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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Aghajanian GK (1981) The modulatory role of serotonin at multiple receptors in brain. In: Jacobs BL, Gelperin AM (eds) Serotonin neurotransmission and behavior. MIT Press, Cambridge MA, pp 156–185
Bradley PB, Engel G, Fenuik W, Fozard JR, Humphrey PPA, Middlemiss DN, Mylecharane EJ, Richardson BP, Saxena PR (1986) Proposal for the classification and nomenclature of functional receptors for 5-hydroxytryptamine. Neuropharmacology 25:563–576
Brodal A, Pompeiano O, Walberg F (1962) The vestibular nuclei and their connections: anatomy and functional correlations. Oliver and Boyd, Edinburgh London
Colino A, Halliwell JC (1987) Differential modulation of three separate K-conductances in hippocampal CA1 neurons by serotonin. Nature 328:73–77
Corvaja N, Mergner T, Pompeiano O (1969) Organization of reticular projections to the vestibular nuclei in the cat. Progr Brain Res 50:631–644
Cottingham SL, Pfaff DW (1987) Electrical stimulation of the midbrain central gray facilitates lateral vestibulospinal activation of back muscle EMG in the rat. Brain Res 421:397–400
Curtis DR, Duggan AW, Felix D (1970) GABA and inhibition of Deiters' neurones. Brain Res 23:117–120
Fischette CT, Nock B, Renner K (1987) Effects of 5,7-dihydroxytryptamine on serotonin 1 and serotonin 2 receptors throughout the rat central nervous system using quantitative autoradiography. Brain Res 421:263–279
Gardette R, Krupa M, Crepel F (1987) Differential effects of serotonin on the spontaneous discharge and on the excitatory amino acid-induced responses of deep cerebellar nuclei neurons in rat cerebellar slices. Neuroscience 23:491–500
Haigler HJ, Aghajanian CK (1974) Peripheral serotonin antagonists: failure to antagonise serotonin in brain areas receiving a prominent serotonergic input. J Neur Transm 35:257–273
Kimura H, McGeer PH, Peng JH, McGeer EG (1981) The central cholinergic system studied by choline acetyltransferase immunohistochemistry. J Comp Neurol 200:151–201
Leysen JE, Awouters F, Kennis L, Laduron PM, Vandenberk J, Janssen PAJ (1981) Receptor binding profile of R41 468, a novel antagonist at 5-HT2 receptors. Life Sei 28: 1015–1022
Obata K, Ito M, Ochi R, Sato N (1967) Pharmacological properties of the postsynaptic inhibition by Purkinje cell axons and the action of γ-aminobutyric acid on Deiters' neurones. Exp Brain Res 4:43–57
Ottersen OP, Storm-Mathisen J (1984) Glutamate and GABA-containing neurons in the mouse and rat brain, as demonstrated with a new immunocytochemical technique. J Comp Neurol 229:374–392
Palkovits M, Brownstein M, Saavedra JM (1974) Serotonin content of the brainstem nuclei in the rat. Brain Res 80:237–249
Paxinos G, Watson C (1982) The rat brain in stereotaxic coordinates. Academic Press, New York
Peroutka SJ (1985) Selective labeling of 5-HT1a and 5-HT1b binding sites in bovine brain. Brain Res 344:167–171
Peroutka SJ, Lebovitz RM, Snyder SH (1981) Two distinct central serotonin receptors with different physiological functions. Science 212:827–829
Poitras D, Parent A (1978) Atlas of the distribution of monoamine-containing nerve cell bodies in the brain stem of the cat. J Comp Neurol 179:699–718
Steinbusch HWM (1981) Distribution of serotonin-immunoreactivity in the central nervous system of the rat: cell bodies and terminals. Neuroscience 6:557–618
Steinbusch HWM (1984) Serotonin-immunoreactive neurons and their projections in the C.N.S. In: Björklund A, Hökfelt T (eds) Handbook of chemical neuroanatomy, Vol III. Elsevier, Amsterdam, pp 68–125
Strahlendorf JC, Lee M, Strahlendorf HK (1984) Effects of serotonin on cerebellar Purkinje cells are dependent on the baseline firing rate. Exp Brain Res 56:50–58
Strahlendorf JC, Strahlendorf HK, Lee M (1986) Enhancement of cerebellar Purkinje cell complex discharge activity by microiontophoretic serotonin. Exp Brain Res 61:614–624
ten Bruggengate G, Engberg I (1971) Iontophoretic studies in Deiters' nucleus of the inhibitory actions of GABA and related aminoacids and the interactions of strychnine and picrotoxin. Brain Res 25:431–448
VanderMaelen CP (1985) Serotonin. In: Rogawsky MA, Barker JL (eds) Neurotransmitter actions in the vertebrates nervous system. Plenum Press, New York, pp 201–240
Wilson VJ, Yoshida M (1969) Comparison of effects of stimulation of Deiters' nucleus and medial longitudinal fasciculus on neck, forelimb and hindlimb motoneurons. J Neurophysiol 32:743–758
Wu PH, Gurevich N, Carlen PL (1988) Serotonin-1A receptor activation in hippocampal CA1 neurons by 8-hydroxy-2-(di-n-propylamino)tetralin, 5-methoxytryptamine and 5-hydroxytryptamine. Neurosci Lett 86:72–76
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Licata, F., Li Volsi, G., Maugeri, G. et al. Effects of 5-hydroxytryptamine on the firing rates of neurons of the lateral vestibular nucleus in the rat. Exp Brain Res 79, 293–298 (1990). https://doi.org/10.1007/BF00608238
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00608238