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Chronic steroid contraceptive treatment decreases renal a-adrenoceptor levels in the rat


Geraghty, DP and Burcher, E, Chronic steroid contraceptive treatment decreases renal a-adrenoceptor levels in the rat, European Journal of Pharmacology, 129, (3) pp. 225-233. ISSN 1879-0712 (1986) [Refereed Article]

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DOI: doi:10.1016/0014-2999(86)90432-2


Female Sprague-Dawley rats were injected s.c. with ethynyloestradiol (EE2, 0.2 microgram/day) and levonorgestrel (NG, 2.0 micrograms/day) separately and in combination (EE2/NG). Binding of [3H]rauwolscine (alpha 2-adrenoceptor specific) and [3H]prazosin (alpha 1-adrenoceptor specific) was examined in crude membrane suspensions prepared from whole rat kidney after 3, 6 and 12 weeks of steroid administration. Receptor affinity was high for both ligands (KD, equilibrium dissociation constant [3H]rauwolscine, congruent to 2.0 nM; [3H]prazosin, congruent to 0.2 nM) and was not altered in rats chronically treated with steroid contraceptives. The Bmax (maximum density of binding sites) for [3H]prazosin binding was not altered, indicating no change in the number of renal alpha 1-adrenoceptors. NG administered alone did not affect the numbers of alpha 1- or alpha 2-adrenoceptors. Catechol metabolites of endogenous oestrogens did not displace the binding of either radioligand, suggesting that these metabolites do not directly interact with renal alpha-adrenoceptors. However, after 12 weeks treatment, the number of [3H]rauwolscine binding sites was reduced in both EE2 (Bmax, 133 +/- 7 fmol/mg protein)- and combined EE2/NG (135 +/- 11 fmol/mg protein)-treated rats, compared to controls (162 +/- 9 fmol/mg protein). Since renal alpha 2-adrenoceptors inhibit renin release, this reduction in alpha 2-adrenoceptor number may contribute to increased renin levels associated with oestrogen-induced hypertension.

Item Details

Item Type:Refereed Article
Keywords:Ethynyloestradiol; Levonorgestrel; Radioligand binding; -Adrenoceptors; Hypertension; Kidney
Research Division:Biomedical and Clinical Sciences
Research Group:Pharmacology and pharmaceutical sciences
Research Field:Basic pharmacology
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Geraghty, DP (Professor Dominic Geraghty)
ID Code:69027
Year Published:1986
Web of Science® Times Cited:3
Deposited By:Health Sciences A
Deposited On:2011-04-15
Last Modified:2011-04-19

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