This is a proposal to study the heterogeneity of opiate-receptor interaction, with particular emphasis on identifying and characterizing the distinct sites or classes of analgesic binding sites, believed to exist for alkaloids and peptides. A protein-lipid model of the opiate receptor is proposed which has two binding sites, one for enkephalin on the protein portion and one for alkaloids on the lipid portion, with B-endorphin interacting with both. The following types of experiments are used to test this model: 1) The effect of intracerebroventricularly (icv) injections of various enkephalins and endorphin fragments on morphine analgesia in mice; preliminary experiments have already shown that certain peptides potentiate morphine analgesia at doses at which the peptide alone has no effect, suggesting that they act at a different site from that of the alkaloid; 2) Comparison of the ability of various unlabelled opiates to displace binding of radioactive alkaloid or peptide to brain subcellular fractions, with particular attention to various peptides which have not been studied this way before; 3) Biochemical characterization of the binding sites, both by testing the effect of specific protein- or lipid-modifying reagents on in vitro binding, and directly by solubilizing binding material in Brij 36-T and further analyzing; 4) Circular dichroism measurements of B-endorphin and various endorphin fragments; we have shown in preliminary experiments that B-endorphin, though normally existing as a random chain in solution, forms alpha-helical structure in the presence of lipid, which may be necessary for receptor interaction. These experiments should allow us: 1) to conform the existence of separate binding sites for alkaloids and peptides; 2) to identify distinct sites that may exist for different types of alkaloids or different types of peptides; 3) to gain some insight into the chemical nature of these sites, particularly with respect to whether they are located on lipid or protein, and whether they are on distinct molecules; and 4) to begin purification of some of these receptors.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA002643-06
Application #
3207476
Study Section
(DABB)
Project Start
1981-01-01
Project End
1987-06-30
Budget Start
1986-07-01
Budget End
1987-06-30
Support Year
6
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of California San Francisco
Department
Type
Schools of Medicine
DUNS #
073133571
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Riba, Pal; Ben, Yong; Nguyen, Thi M-D et al. (2002) [Dmt(1)]DALDA is highly selective and potent at mu opioid receptors, but is not cross-tolerant with systemic morphine. Curr Med Chem 9:31-9
Riba, Pal; Ben, Yong; Smith, Andrew P et al. (2002) Morphine tolerance in spinal cord is due to interaction between mu- and delta-receptors. J Pharmacol Exp Ther 300:265-72
Gant, T M; Riba, P; Lee, N M (2001) Morphine tolerance in mice is independent of polymorphisms in opioid receptor sequences. Brain Res Bull 55:59-63
He, L; Lee, N M (1998) Delta opioid receptor enhancement of mu opioid receptor-induced antinociception in spinal cord. J Pharmacol Exp Ther 285:1181-6
He, L; Lee, N M (1997) DynorphinA-(2-17) restores spinal/supraspinal morphine synergy in morphine-tolerant mice. J Pharmacol Exp Ther 280:1210-4
Shark, K B; Lee, N M (1995) Cloning, sequencing and localization to chromosome 11 of a cDNA encoding a human opioid-binding cell adhesion molecule (OBCAM). Gene 155:213-7
Hooke, L P; He, L; Lee, N M (1995) [Des-Tyr1]dynorphin A-(2-17) has naloxone-insensitive antinociceptive effect in the writhing assay. J Pharmacol Exp Ther 273:802-7
Lee, N M (1995) Dynorphin A: a rectifying peptide. NIDA Res Monogr 147:161-9
Lane, C M; Jones, C R; Reisine, T et al. (1995) Alteration of OBCAM conformation as a result of opioid receptor expression and opioid ligand treatment. Brain Res 698:15-22
Kalyuzhny, A; Lee, N M; Elde, R (1995) An opioid binding protein is specifically down-regulated by chronic morphine treatment in dorsal root and trigeminal ganglia. Neuroscience 66:943-9

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