Contact Info:Email: galliga1@msu.edu Phone: (517) 353-4776 Fax: (517) 353-8915

Research Synopsis

Research interests in the Galligan laboratory are focused on neural control of gastrointestinal (GI) motility and blood flow. GI problems are among the most frequently cited reasons a patient will see their physician in the United States. Although GI disorders are an important health issue little is known about neural control of gut function. GI function is controlled by the enteric nervous system (ENS), the division of the autonomic nervous system that resides in the gut wall. The ENS can perform its diverse functions independent of connections with the central nervous system.

Our research is focused on identifying the unique mechanisms of neurotransmission that allow the ENS to control gut function. We use electrophysiological methods to record from single enteric nerves in vitro in acutely isolated preparations of guinea pig small intestine. We also use patch clamp methods to record from enteric neurons maintained in primary tissue culture. Using patch clamp methods, we can study in the molecular and cellular mechanisms of neurotransmission in great detail. We are using video-based digital microscopy to study neuronal control of the diameter of small blood vessels that provide the blood supply for the intestine. These methods allow combined electrophysiological and pharmacological analysis of the neural mechanisms that regulate GI blood flow. We are studying how these mechanisms may change in animal models of hypertension in order to identify potential new drug targets for the treatment of high blood pressure. Students training in the Galligan lab will develop expertise in neurophysiology and neuropharmacology. In addition, students will develop expertise in autonomic neuropharmacology, a research focus with broad applicability that will facilitate the student's development as an independent investigator.

Current Projects

“Presynaptic mechanisms in the intestine” This project is focused on identifying the unique mechanisms of neurotransmission that allow the enteric nervous system to control gut function. Electrophysiological methods are the principal techniques that are used to address this research problem. We are using electrophysiological methods to record from single enteric nerves in vitro in acutely isolated preparations of guinea pig small intestine. This preparation is useful as most neural connections present in the intact intestine are preserved and the endogenous neural circuits that control gastrointestinal function can be studied. We are also using patch clamp methods to record from enteric neurons maintained in primary tissue culture. Using patch clamp methods, we can study in great detail the ionic mechanisms of neurotransmission, the kinetics of neurotransmitter action and the intracellular signal transduction mechanisms mediating neuron to neuron communication. In addition, the behavior of single ion channels in membrane patches of nerves cells using the patch clamp method can be examined.

Selected Achievements since 2001

Editorial Boards
Journal of Pharmacology and Experimental Therapeutics, 1993-1995; 1999-present
American Journal of Physiology: Gastrointestinal and Liver, 1999-present
Autonomic Neuroscience, 2003-present

Honors/Awards/Service

• Elected Member of the American Heart Association, Council for High Blood Pressure Research, 2002
• Janssen Award for Basic Research in Digestive Sciences, 2004
• Chair, Motility and Nerve Gut Interaction Section, American Gastroenterological Association, 2005-2007
• Elected Fellow, American Gastroenterological Association, 2006
• Councilor, Nervous Control of Motility Section, American Gastroenterology Association, 1999-2003
• Vice Chair (elected), Motility and Nerve-Gut Interaction Section, American Gastroenterology Association, 2003-2004
• Member, Natl Scientific Advisory Board, Intl Group for the Study of Neurogastroenterology Motility, 2000-2001
• Jim Long Memorial Lectureship, American Motility Society, 2005
• Motility and Nerve-Gut Interaction Section Chair, American Gastroenterology Association, (2005-2007)
• American Gastroenterological Association Council (elected: 2003-2007)
• Member Clinical and Integrative Gastrointestinal Pathobiology (CIGP) Study Section (2004-present)
• American Motility Society, Research Committee (2004- present)
• Scientific Committee, Joint International Neurogastroenterology and Motility Meeting (2004-2006)

Selected Samples of Publications Since 2006

Wang LH, Luo M, Wang Y, Galligan JJ, Wang DH. Impaired vasodilation in response to perivascular nerve stimulation in mesenteric arteries of TRPV1-null mutant mice. J Hypertension 24: 2399-2408, 2006.

Park J, Galligan JJ, Fink GD, Swain GM. In vitro continuous amperometry with a diamond microelectrode coupled with video microscopy for simultaneously monitoring endogenous norepinephrine and its effect on the contractile response of a rat mesenteric artery. Analytical Chem 78: 6756-6764, 2006.

Patel BA, Bian X, Galligan JJ, Swain GM. In Vitro continuous amperometric monitoring of 5- hydroxytryptamine release from enterochromaffin cells of the guinea pig ileum. The Analyst 131:, 41 – 47, 2006.

Xu H, Jackson WF, Fink GD, Galligan JJ. Activation of BK channels by tempol in arterial smooth muscle cells from normotensive and DOCA-salt hypertensive rats. Hypertension 48: 1080-1087, 2006.

Thakali KM, Lau Y, Fink GD, Galligan JJ, Chen AF, Watts SW. Mechanisms of hypertension induced by nitric oxide (NO) deficiency: focus on venous function. J Cardiovasc Pharmacol 47: 742-750, 2006.

Pérez-Rivera AA, Hlavacova A, Rosario-Colón LA, Fink GD, Galligan JJ. Differential contributions of a-1 and a2-adrenoceptors to vasoconstriction in mesenteric arteries and veins of normal and hypertensive mice. Vascular Pharmacol 46: 373-382, 2007.

Bian X, Patel P, Dai X, Galligan JJ, Swain GM. Elevated serotonin availability in the mucosa of neonatal guinea pig ileum is associated with reduced SERT expression. Gastroenterology 132: 2438-2447, 2007.

Ren J, Galligan JJ. A calcium-activated potassium conductance is coupled to P2X receptors in myenteric neurons of guinea pig ileum. Neurogastroentrol Motil (in press), 2007.

Bian X, Galligan JJ. a-Adrenoceptors couple to inhibition of R-type calcium currents in myenteric neurons. Neurogastroenterol Motil (in press), 2007.

Tan J, Galligan JJ, Hollingworth R. Agonist actions of neonicotinoids on nicotinic acetylcholine receptors expressed by cockroach neurons. J Neurotoxicology (in press), 2007.

Xu H, Fink GD, Galligan JJ. Increased sympathetic venoconstriction and reactivity to norepinephrine in mesenteric veins in anesthetized DOCA-salt hypertensive rats. Am J Physiol (in press), 2007.