Pharmacological Studies on the Regulation of N‐Acetyltransferase Activity and Melatonin Content of the Pineal Gland of the Syrian Hamster

Stephan Steinlechner, Thomas S. King, Thomas H. Champney, Bruce A. Richardson, Russel J. Reiter

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

Thus far, all attempts to stimulate melatonin synthesis by β-adrenergic receptor agonists in the Syrian hamster pineal gland have failed. Neither a wide range of dosages of isoproterenol (0.5 mg/kg to 24 mg/kg), nor prolonged treatment with norepinephrine, the natural neurotransmitter, increased N-acetyltransferase (NAT) activity or melatonin production. In the present study, the administration of isoproterenol at night was likewise ineffective in advancing or enhancing the normal nightly melatonin peak. Also, we did not find a delayed effect 7 or 8 h after the administration of the drug. Furthermore, we tested the idea of coneurotransmitters such as octopamine or dopamine being possibly necessary for stimulation, but could not find any effect of these substances on melatonin synthesis. In addition, a parasympatholytic agent, atropine, did not increase the responsiveness to sympathomimetic agents. Administration of a phosphodiesterase inhibitor was also ineffective in stimulating NAT activity. On the other hand, isoproterenol did retard the drop in NAT and melatonin after lights-on at night, indicating that β-receptors are involved in maintaining elevated melatonin levels.

Original languageEnglish (US)
Pages (from-to)109-119
Number of pages11
JournalJournal of Pineal Research
Volume2
Issue number2
DOIs
StatePublished - Apr 1985
Externally publishedYes

Keywords

  • N‐acetyltransferase activity
  • catecholamines
  • isoproterenol
  • melatonin
  • norepinephrine
  • pineal gland

ASJC Scopus subject areas

  • Endocrinology

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