AJP - Gastrointestinal and Liver Physiology, Vol 271, Issue 5 858-G865, Copyright © 1996 by American Physiological Society
Interactions of gastric vagal and peripheral nerves on single neurons of lateral hypothalamus in the cat
C. S. Yuan and W. D. Barber
Department of Anatomy, College of Medicine, Arizona Health Sciences Center, University of Arizona, Tucson 85724, USA.
Extracellularly recorded unitary responses in the lateral hypothalamus were
evaluated in anesthetized cats during electrical stimulation of the gastric
branches of the ventral and dorsal vagal trunks, the T9 intercostal nerve,
and the common peroneal nerve (L6-S2). These nerves were stimulated with
single or paired (10-ms interval) pulses of 300-500 microA for 0.3 ms at a
frequency of 0.5 Hz. The latency of the evoked lateral hypothalamic
responses after stimulation of the gastric vagal branches (373 +/- 39.8 ms;
means +/- SD) was significantly longer than the latencies after intercostal
nerve (62 +/- 17.0 ms) or common peroneal nerve (109 +/- 29.3 ms)
stimulation. Convergence of gastric vagal input from the proximal stomach
and peripheral nerves (PNs) on single neurons in the lateral hypothalamus
was observed. Ninety-two percent of the lateral hypothalamic neurons tested
that responded to gastric vagal stimulation also received inputs from the
T9 intercostal nerve. Seventy-seven percent of the lateral hypothalamic
gastric vagally evoked unitary responses received convergent inputs from
the intercostal nerve and the common peroneal nerve. A condition-test
paradigm was applied to determine the time course of convergent gastric and
PN input on single lateral hypothalamic neurons. The test revealed that
stimulation of the T9 intercostal nerve had a more pronounced effect than
common peroneal nerve stimulation on the lateral hypothalamic neurons that
receive gastric vagal input. The results demonstrated that gastric vagal
afferent and PN inputs converge onto single lateral hypothalamic neurons
and suggested that the central processing of visceral input from the
stomach can be substantially affected by peripheral nerve stimulation.
