Effects of etonitazene consumption and abstinence on the signal transmission of mu-opioid receptors in brain membranes of rats.
Rats, for 8 weeks consuming the mu-opioid agonist etonitazene (forced and free choice conditions yielding high and low drug-consumers), were sacrificed after 2 days or 6 weeks lasting drug deprivation. Binding characteristics of membranes from the parieto-occipital cortex of these four groups were compared with those of drug-naive controls. In all five groups, 1 microM of the mu-opioid receptor agonist [D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO) increased the guanosine-5'-O([35S]3'thio)triphosphate ([35S]GTPgammaS) binding activity on guanine nucleotide-binding (G) proteins, and 500 nM of GTPgammaS decreased the [3H]DAMGO binding affinity. During acute withdrawal, both opioid consuming groups displayed a higher maximum efficacy (Emax) in basal [35S]GTPgammaS binding (34 and 31%, each P < 0.01), but only the forced group showed a 58% higher net DAMGO-stimulated binding density Bmax (P < 0.01) and 53% more activated G proteins per mu-opioid receptor (P < 0.05). In the presence of GTPgammaS both groups revealed a higher affinity in [3H]DAMGO binding (each 25%, P < 0.01). The long-term drug-deprived groups displayed no differences in their binding characteristics.
May
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Abteilung für Klinische Neurobiologie, Psychiatrische Klinik und Poliklinik, Freie Universität Berlin, Germany. drtorstenmay@hotmail.com
Juilfs
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Wolffgramm
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D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology*; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D008297:Male; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D012646:Self Administration; D015398:Signal Transduction / Q000187:drug effects*; D013375:Substance Withdrawal Syndrome / Q000378:metabolism; D019966:Substance-Related Disorders / Q000378:metabolism
D001562:Benzimidazoles; D009294:Narcotics; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C084835:etonitazene; D019204:GTP-Binding Proteins