Suzanne Appleyard, Ph.D of the Department of VCAPP in the College of Veterinary Medicine at Washington State University

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.

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 VCAPP as an Assistant Professor in August 2007.

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

Appleyard, S.M., Bailey, T.W., Doyle, M.W., Jin,Y-H, Low, M.J., Andresen, M.C. Pro-opiomelanocortin neurons in nucleus tractus solitarius are activated by visceral afferents - Regulation by cholecystokinin and opioids. (2005) Journal of 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.