Tau reduction affects excitatory and inhibitory neurons differently, reduces excitation/inhibition ratios, and counteracts network hypersynchrony

Cell Rep. 2021 Oct 19;37(3):109855. doi: 10.1016/j.celrep.2021.109855.

Abstract

The protein tau has been implicated in many brain disorders. In animal models, tau reduction suppresses epileptogenesis of diverse causes and ameliorates synaptic and behavioral abnormalities in various conditions associated with excessive excitation-inhibition (E/I) ratios. However, the underlying mechanisms are unknown. Global genetic ablation of tau in mice reduces the action potential (AP) firing and E/I ratio of pyramidal cells in acute cortical slices without affecting the excitability of these cells. Tau ablation reduces the excitatory inputs to inhibitory neurons, increases the excitability of these cells, and structurally alters their axon initial segments (AISs). In primary neuronal cultures subjected to prolonged overstimulation, tau ablation diminishes the homeostatic response of AISs in inhibitory neurons, promotes inhibition, and suppresses hypersynchrony. Together, these differential alterations in excitatory and inhibitory neurons help explain how tau reduction prevents network hypersynchrony and counteracts brain disorders causing abnormally increased E/I ratios.

Keywords: Alzheimer’s disease; axon initial segment; epilepsy; excitation-inhibition balance; hypersynchrony; interneurons; intrinsic excitability; neuronal plasticity; pyramidal cells; tau.

Publication types

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

MeSH terms

  • Alzheimer Disease / genetics
  • Alzheimer Disease / metabolism
  • Alzheimer Disease / physiopathology
  • Animals
  • Cells, Cultured
  • Epilepsy / genetics
  • Epilepsy / metabolism
  • Epilepsy / physiopathology
  • Excitatory Postsynaptic Potentials*
  • Female
  • Inhibitory Postsynaptic Potentials*
  • Interneurons / metabolism*
  • Male
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neural Inhibition*
  • Neural Pathways / cytology
  • Neural Pathways / metabolism*
  • Neuronal Plasticity
  • Pyramidal Cells / metabolism*
  • Somatosensory Cortex / cytology
  • Somatosensory Cortex / metabolism*
  • Time Factors
  • tau Proteins / deficiency*
  • tau Proteins / genetics

Substances

  • Mapt protein, mouse
  • tau Proteins