Some 25 million patients are given general anesthesia each year in the USA using agents with very low therapeutic indices. The molecular mechanisms of general anesthesia remain unknown, hampering the design of improved agents. General anesthetics are believed to modulate the function of a homologous super-family of postsynaptic ligand-gated ion channels. This PPG focuses on the enhancing action on the inhibitory GABA/A receptor (GABAAR) and the inhibitory action on the excitatory nicotinic receptor, nAcChoR. The overall hypothesis is that general anesthetics bind to a number of sites on these receptors, that their location and affinity varies with the anesthetic's structure and the receptor's conformation, and that parallels exist between the two homologous receptors. The overall aims of the PPG are to: (i) locate anesthetics sites on the GABA/A and nAcCho receptors, and (ii) define their functional significance. The focus is on three regions of the receptors: the extracellular portion, particularly just before the fist transmembrane helix, the second transmembrane helix, and the lipid protein interface. Two complementary techniques will be employed to detect sites, photoaffinity labeling (Projects I, II & IV) and site directed mutagenesis (Projects III and IV). Project II will locate the sites where volatile, alcohol and steroid anesthetics photo-label the equilibrium states of the nAcChoR, and Project IV will use similar techniques, as well as site directed mutagenesis, to locate sites on the GABAAR. Project I will determine which sites inhibit the nAcChoR's open channel using time resolved photo-labeling. Project III will define mechanisms kinetically using rapid perfusion patch clamp techniques in wild type and mutated receptors, incorporating the photo- labeling results to guide mutagenesis and interpretation. Projects I & II will investigate the role of cholesterol sites in modulating allosteric interactions between anesthetic sites and steroid anesthetic action, respectively. Synthetic and Protein Chemistry Cores are essential for developing novel photoaffinity general anesthetics and for locating the sites of photo-incorporation, respectively.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Program Projects (P01)
Project #
5P01GM058448-03
Application #
6329772
Study Section
Special Emphasis Panel (ZGM1-PS-5 (01))
Program Officer
Cole, Alison E
Project Start
1998-12-01
Project End
2003-11-30
Budget Start
2000-12-01
Budget End
2001-11-30
Support Year
3
Fiscal Year
2001
Total Cost
$1,099,753
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Ziemba, Alexis M; Szabo, Andrea; Pierce, David W et al. (2018) Alphaxalone Binds in Inner Transmembrane ?+-?- Interfaces of ?1?3?2 ?-Aminobutyric Acid Type A Receptors. Anesthesiology 128:338-351
Forman, Stuart A (2018) Combining Mutations and Electrophysiology to Map Anesthetic Sites on Ligand-Gated Ion Channels. Methods Enzymol 602:369-389
Woll, Kellie A; Zhou, Xiaojuan; Bhanu, Natarajan V et al. (2018) Identification of binding sites contributing to volatile anesthetic effects on GABA type A receptors. FASEB J 32:4172-4189
McGrath, Megan; Yu, Zhiyi; Jayakar, Selwyn S et al. (2018) Etomidate and Etomidate Analog Binding and Positive Modulation of ?-Aminobutyric Acid Type A Receptors: Evidence for a State-dependent Cutoff Effect. Anesthesiology 129:959-969
Feng, Hua-Jun; Forman, Stuart A (2018) Comparison of ??? and ??? GABAA receptors: Allosteric modulation and identification of subunit arrangement by site-selective general anesthetics. Pharmacol Res 133:289-300
McGrath, Megan; Ma, Celena; Raines, Douglas E (2018) Dimethoxy-etomidate: A Nonhypnotic Etomidate Analog that Potently Inhibits Steroidogenesis. J Pharmacol Exp Ther 364:229-237
Zhou, Xiaojuan; Desai, Rooma; Zhang, Yinghui et al. (2018) High-level production and purification in a functional state of an extrasynaptic gamma-aminobutyric acid type A receptor containing ?4?3? subunits. PLoS One 13:e0191583
Ma, Celena; Pejo, Ervin; McGrath, Megan et al. (2017) Competitive Antagonism of Anesthetic Action at the ?-Aminobutyric Acid Type A Receptor by a Novel Etomidate Analog with Low Intrinsic Efficacy. Anesthesiology 127:824-837
Jounaidi, Youssef; Cotten, Joseph F; Miller, Keith W et al. (2017) Tethering IL2 to Its Receptor IL2R? Enhances Antitumor Activity and Expansion of Natural Killer NK92 Cells. Cancer Res 77:5938-5951
Yu, Zhiyi; Cohen, Jonathan B (2017) Enantiomeric barbiturates bind distinct inter- and intrasubunit binding sites in a nicotinic acetylcholine receptor (nAChR). J Biol Chem 292:17258-17271

Showing the most recent 10 out of 116 publications