Premium
GABAergic and glycinergic synapses onto 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,
Jiao XiYing,
Ju And Gong
Publication year - 2002
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.1460-9568.2002.02163.x
Subject(s) - tachykinin receptor 1 , inhibitory postsynaptic potential , biology , neuroscience , medulla oblongata , biophysics , chemistry , neuropeptide , substance p , receptor , central nervous system , biochemistry
The pre‐Bötzinger complex (preBötC) in the ventrolateral medulla is thought to be the kernel for respiratory rhythm generation. Neurons in the preBötC contain intense neurokinin‐1 receptor (NK1R) immunoreactivity. Some of these neurons in the adult preBötC are presumed to be the pre‐inspiratory interneurons that are essential for generating respiratory rhythm in the neonate. Chloride‐mediated synaptic inhibition is critical for rhythmogenesis in the adult. The present study used immunofluorescence histochemistry and immunogold‐silver staining to determine the inhibitory synaptic relationship between glutamic acid decarboxylase (GAD)‐ or glycine transporter 2 (GlyT2)‐immunoreactive (ir) boutons and NK1R‐ir neurons in the preBötC of adult rats. Under the confocal microscope, we found that GAD‐ and GlyT2‐ir boutons were in close apposition to NK1R‐ir somas and dendrites in the preBötC. Under the electron microscope, GAD‐ and GlyT2‐ir terminals were in close apposition to NK1R‐ir somas and dendrites. Symmetric synapses were identified between GAD‐ or GlyT2‐ir terminals and NK1R‐ir neurons. A total of 51.6% GAD‐ir and 38.2% GlyT2‐ir terminals were found to contact or make synapses with NK1R‐ir profiles, respectively. GAD‐ and GlyT2‐ir terminals synapsed not only upon NK1R‐ir neurons but also upon NK1R immuno‐negative neurons. NK1R‐ir neurons received both symmetric (presumed inhibitory) and asymmetric (presumed excitatory) synapses. Thus, the present findings provide the morphological basis for inhibitory inputs to NK1R‐ir neurons in the preBötC, consistent with the suggestion that chloride‐mediated synaptic inhibition may contribute importantly to rhythm generation by controlling the membrane potential trajectory and resetting rhythmic bursting of the kernel neurons in the adult.