Involvement of capsaicin-sensitive nerves in regulating the hormone
and glucose metabolic response to endotoxin.
Morgan, Alexander E., Charles H. Lang.
Department of Surgery, Division of Surgical Research, State
University of New York at Stony Brook, Stony Brook, NY 11794-8191
APStracts 4:0087E, 1997.
This study investigated the role that sensory nerves play in mediating
the hormone and glucose metabolic response to endotoxin (LPS). Adult
rats were pretreated subcutaneously with capsaicin to selectively
destroy primary sensory afferent nerve fibers. Ten days later, [3
-3H]glucose was infused iv to assess whole body glucose flux prior to
and following the iv injection of Escherichia coli LPS (100 [mu]g/100
g BW). Control animals responded to LPS with characteristic increases
in the plasma concentration of glucose (91%) and lactate (3-fold),
and elevations in the rates of glucose appearance and disappearance
(77%). In capsaicin-treated rats, the maximal LPS-induced increase in
these parameters was attenuated by 50-60%. In addition, these animals
were hypoglycemic at the conclusion of the experiment. Control
animals demonstrated early and sustained elevations in circulating
levels of corticosterone, glucagon and catecholamines. In contrast,
the early LPS-induced elevation in epinephrine and norepinephrine,
and to a lesser extent glucagon, was completely absent or greatly
impaired by capsaicin pretreatment. In a separate study, the
epinephrine-induced increase in glucose flux was blunted by 75% in
capsaicin-treated rats. These data indicate that sensory afferent
neurons play a critical role in the early secretory response of
glucagon and catecholamines, the maintenance of tissue catecholamine
responsiveness as well as the stimulation of glucose production after
LPS.
Received 20 November 1996; accepted in final form 4 April 1997.
APS Manuscript Number E580-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 13 May 1997