Skip to main content
SpringerLink
Log in

Efflux of 3H-5-hydroxytryptamine from rat hypothalamic slices by continuous electrical stimulation: Frequency-dependent responses to serotonergic antagonists and 5-hydroxytryptamine

  • Published:
Naunyn-Schmiedeberg's Archives of Pharmacology Aims and scope Submit manuscript

Summary

Rat hypothalamic slices were incubated with 3H-5-hydroxytryptamine and superfused in the presence of paroxetine to inhibit 5-hydroxytryptamine (5-HT) reuptake. The slices were continuously stimulated electrically with rectangular pulses at varying frequencies.

  1. 1.

    Continuous stimulation for up to 42 min at 1 Hz or at 3 Hz evoked a steady efflux of tritium that slowly decayed with time. The efflux produced by continuous stimulation at 5 Hz declined more rapidly with time.

  2. 2.

    Continuous stimulation at 1 Hz in the presence of increasing concentrations of unlabelled 5-HT produced a concentration-dependent decrease in tritium efflux. The presence of methiothepin (0.5 μmol/l), quipazine (10 μmol/l) and (−)- but not (+)-propranolol (1 μmol/l) attenuated this response to 5-HT. From these data, the apparent pA2 values were calculated and found to be in agreement with published values.

  3. 3.

    Frequency-dependent responses were determined using a “cumulative stimulation” protocol whereby the slices were subjected to three consecutive 14 min periods of stimulation at increasing frequencies (1,3 and then 5 Hz). Unlabelled 5-HT (1 μmol/l) inhibited electrically-evoked tritium efflux more at 1 than at 5 Hz. Methiothepin (0.5 μmol/l) and quipazine (10 μmol/l) enhanced the stimulated eflux in a manner inversely related to the frequency of stimulation. Neither (+)- nor (−)-propranolol enhanced stimulated tritium efflux at any of the three frequencies tested.

It is concluded that continuous electrical stimulation of rat hypothalamic slices at a low frequency provides a rapid means of obtaining apparent affinities and intrinsic activities of drugs that modify the serotonergic autoreceptor. Determining the frequency-dependent responses to 5-HT and to the autoreceptor antagonists has provided evidence that the enhancement of stimulated release usually seen in the presence of antagonists is not a necessary condition for blockade at the autoreceptor. These observations may be pertinent to refining the description of the serotonergic autoreceptor in the CNS.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Arbilla S, Kamal L, Langer SZ (1979) Presynaptic GABA autoreceptors on GABA ergic nerve endings of the rat substantia nigra. Eur J Pharmacol 57:211–217

    Google Scholar 

  • Arbilla S, Langer SZ, Lehmann J (1981) Dopamine autoreceptors inhibiting [3H]-dopamine release in the caudate nucleus of the cat: evidence for a role of endogenously released dopamine. Proc Br Pharmacol Soc 74:226P

    Google Scholar 

  • Barrett AM, Cullum VA (1968) The biological properties of the optical isomers of propranolol and their effects on cardiac arrhythmias. Br J Pharmacol 34:43–55

    Google Scholar 

  • Baumann PA, Koella WP (1980) Feedback control of noradrenaline release as a function of noradrenaline concentration in the synaptic cleft in cortical slices of the rat. Brain Res 189:437–448

    Google Scholar 

  • Baumann PA, Waldmeier PC (1981) Further evidence for negative feedback control of serotonin release in the central nervous system. Naunyn-Schmiedeberg's Arch Pharmacol 317:36–43

    Google Scholar 

  • Cubeddu LX, Hoffmann IS (1982) Operational characteristics of the inhibitory feedback mechanism for the regulation of dopamine release via presynaptic receptors. J Pharmacol Exp Ther 223: 497–501

    Google Scholar 

  • Engel G, Göthert M, Müller-Schweinitzer E, Schlicker E, Sistonen L, Stadler PA (1983) Evidence for common pharmacological properties of [3H] 5-hydroxytryptamine binding sites, presynaptic 5-hydroxytryptamine autoreceptors in CNS and inhibitory presynaptic 5-hydrotryptamine receptors on sympathetic nerves. Naunyn-Schmiedeberg's Arch Pharmacol 324:116–124

    Google Scholar 

  • Frankhuyzen AL, Mulder AH (1980) Noradrenaline inhibits depolarization-induced 3H-serotonin release from slices of rat hippocampus. Eur J Pharmacol 63:179–182

    Google Scholar 

  • Frankhuyzen AL, Mulder AH (1982) A cumulative dose-response technique for the characterization of presynaptic receptors modulating [3H]-noradrenaline release from rat brain slices. Eur J Pharmacol 78:91–97

    Google Scholar 

  • Furchgott RF (1972) The classification of adrenoceptors (adrenergic receptors). An evaluation from the standpoint of receptor theory. In: Blaschko H, Muscholl E (eds) Handbook of experimental pharmacology. Catecholamines, vol XXXIII, Springer, Berlin Heidelberg New York, pp 283–335

    Google Scholar 

  • Göthert M (1980) Serotonin-receptor-mediated modulation of Ca2+-dependent 5-hydroxytryptamine release from neurones of the rat brain cortex. Naunyn-Schmiedeberg's Arch Pharmacol 314:223–230

    Google Scholar 

  • Göthert M, Schlicker E (1983) Autoreceptor-mediated inhibition of 3H-5-hydroxytryptamine release from rat brain cortex slices by analogues of 5-hydroxytryptamine. Life Sci 32:1183–1191

