Suzanne M. Appleyard, Ph.D.
Assistant Professor
Wegner G-11
E-Mail:
appleyas@vetmed.wsu.edu
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 VCAPP as an Assistant Professor in August 2007.
Selected Publications
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.
Additional Publications
