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Cholecystokinin-8 suppressed /sup 3/H-etorphine binding to rat brain opiate receptors

Journal Article · · Life Sci.; (United States)
Radioreceptor assay (RRA) was adopted to analyze the influence of CCK-8 on /sup 3/H-etorphine binding to opiate receptors in rat brain synaptosomal membranes (P2). In the competition experiment CCK-8 suppressed the binding of /sup 3/H-etorphine. This effect was completely reversed by proglumide at 1/mu/M. Rosenthal analysis for saturation revealed two populations of /sup 3/H-etorphine binding sites. CCK-8 inhibited /sup 3/H-etorphine binding to the high affinity sites by an increase in Kd and decrease in Bmax without significant changes in the Kd and Bmax of the low affinity sites. This effect of CCK-8 was also completely reversed by proglumide at 1/mu/M. Unsulfated CCK-8 produced only a slight increase in Kd of the high affinity sites without affecting Bmax. The results suggest that CCK-8 might be capable of suppressing the high affinity opioid binding sites via the activation of CCK receptor.
Research Organization:
Beijing Medical Univ. (China)
OSTI ID:
5728973
Journal Information:
Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 45:2; ISSN LIFSA
Country of Publication:
United States
Language:
English