The Pedunculopontine Nucleus: A Potential Site of Respiratory Modulation During Muscle Contraction and Hypoxia

"The studies contained in this dissertation begin to examine a potential role for the pedunculopontine nucleus (PPN) in the regulation of respiratory adjustments that accompany motor activity and hypoxia. The PPN, located in the dorsal mesencephalic tegmentum at the lateral extent of the brachium conjunctivum, has previously been implicated in regulation of cardiorespiratory adjustments that accompany physical activity through a feed-forward mechanism termed ""central command"". The primary goal of this dissertation was to address the hypothesis that the PPN mediates influences on reflex respiratory adjustments that accompany skeletal muscle contraction in anesthetized rats. Extracellular single-unit electrophysiologic recordings were employed in the first group of studies to demonstrate that individual PPN neurons exhibited increases in firing rate during activation of muscle reflex pathways during static muscle contraction. Activation of PPN neurons was shown to have functional significance in that microinjections of bicuculline, a GABAA receptor antagonist, into the PPN resulted in significant increases in respiratory activity. The second set of studies demonstrated importance of the integrity of pathways that synapse in the PPN to the respiratory responses observed during muscle contraction in that injections of CoCl2 into the PPN resulted in significant attenuation of the reflex diaphragmatic responses to muscle contraction. Finally, responses of PPN neurons were also examined during hypoxia-related stimuli. PPN neurons were found to exhibit increases in firing rate during systemic hypoxia in anesthetized adult rats. However, inhibitory responses during chemical hypoxia were documented amongst most PPN neurons recorded in brain slice preparations from neonatal rats. The results of the studies that comprise this dissertation suggest that the PPN may mediate influences on the respiratory system during physical activity and hypoxia and that the PPN warrants future attention to elucidate its role in the regulation of respiratory adjustments in these and other physiologic and pathophysiologic contexts."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Molecular and Integrative Physiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Plowey, Edward Douglas

Contributors dc:contributor

• Waldrop, Tony G.

• Biology, Neuroscience

Language dc:language

eng

Identifier

(MiAaPQ)AAI3153401

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87231