title: Quantitative ultrastructural analysis of glycine- and gamma-aminobutyric acid-immunoreactive terminals on trigeminal alpha- and gamma-motoneuron somata in the rat.
abstract: Detailed knowledge of the inhibitory input to trigeminal motoneurons is needed to understand better the central mechanisms of jaw movements. Here a quantitative analysis of terminals contacting somata of jaw-closing (JC) and jaw-opening (JO) alpha-motoneurons, and of JC gamma-motoneurons, was performed by use of serial sectioning and postembedding immunogold cytochemistry. For each type of motoneuron, the synaptic boutons were classified into four groups, i.e., immunonegative boutons or boutons immunoreactive to glycine only, to gamma-aminobutyric acid (GABA) only, or to both glycine and GABA. The density of immunolabeled boutons was much higher for the alpha- than for the gamma-motoneurons. In the alpha-motoneuron populations, the immunolabeled boutons were subdivided into one large group of boutons containing glycine-like immunoreactivity only, one group of intermediate size harboring both glycine- and GABA-like immunoreactivity, and a small group of boutons containing GABA-like immunoreactivity only. The percentage of immunolabeled boutons was higher for JC than JO alpha-motoneurons, the most pronounced difference being observed for glycine-like immunoreactivity. In contrast, on the somatic membrane of gamma-motoneurons, the three types of immunoreactive bouton occurred at similar frequencies. These results indicate that trigeminal motoneurons are strongly and differentially controlled by premotoneurons containing glycine and/or GABA and suggest that these neurons play an important role for the generation of masticatory patterns.
authors.affiliation: Department of Oral Anatomy, School of Dentistry, Kyungpook University, Taegu 700-422, Korea. ycbae@knu.ac.kr
authors.forename: Yong Chul
authors.initials: YC
authors.lastname: Bae
authors.forename: Byung Ju
authors.initials: BJ
authors.lastname: Choi
authors.forename: Maan Gee
authors.initials: MG
authors.lastname: Lee
authors.forename: Hyo Jeong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Kuk Pil
authors.initials: KP
authors.lastname: Park
authors.forename: Li Fen
authors.initials: LF
authors.lastname: Zhang
authors.forename: Shiho
authors.initials: S
authors.lastname: Honma
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Fukami
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshida
authors.forename: Ole Petter
authors.initials: OP
authors.lastname: Ottersen
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Shigenaga
mesh_terms: D000818:Animals; D048429:Cell Size / Q000502:physiology; D005998:Glycine / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008410:Masticatory Muscles / Q000294:innervation / Q000502:physiology; D008854:Microscopy, Electron; D009047:Motor Neurons, Gamma / Q000378:metabolism / Q000648:ultrastructure*; D009433:Neural Inhibition / Q000502:physiology; D011149:Pons / Q000378:metabolism / Q000648:ultrastructure*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000033:anatomy & histology* / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000378:metabolism / Q000648:ultrastructure; D014278:Trigeminal Nuclei / Q000378:metabolism / Q000648:ultrastructure*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid; D005998:Glycine