CNS innervation of vagal preganglionic neurons controlling peripheral airways: a transneuronal labeling study using pseudorabies virus
Hadziefendic S and Haxhiu MA (1999) CNS innervation of vagal preganglionic neurons con- trolling peripheral airways: A transneuronal labeling study using pseudorabies virus. J Auton Nerv Syst 76:2-3 135–45.
Abstract: The CNS cell groups that project to vagal preganglionic neurons which innervate the most distal part of the airways were identified by the viral retrograde transneuronal labeling method. Pseudorabies virus (PRV) was injected into the lung parenchyma of C8 spinal rats and after 5 days survival, brain tissue sections from these animals were processed for immunohistochemical detection of PRV. Retrogradely labeled parasympathetic preganglionic cells (first-order neurons) were seen mainly in the ventral medulla oblongata: the compact portion of the nucleus ambiguus and the area ventral to it. Occasionally, a few labeled cells were seen within the rostral part of the dorsal vagal nucleus. This labeling pattern correlated well with the retrograde cell body labeling seen following cholera toxin beta-subunit (CT-b) injections in the lung parenchyma. PRV transneuronally labeled neurons (second-order and/or presumed third-order neurons) were found throughout the CNS with the characteristic labeling in the brainstem. Labeled neurons were identified along and just beneath the ventral medullary surface, and in nearby areas: the parapyramidal, retrotrapezoid, gigantocellular and lateral paragigantocellular reticular nuclei, as well as the caudal raphe nuclei (raphe pallidus, obscurus, and magnus). Several nucleus tractus solitarius (nTS) regions contained labeled cells including the commissural, medial, and ventrolateral nTS subnuclei. The A5 cell group and a small number of locus coeruleus neurons were also labeled. PRV-infected neurons were present in the Kölliker-Fuse and Barrington's nuclei. In the mesencephalon, neurons within the ventral periventricular gray matter were labeled. Labeling was present in the dorsal, lateral and paraventricular hypothalamic nuclei, and within the amygdaloid complex. In summary, the parasympathetic preganglionic neurons that innervate the peripheral airways are controlled by networks of lower brainstem and suprapontine neurons that lie in the same regions known to be involved in central regulation of autonomic functions.
Keywords: Airway control; Autonomic nervous system; Bronchial system; Intrapulmonary airways; Vagus nerve
Context
- Addresses the issue of CNS control of peripheral airways through the vagus nerve using viral transnueuronal labeling in rat. Pseudorabies virus, which is transported retrograde and transynaptically, was injected into the lung. Ventral medulla (nucleus ambiguus) was heavily labeled, indicating a strong innervation. Second- and third-order labeling was seen in multiple brain stem nuclei and subnuclei, as well as in mesencephalic gray matter, hypothalamus, and amygdala, providing anatomical evidence of amygdalar involvement in control of respiration.