Suzanne M. Appleyard, Ph.D.
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
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 IPN as an Assistant Professor in August 2007.
Cui, RJ, Li X, Appleyard SM.
Ghrelin inhibits visceral afferent activation of catecholamine neurons
in the solitary tract nucleus. J Neurosci
. (2011) 31(9):
Lighting up neuronal pathways: the development of a novel transgenic rat
that identifies Fos-activated neurons using a red fluorescent protein
(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.
, Marks D, Kobayashi K, Okano H, Low MJ, Andresen
MC. Visceral afferents directly activate catecholamine neurons in the
solitary tract nucleus. (2007) J Neuroscience
, 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
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
. 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.
, 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