title: Guanine nucleotide and cation regulation of mu, delta, and kappa opioid receptor binding: evidence for differential postnatal development in rat brain.
abstract: A study of the onset of cation and guanine nucleotide regulation of delta, mu, and kappa rat brain opioid receptors during postnatal development was undertaken. Site-specific binding assays were utilized for each receptor type and the effects of 0.5 mM MnCl2, 100 mM NaCl, and/or 50 microM guanosine-5'-(beta, gamma-imido) triphosphate [Gpp(NH)p] were assessed. The most pronounced changes of opioid binding were seen in the presence of Mn2+. In adults, agonist binding to delta sites was stimulated by Mn2+, whereas that to mu sites was not affected and kappa binding was inhibited. The postnatal development of Mn2+ regulation for the three receptor subtypes was distinctly different. The largest effects were seen on delta sites detected in the early neonatal period, Mn2+ eliciting a 68% stimulation of binding over controls at day 1. Significant inhibition of kappa site binding by Mn2+ was detected only after the third postnatal week. Mn2+ caused a significant reversal of Gpp(NH)p inhibition of delta binding in the early neonatal period, exceeding that in the absence of regulators. Inhibition of mu and delta receptor binding by Na+ was greater, and the Mn2+ reversal of this effect was smaller, in the first 2 postnatal weeks than in adults. Gpp(NH)p + Na+ regulation did not change appreciably during the postnatal period. However, Mn2+ reversal of the considerable inhibition elicited by the combination of Na+ and Gpp(HN)p was developmental time-dependent. The data are discussed in terms of multiple sites of interaction for guanine nucleotides and cations.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development* / Q000378:metabolism; D002412:Cations; D002712:Chlorides; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000378:metabolism; D016308:Enkephalin, Leucine-2-Alanine; D006150:Guanine Nucleotides / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D017895:Manganese Compounds; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D002412:Cations; D002712:Chlorides; D006150:Guanine Nucleotides; D017895:Manganese Compounds; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D006165:Guanylyl Imidodiphosphate; D008345:Manganese; D012965:Sodium Chloride; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D006160:Guanosine Triphosphate; C025340:manganese chloride