The aim of the proposed research is to understand how ethanol affects the function of muscarinic acetylcholine receptor complexes in the brain. We have demonstrated that ethanol 1) alters ligand binding to the receptor and 2) disrupts receptor coupling to guanine nucleotide-dependent transducer proteins (G proteins). The latter effect represents a novel mechanism for disruption of synaptic transmission. The hypotheses to be tested are that ethanol interacts with muscarinic-G protein complexes in the brain, thereby affecting 1) ligand binding to the receptor, 2) gaunine nucleotide regulation of receptor binding, 3) receptor regulation of postsynaptic biochemical events, 4) guanine nucleotide binding to receptor-associated G proteins, and/or 5) the GTPase activity of G proteins. Accordingly, the Specific Aims of the proposed research are to determine the effects of ethanol and other short cahin alcohols on muscarinic (and other) receptors and their associated G proteins in rat brain. Receptor processes to be studied are 1) ligand binding, including antagonist binding site density, affinity, kinetics and thermodynamics, and agonist binding propetties (subpopulation distribution and affinities), 2) receptor-G protein coupling, as revealed by guanine nucleotide regulation of agonist binding, 3) muscarinic receptor-mediated inhibition of adenylate cyclase activity and stimulation of phosphatidylinositol breakdown in brain membranes, as an indication functional muscarinic transmission, and 4) the GTPase and (345)GTP binding activities of G protein species isolated from rat brain, to evaluate the possibility of direct alcohol-G protein interactions. This research will increase our understanding of muscarinic receptor organization and function in the brain and provide insight into the molecular bases for ethanol disruption of synaptic transmission.

Agency
National Institute of Health (NIH)
Institute
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Type
Research Project (R01)
Project #
5R01AA007698-03
Application #
3111525
Study Section
Biochemistry, Physiology and Medicine Subcommittee (ALCB)
Project Start
1988-04-01
Project End
1992-03-31
Budget Start
1990-04-01
Budget End
1992-03-31
Support Year
3
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Medical College of Georgia (MCG)
Department
Type
Schools of Medicine
DUNS #
City
Augusta
State
GA
Country
United States
Zip Code
30912
Ravindra, R; Aronstam, R S (1993) Effect of colchicine and taxol on stimulation of G protein GTPase activity in anterior pituitary lobe of rats by gonadotrophin- and thyrotrophin-releasing hormones. J Reprod Fertil 97:27-33
Ravindra, R; Aronstam, R S (1992) Stimulation of the release of [32P]guanosine 5'-diphosphate from G proteins in the rat anterior pituitary lobe by gonadotrophin-releasing and thyrotrophin-releasing hormones. J Reprod Fertil 95:669-77
Ravindra, R; Aronstam, R S (1992) Progesterone, testosterone and estradiol-17 beta inhibit gonadotropin-releasing hormone stimulation of G protein GTPase activity in plasma membranes from rat anterior pituitary lobe. Acta Endocrinol (Copenh) 126:345-9
Swanson, K L; Albuquerque, E X (1992) Progress in understanding the nicotinic acetylcholine receptor function at central and peripheral nervous system synapses through toxin interactions. Md Med J 41:623-31
Swanson, K L; Aronstam, R S; Wonnacott, S et al. (1991) Nicotinic pharmacology of anatoxin analogs. I. Side chain structure-activity relationships at peripheral agonist and noncompetitive antagonist sites. J Pharmacol Exp Ther 259:377-86
Ravindra, R; Aronstam, R S (1991) Colchicine inhibits acetylcholine receptor stimulation of G protein GTPase activity in rat striatum. Pharmacol Toxicol 69:259-62
Martin, D C; Abraham, J E; Plagenhoef, M et al. (1991) Volatile anesthetics and NMDA receptors. Enflurane inhibition of glutamate-stimulated [3H]MK-801 binding and reversal by glycine. Neurosci Lett 132:73-6
Ravindra, R; Aronstam, R S (1991) Acetylcholine stimulates GTP binding to G proteins in rat striatum. Neuroreport 2:127-30
Martin, D C; Introna, R P; Aronstam, R S (1991) Fentanyl and sufentanil inhibit agonist binding to 5-HT1A receptors in membranes from the rat brain. Neuropharmacology 30:323-7
Carrier, G O; Aronstam, R S (1990) Increased muscarinic responsiveness and decreased muscarinic receptor content in ileal smooth muscle in diabetes. J Pharmacol Exp Ther 254:445-9

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