Dichotomous Anatomical Properties of Adult Striatal Medium Spiny Neurons

J Neurosci. 2008 Oct 22;28(43):10814-24. doi: 10.1523/JNEUROSCI.2660-08.2008.

Abstract

Principal medium spiny projection neurons (MSNs) of the striatum have long been thought to be homogeneous in their somatodendritic morphology and physiology. Recent work using transgenic mice, in which the two major classes of MSN are labeled, has challenged this assumption. To explore the basis for this difference, D(1) and D(2) receptor-expressing MSNs (D(1) and D(2) MSNs) in brain slices from adult transgenic mice were characterized electrophysiologically and anatomically. These studies revealed that D(1) MSNs were less excitable than D(2) MSNs over a broad range of developmental time points. Although M(1) muscarinic receptor signaling was a factor, it was not sufficient to explain the dichotomy between D(1) and D(2) MSNs. Reconstructions of biocytin-filled MSNs revealed that the physiological divergence was paralleled by a divergence in total dendritic area. Experimentally grounded simulations suggested that the dichotomy in MSN dendritic area was a major contributor to the dichotomy in electrophysiological properties. Thus, rather than being an intrinsically homogenous population, striatal MSNs have dichotomous somatodendritic properties that mirror differences in their network connections and biochemistry.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cells, Cultured
  • Corpus Striatum / cytology*
  • Dendrites / physiology
  • Dendritic Spines / physiology*
  • Embryo, Mammalian
  • Green Fluorescent Proteins / genetics
  • In Vitro Techniques
  • Lysine / analogs & derivatives
  • Lysine / metabolism
  • Membrane Potentials / physiology
  • Membrane Potentials / radiation effects
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microscopy, Confocal
  • Models, Neurological
  • Neurons* / classification
  • Neurons* / cytology
  • Neurons* / physiology
  • Patch-Clamp Techniques
  • Potassium Channels, Inwardly Rectifying / physiology
  • Receptors, Dopamine D1 / genetics
  • Receptors, Dopamine D1 / physiology*
  • Receptors, Dopamine D2 / genetics
  • Receptors, Dopamine D2 / physiology*

Substances

  • Kir2.1 channel
  • Potassium Channels, Inwardly Rectifying
  • Receptors, Dopamine D1
  • Receptors, Dopamine D2
  • Green Fluorescent Proteins
  • biocytin
  • Lysine