Dr. Michael Morgan

Title:	Professor of Psychology
Office Location:	CL 208V
Address:	Washington State University 14204 NE Salmon Creek Ave. Vancouver, WA 98686
Phone Number:	360 546-9726
Support Person:	Janet DeWitt	Phone: 546-9720
E-Mail:	morgan@vancouver.wsu.edu	FAX: 546-9038

Fall 2009: Psych 312: Research Methods in Psychology

Links to Graduate Programs

Experimental Psychology

Neuroscience

Return to WSU Vancouver Homepage

Research Interests

Neural Mechanisms of Pain Modulation and Morphine Tolerance

Pain messages traveling from the skin to the brain are subject to powerful modulation in the spinal cord. This modulation can occur by direct application of narcotics to the spinal cord or via descending messages from the brain. The primary descending system involved in pain modulation runs from the periaqueductal gray (PAG) to the rostral ventrolmedial medulla (RVM) to the spinal cord. Microinjection of opiates such as morphine into the PAG or RVM inhibit pain throughout the body. Our research is focused on understanding the function of the PAG and RVM, and how these structures contribute to tolerance to the pain inhibitory effects of morphine.

Although opiates are the most effective treatment for pain, morphine effectiveness is diminished by the development of tolerance with repeated administration. Our research has shown that the PAG plays an important role in this tolerance. Tolerance develops to microinjection of morphine into the ventrolateral, but not the lateral PAG or RVM. Blocking morphine binding in the PAG is sufficient to block the development of tolerance. Additional behavioral and electrophysiological studies indicate that opioid-sensitive GABAergic neurons are involved in morphine tolerance. Currently, we are examining the role of mu-opioid receptor internalization and other cellular mechanisms in morphine tolerance.

Research Team:

Dr. Susan Ingram --Colleague and co-PI:

Tara Macey--Post-Doctoral Fellow

Graduate Students:

Erin Bobeck—Experimental Psychology

Michelle Cyr—Experimental Psychology

Adie Wilson--Neuroscience

Undergraduate Assistants:

Edvinas Pocius

Rachel Haseman

Jessica Yahm

Amanda Gunn

Todd Wisinski

Kevin Guzman

High School Assistants:

Rebecca Leong

Kenny Phu --Animal Care Technician

Recent Publications (Morgan in PubMed):

Meyer, P.J., Morgan, M.M., Kozell, L.B., & Ingram, S.L. (2009). Periaqueductal gray dopamine contributes to the antinociceptive effect of morphine. Psychopharmacology, 204(3):531-40. PMID: 19225762

Morgan, M. M., Ashley, M. D., Ingram, S. L., & Christie, M. (2009). Behavioral consequences of chronic morphine-induced delta receptor upregulation in the periaqueductal gray of the rat. Neural Plasticity, 2009:516328. PMID: 19266049

Morgan, M. M., Whittier, K. L., Hegarty, D. M., & Aicher, S. A. (2008). Periaqueductal gray neurons project to spinally projecting GABAergic neurons in the rostral ventromedial medulla. Pain, 140(2):376-86. PMID: 18926635

Wilson, A. R., Maher, L., & Morgan, M. M. (2008). Repeated Cannabinoid Injections into the Rat Periaqueductal Gray Enhances Subsequent Morphine Antinociception. Neuropharmacology, 55:1219-25. PMID: 18723035

Fossum, E. N., Lisowski, M. J., Macey, T. A., Ingram, S. L., & Morgan, M. M. (2008). Microinjection of the vehicle dimethyl sulfoxide (DMSO) into the periaqueductal gray modulates morphine antinociception. Brain Research, 1204:53-58. PMID: 18342296

Loyd, D., Morgan, M.M., & Murphy, A.Z. (2008). Sexually dimorphic activation of the periaqueductal gray-rostral ventromedial medullary circuit during the development of tolerance to morphine in the rat. European Journal of Neuroscience, 27(6):1517-24. PMID: 18364026

Ingram, S.L., Macey, T.A., Fossum, E.N., & Morgan, M.M. (2008). Tolerance to repeated morphine administration is associated with increased potency of opioid agonists. Neuropsychopharmacology, 33:2494-2504. PMID: 18046309

Loyd, D., Morgan, M.M., & Murphy, A.Z. (2007). Morphine preferentially activates the periaqueductal gray – rostral ventromedial medullary pathway in the male rat: A potential mechanism for sex differences in antinociception. Neuroscience, 147(2):456-468. PMID: 17540508

Meyer, P.J., Fossum, E.N., Ingram, S.L., & Morgan, M.M. (2007). Analgesic tolerance to microinjection of the mu-opioid agonist DAMGO into the periaqueductal gray. Neuropharmacology, 52:1580-1585. PMID: 17445843

Ingram, S.L., Fossum, E.N., & Morgan, M.M. (2007). Behavioral and electrophysiological evidence for opioid tolerance in adolescent rats. Neuropsychopharmacology, 32(3):600-6. PMID: 16823389

Bernal, S.A., Morgan, M.M., & Craft, R.M. (2007). PAG mu opioid receptor activation underlies sex differences in morphine antinociception. Behav Brain Research, 177:126-133. PMID: 17118467

Current Grant Support:

Morgan, M. M. & Ingram, S. L. (co-P.I) National Institute on Drug Abuse. Cellular mechanisms of opioid tolerance. (RO1 DA015498-06). August 2009 to June 2011. $500,000 direct costs.

Morgan, M. M. National Institute on Drug Abuse. Neural Mechanisms of Enhanced Cannabinoid/Opioid Antinociception. (R03 DA026591). May, 2009 to April, 2011. $100,000 direct costs.

Education:

Ph.D. in Physiological Psychology from UCLA, 1989.

Dr. John Liebeskind, Mentor

Post-doctoral research in the Dept. of Neurology, UC, San Francisco, 1989 – 1993

Dr. Howard Fields, Mentor

Videos:

RVM Morphine Microinjection Video

PAG Morphine Microinjection Videos

PAG Saline

Lateral PAG morphine

Ventral PAG morphine

Photographs:

Lab Photo (January 2009)

Mike in the Electrophysiology Lab

WSU Vancouver Psychology Colleagues