Voltage-dependent calcium signaling in rat cerebellar unipolar brush cells

Neuroscience. 2009 Sep 1;162(3):702-12. doi: 10.1016/j.neuroscience.2009.01.051. Epub 2009 Feb 3.

Abstract

Unipolar brush cells (UBCs) are a class of excitatory interneuron found in the granule cell layer of the vestibulocerebellum. Mossy fibers form excitatory inputs on to the paint brush shaped dendrioles in the form of giant, glutamatergic synapses, activation of which results in prolonged bursts of action potentials in the postsynaptic UBC. The axons of UBCs themselves form mossy fiber contacts with other UBCs and granule cells, forming an excitatory, intrinsic cerebellar network that has the capacity to synchronize and amplify mossy fiber inputs to potentially large populations of granule cells. In this paper, we demonstrate that UBCs in rat cerebellar slices express low voltage activated (LVA) fast-inactivating and high voltage activated (HVA) slowly inactivating calcium channels. LVA calcium currents are mediated by T-type calcium channels and they are associated with calcium increases in the dendrites and to a lesser extent the cell soma. HVA currents, mediated by L-type calcium channels, are slowly inactivating and they produce larger overall increases in intracellular calcium but with a similar distribution pattern. We review these observations alongside several recent papers that examine how intrinsic membrane properties influence UBCs firing patterns and we discuss how UBC signaling may affect downstream cerebellar processing.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Animals, Newborn
  • Biophysics
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / physiology*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Cerebellum / cytology*
  • Electric Stimulation / methods
  • In Vitro Techniques
  • Male
  • Neurons / classification
  • Neurons / physiology*
  • Patch-Clamp Techniques / methods
  • Rats
  • Rats, Sprague-Dawley
  • Rats, Wistar
  • Sodium Channel Blockers / pharmacology
  • Tetrodotoxin / pharmacology

Substances

  • Calcium Channel Blockers
  • Calcium Channels
  • Sodium Channel Blockers
  • Tetrodotoxin
  • Calcium