Comparative analysis of the effects of iontophoretically applied dopamine in different regions of the rat brain, with special reference to the cingulate cortex

Comparative analysis of the effects of iontophoretically applied dopamine in different regions of... A systematic comparison of the effects of iontophoresed dopamine (DA) was carried out in the neostriatum (NS), nucleus accumbens (Acb) and anterior cingulate (ACg), prefrontal (PF) and parietal (Par) cortex of urethane‐anesthetized rats, before and after treatment with the specific DA uptake blockers GBR 12909 and Bupropion. Similar experiments were also conducted after DA denervation with 6‐hydroxydopamine and after DA depletion with α‐methyl‐p‐tyrosine. The average rate of spontaneous neuronal firing was comparable in all regions, except in the NS after DA depletion. A majority of the units were inhibited by DA in every region and condition tested. As assessed with the IT50 index, the responsiveness to DA was not markedly different between regions, indicating that the postsynaptic sensitivity to this amine is independent of the density of DA receptors and of DA innervation. In contrast, the average duration of DA inhibitions (RT90) was considerably longer (5‐fold) in the intact ACg than in the PF, Par, NS, or Acb. Moreover, treatment with both DA uptake blockers reduced the duration of DA inhibitions in ACg (4‐ to 9‐fold); while lengthening it in PF, NS and Acb; and having no apparent effect in Par. DA depletion and DA denervation also reduced the duration of the DA inhibitions in ACg without effect in Par. Taken together, these results provide further evidence for the existence of a presynaptic, positive‐feedback mechanism in ACg, triggered by DA, and favouring the further release of this transmitter upon its reuptake in DA nerve terminals. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Synapse Wiley

Comparative analysis of the effects of iontophoretically applied dopamine in different regions of the rat brain, with special reference to the cingulate cortex

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Publisher
Wiley
Copyright
Copyright © 1991 Wiley‐Liss, Inc.
ISSN
0887-4476
eISSN
1098-2396
D.O.I.
10.1002/syn.890090105
Publisher site
See Article on Publisher Site

Abstract

A systematic comparison of the effects of iontophoresed dopamine (DA) was carried out in the neostriatum (NS), nucleus accumbens (Acb) and anterior cingulate (ACg), prefrontal (PF) and parietal (Par) cortex of urethane‐anesthetized rats, before and after treatment with the specific DA uptake blockers GBR 12909 and Bupropion. Similar experiments were also conducted after DA denervation with 6‐hydroxydopamine and after DA depletion with α‐methyl‐p‐tyrosine. The average rate of spontaneous neuronal firing was comparable in all regions, except in the NS after DA depletion. A majority of the units were inhibited by DA in every region and condition tested. As assessed with the IT50 index, the responsiveness to DA was not markedly different between regions, indicating that the postsynaptic sensitivity to this amine is independent of the density of DA receptors and of DA innervation. In contrast, the average duration of DA inhibitions (RT90) was considerably longer (5‐fold) in the intact ACg than in the PF, Par, NS, or Acb. Moreover, treatment with both DA uptake blockers reduced the duration of DA inhibitions in ACg (4‐ to 9‐fold); while lengthening it in PF, NS and Acb; and having no apparent effect in Par. DA depletion and DA denervation also reduced the duration of the DA inhibitions in ACg without effect in Par. Taken together, these results provide further evidence for the existence of a presynaptic, positive‐feedback mechanism in ACg, triggered by DA, and favouring the further release of this transmitter upon its reuptake in DA nerve terminals.

Journal

SynapseWiley

Published: Sep 1, 1991

References

  • Depletion of brain noradrenaline and dopamine by 6‐hydroxydopamine
    Breese, Breese; Traylor, Traylor
  • Caudate nucleus neurones: Correlation of the effects of substantia nigra stimulation with iontophoretic dopamine
    Connor, Connor
  • Evidence for a receptor‐mediated feedback control of tyrosine hydroxylase activity
    Kehr, Kehr; Carlsson, Carlsson; Lindgvist, Lindgvist; Magnusson, Magnusson; Atack, Atack
  • Excitatory nature of dopamine in the nigro‐caudate pathway
    Kitai, Kitai; Sugimori, Sugimori; Kocsis, Kocsis
  • Function comparison of neurotransmitter receptor subtypes in mammalian central nervous system
    Nicoll, Nicoll; Malenka, Malenka; Kauer, Kauer

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