Somatostatinergic modulation of firing pattern and calcium-activated potassium currents in medium spiny neostriatal neurons

E. Galarraga*, C. Vilchis, T. Tkatch, H. Salgado, F. Tecuapetla, T. Perez-Rosello, E. Perez-Garci, E. Hernandez-Echeagaray, D. J. Surmeier, J. Bargas

*Corresponding author for this work

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Somatostatin is synthesized and released by aspiny GABAergic interneurons of the neostriatum, some of them identified as low threshold spike generating neurons (LTS-interneurons). These neurons make synaptic contacts with spiny neostriatal projection neurons. However, very few somatostatin actions on projection neurons have been described. The present work reports that somatostatin modulates the Ca2+ activated K+ currents (KCa currents) expressed by projection cells. These actions contribute in designing the firing pattern of the spiny projection neuron; which is the output of the neostriatum. Small conductance (SK) and large conductance (BK) KCa currents represent between 30% and 50% of the sustained outward current in spiny cells. Somatostatin reduces SK-type K+ currents and at the same time enhances BK-type K+ currents. This dual effect enhances the fast component of the afterhyperpolarizing potential while reducing the slow component. Somatostatin then modifies the firing pattern of spiny neurons which changed from a tonic regular pattern to an interrupted "stuttering"-like pattern. Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) tissue expression analysis of dorsal striatal somatostatinergic receptors (SSTR) mRNA revealed that all five SSTR mRNAs are present. However, single cell RT-PCR profiling suggests that the most probable receptor in charge of this modulation is the SSTR2 receptor. Interestingly, aspiny interneurons may exhibit a "stuttering"-like firing pattern. Therefore, somatostatin actions appear to be the entrainment of projection neurons to the rhythms generated by some interneurons. Somatostatin is then capable of modifying the processing and output of the neostriatum.

Original languageEnglish (US)
Pages (from-to)537-554
Number of pages18
JournalNeuroscience
Volume146
Issue number2
DOIs
StatePublished - May 11 2007

Keywords

  • AHP
  • BK channel
  • LTS-interneurons
  • SK channel
  • medium spiny neurons
  • neostriatum

ASJC Scopus subject areas

  • Neuroscience(all)

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    Galarraga, E., Vilchis, C., Tkatch, T., Salgado, H., Tecuapetla, F., Perez-Rosello, T., Perez-Garci, E., Hernandez-Echeagaray, E., Surmeier, D. J., & Bargas, J. (2007). Somatostatinergic modulation of firing pattern and calcium-activated potassium currents in medium spiny neostriatal neurons. Neuroscience, 146(2), 537-554. https://doi.org/10.1016/j.neuroscience.2007.01.032