Characterization and measurement of [125I]iodopindolol binding in individual rat pineal glands: existence of a 24-h rhythm in β-adrenergic receptor density

Aldo Gonzalez-Brito, David J. Jones, Rosa M. Ademe, Russel J. Reiter

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

A simple procedure has been developed that permits measurement of β-receptors in membrane preparations from individual rat pineal glands using [125I]iodopindolol ([125I]PIN). [125I]PIN binding to pineal membranes was stereospecific and saturable. Scatchard analysis of saturation isotherms yielded a Kd of 147.3 ± 54 pM and a Bmax of ± 1.5 mol/pineal glands. Binding was linear suggesting that [125I]PIN binds to a single population of pineal β-adrenergic receptors. This procedure was used to evaluate 24-h variations in density of pineal [125I]PIN binding sites in male rats maintained in a 14:10 h light:dark cycle. Binding remained uniformly low during the daytime, increased slightly prior to lights off and peaked after 6 h of darkness decreasing abruptly 2 h later, before lights on. In animals maintained in light at night, the number of binding sites also increased, but did not exhibit the darkness-related decrease. The results demonstrate that β-adrenergic receptors defined via [125I]PIN binding can be measured in tissue samples equivalent to less than one pineal gland. Moreover, the technique can be used in studies concerning the noradrenergic regulation of pineal function.

Original languageEnglish (US)
Pages (from-to)108-114
Number of pages7
JournalBrain Research
Volume438
Issue number1-2
DOIs
StatePublished - Jan 12 1988

Keywords

  • Daily (24 h) rhythm
  • Light-dark cycle
  • Male rat
  • Pineal gland
  • [I]Iodopindolol
  • β-Adrenoceptor

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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