The Journal of Neuroscience, August 1, 1998, 18(15):6048-6056
A Brainstem Network Mediating Apneic Reflexes in the Rat
Nancy L.
Chamberlin and
Clifford B.
Saper
Department of Neurology, Harvard Medical School and Beth Israel
Hospital, Boston, Massachusetts 02115
Apnea is an important protective response to upper airway
irritation, but the central mechanisms responsible for eliciting sensory-induced apnea are not well understood. Recent studies have
emphasized the Kölliker-Fuse nucleus in producing apnea and
proposed a trigeminoparabrachial pathway for mediating these reflexes.
However, in our earlier study of apneic responses produced by glutamate
stimulation in the dorsolateral pons, we found that apnea was elicited
from the area just ventral to the Kölliker-Fuse nucleus, rather
than within it. Because this region was not known to be involved in
respiratory control, we combined chemical microstimulation with both
anterograde and retrograde axonal tracing to characterize the sites in
the pons that produce apneic responses. We found that apneic sites were
consistently associated with the intertrigeminal region, between the
principal sensory and motor trigeminal nuclei. Injections of
anterograde tracer at these sites labeled terminals in the ventral
respiratory group, in the ventrolateral medulla. Injection of
retrograde tracer into this target region in the ventrolateral medulla
disclosed a previously unrecognized population of neurons among the
trigeminal motor rootlets. Injection of retrograde tracer into this
intertrigeminal region demonstrated inputs from portions of the spinal
trigeminal nucleus and the nucleus of the solitary tract that have been
associated with producing sensory apnea. Our observations suggest that
the intertrigeminal region receives a convergence of sensory inputs
capable of driving apneic responses and that it may represent a common
link between input from different portions of the airway and the
respiratory neurons that mediate apneic reflexes.
Key words:
intertrigeminal region; apnea; respiration; chemical
microstimulation; tract tracing; trigeminal
Copyright © 1998 Society for Neuroscience 0270-6474/98/18156048-09$05.00/0
Previous Article | Next Article
