opium is one of the oldest herbal medicines currently used as an analgesic, sedative and antidiarrheal treatment. the effects of opium are principally mediated by the μ -,κ- and δ-opioid receptors. opioid substances consist of all natural and synthetic alkaloids that are derived from opium. most of their effects on gastrointestinal motility and secretion result from suppression of neural activi...

Opioid agonists and antagonists can regulate the density of mu-opioid receptors in whole animal and in cell culture. High intrinsic efficacy agonists (e.g., etorphine), but not lower intrinsic efficacy agonists (e.g., morphine), produce mu-opioid receptor down-regulation and can alter the abundance of mu-opioid receptor mRNA. Conversely, opioid antagonists substantially increase the density of ...

The purpose of the current study is to investigate the effect of opioid-independent, heterologous activation of protein kinase C (PKC) on the responsiveness of opioid receptor and the underlying molecular mechanisms. Our result showed that removing the C terminus of d opioid receptor (DOR) containing six Ser/Thr residues abolished both DPDPEand phorbol 12-myristate 13acetate (PMA)-induced DOR p...

The NOP receptor (nociceptin/orphanin FQ opioid peptide receptor) is the most recently discovered member of the opioid receptor family and, together with its endogenous ligand, N/OFQ, make up the fourth members of the opioid receptor and opioid peptide family. Because of its more recent discovery, an understanding of the cellular and behavioral actions induced by NOP receptor activation are les...

Cyclic AMP (cAMP) regulates a number of cellular processes and modulates cell death induction. cAMP levels are altered upon stimulation of specific G-protein-coupled receptors inhibiting or activating adenylyl cyclases. Opioid receptor stimulation can activate inhibitory Gi-proteins which in turn block adenylyl cyclase activity reducing cAMP. Opioids such as D,L-methadone induce cell death in l...

The sigma-receptor, a broadly distributed integral membrane protein with a novel structure, is known to modulate various voltage-gated K(+) and Ca(2+) channels through a mechanism that involves neither G proteins nor phosphorylation. The present study investigated the modulation of the heart voltage-gated Na(+) channel (Na(v)1.5) by sigma-receptors. The sigma(1)-receptor ligands [SKF-10047 and ...

The high-affinity binding of benzomorphan drugs (ethylketocyclazocine and N-allylnorcyclazocine) and [DAla2,DLeu5] enkephalin was examined in a mouse neuroblastoma--Chinese hamster brain clonal hybrid cell line (NCB-20). Scatchard analysis of saturation binding isotherms indicated the presence of a single binding site for 3H-labeled [DAla2,DLeu5]enkephalin (Kd = 3 nM) and multiple binding sites...

     The aim of this study was to use site directed mutagenesis technique to construct a vector in which serine363 and serine375 residues of the COOH-terminal portion of the μ-opioid receptor (MOR) were substituted by alanine. These constructs are essential in studying G-protein coupled receptor kinase-mediated MOR desensiti-zation. The nested PCR carried out for conversio...

Originally mistaken as an opioid receptor, the sigma-1 receptor (Sig1R) is a ubiquitous membrane protein that has been involved in many cellular processes. While the precise function of Sig1R has long remained mysterious, recent studies have shed light on its role and the molecular mechanisms triggered. Sig1R is in fact a stress-activated chaperone mainly associated with the ER-mitochondria int...

In the present study, the effects of intracuneiformis nucleus microinjection of gamma-aminobutyric acidA (GABAA) receptor agonist and antagonist on antinociception inducced by morphine were investigated with formalin test in rat. Intracuneiformis nucleus microinjection of morphine (10µgr/rat) and Bicuculline (50, 100 ng/rat) induced antinociception in the both first and second phases of formali...