Monoamine oxidase A and B activities in embryonic chick hepatocytes: Differential regulation by retinoic acid

Antonietta Nicotra, Laura Falasca, Ornella Senatori, Laura Conti Devirgiliis

Research output: Contribution to journalArticle

Abstract

Monoamine oxidases (MAOs) A and B are two isoenzymes involved in the degradation of many biological amines in the nervous system and in peripheral organs. In the present work hepatocytes isolated from 14-day-old chick embryos were used as a model system to determine whether retinoic acid (RA) is capable of modulating the activity of the two MAO forms. RA is a retinoid that, by binding with nuclear receptors, interferes with the expression of specific genes in many differentiation processes. Enzymic activity was measured with a radiochemical method using serotonin and β-phenylethylamine as preferential substrates for MAO A and MAO B, respectively. The specific activity of the two forms was measured in hepatocytes cultured for 24, 48 and 72 h in the presence and the absence of serum. RA stimulated MAO B but not MAO A activity, in a dose- and time-dependent way, and only in the presence of serum. Maximum stimulation (about 3.5-fold) was obtained after treatment with 5 μm RA for 72 h. Kinetic analysis of MAO B activity showed an increase in Vmax in treated hepatocytes (5 μm RA for 72 h) with no change in Km. In conclusion, the present work shows that RA selectively elicits MAO B activity in cultured chick embryonic hepatocytes, this stimulation requires the presence of some factors present in the serum and is probably due to an increase in the number of enzyme molecules.

Original languageEnglish
Pages (from-to)87-94
Number of pages8
JournalCell Biochemistry and Function
Volume20
Issue number2
DOIs
Publication statusPublished - 2002

Keywords

  • Chick hepatocytes
  • Monoamine oxidase
  • Retinoic acid

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology

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