Dept. of Physiology, Anatomy and Genetics

Research Topic and Supervisor willing to supervise Chemistry Part II students.

MChem Pt II Project Description

Title: Electrochemical analysis of synaptic dopamine release in the brain

Supervisor: Dr S.J. Cragg
University Lecturer, Dept. Physiology, Anatomy & Genetics and Oxford Parkinson’s Disease Centre
Tutor, Christ Church
E-mail: stephanie.cragg@dpag.ox.ac.uk.
Tel: 282513

Department: Physiology, Anatomy & Genetics, Sherrington Building

Outline

Nerve cell to nerve cell communication in the brain occurs by the release and detection of chemical neurotransmitters at specialised interfaces called synapses. Electrochemical analytical techniques such as voltammetry, can be used in the brain environment to monitor neurotransmitters, notably the monoamines dopamine, noradrenaline and serotonin, by using voltage waveforms that oxidise and reduce these compounds but not other biological molecules (Troyer et al., 2002; Phillips and Wightman, 2003). By using a microelectrode probe and fast-scan rates, these measurements can be conducted on scales of space and time approaching single cells and milliseconds respectively. Thus, fast electrochemistry at microelectrodes can be used to probe mechanisms governing synaptic neurotransmitter release with a timescale that parallels physiological patterns of neuron activity (Robinson et al., 2008; Rice and Cragg, 2004).

The catecholamine neurotransmitter dopamine in the region called the striatum is critical to the regulation of our normal motivations and actions (Cragg, 2006). However, our knowledge of the mechanisms that govern dopamine function is far from complete. Recently, we have combined electrochemical detection of dopamine with a state-of-the-art optical technique to drive specific brain circuits, and have revealed a previously unknown role for another brain circuit in triggering dopamine transmission (Threlfell et al., 2012). This has radically revised the way we think dopamine neurotransmission is regulated. This project will use fast-scan cyclic voltammetry at carbon-fibre microelectrodes in conjunction with optogenetic technology to monitor and explore further the neurochemical mechanisms that govern the release of dopamine (e.g. Rice and Cragg 2004; Threlfell and Cragg 2006). In overview, the project will involve exploring the control of dopamine release probability by specific neurochemical receptors and by drugs of addiction. These studies will be done in regions of the brain in which dysfunction is associated with drug addiction and Parkinson’s disease (PD). Thus, this project should not only shed light on fundamental mechanisms of neurochemical signalling by the brain, but may also offer insights into nicotine addiction as well as PD.

Background references

Cragg SJ (2006) Meaningful silences: how dopamine listens to the ACh pause. Trends Neurosci 29:125-131.

Phillips PEM, Wightman RM (2003) Critical guidelines for validation of the selectivity of in vivo chemical microsensors. Trends Anal Chem 22:509-514.

Rice ME, Cragg SJ (2004) Nicotine amplifies reward-related dopamine signals in striatum. Nat Neurosci 7:583-584.

Robinson DL, Hermans A, Seipel AT, Wightman RM (2008) Monitoring Rapid Chemical Communication in the Brain. Chemical Reviews 108:2554-2584.

Threlfell S, Lalic T, Platt NJ, Jennings KA, Deisseroth K, Cragg SJ (2012) Striatal Dopamine Release Is Triggered by Synchronized Activity in Cholinergic Interneurons. Neuron 75:58-64.

Troyer KP, Heien ML, Venton BJ, Wightman RM (2002) Neurochemistry and electroanalytical probes. Curr Opin Chem Biol 6:696-703.

Supervisor: Professor Kieran Clarke

Maximum number of students: 3
Telephone number: 282248
Email: kieran.clarke@dpag.ox.ac.uk
Webpage: http://www.dpag.ox.ac.uk/academic_staff/kieran_clarke/

Energetics, uncoupling proteins and nuclear hormone receptors in heart disease
Most forms of heart disease are associated with alterations in cardiac and skeletal muscle energy and substrate metabolism. We study common diseases in Western society that have high mortality, such as ischaemic heart disease, hypertension, muscular dystrophy and heart failure, focussing on the molecular changes that cause the disease. The work involves a wide range of molecular, physiological and biochemical techniques, including multinuclear magnetic resonance spectroscopy (MRS) and imaging (MRI). We also study the causes of common metabolic diseases (e.g. obesity, diabetes), using dynamic nuclear polarisation (DNP) techniques, and the effects of diet on exercise and cognitive function in elite athletes and couch potatoes.

