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Naunyn-Schmiedeberg's Archives of Pharmacology

, Volume 306, Issue 3, pp 263–266 | Cite as

Selective stimulation of central α-autoreceptors following treatment with α-methyldopa and FLA 136

  • Nils-Erik Andén
Article

Summary

  1. 1.

    The accumulation of normetanephrine in the rat brain induced by the monoamine oxidase inhibitor nialamide was inhibited following α-methyldopa and 4-amino-3-(2,6-dichlorobenzylidenehydrazino)-1,2,4-triazole (FLA 136). It was not changed following α-methylmetatyrosine despite a greater disappearance of noradrenaline than after α-methyldopa. The α-adrenoreceptor blocking agent yohimbine increased the nialamide-induced accumulation of normetanephrine and completely antagonized the actions of α-methyldopa and FLA 136, indicating that the effects of the two drugs are due to stimulation of α-adrenoreceptors.

     
  2. 2.

    The flexor reflex activity of spinalized rats was not influenced by α-methyldopa and α-methylmeta-tyrosine at the doses used in the biochemical experiments, as previously found for FLA 136, indicating no stimulation of classical, postsynaptic, central α-adrenoreceptors.

     
  3. 3.

    The biochemical effects of α-methyldopa and FLA 136 might be caused by stimulation of α-autoreceptors on the cell bodies and the nerve terminals of noradrenaline neurons. A similar mechanism might be involved in the hypotension reported by other investigators following these drugs.

     

Key words

Alpha-adrenoreceptors Autoreceptors Noradrenaline release α-Methyldopa 

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Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • Nils-Erik Andén
    • 1
  1. 1.Department of PharmacologyUniversity of GöteborgGöteborgSweden

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