Kappa Opioid Receptors on Three Related Thymoma Cell Lines
The search for opioid binding sites on leukocytes has been difficult. The presence of opioid binding sites has been reported on human and murine leukocytes (1–3) as well as on some cell lines (4,5). However, in contrast to brain opioid receptors, these sites do not exhibit all of the classical opioid binding characteristics, such as stereoselectivity and high affinity for both alkaloids and peptides (6). In addition, agonist-induced functional responses have not been correlated with these binding sites. It seems likely that only a small population of leukocytes actually express opioid receptors, and possibly only under certain conditions. If this is the case, binding studies with mixed cell populations may not show a detectable signal-to-noise ratio, even when receptors are present.
KeywordsLeukemia Cortisol Morphine Dexamethasone Alkaloid
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