Extension of the jaw opening reflex and effects of a central muscle relaxant (afloqualone) in the rat.
How widely the jaw opening reflex (JOR) extends was examined in the rat. Recording was done in the anterior (AD) and posterior (PD) digastric, sternohyoid (SH) and sternomastoid (SCM) muscles. Electric stimulation was given to the mandibular incisor pulp. Evoked electromyogram (EMG) activities could be recorded in each muscle. The thresholds for JOR increased from AD to SCM. Intravenously administered afloqualone, a centrally acting muscle relaxant, inhibited both JOR and its parallels promptly and dose-dependently. The possible clinical significance in temporomandibular joint dysfunction will be discussed.
Shohara
E
E
Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara, Japan.
Matsushita
K
K
Hosoi
E
E
Tatsumi
Y
Y
Sugimura
M
M
D000818:Animals; D004558:Electric Stimulation; D004576:Electromyography; D008297:Male; D008410:Masticatory Muscles / Q000502:physiology*; D015394:Molecular Structure; D009125:Muscle Relaxants, Central / Q000494:pharmacology*; D009334:Neck Muscles / Q000187:drug effects*; D010146:Pain / Q000209:etiology; D011799:Quinazolines / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D012018:Reflex / Q000187:drug effects*; D013704:Temporomandibular Joint / Q000502:physiology*; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000503:physiopathology
D009125:Muscle Relaxants, Central; D011799:Quinazolines; C033541:afloqualone