ABSTRACT
Ontogeny of the rat brain delta opioid receptor in 1-60 days old animals has been studied with anti-idiotypic antibodies to anti-leucine enkephalin. It is found that delta opioid receptors are present in rats from birth and attain adult levels by 28 days and these receptors are glycosylated and inhibited by Na+, GTP, ATP and CTP at all ages. Adult membrane-bound and solubilized delta opioid receptors are inhibited to similar extents by Na+ (100 mM), GTP, ATP and CTP (50 microM). Dialysis of the adult membrane-bound receptor led to 81% loss in binding which was restored by 100 mM Na+, 50 microM GTP, ATP and CTP to 77, 72, 87 and 94% respectively and by 100 mM NH4+, Mg2+, Ca2+ and Mn2+ to 63, 43, 57 and 73% respectively. Dialysis of the solubilized receptor resulted in 23% loss in binding with Na+ (100 mM), GTP and ATP (50 microM) inhibiting receptor binding to 46, 62 and 54% respectively, while CTP (50 microM) restored binding to 88%. These studies indicate that the delta opioid receptor can be probed with anti-idiotypic antibodies to anti-leucine enkephalin, that functional, glycosylated receptors are present at birth in rats and that the adult membrane-bound and solubilized receptors are modulated differently by dialysis.
Subject(s)
Animals , Antibodies, Anti-Idiotypic/diagnosis , Brain/growth & development , Dialysis , Enkephalin, Leucine/immunology , Glycosylation , Nucleotides/metabolism , Rats , Receptors, Opioid, delta/metabolism , Sodium/metabolismABSTRACT
Anti-idiotypic antibodies to anti-leucine enkephalin raised in rabbits immunized with leucine enkephalin conjugated to BSA, were purified and characterized for their ability to mimic leucine enkephalin in binding to the rat brain delta opioid receptor. An ELISA was standardized to assay the delta opioid receptor using these antibodies. The rat brain receptor was purified to 308 fold with a yield of 1.5% using these antibodies for assay. The receptor, probed with these anti-idiotypic antibodies, was characterized with respect to binding parameters, molecular weight and effect of divalent cations.