Glycosylated phosducin-like protein long regulates opioid receptor function in mouse brain.
Phosducin (Phd), a protein that in retina regulates rhodopsin desensitization by controlling the activity of Gt beta gamma-dependent G-protein-coupled receptor kinases (GRKs), is present in very low levels in the CNS of mammals. However, this tissue contains proteins of related sequence and function. This paper reports the presence of N-glycosylated phosducin-like protein long (PhLP(L)) in all structures of mouse CNS, mainly in synaptic plasma membranes and associated with G beta subunits and 14-3-3 proteins. To analyze the role PhLP(L) in opioid receptor desensitization, its expression was reduced by the use of antisense oligodeoxynucleotides (ODNs). The antinociception induced by morphine, [D-Ala(2), N-MePhe(4),Gly-ol(5)]-enkephalin (DAMGO), beta-endorphin, [D-Ala(2)]deltorphin II, [D-Pen(2,5)]-enkephalin (DPDPE) or clonidine in the tail-flick test was reduced in PhLP(L)-knock-down mice. A single intracerebroventricular (icv)-ED(80) analgesic dose of morphine gave rise to acute tolerance that lasted for 4 days, but which was prevented or reversed by icv-injection of myristoylated (myr(+)) G(i2)alpha subunits. PhLP(L) knock-down brought about a myr(+)-G(i2)alpha subunit-insensitive acute tolerance to morphine that was still present after 8 days. It also diminished the specific binding of (125)I-Tyr(27)-beta-endorphin-(1-31) (human) to mouse periaqueductal gray matter membranes. After being exposed to chronic morphine treatment, post-dependent mice required about 10 days for complete recovery of morphine antinociception. The impairment of PhLP(L) extended this period beyond 17 days. It is concluded that PhLP(L) knock-down facilitates desensitization and uncoupling of opioid receptors.
Garzón
J
J
Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avd Doctor Arce, 37, E-28002 Madrid, Spain. jgarzon@cajal.csic.es
Rodríguez-Díaz
M
M
López-Fando
A
A
García-España
A
A
Sánchez-Blázquez
P
P
D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D006031:Glycosylation; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018832:Molecular Chaperones; D009020:Morphine / Q000009:adverse effects / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051381:Rats; D011957:Receptors, Opioid / Q000819:agonists / Q000502:physiology*; D012160:Retina / Q000187:drug effects / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000235:genetics / Q000378:metabolism
D000701:Analgesics, Opioid; D002352:Carrier Proteins; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; C098789:PDCL protein, human; C498319:Pdcl protein, mouse; C498320:Pdcl protein, rat; D011957:Receptors, Opioid; D009270:Naloxone; D009020:Morphine