Supraspinal delta opioid receptor mRNA levels are not altered in [D-Ala2]deltorphin II tolerant mice.
Delta opioid receptor (DOR) mRNA levels were studied in mice rendered tolerant to [D-Ala2]deltorphin II by 4 days of repeated intracerebroventricular administration (10 micrograms, [tid]). ED50 determinations on day 5 revealed a 10-fold loss in [D-Ala2]deltorphin II potency with the tail-flick test. Utilization of a microdissection technique followed by quantitative solution hybridization of RNA extracts from mouse brain revealed mean levels of DOR mRNA ranging from 3.9 pg/micrograms RNA in the caudate-putamen to 0.4 pg/micrograms RNA in the cerebellum. DOR mRNA levels were not different when RNA extracts from tolerant and non-tolerant mice were compared. These data suggest that altered DOR mRNA levels are not one of the adaptive changes that occur with delta opioid ([D-Ala2]deltorphin II) tolerance.
Kest
B
B
Department of Pharmacology, Cornell University Medical College, New York, New York 10021.
Jenab
S
S
Brodsky
M
M
Elliott
K
K
Inturrisi
C E
CE
D000818:Animals; D018076:DNA, Complementary / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D017403:In Situ Hybridization; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D010147:Pain Measurement / Q000187:drug effects; D015347:RNA Probes; D012333:RNA, Messenger / Q000096:biosynthesis*; D017465:Receptors, Opioid, delta / Q000819:agonists* / Q000096:biosynthesis* / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
D018076:DNA, Complementary; D004745:Enkephalins; D015347:RNA Probes; D012333:RNA, Messenger; D017465:Receptors, Opioid, delta; D020881:Enkephalin, D-Penicillamine (2,5)-