RT Journal Article
SR Electronic
T1 Role of Parafacial Nuclei in Control of Breathing in Adult Rats
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1052
OP 1067
DO 10.1523/JNEUROSCI.2953-14.2015
VO 35
IS 3
A1 Robert T.R. Huckstepp
A1 Kathryn P. Cardoza
A1 Lauren E. Henderson
A1 Jack L. Feldman
YR 2015
UL http://www.jneurosci.org/content/35/3/1052.abstract
AB Contiguous brain regions associated with a given behavior are increasingly being divided into subregions associated with distinct aspects of that behavior. Using recently developed neuronal hyperpolarizing technologies, we functionally dissect the parafacial region in the medulla, which contains key elements of the central pattern generator for breathing that are important in central CO2-chemoreception and for gating active expiration. By transfecting different populations of neighboring neurons with allatostatin or HM4D Gi/o-coupled receptors, we analyzed the effect of their hyperpolarization on respiration in spontaneously breathing vagotomized urethane-anesthetized rats. We identify two functionally separate parafacial nuclei: ventral (pFV) and lateral (pFL). Disinhibition of the pFL with bicuculline and strychnine led to active expiration. Hyperpolarizing pFL neurons had no effect on breathing at rest, or changes in inspiratory activity induced by hypoxia and hypercapnia; however, hyperpolarizing pFL neurons attenuated active expiration when it was induced by hypercapnia, hypoxia, or disinhibition of the pFL. In contrast, hyperpolarizing pFV neurons affected breathing at rest by decreasing inspiratory-related activity, attenuating the hypoxia- and hypercapnia-induced increase in inspiratory activity, and when present, reducing expiratory-related abdominal activity. Together with previous observations, we conclude that the pFV provides a generic excitatory drive to breathe, even at rest, whereas the pFL is a conditional oscillator quiet at rest that, when activated, e.g., during exercise, drives active expiration.