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Journal of Comparative Physiology A

, Volume 161, Issue 1, pp 23–32 | Cite as

GABA-mediated synaptic inhibition of projection neurons in the antennal lobes of the sphinx moth,Manduca sexta

  • Brian Waldrop
  • Thomas A. Christensen
  • John G. Hildebrand
Article

Summary

  1. 1.

    Responses of neurons in the antennal lobe (AL) of the mothManduca sexta to stimulation of the ipsilateral antenna by odors consist of excitatory and inhibitory synaptic potentials (Fig. 2A). Stimulation of primary afferent fibers by electrical shock of the antennal nerve causes a characteristic IPSP-EPSP synaptic response in AL projection neurons (Fig. 2B).

     
  2. 2.

    The IPSP in projection neurons reverses below the resting potential (Fig. 3), is sensitive to changes in external (Fig. 4) and internal (Fig. 5) chloride concentration, and thus is apparently mediated by an increase in chloride conductance.

     
  3. 3.

    The IPSP is reversibly blocked by 100 μM picrotoxin (Fig. 6) or bicuculline (Fig. 7).

     
  4. 4.

    Many AL neurons respond to application of GABA with a strong hyperpolarization and an inhibition of spontaneous spiking activity (Fig. 8). GABA responses are associated with an increase in neuronal input conductance (Fig. 9) and a reversal potential below the resting potential (Fig. 11).

     
  5. 5.

    Application of GABA blocks inhibitory synaptic inputs (Fig. 12 A) and reduces or blocks excitatory inputs (Fig. 12B). EPSPs can be protected from depression by application of GABA (Fig. 12B).

     
  6. 6.

    Muscimol, a GABA analog that mimics GABA responses at GABAA receptors but not at GABAB receptors in the vertebrate CNS, inhibits many AL neurons in the moth (Fig. 13).

     

Keywords

Projection Neuron Bicuculline GABAB Receptor Muscimol Antennal Lobe 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

AL

antennal lobe

BMI

bicuculline methiodide

IACT

inner antenno-cerebral tract

LY

Lucifer Yellow

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Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • Brian Waldrop
    • 1
  • Thomas A. Christensen
    • 1
  • John G. Hildebrand
    • 1
  1. 1.Arizona Research Laboratories, Division of NeurobiologyUniversity of ArizonaTucsonUSA

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