Repeated administration of opioids alters characteristics of membrane-bound phorbol ester binding in rat brain.
Scatchard analysis of saturation binding data indicated that dissociation constant (KD) of [3H]phorbol 12,13-dibutyrate (PDB) binding to the membrane-bound protein kinase C of rat cortex and midbrain was significantly decreased following systemic repeated administration of morphine (mu-opioid receptor agonist) and butorphanol (mu/delta/kappa-mixed opioid receptor agonist). No change in the receptor density (Bmax) of [3H]PDB binding was found following repeated treatment with morphine and butorphanol. On the other hand, neither the Bmax nor KD values in pons/medulla were altered in these rats. These results suggest that systemic repeated opioid treatment, such as morphine and butorphanol leads to an increased affinity for phorbol ester binding to the membrane-bound protein kinase C in rat cortex and midbrain.
Narita
M
M
Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216-4505.
Feng
Y
Y
Makimura
M
M
Hoskins
B
B
Ho
I K
IK
D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002077:Butorphanol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D015240:Phorbol 12,13-Dibutyrate; D009020:Morphine; D002077:Butorphanol; D002118:Calcium