We evaluated the effects of s1-receptor inhibition on m-opioid– induced mechanical antinociception and constipation. s1-Knockout mice exhibited marked mechanical antinociception in response to several m-opioid analgesics (fentanyl, oxycodone, morphine, buprenorphine, and tramadol) at systemic (subcutaneous) doses that were inactive in wild-type mice and even unmasked the antinociceptive effects...

G proteins couple delta opioid receptors to multiple cellular effector systems and are critical components of the delta opioid signal transduction cascade. To investigate the physical association of delta opioid receptors with G proteins, the cloned mouse delta opioid receptor was solubilized, and the G proteins associated with the receptor were identified through coimmunoprecipitation of the r...

To determine whether opioid peptide-receptor pharmacological association found in vitro (e.g., enkephalin-delta, dynorphin-kappa) predict anatomical relationships in situ, immunocytochemical and receptor autoradiographic studies were carried out on adjacent sections from the same brains of formaldehyde-perfused rhesus monkeys. Apparent mu and kappa opioid receptors (labeled, respectively, by [3...

BACKGROUND The opioid system is involved in the control of pain, reward, addictive behaviors and vegetative effects. Opioids exert their pharmacological actions through the agonistic binding at opioid receptors and variation in the coding genes has been found to modulate opioid receptor expression or signaling. However, a limited selection of functional opioid receptor variants is perceived as ...

(D-ALa2, NMePhe4, Gly-ol5) encephalin (DAMGO), a selective mu-opioid receptor agonist, has previously been demonstrated to inhibit the cholinergic and the noncholinergic contraction in guinea-pig airways. In contrast, opioids had no inhibitory effect on cholinergic neurotransmission in the upper trachea when stimulated at 8 Hz. We investigated whether DAMGO, a selective mu-opioid receptor agoni...

BACKGROUND Human affective responses appear to be regulated by limbic and paralimbic circuits. However, much less is known about the neurochemical systems engaged in this regulation. The mu-opioid neurotransmitter system is distributed in, and thought to regulate the function of, brain regions centrally implicated in affective processing. OBJECTIVE To examine the involvement of mu-opioid neur...

The molecular evolution of the opioid receptor family has been studied by isolating cDNAs that encode six distinct opioid receptor-like proteins from a lower vertebrate, the teleost fish Catostomus commersoni. One of these, which has been obtained in full-length form, encodes a 383-amino acid protein that exhibits greatest sequence similarity to mammalian mu-opioid receptors; the corresponding ...

The objective of the present study was to investigate the role of delta(1)-opioid receptors in mediating cardioprotection in isolated chick cardiac myocytes and to investigate whether protein kinase C and mitochondrial ATP-sensitive K(+) (K(ATP)) channels act downstream of the delta(1)-opioid receptor in mediating this beneficial effect. A 5-min preexposure to the selective delta(1)-opioid rece...

BACKGROUND Opioid receptors regulate a diverse array of physiological functions. Mu opioid receptor agonists are well-known analgesics for treating acute pain. In contrast, animal models suggest that chronic pain is more effectively relieved by delta opioid receptor agonists. A number of studies have shown that chronic pain results in increased function of delta opioid receptors. This is propos...

Activation of myocardial kappa-opioid receptor-protein kinase C (PKC) pathways may improve postischemic contractile function through a myofilament reduction in ATP utilization. To test this, we first examined the effects of PKC inhibitors on kappa-opioid receptor-dependent cardioprotection. The kappa-opioid receptor agonist U50,488H (U50) increased postischemic left ventricular developed pressu...