European Journal of Endocrinology · 1973 · 39 citations · 0 references
Life SciencesEndocrinologyPharmacologyNeurochemistryNeuroendocrinologySteroid BiochemistryAdrenal HormonesAdrenal Steroid HormonesAdrenal SteroidogenesisHormonal InfluencesSteroid BiosynthesisSteroid MetabolismAdrenal Cortex FunctionAdrenal Cortex PhysiologyAdrenal Cortex SteroidogenesisAdrenal Cortical HormonesAdrenal Hormone MetabolismAdrenal Steroid MetabolismMonoamine Oxidase InhibitionRate Limiting
ABSTRACT The activity of the enzyme monoamine oxidase (MAO) in the brain, heart, liver and spleen of rats 10 weeks after adrenalectomy was determined. Another group of adrenalectomized rats received 5 mg of hydrocortisone daily for the period of 10 days and their MAO activity was compared with that of control adrenalectomized rats. There was a significant rise in MAO activity following adrenalectomy in the tissue homogenate, mitochondrial and supernatant fractions of all the organs studied. Hydrocortisone administration decreased MAO activity to the level of normal rats. These results suggest that corticoids serve as a rate limiting factor for the activity of the enzyme MAO. This hypothesis was further tested in normal rats by blocking the biosynthesis of glucocorticoids with Metopirone®. Four hours after a single injection of 75 mg Metopirone the cerebral, hepatic and cardiac MAO showed marked increases from control levels. These results suggest that adrenal cortical steroids present in the circulation of normal animals regulate the activity of the enzyme MAO in most organs.