The goal of this research is to gain an understanding, on a molecular level, of the control mechanisms and/or chemical signals that regulate receptor number, affinity and distribution in neuronal cells. In particular, we wish to determine how mechanisms for control of receptor number and distribution in neurons compare to those in non-neural cells. While much is known of receptor turnover (synthesis and degradation) in non-neural cells, there have been, to the best of our knowledge, no thorough studies of the synthesis and degradation of a receptor localized to the central nervous system. Much of the work that has appeared has focused upon 'down-regulation' or 'up-regulation' of receptor numbers; however, the kinetics of such changes provide only limited information about cellular mechanisms of receptor synthesis and degradation. Receptor regulation may be investigated more meaningfully if the fate of the receptor is followed directly with a specific probe that does not alter the rates of receptor turnover. We have shown that the chemosensitivity of neurons in culture to gamma-aminobutyric acid is potentiated by benzodiazepines which are minor tranquilizers, anticonvulsants and skeletal muscle relaxants that probably act by enhancing inhibitory neuronal activity in the CNS. The results of combined binding and electrophysiological experiments are consistent with the presence of a functional high affinity benzodiazepine receptor that can be specifically and irreversibly labeled with flunitrazepam as a photoaffinity ligand. Initial experiments suggest that benzodiazepine receptor turnover can be investigated with this probe. These studies will be extended under the current proposal. The principal objectives of this proposal are 1) to investigate the relationship of the biosynthetic and degradative steps to the maintenance of receptor number, and 2) o determine the effects of acute and long term exposure of receptor to ligands on receptor number and/or affinity, using cell cultures derived from embryonic chick brain and spinal cord.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS023140-01A1
Application #
3406332
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1986-09-01
Project End
1989-08-31
Budget Start
1986-09-01
Budget End
1987-08-31
Support Year
1
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Suny Downstate Medical Center
Department
Type
Schools of Medicine
DUNS #
068552207
City
Brooklyn
State
NY
Country
United States
Zip Code
11203
Gyenes, M; Wang, Q; Gibbs, T T et al. (1994) Phosphorylation factors control neurotransmitter and neuromodulator actions at the gamma-aminobutyric acid type A receptor. Mol Pharmacol 46:542-9
Friedman, L; Gibbs, T T; Farb, D H (1993) Gamma-aminobutyric acidA receptor regulation: chronic treatment with pregnanolone uncouples allosteric interactions between steroid and benzodiazepine recognition sites. Mol Pharmacol 44:191-7
Celentano, J J; Gyenes, M; Gibbs, T T et al. (1991) Negative modulation of the gamma-aminobutyric acid response by extracellular zinc. Mol Pharmacol 40:766-73
Wu, F S; Gibbs, T T; Farb, D H (1991) Pregnenolone sulfate: a positive allosteric modulator at the N-methyl-D-aspartate receptor. Mol Pharmacol 40:333-6
Wu, F S; Gibbs, T T; Farb, D H (1990) Inverse modulation of gamma-aminobutyric acid- and glycine-induced currents by progesterone. Mol Pharmacol 37:597-602
Borden, L A; Gibbs, T T (1990) Flunitrazepam photoaffinity labeling of the GABA(A) receptor reduces inhibition of [3H]Ro15-4513 binding by GABA. Eur J Pharmacol 188:391-7
Roca, D J; Rozenberg, I; Farrant, M et al. (1990) Chronic agonist exposure induces down-regulation and allosteric uncoupling of the gamma-aminobutyric acid/benzodiazepine receptor complex. Mol Pharmacol 37:37-43
Roca, D J; Schiller, G D; Friedman, L et al. (1990) gamma-Aminobutyric acidA receptor regulation in culture: altered allosteric interactions following prolonged exposure to benzodiazepines, barbiturates, and methylxanthines. Mol Pharmacol 37:710-9
Czajkowski, C; Farb, D H (1989) Identification of an intracellular pool of gamma-aminobutyric acidA/benzodiazepine receptors en route to the cell surface of brain neurons in culture. Mol Pharmacol 35:183-8
Czajkowski, C; Gibbs, T T; Farb, D H (1989) Transmembrane topology of the gamma-aminobutyric acidA/benzodiazepine receptor: subcellular distribution and allosteric coupling determined in situ. Mol Pharmacol 35:75-84

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