Respiratory centers in the albino rat

Abstract

The organization of the central nervous system mechanisms involved in respiration in the albino rat as shown by electrical stimulation and surgical transection is similar to that in other species previously studied. Areas of the medulla producing inspiratory or expiratory movements on stimulation are distinct and separated. The inspiratory center occupies about 1.1 cu mm on each side and overlies the rostral one-third of the inferior olive. The expiratory center is somewhat more diffuse and lies dorsal and caudal to the inspiratory center. Serial transections produce the usual phenomena which lead to the identification of the pneumotaxic center and apneustic center. In the medullary rat ataxic breathing shows a dissociation of the inspiratory-expiratory sequence in breathing.

Persistence of the nasotrigeminal reflex after pontomedullary transection

“…This studied showed that transections judged complete through the brainstem at the pontomedullary junction induced resting HR and MABP to rise significantly, but did not disrupt the rhythm of normal respiration similar to that seen by others (Ondina et al, 1960; Radulovacki et al, 2003). Moreover, the bradycardia and apnea induced by nasal stimulation with ammonia vapors persisted after transections through the pontomedullary junction, suggesting that the neural circuitry mediating these responses of the nasotrigeminal reflex is intrinsic to the medulla and spinal cord.…”

“…1H). Nonetheless, our designation of transection categories was supported with significant differences between these transections in resting HR and in resting MABP after complete transections, while resting respiration was maintained similar to other studies (Ondina et al, 1960; Radulovacki et al, 2003). …”

“…However transection at the level of the colliculi as done in these studies spares several pontine structures modulating respiration, such as the pneumotaxic area in the dorsolateral pons, the intertrigeminal area lateral to the trigeminal motor nucleus, and the apneustic area more caudally and ventrally. The brainstem was transected at more caudal levels in a few early studies (Lumsden, 1923a; Lumsden, 1923b; Ondina et al, 1960; Radulovacki et al, 2003) to determine loci where neurons drive respiration, but the maintenance of reflex circuitry driving behaviors such as the nasotrigeminal reflex was not investigated. Since the responses to stimulation of the nasal mucosa are similar to those of underwater submersion (Panneton et al, 2010b), we elected to stimulate the nasal mucosa of an anesthetized rat with ammonia vapors to induce an apnea, bradycardia and peripheral vasoconstriction in rats transected at the pontomedullary junction.…”

Wdr47 Controls Neuronal Polarization through the Camsap Family Microtubule Minus-End-Binding Proteins

“…The CNS functions of Wdr47 are essential to mouse survival. We attributed the lethality of Wdr47-deficient mice (Kannan et al, 2017) to severe suffocation immediately after birth and, more importantly, to defects in the CNS (Figures 1 and S1), possibly in the brainstem-located breath controlling center (Mironov and Richter, 2001;Ondina et al, 1960). The slightly alleviated phenotypes of the neonatal Wdr47 flox/flox ;Nestin-Cre mice as compared to the Wdr47 À/À mice are possibly due to inefficient recombination of the Nestin-Cre line in early embryos (Liang et al, 2012) and the presence of intact Wdr47 in non-neural cells.…”

Respiration

“…The respiratory centers in the albino rat are organized in a manner similar to those of other species (207), but there is some evidence that expiration is a more active process.…”