College of Veterinary Medicine

Research in IPN

Suzanne M. Appleyard, Ph.D.


Suzanne M. Appleyard, Ph.D.
Associate Professor
Office: VBR 351
Phone: (509) 335-7784
Lab: (509) 335-0905

Even a slight imbalance between food intake and energy expenditure can result in significant weight gain over time and the development of obesity.  The incidence of obesity has more than doubled over the last 30 years and now afflicts greater than 34% of adults in the United States.  It is one of the greatest threats to health due to the numerous complications that are associated with excess weight, including type 2 diabetes mellitus, hypertension, stroke, cardiovascular disease and cancer.  In order to develop effective drugs or design more helpful therapeutic strategies it is essential to understand the normal physiology of energy balance and pathology of obesity.

The main focus of the Appleyard lab is to determine how neuronal circuits control energy balance with a particular emphasis on the role of neurons in the nucleus of the solitary tract (NTS) in the brain stem.  The NTS is the primary site of entry for visceral afferent nerve fibers carrying information about satiety from the periphery and as such it is the gate that determines what afferent information gets through to the rest of the CNS.  It also receives inputs from many other brain regions and possesses a weak blood brain barrier making neurons in this region ideally suited to coordinate information from many sources.  Lesion studies show that NTS neurons are essential for normal energy balance.

In the Appleyard lab we use a multidisciplinary approach to identify the cellular and molecular mechanisms by which NTS neurons respond to appetite-regulating signals and to determine whether these pathways become altered by different behaviors.  We combine targeted disruption of specific cellular pathways using pharmacological and genetic approaches with patch clamp recordings from brain slices.  The two populations of NTS neurons that we are particularly interested in are the pro-opiomelanocortin (POMC) and catecholamine neurons due to the vital role both these groups of neurons play in controlling food intake.  We use transgenic models that express enhanced green florescent protein (EGFP) under the control of the POMC and tyrosine hydroxylase promoters to specifically identify these two populations of NTS neurons in horizontal brain slices and labeling techniques to study particular projection pathways.  The combination of these approaches allows us to determine how specifically identified NTS neuronal pathways integrate signals about energy balance and whether plasticity occurs in these pathways during disease states such as obesity. 

Biographical Information

Suzanne Appleyard received her B.Sc. in Pharmacology from University College London in 1991 and earned a PhD. in Pharmacology/Neurobiology from the University of Washington in 1998.  She carried out her postdoctoral training at Oregon Health & Science University (OHSU) from 1999-2003.  In 2004 she became a Research Assistant Professor in the Vollum Institute and the Department of Physiology & Pharmacology at OHSU.  Dr. Appleyard joined the Department of IPN as an Assistant Professor in August 2007.

Selected Publications

Cui, RJ, Li X, Appleyard SM. Ghrelin inhibits visceral afferent activation of catecholamine neurons in the solitary tract nucleus. J Neurosci. (2011) 31(9): 3484-92.

Appleyard, SM.
  Lighting up neuronal pathways: the development of a novel transgenic rat that identifies Fos-activated neurons using a red fluorescent protein. Endocrinology (2009) 150(12): 5199-201.

Bailey TW, Appleyard SM, Jin YH, Andresen MC. Organization and properties of GABAergic neurons in solitary tract nucleus (NTS). J Neurophysiol. (2008) 99(4): 1712-22.

Appleyard SM
, Marks D, Kobayashi K, Okano H, Low MJ, Andresen MC.  Visceral afferents directly activate catecholamine neurons in the solitary tract nucleus. (2007)  J Neuroscience 27 (48): 13292-302.

Appleyard SM, Bailey TW, Doyle MW, Jin Y-H, Low MJ, Andresen MC.  Pro-opiomelanocortin neurons in nucleus tractus solitarius are activated by visceral afferents - Regulation by cholecystokinin and opioids. (2005)  J Neuroscience 25(14): 3578-85.

Doyle, M.W., Bailey, T.W., Jin, Y.H., Appleyard, S.M., Low, M.J., Andresen, M.C.  (2004)  Strategies for cellular identification in nucleus tractus solitarius slices.  J Neurosci Methods 137(1): 37-48.

Appleyard, S.M.  Appetite Regulation, Neuronal Control. (2003) Encyclopedia of hormones & related cell regulators: p171-179.  Henry, H.L., Norman, A.W. Eds.  Academic Press, San Diego.

Low M.J., Hayward M.D., Appleyard S.M., Rubinstein M. (2003)  State-dependent modulation of feeding behavior by proopiomelanocortin-derived beta-endorphin.  Ann N Y Acad Sci. 994: 192-201.

Appleyard, S.M., Hayward, M, Young, J.I., Butler, A.A., Cone, R.D., Rubinstein, M., Low, M.J. (2003)  A role for the endogenous opioid beta-endorphin in energy homeostasis.  Endocrinology 144(5): 1753-60.

Additional Publications
Last Edited: May 02, 2013 10:46 AM   

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