In addition to their ability to convert chemical signals into electrical responses, neurotransmitter-gated ion channels, they are dynamic molecular entities, subject to regulation of their responsiveness over a wide temporal range. The focus of the experiments described in this proposal is on the mechanisms that regulate the neural acetylcholine receptor (AcChR) of PC12 cells, a clonal sympathetic cell line. The kinetic properties of agonist- mediated desensitization will be examined by sodium influx measurements of receptor activity. The possibility that phosphorylation-dephosphorylation reactions are involved in the development of long lasting desensitization that is characterized by slow onset and recovery rates, will be investigated by obtaining measurements, in parallel, of the extent of AcChR phosphorylation. A binding assay to quantitate nAcChRs of PC12 cells will be developed to examine whether deactivation, an agonist-induced process that produces an irreversible dimunution of the permeability response, involves a rapid loss of surface receptors. The relationship between deactivation and the receptor states involved in desensitization will be examined by kinetic analysis of the effects on the rates of each of these processes by different cholinergic antagonists. The role of other synaptic components both extracellular, e.g. substance P, and intracellular, e.g. Ca2+ and cAMP, in modulating further these agonist-mediated processes will also be evaluated by the same biochemical techniques. By examining the mechanisms of short- and long-term regulation of nAcChR by agonists and other synaptic components, the proposed studies will aid in evaluating the possible role of postsynaptic mechanisms in modulating synaptic efficacy. A better understanding of these processes will shed light on one of the most remarkable properties of the brain: its ability to be regulated by experience.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29NS025151-04
Application #
3477022
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1987-07-01
Project End
1992-06-30
Budget Start
1990-07-01
Budget End
1991-06-30
Support Year
4
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Type
Schools of Medicine
DUNS #
660735098
City
Worcester
State
MA
Country
United States
Zip Code
01655
Kage, R; Hershey, A D; Krause, J E et al. (1995) Characterization of the substance P (NK-1) receptor in tunicamycin-treated transfected cells using a photoaffinity analogue of substance P. J Neurochem 64:316-21
Kage, R; Leeman, S E; Boyd, N D (1993) Biochemical characterization of two different forms of the substance P receptor in rat submaxillary gland. J Neurochem 60:347-51
Boyd, N D; White, C F; Cerpa, R et al. (1991) Photoaffinity labeling the substance P receptor using a derivative of substance P containing p-benzoylphenylalanine. Biochemistry 30:336-42
Boyd, N D; MacDonald, S G; Kage, R et al. (1991) Substance P receptor. Biochemical characterization and interactions with G proteins. Ann N Y Acad Sci 632:79-93
Luber-Narod, J; Boyd, N D; Leeman, S E (1990) Guanine nucleotides decrease the affinity of substance P binding to its receptor. Eur J Pharmacol 188:185-91
Macdonald, S G; Boyd, N D (1989) Regulation of substance P receptor affinity by guanine nucleotide-binding proteins. J Neurochem 53:264-72