Neural mechanisms controlling jaw-jerk reflex in the cat.
Signal substances of axon terminals presynaptic to jaw spindle Ia afferents and their ultrastructural features were examined using a combination of intra-axonal horseradish peroxidase injection and postembedding immunogold-labeling techniques in cats. A total of 35 axon terminals presynaptic to 22 horseradish peroxidase-labeled Ia boutons were examined. Of the 35 presynaptic axon terminals, 14 (40%) were immunoreactive for both gamma-aminobutyric acid and glycine, 9 (26%) for gamma-aminobutyric acid alone and 9 (26%) for glycine alone. The bouton volume, mitochondrial volume, active zone area, and apposed surface area were larger for Ia boutons than for presynaptic axon terminals, while each of the values is similar among the three types of presynaptic axon terminals. These results suggest that gamma-aminobutyric acid and glycine play an important role for modulating the jaw-jerk reflex presynaptically and that the smaller size of presynaptic axon terminals is important to prevent action potential generation from Ia afferents.
Paik
Sang Kyoo
SK
Department of Neurobiology, Graduate School of Dentistry, Kyungpook National University, Daegu, Korea.
Oh
Soo Jin
SJ
Son
Young Jin
YJ
Ma
Su Kyung
SK
Ahn
Chang Hyeon
CH
Kim
Sung Kyo
SK
Chang
Zheng
Z
Moritani
Masayuki
M
Yoshida
Atsushi
A
Bae
Yong Chul
YC
D000704:Analysis of Variance; D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D002415:Cats; D002452:Cell Count / Q000379:methods; D005998:Glycine / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D007568:Jaw / Q000502:physiology*; D016253:Microscopy, Immunoelectron / Q000379:methods; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D009470:Muscle Spindles / Q000378:metabolism; D009412:Nerve Fibers / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D012018:Reflex / Q000502:physiology*; D014279:Trigeminal Nucleus, Spinal / Q000166:cytology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D005680:gamma-Aminobutyric Acid; D006735:Horseradish Peroxidase; D005998:Glycine