analgesia and respiratory depression in a single group of healthy volunteers. Both respiratory and pain measurements were performed over single 24-h time spans. METHODS Eight subjects (four men, four women) received a 90-s int...

Chronic opioid antagonist treatment up-regulates opioid receptors and produces functional supersensitivity. Although opioid antagonists vary from neutral to inverse, the role of antagonist efficacy in mediating the chronic effects of opioid antagonists is not known. In this study, the effects of two putative inverse agonists (naltrexone, naloxone) and a putative neutral antagonist (6beta-naltre...

Agonists acting at alpha2 adrenergic and opioid receptors have analgesic properties and act synergistically when co-administered in the spinal cord; this synergy may also contribute to the potency and efficacy of spinally administered morphine. The lack of subtype-selective pharmacological agents has previously impeded the definition of the adrenergic receptor subtype(s) mediating these effects...

UNLABELLED To explore further the role of inflammatory processing on peripheral opioid pharmacology, we examined whether the potency of intraarticular (i.a.) or intrathecal (i.t) morphine in tests of thermal and mechanical nociception changed during the induction of experimental arthritis in the rat. Thermal nociception by i.t. morphine (3, 10, and 50 micrograms) or i.a. morphine (100, 1000, an...

Opioid-based narcotics are the most widely prescribed therapeutic agent for the alleviation of persistent pain; however, it is becoming increasingly clear that morphine is significantly less potent in women compared with men. Morphine primarily binds to mu-opioid receptors (MORs), and the periaqueductal gray (PAG) contains a dense population of MOR-expressing neurons. Via its descending project...

Opioid-based narcotics are the most widely prescribed therapeutic agent for the alleviation of persistent pain; however, it is becoming increasingly clear that morphine is significantly less potent in women compared with men. Morphine primarily binds to -opioid receptors (MORs), and the periaqueductal gray (PAG) contains a dense population of MOR-expressing neurons. Via its descending projectio...

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....

Currently, opioid-based drugs are the most effective pain relievers that are widely used in the treatment of pain. However, the analgesic efficacy of opioids is significantly limited by the development of tolerance after repeated opioid administration. Glutamate receptors have been reported to critically participate in the development and maintenance of opioid tolerance, but the underlying mech...

Correspondence: Shailendra Kapoor 2300 E Cary St Richmond, VA 23223, USA Tel +1 804 2342345 Fax +1 804 3454561 Email [email protected] To the editor The recent article by Villesen et al in a recent issue of your journal was most interesting. Recent studies show that the potency of morphine in efficacious pain control may be influenced greatly by polymorphisms of certain genes. For inst...