Differential release of endogenous 5-hydroxytryptamine, substance P, and neurokinin A from rat ventral spinal cord in response to electrical stimulation

J Neurochem. 1993 Aug;61(2):704-11. doi: 10.1111/j.1471-4159.1993.tb02176.x.

Abstract

The release of endogenous 5-hydroxytryptamine (5-HT), substance P (SP), and neurokinin A (NKA) from superfused tissue slices of rat ventral lumbar spinal cord, where SP and NKA coexist with 5-HT in terminals of descending bulbospinal neurons, was investigated. Electrical field stimulation was performed using square-wave pulses of 2-ms duration and 30 mA stimulus intensity. The following four different patterns of stimulation were used: 2 Hz continuous, 20 Hz continuous, 20 Hz intermittent, and 50 Hz intermittent. 5-HT was measured in the slice superfusates by HPLC with electrochemical detection. SP and NKA were measured by radioimmunoassay. The release of 5-HT was significantly enhanced using all stimulation paradigms and the evoked release of 5-HT per pulse was independent of the stimulation frequency. The release was found to be calcium dependent and there was no increase in the efflux of 5-hydroxyindoleacetic acid in response to stimulation. At 2 Hz (continuous), no significant increase in the release of SP was observed. Stimulation at higher frequencies yielded a significant increase in the release of SP per pulse. At 20 Hz, the release was increased by 73% (continuous) and 74% (intermittent), and at 50 Hz (intermittent) by 175% of basal efflux. The evoked release of NKA was also frequency dependent. At 2 Hz (continuous), no significant increase in the release of NKA was observed. At 20 Hz (intermittent), the evoked release per pulse was increased by 33% and at 50 Hz (intermittent) by 53% compared with the basal efflux of NKA.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / pharmacology
  • Chromatography, High Pressure Liquid
  • Electric Stimulation*
  • In Vitro Techniques
  • Male
  • Neurokinin A / metabolism*
  • Radioimmunoassay
  • Rats
  • Rats, Sprague-Dawley
  • Serotonin / metabolism*
  • Spinal Cord / metabolism*
  • Substance P / metabolism*

Substances

  • Serotonin
  • Substance P
  • Neurokinin A
  • Calcium