Evidence for functional separation of alpha-1 and alpha-2 noradrenaline receptors by pre-synaptic terminal re-uptake mechanisms

Andrew J. M. Clark, Steven P. Butcher, Philip Winn

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Abstract

Information transfer within the central nervous system is predominantly chemical in nature, and occurs both through synaptic specialisations and non-specific diffuse release. The localisation and description of receptors for these two types of neurotransmission is currently a contentious issue. In the present study, the noradrenaline reuptake inhibitor cocaine has been shown to overcome the inhibitory effects of idazoxan, a selective alpha-2 receptor antagonist, but not phentolamine, a non-selective alpha receptor antagonist, on eating following injection of noradrenaline into the rat hypothalamic paraventricular nucleus. Similarly, lesion by 6-hydroxydopamine of noradrenaline terminals in the paraventricular nucleus also reduced the efficacy of idazoxan in blocking eating induced by noradrenaline. These data confirm that post-synaptic alpha-2 receptors are involved in the feeding response to exogenous noradrenaline, but in addition, when taken in conjunction with previously published data, are used to suggest a differential distribution of NA receptors within the hypothalamic paraventricular nucleus. It is proposed that the alpha-2 subtype may be extrasynaptic, the alpha-1 subtype intrasynaptic.
Original languageEnglish
Pages (from-to)366-374
Number of pages9
JournalPsychopharmacology
Volume103
Issue number3
DOIs
Publication statusPublished - 31 Mar 1991

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Keywords

  • extrasynaptic receptors
  • feeding
  • hypothalamic paraventricular nucleus
  • paracrine transmission
  • rat

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