College of Veterinary Medicine

Research in IPN

James H. Peters, Ph.D.


JamesPeters

Assistant Professor
E-Mail: jamespeters@vetmed.wsu.edu
Office:  VBR rm. 435
Phone: (509) 335-0517

Our laboratory investigates the peripheral and central neurocircuitry that provides critical controls of food intake and energy homeostasis. In the caudal brainstem the nucleus of the solitary tract (NTS) integrates vagal afferent information arriving from across visceral organ systems to initiate homeostatic reflex pathways, including those essential for the controls of food intake. Centrally, vagal afferents converge to form the solitary tract (ST) and contact second order NTS neurons via strong excitatory glutamatergic synapses. A major focus of ongoing work is to understand the pre- and post-synaptic controls of this first central synapse. We use a combination of in vivo and in vitro experimental approaches, including; primary culture, patch-clamp electrophysiology, and fluorescent calcium imaging.

Recently we have been actively pursuing the contribution of thermosensitive TRP channels in the control neuronal activation and central glutamate release. At central ST-NTS synapses action-potential invasion releases multiple glutamate vesicles that are precisely synchronized with terminal depolarization. This robust 'synchronous' form of glutamate release is thought to be the predominate mode of fast neurotransmission at the ST-NTS synapse. Recently, however we identified a novel form of activity-dependent 'asynchronous' glutamate release from a subgroup of vagal afferents. In contrast with synchronous release, this additional form of neurotransmission is only loosely coordinated with depolarization and continues for many seconds, effectively doubling the synaptic strength. As a result of this additional charge transfer the postsynaptic excitatory period is significantly extended, dramatically transforming the nature of information transfer. ST afferents are divided into myelinated (A-fiber) and unmyelinated (C-fiber) phenotypes with physiologically distinct functions. One important difference between subtypes is that C-fiber afferents express the calcium permeable non-selective ion channel 'transient receptor potential vanilloid type 1' (TRPV1). We find that all afferents with activity-dependent asynchronous release are also activated by the TRPV1 agonist capsaicin. Further, antagonism of TRPV1 activity selectively reduced the asynchronous release profile with no effect on synchronous. An attenuated asynchronous release process persists in TRPV1 KO mice and is reduced by ruthenium red. Together these findings suggest membrane depolarization endogenously activates TRPV1, and other JamesPetersthermosensitive-TRP channels, expressed in the central terminals of vagal afferents resulting in asynchronous glutamate release. Delineation of the endogenous cellular mechanisms underlying TRP channel activation and their role in the control of food intake are the primary ongoing projects in the lab.

Biographical Information

James Peters earned his bachelor’s of science (B.S.) in biology from Eastern Oregon University (La Grande, OR) in 2001 and his Ph.D. in Neuroscience from Washington State University (Pullman, WA) in 2005. His graduate thesis advisors were Dr. Robert Ritter and Dr. Steven Simasko. During his graduate training he was privileged to receive an ARCS Foundation Fellowship and Poncin Foundation Fellowship to help support his studies. Following graduate work he did a postdoctoral fellowship at Oregon Health and Science University (OHSU) in Portland, OR with Dr. Michael C. Andresen. This work was supported by an individual postdoctoral fellowship through the NIH. Returning to Pullman he assumed a faculty position at Washington State University as a Research Assistant Professor from 2010-2012; and in 2012 began as an Assistant professor in IPN and the Neuroscience Graduate Faculty at Washington State University.

Selected Publications

1. Kinch DC, Peters JH, and Simasko SM (2012) Comparative pharmacology of cholecystokinin induced activation of cultured vagal afferent neurons from rats and mice. PLoS One

2. Peters JH, McDougall SJ, Fawley JA, and Andresen MC (2011) TRPV1 marks synaptic segregation of multiple convergent afferents at the rat medial solitary tract nucleus. PLoS One 6: 25015.PMID: 21949835

3. Fawley JA, Peters JH, and Andresen MC (2011) GABAB-mediated inhibition of multiple modes of glutamate release in the nucleus of the solitary tract. Journal of Neurophysiology 106:1833-40. PMID: 21734101

4. Shoudai K, Peters JH, McDougall SJ, and Andresen MC (2010) Thermally active TRPV1 tonically drives central spontaneous glutamate release. J Neuroscience 30: 14470-5. PMID: 20980604

5. Peters JH, McDougall SJ, Fawley JA, Smith SM, and Andresen MC (2010) Primary afferent activation of thermosensitive TRPV1 triggers asynchronous glutamate release at central neurons. Neuron 65:657-69. PMID: 20223201

6. McDougall SJ, Peters JH, and Andresen MC (2009) Convergence of cranial visceral afferents within the solitary tract nucleus. J Neuroscience 29:12886-95. PMID: 19828803

7. Peters JH, McDougall SJ, Kellett DO, Jordan D, Llewellyn-Smith IJ, and Andresen MC (2008) Oxytocin enhances cranial visceral afferent synaptic transmission to the solitary tract nucleus. J Neuroscience 28:11731-40. *See comment in J Neuroscience 2009, 29:4687-9. PMID: 18987209

8. Andresen MC and Peters JH (2008) Comparison of baroreceptive to other afferent synaptic transmission to the solitary tract nucleus. Am J Physiol Heart Circ Physiol. 295:H2032-42. PMID: 18790834 PMCID: PMC2614577
Last Edited: Jul 09, 2013 8:32 AM   

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