Estrogen modulation of adrenoceptor responsiveness in the female rat pineal gland: differential expression of intracellular estrogen receptors

Journal of Pineal Research
Juan J SànchezRafael Alonso

Abstract

The effect of different doses of 17beta-estradiol (E2) on the pineal response to beta-adrenoceptor stimulation in female rats was examined. Pinealocytes from 21-day-old ovariectomized rats were exposed to different estrogen doses and treated with beta-adrenergic agonists. Estrogen treatment produced a dose-dependent, biphasic response to beta-adrenoceptor-induced accumulation of cAMP. This effect was inhibitory at estrogen doses up to 0.1 nM and fitted to a negative exponential curve, while at doses from 0.1 to 100 nM the effect was stimulatory and fitted to a standard positive hyperbola. For in vivo studies, ovariectomized rats were treated with equivalent estrogen concentrations plus a single dose of progesterone (250 microg per rat), and their pineals exposed in vitro to beta-adrenergic agonists. Low doses of E2 (0.1-100 ng per rat) reduced both pineal cAMP accumulation and N-acetyltransferase activity after beta-adrenoceptor stimulation, while a high dose (10 microg per rat) induced the opposite response. Apparently, the final estrogen target was the pineal beta-adrenergic receptor, as a low dose of E2 (which had diminished cAMP accumulation after beta-adrenoceptor stimulation) also reduced its maximal binding capacity (Bma...Continue Reading

Citations

Mar 12, 2008·Histochemistry and Cell Biology·Sandy Lenie, Johan Smitz
Mar 16, 2012·Endocrine Reviews·Laura N VandenbergJohn Peterson Myers
Jul 5, 2006·The FEBS Journal·S R Pandi-PerumalR Hardeland
Feb 28, 2006·Journal of Pineal Research·Hugo L FideleffDaniel P Cardinali
Dec 1, 2006·Human Reproduction Update·Andrea Riccardo GenazzaniMichele Luisi

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