Our principal objective is the investigation of the physiological role of the endogenous opioid peptides by correlating the results obtained from the binding at the three major mu-, delta- and kappa-sites with those obtained in pharmacological experiments. Most recently, it has been shown in our laboratories that the hamster vas deferens has delta-receptors but no mu- or kappa-receptors. It has powerful peptidases and inhibitors are required in bioassays. Thus, there are now tissues selective for delta- and kappa-receptors (rabbit vas deferens) and possibly mu-receptors (rat vas deferens). Selective peptidase-resistant opioid ligands are [D-Ala-2, MePhe-4, Gly-ol-5]enkephalin for the mu-site and [D-Pen-2, D-Pen-5]enkephalin for the delta-site. As far as the kappa-site is concerned, the endogenous dynorphins A and B, but not dynorphin A (1-8), are sufficiently selective. The non-endogenous dynorphin A (1-9) is selective but as all dynorphins, with the exception of dynorphin A, is peptidase-sensitive. Another approach to this problem is the use of the guinea-pig cerebellum which has mainly kappa-sites (our laboratories) or the rabbit cerebellum which has mainly mu-sites. The coupling mechanisms between the mu-binding sites and the effector system in the guinea-pig ileum is still not well understood. We are now investigating the differential inhibitory effects of Na+ and other monovalent and divalent ions and GPT in the binding of mu-, delta- and kappa-sites after different degrees of homogenisation. This will lead to an analysis of the reasons for the lack of effects of Na+ and GPT on the binding of antagonists and on binding of agonists at the kappa-site. Recent work in this laboratory has developed HPLC procedures with columns of different properties for the separation of all fragments of the opioid precursors in one sample of tissue. The eluate will be assayed with the mouse vas deferens. The content of the endogenous opioid peptides will be determined in brain regions and in the myenteric plexus. The effect of electrical stimuation will be measured by the amount of opioid peptides released into the bath fluid. The results will be correlated with those obtained by radioimmuno-assay to be established in our laboratories.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA000662-13
Application #
3206810
Study Section
(DABA)
Project Start
1973-06-01
Project End
1989-03-31
Budget Start
1988-04-01
Budget End
1989-03-31
Support Year
13
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Aberdeen
Department
Type
DUNS #
212381045
City
Aberdeen
State
Country
United Kingdom
Zip Code
AB24 3FX
Hughes, J; Kosterlitz, H W; Smith, T W (1997) The distribution of methionine-enkephalin and leucine-enkephalin in the brain and peripheral tissues. 1977. Br J Pharmacol 120:428-36; discussion 426-7
Sagan, S; Corbett, A D; Amiche, M et al. (1991) Opioid activity of dermenkephalin analogues in the guinea-pig myenteric plexus and the hamster vas deferens. Br J Pharmacol 104:428-32
Corbett, A D; Gillan, M G; Kosterlitz, H W (1991) Electrically-induced release of opioid peptides from the guinea-pig myenteric plexus preparation. J Recept Res 11:665-73
Paterson, S J; Robson, L E; Kosterlitz, H W et al. (1990) Effect of Tris, HEPES, and TES buffers on binding at mu-, delta-, and kappa-opioid sites in guinea pig brain. J Pharmacol Methods 23:275-83
Kosterlitz, H W; Corbett, A D; Paterson, S J (1989) Opioid receptors and ligands. NIDA Res Monogr 95:159-66
Petrillo, P; La Regina, A; Sbacchi, M et al. (1989) Regional variations in binding capacities at mu-, delta- and kappa-opioid sites in membrane suspensions from rabbit brain. Eur J Pharmacol 166:213-7
Corbett, A D; McKnight, A T; Kosterlitz, H W (1988) Tissue content of opioid peptides in the myenteric plexus-longitudinal muscle of guinea-pig small intestine. J Neurochem 51:32-7
Kosterlitz, H W; Paterson, S J; Robson, L E (1988) Modulation of binding at opioid receptors by mono- and divalent cations and by cholinergic compounds. J Recept Res 8:363-73
Kosterlitz, H W; Paterson, S J; Robson, L E et al. (1987) Effects of cations on binding, in membrane suspensions, of various opioids at mu-sites of rabbit cerebellum and kappa-sites of guinea-pig cerebellum. Br J Pharmacol 91:431-7
Traynor, J R; Corbett, A D; Kosterlitz, H W (1987) Diprenorphine has agonist activity at opioid kappa-receptors in the myenteric plexus of the guinea-pig ileum. Eur J Pharmacol 137:85-9

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