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Relationship between two types of vesicular glutamate transporters and neurokinin‐1 receptor‐immunoreactive neurons in the pre‐Bötzinger complex of rats: light and electron microscopic studies
Author(s) -
Liu YingYing,
WongRiley Margaret T. T.,
Liu JinPing,
Jia Yi,
Liu HuiLing,
Fujiyama Fumino,
Ju Gong
Publication year - 2003
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2003.02418.x
Subject(s) - tachykinin receptor 1 , glutamatergic , apposition , glutamate receptor , biophysics , neuroscience , synapse , excitatory postsynaptic potential , chemistry , synaptic cleft , biology , neurotransmission , receptor , anatomy , neuropeptide , substance p , biochemistry , inhibitory postsynaptic potential
Our previous study demonstrated GABAergic and glycinergic synapses onto neurokinin‐1 receptor (NK1R)‐immunoreactive (ir) neurons in the pre‐Bötzinger complex (pre‐BötC), the hypothesized kernel of normal respiratory rhythmogenesis. In the present study, we aimed to identify glutamatergic synapses onto NK1R‐ir pre‐BötC neurons, as excitatory synaptic transmission is a prerequisite to normal respiratory rhythmogenesis. Two types of vesicular glutamate transporters (VGLUT), VGLUT1 and VGLUT2, have been recently implicated in glutamate‐mediated transmission. The present study used immunofluorescence and immunogold‐silver staining to determine the relationship between the transporters and NK1R‐ir neurons in the pre‐BötC of adult rats. Under the confocal laser‐scanning microscope, VGLUT2‐ir boutons were found to be widely distributed in the pre‐BötC, some of which were in close apposition to NK1R‐ir somas and dendrites. VGLUT1‐ir boutons were relatively rare and only a few were found to be in close apposition to NK1R‐ir somas and dendrites. Electron microscopic observation revealed that approximately 41% of VGLUT2‐ir terminals were in close apposition to, or made asymmetric synapses with NK1R‐ir somas and dendrites in the pre‐BötC. On the other hand, 50.5% of NK1R‐ir dendrites were closely apposed to, or synapsed with VGLUT2‐ir terminals. Occasionally, VGLUT1‐ir terminals were found in close apposition to NK1R‐ir somas or dendrites, but we were unable to identify synapses between them. The present findings provide the morphological basis for excitatory synaptic inputs onto NK1R‐ir neurons in the pre‐BötC. VGLUT2 may be involved in a dominant excitatory synaptic pathway for normal respiratory rhythmogenesis.