Differential Release of Endogenous 5-Hydroxytryptamine, Substance P., and Neurokinin A from Rat Ventral Spinal Cord in Response to Electrical Stimulation
| Autor: | Gabriel Fried, Ernst Brodin, Johan Franck |
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| Rok vydání: | 2006 |
| Předmět: |
Male
Serotonin medicine.medical_specialty Neurokinin A Central nervous system Radioimmunoassay Neuropeptide Stimulation Substance P In Vitro Techniques Biochemistry Rats Sprague-Dawley Cellular and Molecular Neuroscience chemistry.chemical_compound Internal medicine medicine Animals Chromatography High Pressure Liquid Spinal cord Electric Stimulation Rats Lumbar Spinal Cord medicine.anatomical_structure Endocrinology Spinal Cord chemistry Anesthesia Calcium |
| Zdroj: | Journal of Neurochemistry. 61:704-711 |
| ISSN: | 0022-3042 |
| Popis: | 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. The results suggest that coexisting neurotransmitters/neuromodulators in the spinal cord may be released in different proportions depending on the stimulation frequency and that only 5-HT is released when the nerve terminal is activated by low-frequency stimulation. |
| Databáze: | OpenAIRE |
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