AJP - Gastrointestinal and Liver Physiology, Vol 262, Issue 6 1121-G1126, Copyright © 1992 by American Physiological Society
Locus ceruleus modulates migrating myoelectric complex in rats
B. Bonaz, L. Martin, E. Beurriand, M. Manier, J. Hostein and C. Feuerstein
Laboratoire de Physiologie, Institut National de la Sante et de la Recherche Medicale, U318, Grenoble, France.
The role of the locus ceruleus (LC) in the control of migrating myoelectric
complex (MMC) was investigated in rats with lesions induced by injections
of 6-hydroxydopamine (6-OHDA). Control animals received the vehicle alone.
MMC was recorded in conscious rats chronically fitted with electrodes.
After 6-OHDA was injected into the LC, lesions of the LC were total,
partial (mostly rostral), or ineffective. The MMC period was significantly
longer in animals with a total or partial lesion but was unchanged in
animals with an ineffective lesion. No lesion of other brain noradrenergic
nuclei was observed. The longer MMC period is comparable to that obtained
after intracerebroventricular injection of 6-OHDA, which is responsible for
a more diffuse destruction of brain noradrenergic systems, including LC
itself. Bilateral lesions of the central tegmental tract, which carries
ascending noradrenergic axons from the medullary and pontine cell groups
outside the LC, do not alter the MMC cycle. Consequently, the LC is most
likely the major brain noradrenergic candidate for modulating the MMC
pattern in rats.