    Google Scholar 

  • Göthert M, Weinheimer G (1979) Extracellular 5-hydroxytryptamine inhibits 5-hydroxytryptamine release from rat brain cortex slices. Naunyn-Schmiedeberg's Arch Pharmacol 310:93–96

    Google Scholar 

  • Green AR, Youdim MBH, Grahame-Smith DG (1976) Quipazine: Its effects on rat brain 5-hydroxytryptamine metabolism, monoamine oxidase activity and behaviour. Neuropharmacology 15:173–179

    Google Scholar 

  • Hetey L, Schwitzkowsky R, Oelssner W (1983) Influence of psychomimetics and lisuride on synaptosomal dopamine release in the nucleus accumbens of rats. Eur J Pharmacol 93:213–220

    Google Scholar 

  • Hoffmann IS, Cubeddu LX (1982) Rate and duration of stimulation determine presynaptic effects of haloperidol on dopaminergic neurons. J Neurochem 39:585–588

    Google Scholar 

  • Jacobs BL, Heym J, Rasmussen K (1983) Raphe neurons: firing rate correlates with size of drug response. Eur J Pharmacol 90:275–278

    Google Scholar 

  • Kalsner S (1982a) The presynaptic receptor controversy. Trends in Pharmacol Sci 3:11–21

    Google Scholar 

  • Kalsner S (1982b) Evidence against the unitary hypothesis of agonist and antagonist action at presynaptic adrenoceptors. Br J Pharmacol 77:375–380

    Google Scholar 

  • Katz B, Miledi R (1968) The role of calcium in neuromuscular facilitation. J Physiol 195:481–492.

    Google Scholar 

  • Langer SZ (1981) Presynaptic regulation of the release of catecholamines. Pharmacol Rev 32:337–362

    Google Scholar 

  • Martin LL, Sanders-Bush E (1982) The serotonin autoreceptor: antagonism by quipazine. Neuropharmacology 21:445–450

    Google Scholar 

  • Middlemiss DN (1984a) 8-Hydroxy-2-(Di-n-propylamino)-tetralin is devoid of activity at the 5-HT autoreceptor in the rat frontal cortex. Implications for the proposed link between autoreceptor and the [3H]-5-HT recognition site. Naunyn-Schmiedeberg's Arch Pharmacol 327:18–22

    Google Scholar 

  • Middlemiss DN (1984b) Stereoselective blockade at [3H]-5-HT binding sites and at the 5-HT autoreceptor by propranolol. Eur J Pharmacol 101:289–293

    Google Scholar 

  • Mitchell PR, Martin IL (1978) Is GABA release modulated by presynaptic receptors? Nature 274:904–905

    Google Scholar 

  • Pelayo F, Dubovitch ML, Langer SZ (1980) Inhibition of neuronal uptake reduces the presynaptic effects of clonidine but not of α-methylnoradrenaline on the stimulation-evoked release of 3H-noradrenaline from rat occipital cortex slices. Eur J Pharmacol 64:143–155

    Google Scholar 

  • Rand MJ, McCulloch MW, Story DF (1982) Feedback modulation of noradrenergic transmission. Trends Pharmacol Sci 3:8–18

    Google Scholar 

  • Reichenbacher D, Reimann W, Starke K (1982) α-Adrenoceptormediated inhibition of noradrenaline release in rabbit brain cortex slices. Receptor properties and role of the biophase concentration of noradrenaline. Naunyn-Schmiedeberg's Arch Pharmacol 319:71–77

    Google Scholar 

  • Richards M (1983) Autoreceptor modulation of transmitter release from hypothalamic 5-HT neurons evoked by continuous electrical stimulation. Naunyn-Schmiedeberg's Arch Pharmacol 324:R23

    Google Scholar 

  • Schlicker E, Göthert M (1981) Antagonistic properties of quipazine at presynaptic serotonin receptors and α-adrenoceptors in rat brain cortex slices. Naunyn-Schmiedeberg's Arch Pharmacol 317:204–208

    Google Scholar 

  • Schoffelmeer ANM, Wemer J, Mulder AH (1981) Comparison between electrically evoked and potassium-induced 3H-noradrenaline release from rat neocortex slices: role of calcium ions and transmitter pools. Neurochem Int 3:129–136

    Google Scholar 

  • Shepard P, German DC (1982) Substantia nigra dopamine neurons: relationship between cell firing properties, anatomical localization, and autoreceptor sensitivity. Soc Neurosci Abst 8:921

    Google Scholar 

  • Starke K (1981) Presynaptic receptors. Ann Rev Pharmacol Toxicol 21:7–30

    Google Scholar 

  • Starke K, Altmann KP (1973) Inhibition of adrenergic neurotransmission by clonidine: an action on prejunctional alpha-receptors. Neuropharmacology 12:339–347

    Google Scholar 

  • Starke K, Reimann W, Zumstein A, Hertting G (1978) Effect of dopamine receptor agonists and antagonists on release of dopamine in the rabbit caudate nucleus in vitro. Naunyn-Schmiedeberg's Arch Pharmacol 305:27–36

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Strasbourg Centre, Merrell-Dow Research Institute, 16, rue d'Ankara, F-67084, Strasbourg-Cedex, France

    M. H. Richards

Authors
  1. M. H. Richards
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Richards, M.H. Efflux of 3H-5-hydroxytryptamine from rat hypothalamic slices by continuous electrical stimulation: Frequency-dependent responses to serotonergic antagonists and 5-hydroxytryptamine. Naunyn-Schmiedeberg's Arch. Pharmacol. 329, 359–366 (1985). https://doi.org/10.1007/BF00496368

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00496368

Key words

Search

Navigation