Brainstem neurons projecting to the rostral ventral respiratory group (VRG) in the medulla oblongata of the rat revealed by co-application of NMDA and biocytin

TY - JOUR

T1 - Brainstem neurons projecting to the rostral ventral respiratory group (VRG) in the medulla oblongata of the rat revealed by co-application of NMDA and biocytin

AU - Zheng, Y

AU - Riche, D

AU - Rekling, J C

AU - Foutz, A S

AU - Denavit-Saubié, M

N1 - Keywords: Animals; Brain Mapping; Brain Stem; Dendrites; Drug Combinations; Lysine; Male; Medulla Oblongata; N-Methylaspartate; Neural Pathways; Neurons; Pons; Rats; Rats, Sprague-Dawley; Respiratory Physiological Phenomena

PY - 1998

Y1 - 1998

N2 - Groups of neurons in the medulla and pons are essential for the rhythm generation, pattern formation and modulation of respiration. The rostral Ventral Respiratory Group (rVRG) is thought to be a crucial area for rhythm generation. Here we co-applied biocytin and NMDA in the rVRG to label retrogradely brainstem neurons reciprocally connected to a population of inspiratory neurons in the rat rVRG. The procedure excited rVRG neurons in multi-unit recordings and led to a Golgi-like labelling of distant cells presumably excited by efferents from the rVRG. Injection of biocytin without NMDA did not label neurons in distant structures. Several brainstem ipsi- and contralateral structures were found to project to the rVRG, but three major respiratory-related structures, the nucleus of the solitary tract (NTS), the parabrachialis medialis and Kölliker-Fuse nuclei (PB/KF) and the caudal VRG, which are known to project bilaterally to the rVRG, were exclusively labelled ipsilaterally, suggesting an ipsilateral excitation of these structures by the rVRG. The pathways of efferent axons from labelled neurons in the rVRG were traced rostrally towards the pons and caudally to the spinal cord. Terminal axonal arborizations were seen in the same regions where retrogradely filled neurons were found as well as in a few other motor nuclei (the dorsal vagal motor nucleus and XII nucleus). Moreover, in the NTS and the PB/KF, efferent terminal varicosities were seen closely apposed to the soma and proximal dendrites of labelled neurons, suggesting monosynaptic connections between the rVRG and these nuclei.

AB - Groups of neurons in the medulla and pons are essential for the rhythm generation, pattern formation and modulation of respiration. The rostral Ventral Respiratory Group (rVRG) is thought to be a crucial area for rhythm generation. Here we co-applied biocytin and NMDA in the rVRG to label retrogradely brainstem neurons reciprocally connected to a population of inspiratory neurons in the rat rVRG. The procedure excited rVRG neurons in multi-unit recordings and led to a Golgi-like labelling of distant cells presumably excited by efferents from the rVRG. Injection of biocytin without NMDA did not label neurons in distant structures. Several brainstem ipsi- and contralateral structures were found to project to the rVRG, but three major respiratory-related structures, the nucleus of the solitary tract (NTS), the parabrachialis medialis and Kölliker-Fuse nuclei (PB/KF) and the caudal VRG, which are known to project bilaterally to the rVRG, were exclusively labelled ipsilaterally, suggesting an ipsilateral excitation of these structures by the rVRG. The pathways of efferent axons from labelled neurons in the rVRG were traced rostrally towards the pons and caudally to the spinal cord. Terminal axonal arborizations were seen in the same regions where retrogradely filled neurons were found as well as in a few other motor nuclei (the dorsal vagal motor nucleus and XII nucleus). Moreover, in the NTS and the PB/KF, efferent terminal varicosities were seen closely apposed to the soma and proximal dendrites of labelled neurons, suggesting monosynaptic connections between the rVRG and these nuclei.

M3 - Journal article

C2 - 9519255

SN - 0006-8993

VL - 782

SP - 113

EP - 125

JO - Brain Research

JF - Brain Research

IS - 1-2

ER -