Skip to main content
SpringerLink
Log in

Pharmacological characterization of central α-adrenoceptors which mediate clonidine-induced locomotor hypoactivity in the developing rat

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

Summary

The present experiment was designed to pharmacologically characterize receptors which mediate the clonidine-induced locomotor change in the developing rat. A subcutaneous injection of clonidine (0.78 μmol/kg) produced locomotor hyperactivity in 7-day-old rats but hypoactivity in 20-day-old rats. Phenoxybenzamine (1.5 μmol/kg, 5.9 μmol/kg and 15 μmol/kg) decreased spontaneous activity in a dosedependent manner but did not antagonize clonidineinduced hypoactivity in 20-day-old rats. By contrast, the significant reversal of the clonidine-induced hypoactivity by pretreatment with phentolamine (1.6 μmol/kg and 6.3 μmol/kg), yohimbine (1.3 μmol/kg and 5.1 μmol/kg) and piperoxan (7.4 μmol/kg) was observed at such doses when the blockers did not cause and hypoactivity by themselves. It is suggested that clonidine could induce locomotor hypoactivity by activating presynaptic (α1-type) α-adrenoceptors in the CNS of 20-day-old rat.

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

  • Andén, N.-E., Grabowska, M., Strömbom, U.: Different alphaadrenoceptors in the central nervous system mediating biochemical and functional effects of clonidine and receptor blocking agents. Naunyn-Schmiedeberg's Arch. Pharmacol. 292, 43–52 (1976)

    Google Scholar 

  • Cubeddu, L., Barnes, F. M., Langer, S. Z., Weiner, N.: Release of norepinephrine and dopamine-β-hydroxidase by nerve stimulation. 1. Role of neuronal and extraneuronal uptake of α-presynaptic receptors. J. Pharmacol. Exp. Ther. 190, 431–450 (1974)

    Google Scholar 

  • Delbarre, B., Schmitt, H.: Sedative effects of α-sympathomimetic drug and their antagonism by adrenergic and cholinergic blocking drugs. Eur. J. Pharmacol. 13, 356–363 (1971)

    Google Scholar 

  • Delbarre, B., Schmitt, H.: A further attempt to characterize sedative receptors activated by clonidine in chickens and mice. Eur. J. Pharmacol. 22, 355–359 (1973)

    Google Scholar 

  • Drew, G. M.: Effects of α-adrenoceptor agonists and antagonists on pre- and postsynaptically located α-adrenoceptors. Eur. J. Pharmacol. 36, 313–320 (1976)

    Google Scholar 

  • Drew, G. M., Gower, A. J., Marriott, A. S.: Pharmacological characterization of α-adrenoceptors which mediate clonidineinduced sedation. Br. J. Pharmacol. 61, 463P (1977)

  • Franklin, K. B., Herberg, L. J.: Presynaptic α-adrenoceptors: The depression of self-stimulation by clonidine and its restoration by piperoxan but not by phentolamine or phenoxybenzamine. Eur. J. Pharmacol. 43, 33–38 (1977)

    Google Scholar 

  • Kellogg, C., Lundborg, P.: Ontogenic variations in response to Lxx-DOPA and monoamine-stimulating agents. Psychopharmacologia (Berl.) 23, 187–200 (1972)

    Google Scholar 

  • Kellogg, C., Wennerström, G.: An ontogenic study on the effect of catecholamine receptor-stimulating agents on the turnover of noradrenaline and dopamine in the brain. Brain Res. 79, 451–464 (1974)

    Google Scholar 

  • Langer, S. Z.: Presynaptic regulation of catecholamine release. Biochem. Pharmacol. 23, 1793–1800 (1974)

    Google Scholar 

  • Lassen, J. B.: Piperoxan reduces the effects of clonidine on aggression in mice and on noradrenaline dependent hyperactivity in rats. Eur. J. Pharmacol. 47, 45–49 (1978)

    Google Scholar 

  • Nomura, Y., Segawa, T.: The effect of α-adrenocdptor antagonists and metiamide on clonidine-induced locomotor stimulation in the infant rat. Br. J. Pharmacol. 66, 531–535 (1979)

    Google Scholar 

  • Reinstein, D. K., Isaacson, R. L.: Clonidine sensitivity in the developing rat. Brain. Res. 135, 378–382 (1977)

    Google Scholar 

  • Robson, R. D., Antonaccio, M. J., Saelens, J. K., Liebman, J.: Antagonism by mianserin and classical α-adrenoceptor blocking drugs of some cardiovascular and behavioral effects of clonidine. Eur. J. Pharmacol. 47, 431–442 (1978)

    Google Scholar 

  • Schild, H. O.: pAx and competitive drug antagonism. Br. J. Pharmacol. 4, 277–280 (1949)

    Google Scholar 

  • Starke, K., Borowski, E., Endo, T.: Preferential blockade of presynaptic α-adrenoceptors by yohimbine. Eur. J. Pharmacol. 34, 385–388 (1975)

    Google Scholar 

  • Zebrowska-Łupina, I., Przegaliński, M., Słoniec, M., Kleinrok, Z.: Clonidine-induced locomotor hyperactivity in rats. The role of central postsynaptic α-adrenoceptors. Naunyn-Schmiedeberg's Arch. Pharmacol. 297, 227–237 (1977)

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Pharmacology, Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine, Kasumi 1-2-3, 734, Hiroshima, Japan

    Yasuyuki Nomura, Keiko Oki & Tomio Segawa

Authors
  1. Yasuyuki Nomura
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Keiko Oki
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Tomio Segawa
    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

Nomura, Y., Oki, K. & Segawa, T. Pharmacological characterization of central α-adrenoceptors which mediate clonidine-induced locomotor hypoactivity in the developing rat. Naunyn-Schmiedeberg's Arch. Pharmacol. 311, 41–44 (1980). https://doi.org/10.1007/BF00500300

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00500300

Key words

Search

Navigation