Central trigeminal effects of somatostatin and etorphine on adrenal
and autonomic function in the cat.
Bereiter, David A., Albert P. Benetti, Dominique F. Bereiter, and
Charles B. Hathaway.
Departments of Neuroscience and Surgery, Brown University/ Rhode
Island Hospital, Providence, RI. 02903 USA
APStracts 2:0288R, 1995.
The influence of somatostatin and the potent [mu] opiate receptor
agonist, etorphine, on adrenal and autonomic responses mediated by
trigeminal neurons was examined in chloralose-anesthetized cats.
Microinjections of somatostatin (100 pmol) into laminae I-II of
trigeminal subnucleus caudalis (Vc) evoked increases in the adrenal
secretion of catecholamines and adrenal blood flow without affecting
arterial pressure, heart rate or plasma ACTH. Injections of
somatostatin into laminae III-IV of Vc had no effect. Microinjections
of etorphine (500 pmol) into laminae I-II of Vc had no effect,
whereas injections into laminae III-IV caused small increases in
total adrenal blood flow and peripheral concentrations of
norepinephrine. To assess local effects of these drugs on peripheral
trigeminal nociceptor-evoked autonomic responses, corneal stimulation
was presented before and after topical application of somatostatin or
etorphine to the dorsal brain stem surface. Somatostatin did not
affect the adrenal and autonomic responses evoked by noxious thermal
or chemical irritant stimulation of the cornea. Topical etorphine
blocked completely the increase in adrenal blood flow, arterial
pressure and heart rate after noxious thermal stimulation of the
cornea. These results suggest that somatostatin and [mu] opiate
receptor agonists act by different mechanisms at the level of the
spinal trigeminal complex to affect adrenal and autonomic function.
Received 30 March 1995; accepted in final form 13 October 1995.
APS Manuscript Number R211-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 November 95