Rapid effects of estrogen to modulate G protein-coupled receptors via activation of protein kinase A and protein kinase C pathways

Martin J. Kelly, Andre H. Lagrange, Edward J. Wagner, Oline K. Rønnekleiv

Research output: Contribution to journalArticlepeer-review

189 Scopus citations

Abstract

17β-Estradiol (E2) rapidly (<20 min) attenuates the ability of μ- opioids to hyperpolarize guinea pig hypothalamic neurons. We have used intracellular recordings from female guinea pig hypothalamic slices to characterize the receptor and intracellular pathway(s) mediating E2's rapid effects. E2 acts stereospecifically with physiologically relevant concentration-dependence (EC50 = 8 nM) to cause a fourfold reduction in the potency of the μ-opioid agonist (D-Ala2-N-Me-Phe4-Gly5-ol)-enkephalin and the GABA(B) agonist baclofen to activate an inwardly rectifying K+ conductance in hypothalamic neurons. Both the nonsteroidal estrogen diethylstilbestrol and the anti-estrogen ICI 164,384 blocked E2 actions to uncouple μ-opioid receptors. Using a pharmacological Schild analysis, we found that ICI 164,384 competed for this E2 receptor with a K(e) of approximately 0.3 nM. The protein synthesis inhibitor cycloheximide did not block the estrogenic uncoupling of the μ-opioid receptor from its K+ channel, implying a rapid, nongenomic mechanism of E2 action. The effects of E2 were mimicked by the bath application of the protein kinase A (PKA) activators, forskolin and Sp-cAMP, and the protein kinase C (PKC) activator phorbol-12,13-dibutyrate. Furthermore, the selective PKA antagonists Rp-cAMP and KT5720, which have different chemical structures and modes of action, both blocked the effects of E2. In addition, the actions of E2 were blocked by the selective PKC inhibitor Calphostin C. Therefore, it appears that E2 can activate both PKA and PKC to cause a heterologous desensitization of both μ-opioid and GABA(B) receptors, which has the potential to alter synaptic transmission in many regions of the CNS.

Original languageEnglish (US)
Pages (from-to)64-75
Number of pages12
JournalSteroids
Volume64
Issue number1-2
DOIs
StatePublished - Jan 1 1999

Keywords

  • Estrogen
  • GABA(B)
  • Protein kinase A
  • Protein kinase C
  • Steroid receptor
  • μ- Opioid

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology
  • Pharmacology
  • Clinical Biochemistry
  • Organic Chemistry

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