[Binding of [3H] dihydroetorphine to opioid receptors in rat brain membrane].
OBJECTIVE
To study the binding characteristics of dihydroetorphine (DHE) to opioid receptors.


METHODS
The binding of [3H] DHE to rat brain membrane opioid receptors was observed by radioligand binding study.


RESULTS
Saturation study showed the binding of [3H] DHE to rat brain membrane presented a single high-affinity class of binding sites with Kd = 0.19 nmol.L-1 and Bmax = 115 pmol/g protein. Kinetics study showed the association rate of [3H] DHE to opioid receptor was very rapid and dissociation very slow. NaCl 100 mmol.L-1 + guanosine triphosphate (GTP) 50 mumol.L-1 inhibited the binding of [3H] DHE and made Kd increase to 7.87 nmol.L-1, without effect on Bmax. Competitive inhibition of agonists and antagonists indicated that the affinity of [3H]DHE to mu opioid receptor was higher than to delta and kappa opioid receptors.


CONCLUSIONS
DHE is a selective agonist of mu opioid receptors.
Wang
D X
DX
Institute of Pharmacology & Toxicology, Academy of Military Medical Sciences, Beijing, China.
Qin
B Y
BY
D000701:Analgesics, Opioid / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005048:Etorphine / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism*
D000701:Analgesics, Opioid; D011957:Receptors, Opioid; D005048:Etorphine; C034765:18,19-dihydroetorphine