Experimental Brain Research

, Volume 79, Issue 2, pp 293–298

Effects of 5-hydroxytryptamine on the firing rates of neurons of the lateral vestibular nucleus in the rat

  • F. Licata
  • G. Li Volsi
  • G. Maugeri
  • F. Santangelo
Article

DOI: 10.1007/BF00608238

Cite this article as:
Licata, F., Li Volsi, G., Maugeri, G. et al. Exp Brain Res (1990) 79: 293. doi:10.1007/BF00608238

Summary

5-hydroxytryptamine (5-HT) was delivered microiontophoretically (20–80 nA) to cells of the lateral vestibular nucleus of anaesthetized rats to test its influence on the spontaneous activity of single neurons. 5-HT increased the rate of firing of 94% of the units tested. The enhancement persisted for up to 700 s after the end of the 5-HT ejection and the maximum magnitude of the excitation (10–3400%) showed a hyperbolic correlation (ϱ=0.86) with background firing. In 43% of units the enhancement was preceded by a short-lasting (less than 105 s) depression of the neuronal firing rate, the magnitude of which was unrelated to the background mean firing rate. Both components of the 5-HT response were dose-dependent. Only the excitatory responses were antagonized by metergoline, methysergide and ketanserin. The putative 5-HT agonist, 5-methoxy-N,N-dimethyltryptamine, applied microiontophoretically, depressed the background firing rate and was not antagonized by methysergide. These results demonstrate that 5-HT modifies the responsiveness of vestibular neurons and suggest that at least two mechanisms and maybe two types of receptors are activated by 5-HT in this nucleus.

Key words

Lateral vestibular nucleus 5-hydroxytryptamine Microiontophoresis Rat 

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • F. Licata
    • 1
  • G. Li Volsi
    • 1
  • G. Maugeri
    • 1
  • F. Santangelo
    • 1
  1. 1.Institute of Human PhysiologyCataniaItaly

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