Depolarizing responses recorded from nodose ganglion cells of the rabbit evoked by 5-hydroxytryptamine and other substances

Membrane potential changes induced by 5-hydroxytryptamine (5-HT), γ-aminobutyric acid (GABA) and 1,1-dimethyl-4-phenyl piperazinium (DMPP) were recorded from nodose ganglia (NG) by the sucrose-gap method. An amount of 0.002–0.5 μmol of the depolarizing agent was injected into the superfusion stream...

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Veröffentlicht in:Neuropharmacology 1982, Vol.21 (1), p.31-40
Hauptverfasser: Wallis, D.I., Stansfeld, C.E., Nash, H.L.
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Sprache:eng
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Zusammenfassung:Membrane potential changes induced by 5-hydroxytryptamine (5-HT), γ-aminobutyric acid (GABA) and 1,1-dimethyl-4-phenyl piperazinium (DMPP) were recorded from nodose ganglia (NG) by the sucrose-gap method. An amount of 0.002–0.5 μmol of the depolarizing agent was injected into the superfusion stream to the ganglion. Responses to 5-HT were also evoked from superior cervical (SCG) and dorsal root ganglia (DRG). 5-Hydroxytryptamine elicited depolarizations of graded amplitude. Maximal responses were 4.5 ± 0.4 mV in nodose ganglia compared to 2.2. ± 0.2 mV in superior cervical and 0.6 ± 0.1 mV in dorsal root ganglia (means ± SEM). In nodose ganglia, GABA induced smaller maximal depolarizations than did 5-HT, similar to those evoked by DMPP; dopamine was a weak depolarizing agent while substance P was apparently inactive. The dose-response curve for 5-HT in nodose ganglia was parallel to that for 5-HT in superior cervical ganglia and significantly to the left (ED 50 values 0.029 and 0.098 μmol). Curves for 5-HT and GABA in nodose ganglia were superimposable. The high sensitivity of nodose ganglia cells to 5-HT is briefly discussed. Analogues of 5-HT lacking a hydroxyl group at position 5 on the nucleus were relatively inactive as depolarizing agents. Picrotoxin (10 −6 − 10 −5 M) reduced or suppressed responses in nodose ganglia to GABA, whereas responses to 5-HT and DMPP were not much affected or, in the case of 5-HT, sometimes somewhat reduced. Quipazine (10 −6 M) was a selective antagonist of 5-HT responses in nodose ganglia; those to GABA and DMPP were not significantly altered. Neither trazodone nor LSD displayed antagonist properties at 5-HT receptors in nodose ganglia.
ISSN:0028-3908
1873-7064
DOI:10.1016/0028-3908(82)90207-6