Cardiac stem cells to prevent heart failure
A promising, novel approach to the treatment of myocardial infarction and the prevention of heart failure is cell grafting in the damaged myocardium. The aim of this work is to determine whether cardiac muscle and vasculature can be formed from cardiac-derived stem cells (CSCs) or iPS cells to restore function and metabolism after coronary occlusion. Cells are isolated, expanded, characterized and transplanted into the chronically infarcted rat heart. The effects of the transplanted cells on heart function are monitored non-invasively using MRI.This project will provide training in stem cell techniques, including confocal microscopy, and cardiac MRI.

1. Carr CA, Stuckey DJ, Tatton L, Tyler DJ, Hale SJM, Sweeney D, Schneider JE, Martin-Rendon E, Radda GK, Harding SE, Watt SM, Clarke K. Bone marrow-derived stromal cells home to and remain in the infarcted rat heart, but fail to improve function: An in vivo cine-MRI study. Am J Physiol 295: 533-542, 2008.
2. Heather LC, Carr CA, Stuckey DJ, Pope S, Morten KJ, Carter EE, Edwards LM, Clarke K. Critical role of complex III in the early metabolic changes following myocardial infarction. Cardiovasc Res. 85: 127-36, 2010
3. Heather LC, Catchpole AF, Stuckey DJ, Cole MA, Carr CA, Clarke K. Isoproterenol induces in vivo functional and metabolic abnormalities similar to those found in the infarcted rat heart. J Physiol Pharmacol 60: 31-9, 2009.
4. Heather LC, Cole MA, Atherton HJ, Coumans WA, Evans RD, Tyler DJ, Glatz JFC, Luiken JJFP, Clarke K. Adenosine monophosphate-activated protein kinase activation, substrate transporter translocation, and metabolism in the contracting hyperthyroid rat heart. Endocrinology 151: 422-431, 2010.
5. Murray AJ, Cole MA, Lygate CA, Carr CA, Stuckey DJ, Little SE, Neubauer S, Clarke K. Increased mitochondrial uncoupling proteins, respiratory uncoupling and decreased efficiency in the chronically infarcted rat heart. J Mol Cell Cardiol 44:694-700, 2008.
6. Murray AJ, Knight NS, Cochlin LE, McAleese S, Deacon RMJ, Rawlins JNP, Clarke K. Deterioration of physical performance and cognitive function in rats with short-term high-fat feeding. FASEB J 23: 4353-60, 2009.
7. Schroeder MA, Atherton HJ, Ball DR, Cole MA, Heather LC, Griffin JL, Clarke K, Radda GK, Tyler DJ. Real-time assessment of Krebs cycle metabolism using hyperpolarized 13C magnetic resonance spectroscopy. FASEB J 23: 2529-2538, 2009.
8. Schroeder MA, Cochlin LE, Heather LC, Clarke K, Radda GK, Tyler DJ. In vivo assessment of pyruvate dehydrogenase flux in the heart using hyperpolarized carbon-13 magnetic resonance. PNAS 105: 12051-12056, 2008.
9. Stuckey DJ, Carr CA, Tyler DJ, Aasum EA, Clarke K. A novel MRI method to detect altered left ventricular ejection and filling patterns in rodent models of disease. Magn Reson Med 60: 582-87, 2008.
10. Zhang W, ten Hove M, Schneider JE, Stuckey DJ, Sebag-Montefiore L, Bia BL, Radda GK, Davies KE, Neubauer S and Clarke K. Abnormal cardiac morphology, function and energy metabolism in the dystrophic mdx mouse: An MRI and MRS study. J Mol Cell Cardiol 45: 754-760, 2008.