Weaning-induced development of δ-opioid receptors in rat brain: Differential effects of guanine nucleotides and sodium upon ligand-receptor recognition

M. D.W. Kelly, R. G. Hill, A. Borsodi, G. Toth, I. Kitchen

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

1. We have previously shown that weaning at day 21 increases δ-opioid receptor binding in the brain at day 25, which might be due to stimulation of the development of a δ-opioid receptor subtype or activation of G-protein coupling processes. 2. We have addressed the possibility that weaning stimulates coupling of the δ-receptor by homogenate binding studies with four agonist and one antagonist radioligand in the presence of a GTP analogue and Na+ in brain tissue from weaned and non-weaned animals. 3. Saturation studies with three agonist ligands ([3H]-deltorphin I, [3H]-S-Atc-Ile5,6deltorphin I and [3H]-R-Atc-Ile5,6deltorphin II) showed higher levels of maximal binding in brains from 25-day weaned than in brains from non-weaned rats. The magnitude of the effects of GMPPNP and Na+ in decreasing this binding was ligand dependant and in each case was significantly more marked in brains from weaned animals. GMPPNP and Na+ were completely without effect on B(max) for, [3H]-S-Atc-Ile5,6deltorphin I and [3H]-R-Atc-Ile5,6deltorphin II in brains from non-weaned rats. 4. [3H]-Ile5,6deltorphin II and [3H]-naltrindole showed no differences in labelling between weaned and non-weaned groups and both groups responded similarly to the effects of GMPPNP and Na+ treatment. 5. GMPPNP and Na+ had small effects on binding affinity (K(D)) for some of the agonist radioligands which were similar in both weaned and non-weaned groups. 6. Weaning induced increases in binding of δ-receptors in 25-day rats can be explained in terms of the way δ-agonist radioligands recognize the receptor environment.

Original languageEnglish
Pages (from-to)979-986
Number of pages8
JournalBritish journal of pharmacology
Volume125
Issue number5
DOIs
Publication statusPublished - Nov 11 1998

Keywords

  • Development
  • G-proteins
  • Guanine nucleotides
  • Ontogeny
  • Receptor coupling
  • Weaning
  • δ-opioid receptors

ASJC Scopus subject areas

  • Pharmacology

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