Opioid receptors belong to the G protein coupled receptor family. They modulate brain function at all levels of neural integration and therefore impact on autonomous, sensory, emotional and cognitive processing. In vivo functional interaction between mu and delta opioid receptors are known to take place though it is still debated whether interactions occur at circuitry, cellular or molecular le...

Chronic exposure of mu-and delta-opioid receptors to their agonists leads to different rates in receptor down-regulation. In order to analyze the role of the carboxyl terminus of mu-and delta-opioid receptors in the difference in the rate of down-regulation, two chimeras of these receptors were generated by swapping the carboxyl termini; MORTAGDT and DORTAGMT. These chimeras were tagged at the ...

Morphine and the endogenous opioid peptide beta-endorphin exert neuromodulatory as well as immunomodulatory effects, which are transduced by mu-opioid receptors. In this report we show that stimulation with interleukin-4 induces mu-opioid receptor transcripts in human primary blood cells (T cells and polymorphonuclear leukocytes), immune cell lines (Raji, U-937, and HMEC-1), and dendritic cells...

The aim of the present study was to investigate the role of dopamine D(3) receptors in the rewarding effect and hyperlocomotion induced by a prototypical mu-opioid receptor agonist morphine using dopamine D(3) receptor knock-out mice. The mu-opioid receptor in the brain determined by the [tylosil-3,5-(3)H(N)]-[D-Ala(2),N-MePhe(4),Gly-ol(5)]enkephalin binding assay was not significantly changed ...

The Gbetagamma subunit has been implicated in many downstream signaling events associated with opioids. We previously demonstrated that a small molecule inhibitor of Gbetagamma-subunit-dependent phospholipase (PLC) activation potentiated morphine-induced analgesia (Bonacci et al., 2006). Here, we demonstrate that this inhibitor, M119 (cyclohexanecarboxylic acid [2-(4,5,6-trihydroxy-3-oxo-3H-xan...

In the present study, we demonstrated that repeated treatment with fentanyl, but not morphine or oxycodone, causes a rapid desensitization to its ability to block the hyperalgesia associated with the attenuation of mu-opioid receptor resensitization in mice in a chronic pain-like state. In contrast, no such effect was noted in beta-endorphin knockout mice under the chronic pain-like conditions....

The effects of estrogen on the response of hypothalamic arcuate neurons to mu-opioid and GABAB agonists were investigated. Intracellular recordings were made from arcuate neurons in slices prepared from ovariectomized guinea pigs that were pretreated with estrogen or vehicle. Estrogen shifted the dose-response curve to the mu-opioid agonist DAMGO (Tyr-D-Ala-Gly-MePhe-Gly-ol) by 3.4-fold; the EC...