The peripheral anterograde transport of substance P (SP) in the cervical vagus nerve was reduced 30–40% in male rats following 2 weeks of ACTH or corticosterone administration. In a different model, chronic shock avoidance stress reduced by 20–40% net SP accumulation in subsequently removed 24h explants of nodose ganglion/vagus nerve. The results suggest that in chronic stress the neuroendocrine axis may interact with SP-containing vagal sensory neurons as part of the long term adaptation response.Within the vagus nerve, about 300–500 pg SP are synthesized in sensory ganglia and exported daily for distal transport. One third or less that amount is transported centrally in vivo. When the vagus is crushed at the-rostral pole of the nodose ganglion (NG), the peripheral transport of SP is reduced to 100 pg daily (1).The factors regulating the synthesis and transport of SP in the vagus are largely unknown. The ACTH-adrenal axis or stress might be among such factors as part of the adaptation response of the autonomic nervous system. To test that hypothesis, the 24h transport of SP in the cervical vagus nerve was measured in rats following two weeks administration of ACTH or corticosterone (C). In a separate series of experiments, as part of a project evaluating the effects of stress on the aging nervous system, Fischer 344 rats were exposed to 4–6 months of snock avoidance stress. Because invasive procedures could not be performed prior to sacrifice, the ligation/transport model was not employed. Rather, explants comprised of the NG and attached distal vagus nerve were removed at sacrifice and maintained for 24h in vitro.
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- Evidence of ACTH-Adrenal and Chronic Stress-Induced Down Regulation of Substance P in the Sensory Vagus Nerve
D. B. MacLean
J. C. Eldridge
- Springer New York
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