Opposite effects of chronic cortisol treatment on pre- and postsynaptic actions of clonidine in pithed rats

K. Szemeredi, Z. Zukowska-Grojec, G. Bagdy, M. Fekete, I. J. Kopin

Research output: Contribution to journalArticle

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Abstract

Both clinical and experimental studies have shown that chronic elevation of plasma cortisol levels are attended by altered adrenergic receptor function. In the present study we examined the effects of chronic cortisol treatment (25 mg kg-1 day-1 for 7 days by minipumps) on the peripheral cardiovascular responses of pithed, adrenal demedullated vagotomized rats. Chronic cortisol treated rats had higher basal distolic blood pressures after being pithed, suggesting that sympathetic outflow is not required to sustain elevated peripheral resistance in glucocorticoid-induced hypertension. Whereas alpha1-adrenoreceptor-mediated diastolic blood pressure responses were unaltered, alpha2-adrenoreceptor-mediated vasopressor responses were potentiated in pithed rats which were chronically treated with cortisol. Elevation of plasma noradrenaline induced by the stimulation of the entire sympathetic outflow of pithed rats was not changed but the clonidine-induced presynaptic alpha2-adrenoreceptor inhibition of noradrenaline release was attenuated by chronic cortisol treatment. In conclusion, in adrenal demedullated pithed rats the responses mediated by peripheral pre- and postjunctional alpha2-adrenoreceptors appeared to be affected oppositely after chronic cortisol treatment, suggesting that the pharmacologically homogeneous alpha2-adrenoreceptor population may be modulated differently by chronic elevation of plasma glucocorticoids.

Original languageEnglish
Pages (from-to)35-43
Number of pages9
JournalJournal of Autonomic Pharmacology
Volume9
Issue number1
Publication statusPublished - 1989

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Clonidine
Hydrocortisone
Blood Pressure
Glucocorticoids
Norepinephrine
Vascular Resistance
Adrenergic Receptors
Hypertension
Population

ASJC Scopus subject areas

  • Neuroscience(all)
  • Pharmacology

Cite this

Opposite effects of chronic cortisol treatment on pre- and postsynaptic actions of clonidine in pithed rats. / Szemeredi, K.; Zukowska-Grojec, Z.; Bagdy, G.; Fekete, M.; Kopin, I. J.

In: Journal of Autonomic Pharmacology, Vol. 9, No. 1, 1989, p. 35-43.

Research output: Contribution to journalArticle

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