Fatty acid ethanolamine derivatives: metabolism and function

Alharthi, Nahed (2018) Fatty acid ethanolamine derivatives: metabolism and function. PhD thesis, University of Nottingham.

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Anandamide is the most recognised member of the N-acylethanolamines, NAEs group. It was the first identified endogenous cannabinoid and TRPV1 agonist as well as acting through PPARs. A wide range of endogenous NAE analogues has been detected in tissues and shown to play a role in many physiological properties. The main aim of this thesis was to investigate the profile of a series of saturated, monounsaturated and polyunsaturated NAEs as substrates for FAAH and to investigate their actions on cannabinoids, TRPV1 and PPARs receptors in vitro.

A novel nonradioactive assay was optimised and utilised for measurement of FAAH activity based on ethanolamine detection produced from hydrolysis of NAEs in rat liver microsomal preparations. CHO cells stably transfected with human recombinant CB1 and CB2 receptors were exposed to NAEs in rapid response assays, such as ERK phosphorylation and [Ca2+]i. This range of NAEs was also tested in DRG neurons using a calcium imaging technique. Selected NAEs were investigated for potential modulatory effects on inflammatory markers.

In the FAAH assay, the majority of n-3 and n-6 NAEs showed high affinities and maximal rates of hydrolysis while the saturated and monounsaturated NAEs examined all exhibited low affinities and slower rates of hydrolysis. In signal transduction assays of CB receptor activation, the n-6 NAEs of C20:4, C22:5 and C22:4 elicited responses in both ERK and calcium ion assays of CB1 and CB2 receptor while n-3 NAEs activated CB2 receptors in calcium ion assay. Both n-6 and n-3 but not saturated or monounsaturated NAEs, were able to elicit calcium responses in rat DRG neurones, which were inhibited in the presence of capsazepine. Besides these, n-3 NAE derivatives (including C22:5 and C20:5) and n-6 NAE derivatives (including C20:4 and C22:5) as well as PEA inhibited LPS elevation of IL-1β expression in human immune cells. The PEA effect was blocked by GW6471 a PPARα antagonist in human monocytes.

The data presented demonstrate that saturated and monounsaturated NAEs appear inactive as endocannabinoids or endovanilloids (at least, under the conditions assessed here) and their relatively high levels in tissues may result from their low affinity and slow rates of hydrolysis compared to the n-3 and n-6 PUFA NAEs. The n-6 NAEs as C22:4 and C22:5 as well as C20:4 appear to be ‘genuine’ endocannabinoids and endovanilloids. The n-3 NAEs are less effective at CB1 receptors but seem to be equally effective as the n-6 NAE at CB2 cannabinoids receptors, suggesting they act as endocannabinoids with a CB2 preference as well as endovanilloids. Therefore, the anti-inflammatory properties of n-3NAEs may be mediated by CB2 receptors. A resulting hypothesis from these studies is that part of the beneficial effect of long-term dietary intake of n-3 PUFAs may result, at least in part, from a selective activation of CB2 receptors compared to CB1 receptors.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Alexander, Stephen
Bennett, Andrew
Keywords: Saturated N-acylethanolamines; Monounsaturated N-acylethanolamines; Polyunsaturated N-acylethanolamines; FAAH; n-3 PUFAs; CB receptors
Subjects: Q Science > QP Physiology
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 55577
Depositing User: Alharthi, Nahed
Date Deposited: 04 Apr 2019 10:27
Last Modified: 13 Dec 2020 04:30
URI: https://eprints.nottingham.ac.uk/id/eprint/55577

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