Contribution of the lateral lemniscus to the control of swallowing in decerebrate cats.
Lateral lemniscus, a relay nucleus of auditory sensation, is involved in the control of phonatory movements such as human speech and vocalization of animals. The present study was designed to test whether neurons in the lateral lemniscus contributed to the control of swallowing, one of non-phonic oro-pharyngolaryngeal movements. In acutely decerebrated cats (n=15), swallowing was induced by electrical stimulation (20-80μA at 10Hz for 20s with rectangular pulses of 0.2ms duration) delivered to the superior laryngeal nerve (SLN). Repetitive electrical stimulation (30-50μA at 50Hz for 10-20s) applied to the dorsal nucleus of the lateral lemniscus (LLD) increased the number and reduced the latency to the onset of the SLN-induced swallowing. On the other hand, stimulation of the ventral nucleus of the lateral lemniscus and the paralemniscal area, corresponding to the ventrolateral part of the parabrachial nucleus and the Kölliker-Fuse nucleus, often suppressed the SLN-induced swallowing. Microinjection of NMDA (0.1-0.15μl, 5.0-10mM) into the LLD through a stereotaxically placed glass micropipette facilitated the SLN-induced swallowing, i.e., the number was increased and the latency of swallowing was reduced. We also injected muscimol (a gamma amino-butyric acid (GABA)A receptor agonist), bicuculline (a GABAA receptor antagonist) and baclofen (a GABAB receptor agonist) into the LLD (0.1-0.15μl and 5.0mM for each substance). It was observed that an injection of muscimol suppressed the SLN-induced swallowing. However, an injection of bicuculline facilitated the swallowing. An injection of baclofen did not alter the swallowing. These results suggest the presence of functional topography in the lateral lemniscus and the paralemniscal area in relation to the control of swallowing. The facilitatory LLD-effects on swallowing are modulated by glutamatergic and GABAergic receptors on neurons in the LLD.
Department of Otolaryngology - Head and Neck Surgery, Asahikawa Medical University, School of Medicine, Midorigaoka-Higashi, 2-1, 1-1, 078-8510, Japan.
R
R
Ota
K
K
Takakusaki
A
A
Katada
H
H
Harada
S
S
Nonaka
Y
Y
Harabuchi
D000818:Animals; D001306:Auditory Pathways / Q000187:drug effects / Q000502:physiology*; D001640:Bicuculline / Q000494:pharmacology; D002415:Cats; D003655:Decerebrate State / Q000503:physiopathology*; D003679:Deglutition / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D005260:Female; D008297:Male; D009118:Muscimol / Q000494:pharmacology
D009118:Muscimol; D001640:Bicuculline
ANOVA; CNF; CPG; DC; DIA; DRG; DSG; Diaphragm; EMG; GABAergic projection; GH; H; KFN; Kölliker–Fuse nucleus; L; LLD; LLV; MRF; N-methyl-d-aspartic acid; NA; NMDA; NTS; P; PBN; PCA; PRF; SCP; SD; SLN; SNr; SpO(2); TA; VSG; analysis of variance; audiomotor control; brainstem; central pattern generator; cuneiform nucleus; data recorder; dorsal nucleus of the lateral lemniscus; dorsal respiratory group; dorsal swallowing group; electromyogram; geniohyoideus muscle; horizontal; lateral; medullary reticular formation; nucleus ambiguus; nucleus tractus solitarius; oro-pharyngolaryngeal movement; parabrachial nucleus; pontine reticular formation; posterior; posterior cricoarytenoid muscle; respiratory movements; saturation of percutaneous arterial oxygen; standard deviation; substantia nigra pars reticulata; superior cerebellar peduncle; superior laryngeal nerve; thyroarytenoid muscle; ventral nucleus of the lateral lemniscus; ventral swallowing group