Inhibition of MMP-2 but not MMP-9 influences inner ear spiral ganglion neurons in vitro

Cell Mol Neurobiol. 2014 Oct;34(7):1011-21. doi: 10.1007/s10571-014-0077-2. Epub 2014 Jun 17.

Abstract

Matrix metalloproteinases (MMPs) play an important role in modeling of the extracellular matrix. There is increasing evidence that these proteases are important in neurite elongation and axonal guidance during development in the central nervous system and retina. Moreover, they are also expressed after acute injury and can be the key mediators of pathogenesis. However, the role of MMPs in the inner ear is largely unknown. Our group recently demonstrated that general inhibition of MMPs resulted in auditory hair cell loss in vitro. In the present study, we investigated the role of MMPs in inner ear spiral ganglion neuron (SGN) survival, neuritogenesis and neurite extension by blocking MMPs known to be involved in axonal guidance, neurite elongation, and apoptosis in other neuronal systems. Spiral ganglion (SG) explants from 5-day-old Wistar rats were treated with different concentrations of the general MMP inhibitor GM6001, a specific MMP-2 inhibitor, and a specific MMP-9 inhibitor, in vitro. The general inhibitor of MMPs and the specific inhibition of MMP-2 significantly reduced both the number of neurites that extended from SG explants, as well as the length of individual neurites. However, neither the general inhibitor of MMPs nor the specific inhibition of MMP-2 influenced SGN survival. Inhibition of MMP-9 had no influence on SGNs. The data suggest that MMPs, and more specifically MMP-2, influence the growth of developing afferent neurites in the mammalian inner ear in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Count
  • Cell Survival / drug effects
  • Ear, Inner / cytology*
  • Labyrinth Supporting Cells / cytology
  • Labyrinth Supporting Cells / enzymology
  • Matrix Metalloproteinase 2 / metabolism*
  • Matrix Metalloproteinase 9 / genetics
  • Matrix Metalloproteinase 9 / metabolism*
  • Matrix Metalloproteinase Inhibitors / pharmacology*
  • Neurites / drug effects
  • Neurites / enzymology
  • Neurons / cytology
  • Neurons / drug effects
  • Neurons / enzymology*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats, Wistar
  • Spiral Ganglion / cytology
  • Spiral Ganglion / drug effects
  • Spiral Ganglion / enzymology*

Substances

  • Matrix Metalloproteinase Inhibitors
  • RNA, Messenger
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9