Fentanyls at the mu opioid receptor - how do they workand what do they do?

Fentanyl is a widely used therapeutic drug in anaesthesia and the management of pain. It is also an increasingly abused drug and is related to an upsurge in drug-related deaths in the USA and other countries. Fentanyl acts primarily at the mu opioid receptor (MOPr), which is the target of many opioid agonist drugs such as morphine.Apart from fentanyl itself, a large number of fentanyl-related drugs (fentanyls) have been synthesised and whilst some are used therapeutically, most are increasingly associated with drug abuse. Many of these drugs are much more lipid soluble than morphine, and this probably contributes to their rapid actions following administration.However the nature of the interaction of fentanyls with MOPr (or indeed potentially with other opioid receptors suchas DOPr and KOPr) is not known. This is important because a distinct interaction of fentanyls with MOPr could contribute to the very high potency of many of these drugs.In addition the cell signalling profiles of most fentanyls is not known, and the in vivo effects of many of these fentanyls relating to e.g. analgesia, respiratory depression and the onset of tolerance is also not known in any detail.In this project we will focus on a range of up to six fentanyls, including fentanyl itself, to study their interaction with MOPr.

In this project you will seek to answer this in the following ways:
- in silico - investigate the structural mechanism of interaction of fentanyls with the MOPr using advanced computing in Molecular Dynamics simulations
- in vitro - characterise the cell signalling profile and potential bias of fentanyls, using Bioluminescence (BRET)technology to measure signalling via G protein, arrestin and other pathways in cultured cells
- in vivo - administer fentanyls to mice acutely and chronically to determine their effects with relation to well characterised MOPr effects - analgesia and respiratory depression, and tolerance to these effects.

Using these advanced techniques, the project will answer the following questions:
- How do fentanyls interact with MOPr and what conformational changes in the receptor do they trigger?
- What are the in vitro cell signalling profiles of differentfentanyls - are they the same or do they differ significantly such as in bias?
- What are the in vivo effects of these fentanyls?
- Taken together, can the in vivo effects of the fentanyls be explained by molecular interactions with MOPr that are distinct from well known MOPr agonists such as

In summary this truly translational neuroscience project will allow the student to get to grips with a range of different techniques, and importantly it will equip the student with the means to undertake post PhD research in a number of different subject are. Furthermore it addresses an extremely important and current area of public health.