TY - JOUR
T1 - Tectothalamic inhibitory projection neurons in the avian torus semicircularis
AU - Ito, Tetsufumi
AU - Atoji, Yasuro
N1 - Publisher Copyright:
© 2016 Wiley Periodicals, Inc.
PY - 2016/9/1
Y1 - 2016/9/1
N2 - Inhibitory feedforward projection is one of key features of the organization of the central auditory system. In mammals, the inferior colliculus (IC) is the origin of a substantial inhibitory feedforward projection as well as an excitatory projection to the auditory thalamus. This inhibitory feedforward projection is provided by large γ-aminobutyric acid (GABA)ergic (LG) neurons, which are characterized by their receipt of dense excitatory axosomatic terminals positive for vesicular glutamate transporter (VGLUT) 2. In the avian torus semicircularis (TS), which is the homolog of the IC, neither the homology of cell types nor the presence of inhibitory feedforward inhibition have been established. In this study, we tested the presence of LG neurons in pigeon and chicken by neuroanatomical techniques. The TS contained two types of GABAergic neurons of different soma size. Of these, larger GABA + cells were encircled by dense VGLUT2 + axosomatic terminals. Ultrastructural analyses revealed that more than 30% of the perimeter of a large GABA+, but not small GABA + or GABA−, soma was covered by presumptive excitatory axosomatic terminals, suggesting that large GABA + cells are the sole recipient of dense excitatory axosomatic synapses. After injection of a retrograde tracer into the auditory thalamus, many retrogradely labeled neurons were found bilaterally in the TS, a few of which were GABA+. Almost all tectothalamic GABA + neurons had large somata, and received dense VGLUT2 + axosomatic terminals. These results clearly demonstrated the presence of LG neurons in birds. The similar morphology of LG neurons implies that the function of tectothalamic inhibition is similar among amniotes. J. Comp. Neurol. 524:2604–2622, 2016.
AB - Inhibitory feedforward projection is one of key features of the organization of the central auditory system. In mammals, the inferior colliculus (IC) is the origin of a substantial inhibitory feedforward projection as well as an excitatory projection to the auditory thalamus. This inhibitory feedforward projection is provided by large γ-aminobutyric acid (GABA)ergic (LG) neurons, which are characterized by their receipt of dense excitatory axosomatic terminals positive for vesicular glutamate transporter (VGLUT) 2. In the avian torus semicircularis (TS), which is the homolog of the IC, neither the homology of cell types nor the presence of inhibitory feedforward inhibition have been established. In this study, we tested the presence of LG neurons in pigeon and chicken by neuroanatomical techniques. The TS contained two types of GABAergic neurons of different soma size. Of these, larger GABA + cells were encircled by dense VGLUT2 + axosomatic terminals. Ultrastructural analyses revealed that more than 30% of the perimeter of a large GABA+, but not small GABA + or GABA−, soma was covered by presumptive excitatory axosomatic terminals, suggesting that large GABA + cells are the sole recipient of dense excitatory axosomatic synapses. After injection of a retrograde tracer into the auditory thalamus, many retrogradely labeled neurons were found bilaterally in the TS, a few of which were GABA+. Almost all tectothalamic GABA + neurons had large somata, and received dense VGLUT2 + axosomatic terminals. These results clearly demonstrated the presence of LG neurons in birds. The similar morphology of LG neurons implies that the function of tectothalamic inhibition is similar among amniotes. J. Comp. Neurol. 524:2604–2622, 2016.
KW - GABA
KW - RRID: AB_10013220
KW - RRID: AB_2315560
KW - RRID: AB_476667
KW - inferior colliculus
KW - nucleus mesencephalicus lateralis pars dorsalis
KW - torus semicircularis
KW - vesicular glutamate transporter
UR - http://www.scopus.com/inward/record.url?scp=84979034986&partnerID=8YFLogxK
U2 - 10.1002/cne.23979
DO - 10.1002/cne.23979
M3 - 学術論文
C2 - 26850847
AN - SCOPUS:84979034986
SN - 0021-9967
VL - 524
SP - 2604
EP - 2622
JO - Journal of Comparative Neurology
JF - Journal of Comparative Neurology
IS - 13
ER -