AJP - Endocrinology and Metabolism, Vol 241, Issue 1 22-E27, Copyright © 1981 by American Physiological Society
Nucleus ambiguus stimulation increases plasma insulin levels in the rat
D. A. Bereiter, H. R. Berthoud, M. Brunsmann and B. Jeanrenaud
The ventral lateral brainstem has been explored for sites that facilitate
insulin release unilaterally, using electrical stimulation techniques in
male rats anesthetized with alpha-chloralose/urethane. Stimulation in the
region of nucleus ambiguus (amb) produced a rapid rise (by 1 min) in plasma
insulin levels, whereas stimulation of brainstem regions further than 500
micrometers from amb had no consistent effect on insulin levels. The
amb-induced rise in insulin was markedly exaggerated by the
alpha-adrenergic antagonist, phentolamine, and was greatly diminished by
bilateral cervical vagotomy or atropine pretreatment. These results
strongly suggest that the amb is one source of vagal motoneurons that
facilitate insulin secretion. However, amb electrical stimulation alone
also activated an apparent sympathetic efferent output whose inhibitory
effect on insulin release could be blocked by phentolamine.
