Effects of midbrain and spinal cord transections on sympathetic nerve responses to heating

Citation
Mj. Kenney et al., Effects of midbrain and spinal cord transections on sympathetic nerve responses to heating, AM J P-REG, 278(5), 2000, pp. R1329-R1338
Citations number
34
Categorie Soggetti
Physiology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
ISSN journal
03636119 → ACNP
Volume
278
Issue
5
Year of publication
2000
Pages
R1329 - R1338
Database
ISI
SICI code
0363-6119(200005)278:5<R1329:EOMASC>2.0.ZU;2-5
Abstract
In the present study, we investigated the contributions of forebrain, brain stem, and spinal neural circuits to heating-induced sympathetic nerve disc harge (SND) responses in chloralose-anesthetized rats. Frequency characteri stics of renal and splenic SND bursts and the level of activity in these ne rves were determined in midbrain-transected (superior colliculus), spinal c ord-transected [first cervical vertebra (C1)], and sham-transected (midbrai n and spinal cord) rats during progressive increases in colonic temperature (T-c) from 38 to 41.6-41.7 degrees C. The following observations were made . 1) Significant increases in renal and splenic SND were observed during hy perthermia in midbrain-transected, sham midbrain-transected, C1-transected, and sham C1-transected rats. 2) Heating changed the discharge pattern of r enal and splenic SND bursts and was associated with prominent coupling betw een renal-splenic discharge bursts in midbrain-transected, sham midbrain-tr ansected, and sham C1-transected rats. 3) The pattern of renal and splenic SND bursts remained unchanged from posttransection recovery levels during h eating in C1-transected rats. We conclude that an intact forebrain is not r equired for the full expression of SND responses to increased T-c and that spinal neural systems, in the absence of supraspinal circuits, are unable t o markedly alter the frequency characteristics of SND in response to acute heat stress.