Beta-endorphin receptors on cultured and freshly isolated lymphocytes from normal subjects.
[125I]-[D-Ala2]-beta EP*) binding to Epstein-Barr Virus (EBV) transformed B lymphocytes or to freshly isolated lymphocytes was characterized. The binding was time-, temperature- and pH-dependent; furthermore, it was reversible and cell concentration dependent. Maximum binding appeared at 15C in Tris buffer (pH 7.6) containing both BSA 0.5% and Bacitracin 0.1 mg/ml. beta EP inhibited BEP* binding to transformed lymphocytes and to freshly isolated lymphocytes by 50% at approximately 4 x 10(-8) M and 8 x 10(-9) M, respectively. Peptides representing amino-acid sequences 1-5, 1-16 and 1-17 of beta EP did not inhibit beta EP binding, neither did the opiates compounds Naloxone, Morphine, Bremazocine and Ethylketocyclazocine. On the contrary, beta EPd (6-31) inhibited beta EP* binding as effectively as beta EP, thus indicating that beta EP* binding to lymphocytes does not involve the N-terminal region of beta EP. 2 x 10(7)/ml freshly isolated lymphocytes bound 1.53 +/- 75%, whereas 2 x 10(6)/ml transformed lymphocytes bound 1.64 +/- 0.75% (mean +/- SD) beta EP* at tracer concentration. EBV transformed lymphocytes and freshly isolated lymphocytes may be useful to study beta EP receptors in humans.
Borboni
P
P
Dipartimento di Medicina Interna, II Università di Roma, Italy.
Di Cola
G
G
Sesti
G
G
Marini
M A
MA
Del Porto
P
P
Gilardini Montani
M S
MS
Lauro
R
R
De Pirro
R
R
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D001667:Binding, Competitive; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D004854:Herpesvirus 4, Human; D006801:Humans; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000502:physiology*; D011957:Receptors, Opioid / Q000502:physiology*; D013696:Temperature; D013997:Time Factors; D001615:beta-Endorphin / Q000502:physiology*
D011957:Receptors, Opioid; D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone