A Novel, Synergistic Interaction Between 17 β-Estradiol and Glutathione in the Protection of Neurons against β-Amyloid 25–35-Induced Toxicity In Vitro
- Department of Pharmacodynamics and Center for Neurobiology of Aging, College of Pharmacy, University of Florida, Gainesville, Florida 32610
Abstract
The present studies were undertaken to investigate the possibility of an interaction between 17 β-estradiol (E2) and glutathione in protecting cells against the presence of β-amyloid 25–35 (βAP 25–35). We demonstrate that when evaluated individually, supraphysiological concentrations of either E2 (200 nm) or of reduced glutathione (GSH; 325 μm) can protect SK-N-SH human neuroblastoma cells from βAP 25–35 (20 μm) toxicity. This dose of βAP 25–35 was chosen based on the LD50 (28.9 μm) obtained in our earlier work. However, in the presence of 3.25 μm GSH, the neuroprotective EC50 of E2 was shifted from 126 ± 89 nm to 0.033 ± 0.031 nm, approximately 4000-fold. Similarly, in primary rat cortical neurons, the addition of GSH (3.25 μm) increased the potency of E2 against βAP 25–35 (10 μm) toxicity, as evidenced by a shift in the EC50 values of E2 from 68 ± 79 nm in the absence of GSH to 4 ± 6 nm in its presence. The synergy between E2 and GSH was not antagonized by the addition of the estrogen receptor antagonist, ICI 182,780. Other thiol-containing compounds did not interact synergistically with E2, nor were any synergistic interactions observed between E2 and ascorbic acid or α-tocopherol. Based on these data, we propose an estrogen-receptor independent synergistic interaction between glutathione and E2 that dramatically increases the neuroprotective potency of the steroid and may provide insight for the development of new treatment strategies for neurodegenerative diseases.
Footnotes
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Send reprint requests to: Dr. James W. Simpkins, Box 100487, College of Pharmacy, University of Florida, Gainesville, FL 32610. E-mail:simpkins{at}cop.health.ufl.edu
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This work supported by National Institutes of Health Grant AG10485 and a grant from Apollo BioPharmaceutics, Inc. P.S.G. is a trainee on National Institutes of Health Fellowship AG00196–08.
- Abbreviations:
- AD
- Alzheimer disease
- βAP
- β-amyloid peptide
- DMEM
- Dulbecco’s modified Eagle’s medium
- E2
- 17 β-estradiol
- ERT
- estrogen replacement therapy, GSH, reduced glutathione
- ICI
- ICI 182,780
- RPMI-1640
- Roswell Park Memorial Institute-1640 Medium
- PDHS
- plasma-derived horse serum
- ANOVA
- analysis of variance
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- Received May 22, 1998.
- Accepted July 28, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
