Key result
Targeted brainstem ablation of RVLM, raphe, or PB/KF eliminates the 10-Hz sympathetic nerve discharge rhythm.
Why the study?
The effects of brain stem lesions or transection on the 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge required investigation.
Do brain stem lesions or transection affect the 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge in baroreceptor-denervated unanesthetized decerebrate cats?
Do brain stem lesions or transection affect the 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge in baroreceptor-denervated unanesthetized decerebrate cats?
Demonstrates in a feline model that the 10-Hz and 2- to 6-Hz sympathetic nerve discharge rhythms depend on distinct brain stem regions, with RVLM and medullary raphe directly involved in generating or relaying the 10-Hz rhythm while the PB/KF provides tonic drive.
Answers are grounded in this paper and cite their sources.
Brainstem lesions reveal distinct sites for sympathetic rhythms in cats; leaves open translation to human autonomic control or disease.
We studied the effects of brain stem lesions or transection on the 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge (SND) in baroreceptor-denervated unanesthetized decerebrate cats. The results indicate that these two rhythms depend in part on different brain stem regions. The 10-Hz rhythm was eliminated by ablation of the rostral ventrolateral medulla (RVLM), medullary raphe complex, or pontine parabrachial and Kölliker-Fuse complex (PB/KF) or by pontomedullary border transection. Except for RVLM lesions, these procedures did not disrupt the 2- to 6-Hz rhythm in SND. In fact the power in SND at frequencies less than 6 Hz was increased by raphe or PB/KF lesions. Total power in SND was not significantly affected by raphe or PB/KF lesions, but mean arterial pressure was significantly reduced. Field potentials recorded from the RVLM (11 of 26 sites) and raphe (10 of 20 sites) were correlated to the 10-Hz rhythm in SND, further supporting a role of these areas in either generating or relaying this rhythm to sympathetic nerves. In contrast, field potentials recorded from the PB/KF were not correlated to the 10-Hz rhythm in SND. Thus this region may provide a tonic drive to the 10-Hz generator located elsewhere in the brain stem.
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Zhong et al. (1992) studied Sympathetic nerve discharge rhythms. Brain stem lesions or transection (ablation of RVLM, medullary raphe complex, PB/KF, or pontomedullary border transection) was evaluated on 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge (SND). Brain stem ablation of RVLM, raphe, or PB/KF eliminated the 10-Hz SND rhythm, with field potentials correlating at 11/26 RVLM and 10/20 raphe sites.
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