Immunohistochemical studies on glutamatergic, GABAergic and glycinergic axon varicosities presynaptic to parasympathetic preganglionic neurons in the superior salivatory nucleus of the rat.
After the superior salivatory nucleus (SSN) neurons were labeled by administration of cholera toxin B subunit (CTB) or wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) to the pterygopalatine ganglion, morphological interactions between SSN neurons and fibers afferent to SSN neurons were examined by light and electron microscopy with double-immunostaining techniques. Antibodies to either the neurotransmitters or its receptor were used to label glutamatergic, GABAergic and glycinergic synapses on these neurons. By light microscopy, SSN neurons were identified in the ipsilateral ventrolateral part of the rostral medulla oblongata, and rich distributions of glutamate- and GABA-immunoreactive (ir) axon varicosities were observed around SSN neurons. Electron microscopy revealed that dendrites of SSN neurons received asymmetric synapses from glutamate-ir axon varicosities. Somata as well as dendrites received symmetric synapses from GABA-ir varicosities, or showed immunoreactivity for glycine receptors. Quantitative analysis by electron microscopy showed that glutamate-ir axon varicosities comprised 45.3% of total axon profiles in the SSN region, while GABA-ir varicosities were 20.8% and varicosities presynaptic to glycine receptors were 19.9%. These findings suggest that glutamatergic, GABAergic and glycinergic inputs, originated from a variety of nuclei, directly affect the activity of SSN neurons, and play a role in the regulation of the pterygopalatine ganglion of the rat.
Kobayashi
M
M
Department of Otorhinolaryngology, Chiba University School of Medicine, Japan.
Nemoto
T
T
Nagata
H
H
Konno
A
A
Chiba
T
T
D000818:Animals; D001369:Axons / Q000737:chemistry* / Q000648:ultrastructure; D002772:Cholera Toxin; D003712:Dendrites / Q000737:chemistry / Q000648:ultrastructure; D005726:Ganglia, Parasympathetic / Q000737:chemistry / Q000166:cytology* / Q000502:physiology; D018698:Glutamic Acid / Q000032:analysis / Q000502:physiology*; D005998:Glycine / Q000032:analysis / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D017729:Presynaptic Terminals / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012469:Salivary Glands / Q000294:innervation; D013569:Synapses / Q000737:chemistry / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000502:physiology*
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D002772:Cholera Toxin; D005998:Glycine