Stimulation of the rat medullary raphe nuclei induces differential responses in respiratory muscle activity.
Neural control circuits that coordinate the motor activity of the diaphragm (DIA) and the geniohyoid muscle (GH) are potentially involved in pathological conditions such as various forms of sleep apnea. Here we investigated a differential role of the raphe magnus (RMg), pallidus (RPa) and the obscurus (ROb) nuclei in the neural control of DIA and GH muscle activity in rats under volatile anesthesia. In order to characterize a topographical organization of the raphe nuclei we analyzed changes in DIA and GH during high-frequency stimulation (HFS, 10-130 Hz, 60 micros pulse width, 40-160 microA, 30s). HFS of the RMg and the ROb induced apnea, in the latter case apnea was associated with massive tonic discharge in the GH. By contrast, HFS of the RPa induced tachypnea. At caudal stimulation sites the tachypnea was accompanied by tonic DIA activity and cessation of GH. These data suggest a differential distribution of inhibitory and excitatory drives of DIA and GH muscles within distinct raphe nuclei.
Besnard
S
S
Laboratoire de Physiologie UPRES EA 3917, Attention, Orientation et Fonctions Exécutives, Université de Caen, Av. de la Côte de Nacre, BP 95182, F-14033 Caen Cedex 5, France.
Denise
P
P
Cappelin
B
B
Dutschmann
M
M
Gestreau
C
C
D000758:Anesthesia; D000818:Animals; D004558:Electric Stimulation; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology* / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways; D011903:Raphe Nuclei / Q000166:cytology* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000294:innervation / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology