Regional variations in binding capacities at mu-, delta- and kappa-opioid sites in membrane suspensions from rabbit brain.
The highest maximum binding capacities at the mu-sites of rabbit brain are in the striatum, with intermediate levels in the diencephalon, mesencephalon, cerebellum and cortex and low levels in the pons-medulla and hippocampus. For the delta-site the highest maximum binding capacity is also in the striatum; there are almost equally low levels in the other brain regions. At the kappa-sites the maximum binding capacities are highest in the diencephalon; there are intermediate levels in the cortex and striatum, and low levels in the mesencephalon, cerebellum, hippocampus and pons-medulla. The KD values lack reproducibility; there are no regional variations at the kappa-site as estimated with [3H](-)-bremazocine, but the possibility cannot be excluded that there are regional variations in the KD values for [3H][D-Ala2,MePhe4,Gly-ol5]enkephalin at the mu-site or for [3H][D-Ala2,D-Leu5]enkephalin at the delta-site. It may be important to use saturation analysis in future investigations of the distributions of the binding sites.
Petrillo
P
P
Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
La Regina
A
A
Sbacchi
M
M
Tavani
A
A
Robson
L E
LE
Kosterlitz
H W
HW
D000700:Analgesics / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001575:Benzomorphans / Q000378:metabolism / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine / Q000031:analogs & derivatives*; D004745:Enkephalins / Q000378:metabolism / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011817:Rabbits; D011957:Receptors, Opioid / Q000187:drug effects* / Q000378:metabolism; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu
D000700:Analgesics; D001575:Benzomorphans; D004745:Enkephalins; D009419:Nerve Tissue Proteins; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; C030279:enkephalinamide-Leu, Ala(2)-; C027248:bremazocine