Neuropeptide Y increases the inhibitory effects of clonidine on potassium evoked 3H-noradrenaline but not 3H-5-hydroxytryptamine release from synaptosomes of the hypothalamus and the frontoparietal cortex of the male Sprague-Dawley rat

Maria Martire, Paolo Preziosi, K Fuxe, G Pistritto, Lf Agnati

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

Abstract

The release of 3H-noradrenaline (3H-NA) and of 3H-5-hydroxytryptamine (3H-5-HT) evoked by high-K+ (15 mM) was studied in synaptosomes isolated from the hypothalamus and the frontoparietal cortex of the male Sprague-Dawley rat using a superfusion apparatus. Based on concentration-response curves obtained by analyzing the full-time course of the inhibitory effects of clonidine on 3H-NA and on 3H-5-HT release neuropeptide Y (NPY) (1 nM) was shown to significantly increase the ability of clonidine to inhibit 3H-NA release in synaptosomes isolated from the hypothalamus and from the frontoparietal cortex. NPY (1 nM) alone had no effect on K+-evoked 3H-NA release from these regions. In contrast, NPY (1 nM) did not modulate the inhibitory effects of clonidine on 3H-5-HT release in the above mentioned regions. These results indicate that NPY can increase the sensitivity of the alpha 2-autoreceptors belonging to hypothalamic NA and/or to adrenaline nerve terminals and to cortical NA nerve terminals, while the alpha 2-heteroreceptors inhibiting 3H-HT release in the same brain regions appear not to be regulated by high affinity NPY receptors. Thus, alpha 2-autoreceptors and alpha 2-heteroreceptors appear to be differentially controlled by high affinity NPY receptors at least with regard to regulation of 3H-NA and 3H-5-HT release, respectively.
Lingua originaleEnglish
pagine (da-a)61-72
Numero di pagine12
RivistaJournal of Neural Transmission
Volume78
Stato di pubblicazionePubblicato - 1989

Keywords

  • Animals
  • Clonidine
  • Frontal Lobe
  • Hypothalamus
  • Male
  • Neuropeptide Y
  • Norepinephrine
  • Parietal Lobe
  • Potassium
  • Rats
  • Rats, Inbred Strains
  • Serotonin Antagonists
  • Synaptosomes

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