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- Title
GABAergic and glycinergic synapses onto neurokinin-1 receptor-immunoreactive neurons in the pre-Bötzinger complex of rats: light and electron microscopic studies.
- Authors
Liu, Ying‐Ying; Wong‐Riley, Margaret T. T.; Liu, Jin‐Ping; Jia, Yi; Liu, Hui‐Ling; Jiao, Xi‐Ying; Ju, And Gong
- Abstract
Abstract 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.
- Subjects
GABA receptors; SYNAPSES; TACHYKININS
- Publication
European Journal of Neuroscience, 2002, Vol 16, Issue 6, p1058
- ISSN
0953-816X
- Publication type
Article
- DOI
10.1046/j.1460-9568.2002.02163.x