Unipolar brush cells in the human cochlear nuclei identified by their expression of a metabotropic glutamate receptor (mGluR2/3).

Unipolar brush cells (UBCs) reside in the mammalian vestibulo-cerebellum and the ventral (VCN) and, particularly, dorsal cochlear nuclei (DCN). Human cerebellar UBCs are numerous too, but auditory UBCs have escaped detection. The human DCN, considered a degenerated structure, lost lamination and possibly neurons common in lower mammals, like UBCs. We searched for human auditory UBCs probing their immunoreactivity against the calcium-binding protein calretinin (CR-IR), and a metabotropic glutamate receptor (mGluR2/3-IR). We found: UBCs are constituents of the human DCN and VCN, though in small numbers. These auditory UBCs are not CR-IR, in contrast to human cerebellar UBCs and cerebellar and auditory UBCs in non-primate mammals, but display mGluR2/3-IR. The human DCN, thus, appears more complete than previously thought. This may be of interest regarding auditory brainstem electrode implantations in deaf patients.