125I-beta-endorphin binding to neuroblastoma X glioma NG108-15 cells: distribution of delta opioid receptors.
The mouse neuroblastoma x rat glioma hybrid NG108-15 was previously shown to express delta opioid receptors. Because neuroblastoma cells display different phenotypes and cloned cell lines are heterogenous, we studied the characteristics and distribution of human 125I-beta-endorphin (125I-beta E) binding sites in cultures of NG108-15 cells with the use of micro-autoradiography and light microscopy. 125I-beta E labeled delta sites in NG108-15 in the presence of the non-opioid blocking peptide, beta-endorphin (6-31) (beta E (6-31)). Silver grains resulting from 125I-beta E binding to the opioid sites occurred in diffuse patches over several cells, with preferential location in dense cell patches. Pretreatment of NG108-15 with the delta agonist DADLE, previously shown to decrease beta E binding to delta sites on intact cells, also reduced silver grain density; however, some cells located in dense cell clusters were resistant to substantial agonist induced loss of labeling. These results suggest that delta opioid binding has a heterogenous cellular distribution in NG108.
Cone
R I
RI
Department of Pharmacy, University of California, San Francisco 94143-0446.
Rosenfeld
S
S
Lameh
J
J
Sadée
W
W
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D001667:Binding, Competitive; D005910:Glioma / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D051381:Rats; D017465:Receptors, Opioid, delta / Q000032:analysis / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D001615:beta-Endorphin / Q000378:metabolism*
D017465:Receptors, Opioid, delta; D001615:beta-Endorphin