Zhen Ci Yan Jiu. 1991 ; 16(1): 43-7.

[The role of nucleus tractus solitarii (NTS) in acupuncture inhibition of visceral-somatic reflex (VSR)]

Huang Z, Liu N, Zhong S, Lu J, Zhang N.

Department of Physiology, Chongqing University of Medical Sciences.

Experiments were carried out on 164 rabbits. The transmission of abdominal vagal impulses and the mechanism of inhibitory effect by acupuncture systematically were investigated. 1) Electrical stimulation (single pulse of 20 V, 0.5 ms) of abdominal vagus nerve (AVN) produced two kinds of potential on cervical vagus nerve: the fast wave (10.4-24.4 M/sec) and the slow wave (0.9-1.7 M/sec), the later was more stable. 2) In dorsal medulla oblongata the 'M' shaped evoked potentials with long duration (100 ms or so) were recorded. The results suggest that afferents from AVN are mainly transmitted through the small fibres and multi-synaptic connections in Medulla. 3) Out of 301 response units, 281 units (93.6%) concentrated in NTS and adjacent regions. This result was also confirmed by injection of Horseradish Peroxidase (HRP) in the trunk of AVN. 4) On 24 awake rabbits the VSR were elicited by strong stimulation of AVN. Electroacupuncture (EA) on "Zusanli" points inhibited VSR, an effect lasted over 20 min. This inhibitory effect of EA was reversed partly by Naloxone (0.5 mg/kg iv) and was attenuated after lesion (DC 0.5 mA, 1 min.) of NTS. In conclusion, NTS plays an important role in suppression of VSR by EA (P less than 0.01).