Differential up-regulation of microsomal and synaptic membrane mu opioid receptors.
Naltrexone was administered to rats for 7 days by osmotic minipump (5 mg/kg/day) and thereupon, forebrain mu opioid receptor levels in subcellular fractions were monitored by homologous displacement of [3H]D-ala2-mePhe4-gly-ol5 enkephalin binding. Microsomes displayed increases in mu receptor concentrations that were twofold greater than those associated with synaptic plasma membrane fractions (92 vs. 51%). Levels in crude membranes rose 77%. Binding affinities were unchanged.
D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D004027:Diencephalon / Q000378:metabolism; D008297:Male; D008861:Microsomes / Q000378:metabolism*; D009271:Naltrexone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017450:Receptors, Opioid, mu; D013268:Stimulation, Chemical; D013570:Synaptic Membranes / Q000378:metabolism*; D013687:Telencephalon / Q000378:metabolism
D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D009271:Naltrexone; D003513:Cycloheximide